diff options
Diffstat (limited to 'js/src/irregexp/RegExpEngine.cpp')
| -rw-r--r-- | js/src/irregexp/RegExpEngine.cpp | 5135 |
1 files changed, 5135 insertions, 0 deletions
diff --git a/js/src/irregexp/RegExpEngine.cpp b/js/src/irregexp/RegExpEngine.cpp new file mode 100644 index 000000000..2e19065fd --- /dev/null +++ b/js/src/irregexp/RegExpEngine.cpp @@ -0,0 +1,5135 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- + * vim: set ts=8 sts=4 et sw=4 tw=99: */ + +// Copyright 2012 the V8 project authors. All rights reserved. +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following +// disclaimer in the documentation and/or other materials provided +// with the distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived +// from this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "irregexp/RegExpEngine.h" + +#include "irregexp/NativeRegExpMacroAssembler.h" +#include "irregexp/RegExpMacroAssembler.h" +#include "jit/ExecutableAllocator.h" +#include "jit/JitCommon.h" + +using namespace js; +using namespace js::irregexp; + +using mozilla::ArrayLength; +using mozilla::DebugOnly; +using mozilla::Maybe; + +#define DEFINE_ACCEPT(Type) \ + void Type##Node::Accept(NodeVisitor* visitor) { \ + visitor->Visit##Type(this); \ + } +FOR_EACH_NODE_TYPE(DEFINE_ACCEPT) +#undef DEFINE_ACCEPT + +void LoopChoiceNode::Accept(NodeVisitor* visitor) { + visitor->VisitLoopChoice(this); +} + +static const int kMaxLookaheadForBoyerMoore = 8; + +RegExpNode::RegExpNode(LifoAlloc* alloc) + : replacement_(nullptr), trace_count_(0), alloc_(alloc) +{ + bm_info_[0] = bm_info_[1] = nullptr; +} + +// ------------------------------------------------------------------- +// CharacterRange + +// The '2' variant has inclusive from and exclusive to. +// This covers \s as defined in ECMA-262 5.1, 15.10.2.12, +// which include WhiteSpace (7.2) or LineTerminator (7.3) values. +static const int kSpaceRanges[] = { '\t', '\r' + 1, ' ', ' ' + 1, + 0x00A0, 0x00A1, 0x1680, 0x1681, 0x180E, 0x180F, 0x2000, 0x200B, + 0x2028, 0x202A, 0x202F, 0x2030, 0x205F, 0x2060, 0x3000, 0x3001, + 0xFEFF, 0xFF00, 0x10000 }; +static const int kSpaceRangeCount = ArrayLength(kSpaceRanges); + +static const int kSpaceAndSurrogateRanges[] = { '\t', '\r' + 1, ' ', ' ' + 1, + 0x00A0, 0x00A1, 0x1680, 0x1681, 0x180E, 0x180F, 0x2000, 0x200B, + 0x2028, 0x202A, 0x202F, 0x2030, 0x205F, 0x2060, 0x3000, 0x3001, + unicode::LeadSurrogateMin, unicode::TrailSurrogateMax + 1, + 0xFEFF, 0xFF00, 0x10000 }; +static const int kSpaceAndSurrogateRangeCount = ArrayLength(kSpaceAndSurrogateRanges); +static const int kWordRanges[] = { + '0', '9' + 1, 'A', 'Z' + 1, '_', '_' + 1, 'a', 'z' + 1, 0x10000 }; +static const int kWordRangeCount = ArrayLength(kWordRanges); +static const int kIgnoreCaseWordRanges[] = { + '0', '9' + 1, 'A', 'Z' + 1, '_', '_' + 1, 'a', 'z' + 1, + 0x017F, 0x017F + 1, 0x212A, 0x212A + 1, + 0x10000 }; +static const int kIgnoreCaseWordCount = ArrayLength(kIgnoreCaseWordRanges); +static const int kWordAndSurrogateRanges[] = { + '0', '9' + 1, 'A', 'Z' + 1, '_', '_' + 1, 'a', 'z' + 1, + unicode::LeadSurrogateMin, unicode::TrailSurrogateMax + 1, + 0x10000 }; +static const int kWordAndSurrogateRangeCount = ArrayLength(kWordAndSurrogateRanges); +static const int kNegatedIgnoreCaseWordAndSurrogateRanges[] = { + 0, '0', '9' + 1, 'A', + 'Z' + 1, '_', '_' + 1, 'a', + 'z' + 1, 0x017F, + 0x017F + 1, 0x212A, + 0x212A + 1, unicode::LeadSurrogateMin, + unicode::TrailSurrogateMax + 1, 0x10000, + 0x10000 }; +static const int kNegatedIgnoreCaseWordAndSurrogateRangeCount = + ArrayLength(kNegatedIgnoreCaseWordAndSurrogateRanges); +static const int kDigitRanges[] = { '0', '9' + 1, 0x10000 }; +static const int kDigitRangeCount = ArrayLength(kDigitRanges); +static const int kDigitAndSurrogateRanges[] = { + '0', '9' + 1, + unicode::LeadSurrogateMin, unicode::TrailSurrogateMax + 1, + 0x10000 }; +static const int kDigitAndSurrogateRangeCount = ArrayLength(kDigitAndSurrogateRanges); +static const int kSurrogateRanges[] = { + unicode::LeadSurrogateMin, unicode::TrailSurrogateMax + 1, + 0x10000 }; +static const int kSurrogateRangeCount = ArrayLength(kSurrogateRanges); +static const int kLineTerminatorRanges[] = { 0x000A, 0x000B, 0x000D, 0x000E, + 0x2028, 0x202A, 0x10000 }; +static const int kLineTerminatorRangeCount = ArrayLength(kLineTerminatorRanges); +static const int kMaxOneByteCharCode = 0xff; +static const int kMaxUtf16CodeUnit = 0xffff; + +static char16_t +MaximumCharacter(bool ascii) +{ + return ascii ? kMaxOneByteCharCode : kMaxUtf16CodeUnit; +} + +static void +AddClass(const int* elmv, int elmc, + CharacterRangeVector* ranges) +{ + elmc--; + MOZ_ASSERT(elmv[elmc] == 0x10000); + for (int i = 0; i < elmc; i += 2) { + MOZ_ASSERT(elmv[i] < elmv[i + 1]); + ranges->append(CharacterRange(elmv[i], elmv[i + 1] - 1)); + } +} + +static void +AddClassNegated(const int* elmv, + int elmc, + CharacterRangeVector* ranges) +{ + elmc--; + MOZ_ASSERT(elmv[elmc] == 0x10000); + MOZ_ASSERT(elmv[0] != 0x0000); + MOZ_ASSERT(elmv[elmc-1] != kMaxUtf16CodeUnit); + char16_t last = 0x0000; + for (int i = 0; i < elmc; i += 2) { + MOZ_ASSERT(last <= elmv[i] - 1); + MOZ_ASSERT(elmv[i] < elmv[i + 1]); + ranges->append(CharacterRange(last, elmv[i] - 1)); + last = elmv[i + 1]; + } + ranges->append(CharacterRange(last, kMaxUtf16CodeUnit)); +} + +void +CharacterRange::AddClassEscape(LifoAlloc* alloc, char16_t type, + CharacterRangeVector* ranges) +{ + switch (type) { + case 's': + AddClass(kSpaceRanges, kSpaceRangeCount, ranges); + break; + case 'S': + AddClassNegated(kSpaceRanges, kSpaceRangeCount, ranges); + break; + case 'w': + AddClass(kWordRanges, kWordRangeCount, ranges); + break; + case 'W': + AddClassNegated(kWordRanges, kWordRangeCount, ranges); + break; + case 'd': + AddClass(kDigitRanges, kDigitRangeCount, ranges); + break; + case 'D': + AddClassNegated(kDigitRanges, kDigitRangeCount, ranges); + break; + case '.': + AddClassNegated(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges); + break; + // This is not a character range as defined by the spec but a + // convenient shorthand for a character class that matches any + // character. + case '*': + ranges->append(CharacterRange::Everything()); + break; + // This is the set of characters matched by the $ and ^ symbols + // in multiline mode. + case 'n': + AddClass(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges); + break; + default: + MOZ_CRASH("Bad character class escape"); + } +} + +// Add class escape, excluding surrogate pair range. +void +CharacterRange::AddClassEscapeUnicode(LifoAlloc* alloc, char16_t type, + CharacterRangeVector* ranges, bool ignore_case) +{ + switch (type) { + case 's': + case 'd': + return AddClassEscape(alloc, type, ranges); + break; + case 'S': + AddClassNegated(kSpaceAndSurrogateRanges, kSpaceAndSurrogateRangeCount, ranges); + break; + case 'w': + if (ignore_case) + AddClass(kIgnoreCaseWordRanges, kIgnoreCaseWordCount, ranges); + else + AddClassEscape(alloc, type, ranges); + break; + case 'W': + if (ignore_case) { + AddClass(kNegatedIgnoreCaseWordAndSurrogateRanges, + kNegatedIgnoreCaseWordAndSurrogateRangeCount, ranges); + } else { + AddClassNegated(kWordAndSurrogateRanges, kWordAndSurrogateRangeCount, ranges); + } + break; + case 'D': + AddClassNegated(kDigitAndSurrogateRanges, kDigitAndSurrogateRangeCount, ranges); + break; + default: + MOZ_CRASH("Bad type!"); + } +} + +#define FOR_EACH_NON_ASCII_TO_ASCII_FOLDING(macro) \ + /* LATIN CAPITAL LETTER Y WITH DIAERESIS */ \ + macro(0x0178, 0x00FF) \ + /* LATIN SMALL LETTER LONG S */ \ + macro(0x017F, 0x0073) \ + /* LATIN CAPITAL LETTER SHARP S */ \ + macro(0x1E9E, 0x00DF) \ + /* KELVIN SIGN */ \ + macro(0x212A, 0x006B) \ + /* ANGSTROM SIGN */ \ + macro(0x212B, 0x00E5) + +// We need to check for the following characters: 0x39c 0x3bc 0x178. +static inline bool +RangeContainsLatin1Equivalents(CharacterRange range, bool unicode) +{ + /* TODO(dcarney): this could be a lot more efficient. */ + if (unicode) { +#define CHECK_RANGE(C, F) \ + if (range.Contains(C)) return true; +FOR_EACH_NON_ASCII_TO_ASCII_FOLDING(CHECK_RANGE) +#undef CHECK_RANGE + } + + return range.Contains(0x39c) || range.Contains(0x3bc) || range.Contains(0x178); +} + +static bool +RangesContainLatin1Equivalents(const CharacterRangeVector& ranges, bool unicode) +{ + for (size_t i = 0; i < ranges.length(); i++) { + // TODO(dcarney): this could be a lot more efficient. + if (RangeContainsLatin1Equivalents(ranges[i], unicode)) + return true; + } + return false; +} + +static const size_t kEcma262UnCanonicalizeMaxWidth = 4; + +// Returns the number of characters in the equivalence class, omitting those +// that cannot occur in the source string if it is a one byte string. +static int +GetCaseIndependentLetters(char16_t character, + bool ascii_subject, + bool unicode, + const char16_t* choices, + size_t choices_length, + char16_t* letters) +{ + size_t count = 0; + for (size_t i = 0; i < choices_length; i++) { + char16_t c = choices[i]; + + // Skip characters that can't appear in one byte strings. + if (!unicode && ascii_subject && c > kMaxOneByteCharCode) + continue; + + // Watch for duplicates. + bool found = false; + for (size_t j = 0; j < count; j++) { + if (letters[j] == c) { + found = true; + break; + } + } + if (found) + continue; + + letters[count++] = c; + } + + return count; +} + +static int +GetCaseIndependentLetters(char16_t character, + bool ascii_subject, + bool unicode, + char16_t* letters) +{ + if (unicode) { + const char16_t choices[] = { + character, + unicode::FoldCase(character), + unicode::ReverseFoldCase1(character), + unicode::ReverseFoldCase2(character), + unicode::ReverseFoldCase3(character), + }; + return GetCaseIndependentLetters(character, ascii_subject, unicode, + choices, ArrayLength(choices), letters); + } + + char16_t upper = unicode::ToUpperCase(character); + unicode::CodepointsWithSameUpperCase others(character); + char16_t other1 = others.other1(); + char16_t other2 = others.other2(); + char16_t other3 = others.other3(); + + // ES 2017 draft 996af87b7072b3c3dd2b1def856c66f456102215 21.2.4.2 + // step 3.g. + // The standard requires that non-ASCII characters cannot have ASCII + // character codes in their equivalence class, even though this + // situation occurs multiple times in the unicode tables. + static const unsigned kMaxAsciiCharCode = 127; + if (upper <= kMaxAsciiCharCode) { + if (character > kMaxAsciiCharCode) { + // If Canonicalize(character) == character, all other characters + // should be ignored. + return GetCaseIndependentLetters(character, ascii_subject, unicode, + &character, 1, letters); + } + + if (other1 > kMaxAsciiCharCode) + other1 = character; + if (other2 > kMaxAsciiCharCode) + other2 = character; + if (other3 > kMaxAsciiCharCode) + other3 = character; + } + + const char16_t choices[] = { + character, + upper, + other1, + other2, + other3 + }; + return GetCaseIndependentLetters(character, ascii_subject, unicode, + choices, ArrayLength(choices), letters); +} + +static char16_t +ConvertNonLatin1ToLatin1(char16_t c, bool unicode) +{ + MOZ_ASSERT(c > kMaxOneByteCharCode); + if (unicode) { + switch (c) { +#define CONVERT(C, F) case C: return F; +FOR_EACH_NON_ASCII_TO_ASCII_FOLDING(CONVERT) +#undef CONVERT + } + } + + switch (c) { + // This are equivalent characters in unicode. + case 0x39c: + case 0x3bc: + return 0xb5; + // This is an uppercase of a Latin-1 character + // outside of Latin-1. + case 0x178: + return 0xff; + } + return 0; +} + +void +CharacterRange::AddCaseEquivalents(bool is_ascii, bool unicode, CharacterRangeVector* ranges) +{ + char16_t bottom = from(); + char16_t top = to(); + + if (is_ascii && !RangeContainsLatin1Equivalents(*this, unicode)) { + if (bottom > kMaxOneByteCharCode) + return; + if (top > kMaxOneByteCharCode) + top = kMaxOneByteCharCode; + } + + for (char16_t c = bottom;; c++) { + char16_t chars[kEcma262UnCanonicalizeMaxWidth]; + size_t length = GetCaseIndependentLetters(c, is_ascii, unicode, chars); + + for (size_t i = 0; i < length; i++) { + char16_t other = chars[i]; + if (other == c) + continue; + + // Try to combine with an existing range. + bool found = false; + for (size_t i = 0; i < ranges->length(); i++) { + CharacterRange& range = (*ranges)[i]; + if (range.Contains(other)) { + found = true; + break; + } else if (other == range.from() - 1) { + range.set_from(other); + found = true; + break; + } else if (other == range.to() + 1) { + range.set_to(other); + found = true; + break; + } + } + + if (!found) + ranges->append(CharacterRange::Singleton(other)); + } + + if (c == top) + break; + } +} + +static bool +CompareInverseRanges(const CharacterRangeVector& ranges, const int* special_class, size_t length) +{ + length--; // Remove final 0x10000. + MOZ_ASSERT(special_class[length] == 0x10000); + MOZ_ASSERT(ranges.length() != 0); + MOZ_ASSERT(length != 0); + MOZ_ASSERT(special_class[0] != 0); + if (ranges.length() != (length >> 1) + 1) + return false; + CharacterRange range = ranges[0]; + if (range.from() != 0) + return false; + for (size_t i = 0; i < length; i += 2) { + if (special_class[i] != (range.to() + 1)) + return false; + range = ranges[(i >> 1) + 1]; + if (special_class[i+1] != range.from()) + return false; + } + if (range.to() != 0xffff) + return false; + return true; +} + +static bool +CompareRanges(const CharacterRangeVector& ranges, const int* special_class, size_t length) +{ + length--; // Remove final 0x10000. + MOZ_ASSERT(special_class[length] == 0x10000); + if (ranges.length() * 2 != length) + return false; + for (size_t i = 0; i < length; i += 2) { + CharacterRange range = ranges[i >> 1]; + if (range.from() != special_class[i] || range.to() != special_class[i + 1] - 1) + return false; + } + return true; +} + +bool +RegExpCharacterClass::is_standard(LifoAlloc* alloc) +{ + // TODO(lrn): Remove need for this function, by not throwing away information + // along the way. + if (is_negated_) + return false; + if (set_.is_standard()) + return true; + if (CompareRanges(set_.ranges(alloc), kSpaceRanges, kSpaceRangeCount)) { + set_.set_standard_set_type('s'); + return true; + } + if (CompareInverseRanges(set_.ranges(alloc), kSpaceRanges, kSpaceRangeCount)) { + set_.set_standard_set_type('S'); + return true; + } + if (CompareInverseRanges(set_.ranges(alloc), + kLineTerminatorRanges, + kLineTerminatorRangeCount)) { + set_.set_standard_set_type('.'); + return true; + } + if (CompareRanges(set_.ranges(alloc), + kLineTerminatorRanges, + kLineTerminatorRangeCount)) { + set_.set_standard_set_type('n'); + return true; + } + if (CompareRanges(set_.ranges(alloc), kWordRanges, kWordRangeCount)) { + set_.set_standard_set_type('w'); + return true; + } + if (CompareInverseRanges(set_.ranges(alloc), kWordRanges, kWordRangeCount)) { + set_.set_standard_set_type('W'); + return true; + } + return false; +} + +bool +CharacterRange::IsCanonical(const CharacterRangeVector& ranges) +{ + int n = ranges.length(); + if (n <= 1) + return true; + + int max = ranges[0].to(); + for (int i = 1; i < n; i++) { + CharacterRange next_range = ranges[i]; + if (next_range.from() <= max + 1) + return false; + max = next_range.to(); + } + return true; +} + +// Move a number of elements in a zonelist to another position +// in the same list. Handles overlapping source and target areas. +static +void MoveRanges(CharacterRangeVector& list, int from, int to, int count) +{ + // Ranges are potentially overlapping. + if (from < to) { + for (int i = count - 1; i >= 0; i--) + list[to + i] = list[from + i]; + } else { + for (int i = 0; i < count; i++) + list[to + i] = list[from + i]; + } +} + +static int +InsertRangeInCanonicalList(CharacterRangeVector& list, + int count, + CharacterRange insert) +{ + // Inserts a range into list[0..count[, which must be sorted + // by from value and non-overlapping and non-adjacent, using at most + // list[0..count] for the result. Returns the number of resulting + // canonicalized ranges. Inserting a range may collapse existing ranges into + // fewer ranges, so the return value can be anything in the range 1..count+1. + char16_t from = insert.from(); + char16_t to = insert.to(); + int start_pos = 0; + int end_pos = count; + for (int i = count - 1; i >= 0; i--) { + CharacterRange current = list[i]; + if (current.from() > to + 1) { + end_pos = i; + } else if (current.to() + 1 < from) { + start_pos = i + 1; + break; + } + } + + // Inserted range overlaps, or is adjacent to, ranges at positions + // [start_pos..end_pos[. Ranges before start_pos or at or after end_pos are + // not affected by the insertion. + // If start_pos == end_pos, the range must be inserted before start_pos. + // if start_pos < end_pos, the entire range from start_pos to end_pos + // must be merged with the insert range. + + if (start_pos == end_pos) { + // Insert between existing ranges at position start_pos. + if (start_pos < count) { + MoveRanges(list, start_pos, start_pos + 1, count - start_pos); + } + list[start_pos] = insert; + return count + 1; + } + if (start_pos + 1 == end_pos) { + // Replace single existing range at position start_pos. + CharacterRange to_replace = list[start_pos]; + int new_from = Min(to_replace.from(), from); + int new_to = Max(to_replace.to(), to); + list[start_pos] = CharacterRange(new_from, new_to); + return count; + } + // Replace a number of existing ranges from start_pos to end_pos - 1. + // Move the remaining ranges down. + + int new_from = Min(list[start_pos].from(), from); + int new_to = Max(list[end_pos - 1].to(), to); + if (end_pos < count) { + MoveRanges(list, end_pos, start_pos + 1, count - end_pos); + } + list[start_pos] = CharacterRange(new_from, new_to); + return count - (end_pos - start_pos) + 1; +} + +void +CharacterRange::Canonicalize(CharacterRangeVector& character_ranges) +{ + if (character_ranges.length() <= 1) return; + // Check whether ranges are already canonical (increasing, non-overlapping, + // non-adjacent). + int n = character_ranges.length(); + int max = character_ranges[0].to(); + int i = 1; + while (i < n) { + CharacterRange current = character_ranges[i]; + if (current.from() <= max + 1) { + break; + } + max = current.to(); + i++; + } + // Canonical until the i'th range. If that's all of them, we are done. + if (i == n) return; + + // The ranges at index i and forward are not canonicalized. Make them so by + // doing the equivalent of insertion sort (inserting each into the previous + // list, in order). + // Notice that inserting a range can reduce the number of ranges in the + // result due to combining of adjacent and overlapping ranges. + int read = i; // Range to insert. + size_t num_canonical = i; // Length of canonicalized part of list. + do { + num_canonical = InsertRangeInCanonicalList(character_ranges, + num_canonical, + character_ranges[read]); + read++; + } while (read < n); + + while (character_ranges.length() > num_canonical) + character_ranges.popBack(); + + MOZ_ASSERT(CharacterRange::IsCanonical(character_ranges)); +} + +// ------------------------------------------------------------------- +// SeqRegExpNode + +class VisitMarker +{ + public: + explicit VisitMarker(NodeInfo* info) + : info_(info) + { + MOZ_ASSERT(!info->visited); + info->visited = true; + } + ~VisitMarker() { + info_->visited = false; + } + private: + NodeInfo* info_; +}; + +bool +SeqRegExpNode::FillInBMInfo(int offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + if (!on_success_->FillInBMInfo(offset, budget - 1, bm, not_at_start)) + return false; + if (offset == 0) + set_bm_info(not_at_start, bm); + return true; +} + +RegExpNode* +SeqRegExpNode::FilterASCII(int depth, bool ignore_case, bool unicode) +{ + if (info()->replacement_calculated) + return replacement(); + + if (depth < 0) + return this; + + MOZ_ASSERT(!info()->visited); + VisitMarker marker(info()); + return FilterSuccessor(depth - 1, ignore_case, unicode); +} + +RegExpNode* +SeqRegExpNode::FilterSuccessor(int depth, bool ignore_case, bool unicode) +{ + RegExpNode* next = on_success_->FilterASCII(depth - 1, ignore_case, unicode); + if (next == nullptr) + return set_replacement(nullptr); + + on_success_ = next; + return set_replacement(this); +} + +// ------------------------------------------------------------------- +// ActionNode + +int +ActionNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + if (budget <= 0) + return 0; + if (action_type_ == POSITIVE_SUBMATCH_SUCCESS) + return 0; // Rewinds input! + return on_success()->EatsAtLeast(still_to_find, + budget - 1, + not_at_start); +} + +bool +ActionNode::FillInBMInfo(int offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + + if (action_type_ == BEGIN_SUBMATCH) { + bm->SetRest(offset); + } else if (action_type_ != POSITIVE_SUBMATCH_SUCCESS) { + if (!on_success()->FillInBMInfo(offset, budget - 1, bm, not_at_start)) + return false; + } + SaveBMInfo(bm, not_at_start, offset); + + return true; +} + +/* static */ ActionNode* +ActionNode::SetRegister(int reg, + int val, + RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(SET_REGISTER, on_success); + result->data_.u_store_register.reg = reg; + result->data_.u_store_register.value = val; + return result; +} + +/* static */ ActionNode* +ActionNode::IncrementRegister(int reg, RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(INCREMENT_REGISTER, on_success); + result->data_.u_increment_register.reg = reg; + return result; +} + +/* static */ ActionNode* +ActionNode::StorePosition(int reg, bool is_capture, RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(STORE_POSITION, on_success); + result->data_.u_position_register.reg = reg; + result->data_.u_position_register.is_capture = is_capture; + return result; +} + +/* static */ ActionNode* +ActionNode::ClearCaptures(Interval range, RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(CLEAR_CAPTURES, on_success); + result->data_.u_clear_captures.range_from = range.from(); + result->data_.u_clear_captures.range_to = range.to(); + return result; +} + +/* static */ ActionNode* +ActionNode::BeginSubmatch(int stack_pointer_reg, int position_reg, RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(BEGIN_SUBMATCH, on_success); + result->data_.u_submatch.stack_pointer_register = stack_pointer_reg; + result->data_.u_submatch.current_position_register = position_reg; + return result; +} + +/* static */ ActionNode* +ActionNode::PositiveSubmatchSuccess(int stack_pointer_reg, + int restore_reg, + int clear_capture_count, + int clear_capture_from, + RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(POSITIVE_SUBMATCH_SUCCESS, on_success); + result->data_.u_submatch.stack_pointer_register = stack_pointer_reg; + result->data_.u_submatch.current_position_register = restore_reg; + result->data_.u_submatch.clear_register_count = clear_capture_count; + result->data_.u_submatch.clear_register_from = clear_capture_from; + return result; +} + +/* static */ ActionNode* +ActionNode::EmptyMatchCheck(int start_register, + int repetition_register, + int repetition_limit, + RegExpNode* on_success) +{ + ActionNode* result = on_success->alloc()->newInfallible<ActionNode>(EMPTY_MATCH_CHECK, on_success); + result->data_.u_empty_match_check.start_register = start_register; + result->data_.u_empty_match_check.repetition_register = repetition_register; + result->data_.u_empty_match_check.repetition_limit = repetition_limit; + return result; +} + +// ------------------------------------------------------------------- +// TextNode + +int +TextNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + int answer = Length(); + if (answer >= still_to_find) + return answer; + if (budget <= 0) + return answer; + + // We are not at start after this node so we set the last argument to 'true'. + return answer + on_success()->EatsAtLeast(still_to_find - answer, + budget - 1, + true); +} + +int +TextNode::GreedyLoopTextLength() +{ + TextElement elm = elements()[elements().length() - 1]; + return elm.cp_offset() + elm.length(); +} + +RegExpNode* +TextNode::FilterASCII(int depth, bool ignore_case, bool unicode) +{ + if (info()->replacement_calculated) + return replacement(); + + if (depth < 0) + return this; + + MOZ_ASSERT(!info()->visited); + VisitMarker marker(info()); + int element_count = elements().length(); + for (int i = 0; i < element_count; i++) { + TextElement elm = elements()[i]; + if (elm.text_type() == TextElement::ATOM) { + CharacterVector& quarks = const_cast<CharacterVector&>(elm.atom()->data()); + for (size_t j = 0; j < quarks.length(); j++) { + uint16_t c = quarks[j]; + if (c <= kMaxOneByteCharCode) + continue; + if (!ignore_case) + return set_replacement(nullptr); + + // Here, we need to check for characters whose upper and lower cases + // are outside the Latin-1 range. + char16_t converted = ConvertNonLatin1ToLatin1(c, unicode); + if (converted == 0) { + // Character is outside Latin-1 completely + return set_replacement(nullptr); + } + + // Convert quark to Latin-1 in place. + quarks[j] = converted; + } + } else { + MOZ_ASSERT(elm.text_type() == TextElement::CHAR_CLASS); + RegExpCharacterClass* cc = elm.char_class(); + + CharacterRangeVector& ranges = cc->ranges(alloc()); + if (!CharacterRange::IsCanonical(ranges)) + CharacterRange::Canonicalize(ranges); + + // Now they are in order so we only need to look at the first. + int range_count = ranges.length(); + if (cc->is_negated()) { + if (range_count != 0 && + ranges[0].from() == 0 && + ranges[0].to() >= kMaxOneByteCharCode) + { + // This will be handled in a later filter. + if (ignore_case && RangesContainLatin1Equivalents(ranges, unicode)) + continue; + return set_replacement(nullptr); + } + } else { + if (range_count == 0 || + ranges[0].from() > kMaxOneByteCharCode) + { + // This will be handled in a later filter. + if (ignore_case && RangesContainLatin1Equivalents(ranges, unicode)) + continue; + return set_replacement(nullptr); + } + } + } + } + return FilterSuccessor(depth - 1, ignore_case, unicode); +} + +void +TextNode::CalculateOffsets() +{ + int element_count = elements().length(); + + // Set up the offsets of the elements relative to the start. This is a fixed + // quantity since a TextNode can only contain fixed-width things. + int cp_offset = 0; + for (int i = 0; i < element_count; i++) { + TextElement& elm = elements()[i]; + elm.set_cp_offset(cp_offset); + cp_offset += elm.length(); + } +} + +void TextNode::MakeCaseIndependent(bool is_ascii, bool unicode) +{ + int element_count = elements().length(); + for (int i = 0; i < element_count; i++) { + TextElement elm = elements()[i]; + if (elm.text_type() == TextElement::CHAR_CLASS) { + RegExpCharacterClass* cc = elm.char_class(); + + // None of the standard character classes is different in the case + // independent case and it slows us down if we don't know that. + if (cc->is_standard(alloc())) + continue; + + CharacterRangeVector& ranges = cc->ranges(alloc()); + int range_count = ranges.length(); + for (int j = 0; j < range_count; j++) + ranges[j].AddCaseEquivalents(is_ascii, unicode, &ranges); + } + } +} + +// ------------------------------------------------------------------- +// AssertionNode + +int +AssertionNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + if (budget <= 0) + return 0; + + // If we know we are not at the start and we are asked "how many characters + // will you match if you succeed?" then we can answer anything since false + // implies false. So lets just return the max answer (still_to_find) since + // that won't prevent us from preloading a lot of characters for the other + // branches in the node graph. + if (assertion_type() == AT_START && not_at_start) + return still_to_find; + + return on_success()->EatsAtLeast(still_to_find, budget - 1, not_at_start); +} + +bool +AssertionNode::FillInBMInfo(int offset, int budget, BoyerMooreLookahead* bm, bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + + // Match the behaviour of EatsAtLeast on this node. + if (assertion_type() == AT_START && not_at_start) + return true; + + if (!on_success()->FillInBMInfo(offset, budget - 1, bm, not_at_start)) + return false; + SaveBMInfo(bm, not_at_start, offset); + return true; +} + +// ------------------------------------------------------------------- +// BackReferenceNode + +int +BackReferenceNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + if (budget <= 0) + return 0; + return on_success()->EatsAtLeast(still_to_find, budget - 1, not_at_start); +} + +bool +BackReferenceNode::FillInBMInfo(int offset, int budget, BoyerMooreLookahead* bm, bool not_at_start) +{ + // Working out the set of characters that a backreference can match is too + // hard, so we just say that any character can match. + bm->SetRest(offset); + SaveBMInfo(bm, not_at_start, offset); + return true; +} + +// ------------------------------------------------------------------- +// ChoiceNode + +int +ChoiceNode::EatsAtLeastHelper(int still_to_find, + int budget, + RegExpNode* ignore_this_node, + bool not_at_start) +{ + if (budget <= 0) + return 0; + + int min = 100; + size_t choice_count = alternatives().length(); + budget = (budget - 1) / choice_count; + for (size_t i = 0; i < choice_count; i++) { + RegExpNode* node = alternatives()[i].node(); + if (node == ignore_this_node) continue; + int node_eats_at_least = + node->EatsAtLeast(still_to_find, budget, not_at_start); + if (node_eats_at_least < min) + min = node_eats_at_least; + if (min == 0) + return 0; + } + return min; +} + +int +ChoiceNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + return EatsAtLeastHelper(still_to_find, + budget, + nullptr, + not_at_start); +} + +void +ChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details, + RegExpCompiler* compiler, + int characters_filled_in, + bool not_at_start) +{ + not_at_start = (not_at_start || not_at_start_); + int choice_count = alternatives().length(); + MOZ_ASSERT(choice_count > 0); + alternatives()[0].node()->GetQuickCheckDetails(details, + compiler, + characters_filled_in, + not_at_start); + for (int i = 1; i < choice_count; i++) { + QuickCheckDetails new_details(details->characters()); + RegExpNode* node = alternatives()[i].node(); + node->GetQuickCheckDetails(&new_details, compiler, + characters_filled_in, + not_at_start); + // Here we merge the quick match details of the two branches. + details->Merge(&new_details, characters_filled_in); + } +} + +bool +ChoiceNode::FillInBMInfo(int offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + + const GuardedAlternativeVector& alts = alternatives(); + budget = (budget - 1) / alts.length(); + for (size_t i = 0; i < alts.length(); i++) { + const GuardedAlternative& alt = alts[i]; + if (alt.guards() != nullptr && alt.guards()->length() != 0) { + bm->SetRest(offset); // Give up trying to fill in info. + SaveBMInfo(bm, not_at_start, offset); + return true; + } + if (!alt.node()->FillInBMInfo(offset, budget, bm, not_at_start)) + return false; + } + SaveBMInfo(bm, not_at_start, offset); + return true; +} + +RegExpNode* +ChoiceNode::FilterASCII(int depth, bool ignore_case, bool unicode) +{ + if (info()->replacement_calculated) + return replacement(); + if (depth < 0) + return this; + if (info()->visited) + return this; + VisitMarker marker(info()); + int choice_count = alternatives().length(); + + for (int i = 0; i < choice_count; i++) { + const GuardedAlternative alternative = alternatives()[i]; + if (alternative.guards() != nullptr && alternative.guards()->length() != 0) { + set_replacement(this); + return this; + } + } + + int surviving = 0; + RegExpNode* survivor = nullptr; + for (int i = 0; i < choice_count; i++) { + GuardedAlternative alternative = alternatives()[i]; + RegExpNode* replacement = + alternative.node()->FilterASCII(depth - 1, ignore_case, unicode); + MOZ_ASSERT(replacement != this); // No missing EMPTY_MATCH_CHECK. + if (replacement != nullptr) { + alternatives()[i].set_node(replacement); + surviving++; + survivor = replacement; + } + } + if (surviving < 2) + return set_replacement(survivor); + + set_replacement(this); + if (surviving == choice_count) + return this; + + // Only some of the nodes survived the filtering. We need to rebuild the + // alternatives list. + GuardedAlternativeVector new_alternatives(*alloc()); + new_alternatives.reserve(surviving); + for (int i = 0; i < choice_count; i++) { + RegExpNode* replacement = + alternatives()[i].node()->FilterASCII(depth - 1, ignore_case, unicode); + if (replacement != nullptr) { + alternatives()[i].set_node(replacement); + new_alternatives.append(alternatives()[i]); + } + } + + alternatives_ = Move(new_alternatives); + return this; +} + +// ------------------------------------------------------------------- +// NegativeLookaheadChoiceNode + +bool +NegativeLookaheadChoiceNode::FillInBMInfo(int offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + + if (!alternatives()[1].node()->FillInBMInfo(offset, budget - 1, bm, not_at_start)) + return false; + if (offset == 0) + set_bm_info(not_at_start, bm); + return true; +} + +int +NegativeLookaheadChoiceNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + if (budget <= 0) + return 0; + + // Alternative 0 is the negative lookahead, alternative 1 is what comes + // afterwards. + RegExpNode* node = alternatives()[1].node(); + return node->EatsAtLeast(still_to_find, budget - 1, not_at_start); +} + +void +NegativeLookaheadChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details, + RegExpCompiler* compiler, + int filled_in, + bool not_at_start) +{ + // Alternative 0 is the negative lookahead, alternative 1 is what comes + // afterwards. + RegExpNode* node = alternatives()[1].node(); + return node->GetQuickCheckDetails(details, compiler, filled_in, not_at_start); +} + +RegExpNode* +NegativeLookaheadChoiceNode::FilterASCII(int depth, bool ignore_case, bool unicode) +{ + if (info()->replacement_calculated) + return replacement(); + if (depth < 0) + return this; + if (info()->visited) + return this; + + VisitMarker marker(info()); + + // Alternative 0 is the negative lookahead, alternative 1 is what comes + // afterwards. + RegExpNode* node = alternatives()[1].node(); + RegExpNode* replacement = node->FilterASCII(depth - 1, ignore_case, unicode); + + if (replacement == nullptr) + return set_replacement(nullptr); + alternatives()[1].set_node(replacement); + + RegExpNode* neg_node = alternatives()[0].node(); + RegExpNode* neg_replacement = neg_node->FilterASCII(depth - 1, ignore_case, unicode); + + // If the negative lookahead is always going to fail then + // we don't need to check it. + if (neg_replacement == nullptr) + return set_replacement(replacement); + + alternatives()[0].set_node(neg_replacement); + return set_replacement(this); +} + +// ------------------------------------------------------------------- +// LoopChoiceNode + +void +GuardedAlternative::AddGuard(LifoAlloc* alloc, Guard* guard) +{ + if (guards_ == nullptr) + guards_ = alloc->newInfallible<GuardVector>(*alloc); + guards_->append(guard); +} + +void +LoopChoiceNode::AddLoopAlternative(GuardedAlternative alt) +{ + MOZ_ASSERT(loop_node_ == nullptr); + AddAlternative(alt); + loop_node_ = alt.node(); +} + + +void +LoopChoiceNode::AddContinueAlternative(GuardedAlternative alt) +{ + MOZ_ASSERT(continue_node_ == nullptr); + AddAlternative(alt); + continue_node_ = alt.node(); +} + +int +LoopChoiceNode::EatsAtLeast(int still_to_find, int budget, bool not_at_start) +{ + return EatsAtLeastHelper(still_to_find, + budget - 1, + loop_node_, + not_at_start); +} + +void +LoopChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details, + RegExpCompiler* compiler, + int characters_filled_in, + bool not_at_start) +{ + if (body_can_be_zero_length_ || info()->visited) + return; + VisitMarker marker(info()); + return ChoiceNode::GetQuickCheckDetails(details, + compiler, + characters_filled_in, + not_at_start); +} + +bool +LoopChoiceNode::FillInBMInfo(int offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (body_can_be_zero_length_ || budget <= 0) { + bm->SetRest(offset); + SaveBMInfo(bm, not_at_start, offset); + return true; + } + if (!ChoiceNode::FillInBMInfo(offset, budget - 1, bm, not_at_start)) + return false; + SaveBMInfo(bm, not_at_start, offset); + return true; +} + +RegExpNode* +LoopChoiceNode::FilterASCII(int depth, bool ignore_case, bool unicode) +{ + if (info()->replacement_calculated) + return replacement(); + if (depth < 0) + return this; + if (info()->visited) + return this; + + { + VisitMarker marker(info()); + + RegExpNode* continue_replacement = + continue_node_->FilterASCII(depth - 1, ignore_case, unicode); + + // If we can't continue after the loop then there is no sense in doing the + // loop. + if (continue_replacement == nullptr) + return set_replacement(nullptr); + } + + return ChoiceNode::FilterASCII(depth - 1, ignore_case, unicode); +} + +// ------------------------------------------------------------------- +// Analysis + +void +Analysis::EnsureAnalyzed(RegExpNode* that) +{ + JS_CHECK_RECURSION(cx, failASCII("Stack overflow"); return); + + if (that->info()->been_analyzed || that->info()->being_analyzed) + return; + that->info()->being_analyzed = true; + that->Accept(this); + that->info()->being_analyzed = false; + that->info()->been_analyzed = true; +} + +void +Analysis::VisitEnd(EndNode* that) +{ + // nothing to do +} + +void +Analysis::VisitText(TextNode* that) +{ + if (ignore_case_) + that->MakeCaseIndependent(is_ascii_, unicode_); + EnsureAnalyzed(that->on_success()); + if (!has_failed()) { + that->CalculateOffsets(); + } +} + +void +Analysis::VisitAction(ActionNode* that) +{ + RegExpNode* target = that->on_success(); + EnsureAnalyzed(target); + + if (!has_failed()) { + // If the next node is interested in what it follows then this node + // has to be interested too so it can pass the information on. + that->info()->AddFromFollowing(target->info()); + } +} + +void +Analysis::VisitChoice(ChoiceNode* that) +{ + NodeInfo* info = that->info(); + + for (size_t i = 0; i < that->alternatives().length(); i++) { + RegExpNode* node = that->alternatives()[i].node(); + EnsureAnalyzed(node); + if (has_failed()) return; + + // Anything the following nodes need to know has to be known by + // this node also, so it can pass it on. + info->AddFromFollowing(node->info()); + } +} + +void +Analysis::VisitLoopChoice(LoopChoiceNode* that) +{ + NodeInfo* info = that->info(); + for (size_t i = 0; i < that->alternatives().length(); i++) { + RegExpNode* node = that->alternatives()[i].node(); + if (node != that->loop_node()) { + EnsureAnalyzed(node); + if (has_failed()) return; + info->AddFromFollowing(node->info()); + } + } + + // Check the loop last since it may need the value of this node + // to get a correct result. + EnsureAnalyzed(that->loop_node()); + if (!has_failed()) + info->AddFromFollowing(that->loop_node()->info()); +} + +void +Analysis::VisitBackReference(BackReferenceNode* that) +{ + EnsureAnalyzed(that->on_success()); +} + +void +Analysis::VisitAssertion(AssertionNode* that) +{ + EnsureAnalyzed(that->on_success()); +} + +// ------------------------------------------------------------------- +// Implementation of the Irregexp regular expression engine. +// +// The Irregexp regular expression engine is intended to be a complete +// implementation of ECMAScript regular expressions. It generates either +// bytecodes or native code. + +// The Irregexp regexp engine is structured in three steps. +// 1) The parser generates an abstract syntax tree. See RegExpAST.cpp. +// 2) From the AST a node network is created. The nodes are all +// subclasses of RegExpNode. The nodes represent states when +// executing a regular expression. Several optimizations are +// performed on the node network. +// 3) From the nodes we generate either byte codes or native code +// that can actually execute the regular expression (perform +// the search). The code generation step is described in more +// detail below. + +// Code generation. +// +// The nodes are divided into four main categories. +// * Choice nodes +// These represent places where the regular expression can +// match in more than one way. For example on entry to an +// alternation (foo|bar) or a repetition (*, +, ? or {}). +// * Action nodes +// These represent places where some action should be +// performed. Examples include recording the current position +// in the input string to a register (in order to implement +// captures) or other actions on register for example in order +// to implement the counters needed for {} repetitions. +// * Matching nodes +// These attempt to match some element part of the input string. +// Examples of elements include character classes, plain strings +// or back references. +// * End nodes +// These are used to implement the actions required on finding +// a successful match or failing to find a match. +// +// The code generated (whether as byte codes or native code) maintains +// some state as it runs. This consists of the following elements: +// +// * The capture registers. Used for string captures. +// * Other registers. Used for counters etc. +// * The current position. +// * The stack of backtracking information. Used when a matching node +// fails to find a match and needs to try an alternative. +// +// Conceptual regular expression execution model: +// +// There is a simple conceptual model of regular expression execution +// which will be presented first. The actual code generated is a more +// efficient simulation of the simple conceptual model: +// +// * Choice nodes are implemented as follows: +// For each choice except the last { +// push current position +// push backtrack code location +// <generate code to test for choice> +// backtrack code location: +// pop current position +// } +// <generate code to test for last choice> +// +// * Actions nodes are generated as follows +// <push affected registers on backtrack stack> +// <generate code to perform action> +// push backtrack code location +// <generate code to test for following nodes> +// backtrack code location: +// <pop affected registers to restore their state> +// <pop backtrack location from stack and go to it> +// +// * Matching nodes are generated as follows: +// if input string matches at current position +// update current position +// <generate code to test for following nodes> +// else +// <pop backtrack location from stack and go to it> +// +// Thus it can be seen that the current position is saved and restored +// by the choice nodes, whereas the registers are saved and restored by +// by the action nodes that manipulate them. +// +// The other interesting aspect of this model is that nodes are generated +// at the point where they are needed by a recursive call to Emit(). If +// the node has already been code generated then the Emit() call will +// generate a jump to the previously generated code instead. In order to +// limit recursion it is possible for the Emit() function to put the node +// on a work list for later generation and instead generate a jump. The +// destination of the jump is resolved later when the code is generated. +// +// Actual regular expression code generation. +// +// Code generation is actually more complicated than the above. In order +// to improve the efficiency of the generated code some optimizations are +// performed +// +// * Choice nodes have 1-character lookahead. +// A choice node looks at the following character and eliminates some of +// the choices immediately based on that character. This is not yet +// implemented. +// * Simple greedy loops store reduced backtracking information. +// A quantifier like /.*foo/m will greedily match the whole input. It will +// then need to backtrack to a point where it can match "foo". The naive +// implementation of this would push each character position onto the +// backtracking stack, then pop them off one by one. This would use space +// proportional to the length of the input string. However since the "." +// can only match in one way and always has a constant length (in this case +// of 1) it suffices to store the current position on the top of the stack +// once. Matching now becomes merely incrementing the current position and +// backtracking becomes decrementing the current position and checking the +// result against the stored current position. This is faster and saves +// space. +// * The current state is virtualized. +// This is used to defer expensive operations until it is clear that they +// are needed and to generate code for a node more than once, allowing +// specialized an efficient versions of the code to be created. This is +// explained in the section below. +// +// Execution state virtualization. +// +// Instead of emitting code, nodes that manipulate the state can record their +// manipulation in an object called the Trace. The Trace object can record a +// current position offset, an optional backtrack code location on the top of +// the virtualized backtrack stack and some register changes. When a node is +// to be emitted it can flush the Trace or update it. Flushing the Trace +// will emit code to bring the actual state into line with the virtual state. +// Avoiding flushing the state can postpone some work (e.g. updates of capture +// registers). Postponing work can save time when executing the regular +// expression since it may be found that the work never has to be done as a +// failure to match can occur. In addition it is much faster to jump to a +// known backtrack code location than it is to pop an unknown backtrack +// location from the stack and jump there. +// +// The virtual state found in the Trace affects code generation. For example +// the virtual state contains the difference between the actual current +// position and the virtual current position, and matching code needs to use +// this offset to attempt a match in the correct location of the input +// string. Therefore code generated for a non-trivial trace is specialized +// to that trace. The code generator therefore has the ability to generate +// code for each node several times. In order to limit the size of the +// generated code there is an arbitrary limit on how many specialized sets of +// code may be generated for a given node. If the limit is reached, the +// trace is flushed and a generic version of the code for a node is emitted. +// This is subsequently used for that node. The code emitted for non-generic +// trace is not recorded in the node and so it cannot currently be reused in +// the event that code generation is requested for an identical trace. + +/* static */ TextElement +TextElement::Atom(RegExpAtom* atom) +{ + return TextElement(ATOM, atom); +} + +/* static */ TextElement +TextElement::CharClass(RegExpCharacterClass* char_class) +{ + return TextElement(CHAR_CLASS, char_class); +} + +int +TextElement::length() const +{ + switch (text_type()) { + case ATOM: + return atom()->length(); + case CHAR_CLASS: + return 1; + } + MOZ_CRASH("Bad text type"); +} + +class FrequencyCollator +{ + public: + FrequencyCollator() : total_samples_(0) { + for (int i = 0; i < RegExpMacroAssembler::kTableSize; i++) { + frequencies_[i] = CharacterFrequency(i); + } + } + + void CountCharacter(int character) { + int index = (character & RegExpMacroAssembler::kTableMask); + frequencies_[index].Increment(); + total_samples_++; + } + + // Does not measure in percent, but rather per-128 (the table size from the + // regexp macro assembler). + int Frequency(int in_character) { + MOZ_ASSERT((in_character & RegExpMacroAssembler::kTableMask) == in_character); + if (total_samples_ < 1) return 1; // Division by zero. + int freq_in_per128 = + (frequencies_[in_character].counter() * 128) / total_samples_; + return freq_in_per128; + } + + private: + class CharacterFrequency { + public: + CharacterFrequency() : counter_(0), character_(-1) { } + explicit CharacterFrequency(int character) + : counter_(0), character_(character) + {} + + void Increment() { counter_++; } + int counter() { return counter_; } + int character() { return character_; } + + private: + int counter_; + int character_; + }; + + private: + CharacterFrequency frequencies_[RegExpMacroAssembler::kTableSize]; + int total_samples_; +}; + +class irregexp::RegExpCompiler +{ + public: + RegExpCompiler(JSContext* cx, LifoAlloc* alloc, int capture_count, + bool ignore_case, bool is_ascii, bool match_only, bool unicode); + + int AllocateRegister() { + if (next_register_ >= RegExpMacroAssembler::kMaxRegister) { + reg_exp_too_big_ = true; + return next_register_; + } + return next_register_++; + } + + RegExpCode Assemble(JSContext* cx, + RegExpMacroAssembler* assembler, + RegExpNode* start, + int capture_count); + + inline void AddWork(RegExpNode* node) { + AutoEnterOOMUnsafeRegion oomUnsafe; + if (!work_list_.append(node)) + oomUnsafe.crash("AddWork"); + } + + static const int kImplementationOffset = 0; + static const int kNumberOfRegistersOffset = 0; + static const int kCodeOffset = 1; + + RegExpMacroAssembler* macro_assembler() { return macro_assembler_; } + EndNode* accept() { return accept_; } + + static const int kMaxRecursion = 100; + inline int recursion_depth() { return recursion_depth_; } + inline void IncrementRecursionDepth() { recursion_depth_++; } + inline void DecrementRecursionDepth() { recursion_depth_--; } + + void SetRegExpTooBig() { reg_exp_too_big_ = true; } + + inline bool ignore_case() { return ignore_case_; } + inline bool ascii() { return ascii_; } + inline bool unicode() { return unicode_; } + FrequencyCollator* frequency_collator() { return &frequency_collator_; } + + int current_expansion_factor() { return current_expansion_factor_; } + void set_current_expansion_factor(int value) { + current_expansion_factor_ = value; + } + + JSContext* cx() const { return cx_; } + LifoAlloc* alloc() const { return alloc_; } + + static const int kNoRegister = -1; + + private: + EndNode* accept_; + int next_register_; + Vector<RegExpNode*, 4, SystemAllocPolicy> work_list_; + int recursion_depth_; + RegExpMacroAssembler* macro_assembler_; + bool ignore_case_; + bool ascii_; + bool match_only_; + bool unicode_; + bool reg_exp_too_big_; + int current_expansion_factor_; + FrequencyCollator frequency_collator_; + JSContext* cx_; + LifoAlloc* alloc_; +}; + +class RecursionCheck +{ + public: + explicit RecursionCheck(RegExpCompiler* compiler) : compiler_(compiler) { + compiler->IncrementRecursionDepth(); + } + ~RecursionCheck() { compiler_->DecrementRecursionDepth(); } + + private: + RegExpCompiler* compiler_; +}; + +// Attempts to compile the regexp using an Irregexp code generator. Returns +// a fixed array or a null handle depending on whether it succeeded. +RegExpCompiler::RegExpCompiler(JSContext* cx, LifoAlloc* alloc, int capture_count, + bool ignore_case, bool ascii, bool match_only, bool unicode) + : next_register_(2 * (capture_count + 1)), + recursion_depth_(0), + ignore_case_(ignore_case), + ascii_(ascii), + match_only_(match_only), + unicode_(unicode), + reg_exp_too_big_(false), + current_expansion_factor_(1), + frequency_collator_(), + cx_(cx), + alloc_(alloc) +{ + accept_ = alloc->newInfallible<EndNode>(alloc, EndNode::ACCEPT); + MOZ_ASSERT(next_register_ - 1 <= RegExpMacroAssembler::kMaxRegister); +} + +RegExpCode +RegExpCompiler::Assemble(JSContext* cx, + RegExpMacroAssembler* assembler, + RegExpNode* start, + int capture_count) +{ + macro_assembler_ = assembler; + macro_assembler_->set_slow_safe(false); + + // The LifoAlloc used by the regexp compiler is infallible and is currently + // expected to crash on OOM. Thus we have to disable the assertions made to + // prevent us from allocating any new chunk in the LifoAlloc. This is needed + // because the jit::MacroAssembler turns these assertions on by default. + LifoAlloc::AutoFallibleScope fallibleAllocator(alloc()); + + jit::Label fail; + macro_assembler_->PushBacktrack(&fail); + Trace new_trace; + start->Emit(this, &new_trace); + macro_assembler_->BindBacktrack(&fail); + macro_assembler_->Fail(); + + while (!work_list_.empty()) + work_list_.popCopy()->Emit(this, &new_trace); + + RegExpCode code = macro_assembler_->GenerateCode(cx, match_only_); + if (code.empty()) + return RegExpCode(); + + if (reg_exp_too_big_) { + code.destroy(); + JS_ReportErrorASCII(cx, "regexp too big"); + return RegExpCode(); + } + + return code; +} + +template <typename CharT> +static void +SampleChars(FrequencyCollator* collator, const CharT* chars, size_t length) +{ + // Sample some characters from the middle of the string. + static const int kSampleSize = 128; + + int chars_sampled = 0; + int half_way = (int(length) - kSampleSize) / 2; + for (size_t i = Max(0, half_way); + i < length && chars_sampled < kSampleSize; + i++, chars_sampled++) + { + collator->CountCharacter(chars[i]); + } +} + +static bool +IsNativeRegExpEnabled(JSContext* cx) +{ +#ifdef JS_CODEGEN_NONE + return false; +#else + return cx->options().nativeRegExp(); +#endif +} + +RegExpCode +irregexp::CompilePattern(JSContext* cx, RegExpShared* shared, RegExpCompileData* data, + HandleLinearString sample, bool is_global, bool ignore_case, + bool is_ascii, bool match_only, bool force_bytecode, bool sticky, + bool unicode) +{ + if ((data->capture_count + 1) * 2 - 1 > RegExpMacroAssembler::kMaxRegister) { + JS_ReportErrorASCII(cx, "regexp too big"); + return RegExpCode(); + } + + LifoAlloc& alloc = cx->tempLifoAlloc(); + RegExpCompiler compiler(cx, &alloc, data->capture_count, ignore_case, is_ascii, match_only, + unicode); + + // Sample some characters from the middle of the string. + if (sample->hasLatin1Chars()) { + JS::AutoCheckCannotGC nogc; + SampleChars(compiler.frequency_collator(), sample->latin1Chars(nogc), sample->length()); + } else { + JS::AutoCheckCannotGC nogc; + SampleChars(compiler.frequency_collator(), sample->twoByteChars(nogc), sample->length()); + } + + // Wrap the body of the regexp in capture #0. + RegExpNode* captured_body = RegExpCapture::ToNode(data->tree, + 0, + &compiler, + compiler.accept()); + RegExpNode* node = captured_body; + bool is_end_anchored = data->tree->IsAnchoredAtEnd(); + bool is_start_anchored = sticky || data->tree->IsAnchoredAtStart(); + int max_length = data->tree->max_match(); + if (!is_start_anchored) { + // Add a .*? at the beginning, outside the body capture, unless + // this expression is anchored at the beginning. + RegExpNode* loop_node = + RegExpQuantifier::ToNode(0, + RegExpTree::kInfinity, + false, + alloc.newInfallible<RegExpCharacterClass>('*'), + &compiler, + captured_body, + data->contains_anchor); + + if (data->contains_anchor) { + // Unroll loop once, to take care of the case that might start + // at the start of input. + ChoiceNode* first_step_node = alloc.newInfallible<ChoiceNode>(&alloc, 2); + RegExpNode* char_class = + alloc.newInfallible<TextNode>(alloc.newInfallible<RegExpCharacterClass>('*'), loop_node); + first_step_node->AddAlternative(GuardedAlternative(captured_body)); + first_step_node->AddAlternative(GuardedAlternative(char_class)); + node = first_step_node; + } else { + node = loop_node; + } + } + if (is_ascii) { + node = node->FilterASCII(RegExpCompiler::kMaxRecursion, ignore_case, unicode); + // Do it again to propagate the new nodes to places where they were not + // put because they had not been calculated yet. + if (node != nullptr) { + node = node->FilterASCII(RegExpCompiler::kMaxRecursion, ignore_case, unicode); + } + } + + if (node == nullptr) + node = alloc.newInfallible<EndNode>(&alloc, EndNode::BACKTRACK); + + Analysis analysis(cx, ignore_case, is_ascii, unicode); + analysis.EnsureAnalyzed(node); + if (analysis.has_failed()) { + JS_ReportErrorASCII(cx, "%s", analysis.errorMessage()); + return RegExpCode(); + } + + Maybe<jit::JitContext> ctx; + Maybe<NativeRegExpMacroAssembler> native_assembler; + Maybe<InterpretedRegExpMacroAssembler> interpreted_assembler; + + RegExpMacroAssembler* assembler; + if (IsNativeRegExpEnabled(cx) && + !force_bytecode && + jit::CanLikelyAllocateMoreExecutableMemory() && + shared->getSource()->length() < 32 * 1024) + { + NativeRegExpMacroAssembler::Mode mode = + is_ascii ? NativeRegExpMacroAssembler::ASCII + : NativeRegExpMacroAssembler::CHAR16; + + ctx.emplace(cx, (jit::TempAllocator*) nullptr); + native_assembler.emplace(&alloc, shared, cx->runtime(), mode, (data->capture_count + 1) * 2); + assembler = native_assembler.ptr(); + } else { + interpreted_assembler.emplace(&alloc, shared, (data->capture_count + 1) * 2); + assembler = interpreted_assembler.ptr(); + } + + // Inserted here, instead of in Assembler, because it depends on information + // in the AST that isn't replicated in the Node structure. + static const int kMaxBacksearchLimit = 1024; + if (is_end_anchored && + !is_start_anchored && + max_length < kMaxBacksearchLimit) { + assembler->SetCurrentPositionFromEnd(max_length); + } + + if (is_global) { + assembler->set_global_mode((data->tree->min_match() > 0) + ? RegExpMacroAssembler::GLOBAL_NO_ZERO_LENGTH_CHECK + : RegExpMacroAssembler::GLOBAL); + } + + return compiler.Assemble(cx, assembler, node, data->capture_count); +} + +template <typename CharT> +RegExpRunStatus +irregexp::ExecuteCode(JSContext* cx, jit::JitCode* codeBlock, const CharT* chars, size_t start, + size_t length, MatchPairs* matches, size_t* endIndex) +{ + typedef void (*RegExpCodeSignature)(InputOutputData*); + + InputOutputData data(chars, chars + length, start, matches, endIndex); + + RegExpCodeSignature function = reinterpret_cast<RegExpCodeSignature>(codeBlock->raw()); + + { + JS::AutoSuppressGCAnalysis nogc; + CALL_GENERATED_1(function, &data); + } + + return (RegExpRunStatus) data.result; +} + +template RegExpRunStatus +irregexp::ExecuteCode(JSContext* cx, jit::JitCode* codeBlock, const Latin1Char* chars, size_t start, + size_t length, MatchPairs* matches, size_t* endIndex); + +template RegExpRunStatus +irregexp::ExecuteCode(JSContext* cx, jit::JitCode* codeBlock, const char16_t* chars, size_t start, + size_t length, MatchPairs* matches, size_t* endIndex); + +// ------------------------------------------------------------------- +// Tree to graph conversion + +RegExpNode* +RegExpAtom::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + TextElementVector* elms = + compiler->alloc()->newInfallible<TextElementVector>(*compiler->alloc()); + elms->append(TextElement::Atom(this)); + return compiler->alloc()->newInfallible<TextNode>(elms, on_success); +} + +RegExpNode* +RegExpText::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return compiler->alloc()->newInfallible<TextNode>(&elements_, on_success); +} + +RegExpNode* +RegExpCharacterClass::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return compiler->alloc()->newInfallible<TextNode>(this, on_success); +} + +RegExpNode* +RegExpDisjunction::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + const RegExpTreeVector& alternatives = this->alternatives(); + size_t length = alternatives.length(); + ChoiceNode* result = compiler->alloc()->newInfallible<ChoiceNode>(compiler->alloc(), length); + for (size_t i = 0; i < length; i++) { + GuardedAlternative alternative(alternatives[i]->ToNode(compiler, on_success)); + result->AddAlternative(alternative); + } + return result; +} + +RegExpNode* +RegExpQuantifier::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return ToNode(min(), + max(), + is_greedy(), + body(), + compiler, + on_success); +} + +// Scoped object to keep track of how much we unroll quantifier loops in the +// regexp graph generator. +class RegExpExpansionLimiter +{ + public: + static const int kMaxExpansionFactor = 6; + RegExpExpansionLimiter(RegExpCompiler* compiler, int factor) + : compiler_(compiler), + saved_expansion_factor_(compiler->current_expansion_factor()), + ok_to_expand_(saved_expansion_factor_ <= kMaxExpansionFactor) + { + MOZ_ASSERT(factor > 0); + if (ok_to_expand_) { + if (factor > kMaxExpansionFactor) { + // Avoid integer overflow of the current expansion factor. + ok_to_expand_ = false; + compiler->set_current_expansion_factor(kMaxExpansionFactor + 1); + } else { + int new_factor = saved_expansion_factor_ * factor; + ok_to_expand_ = (new_factor <= kMaxExpansionFactor); + compiler->set_current_expansion_factor(new_factor); + } + } + } + + ~RegExpExpansionLimiter() { + compiler_->set_current_expansion_factor(saved_expansion_factor_); + } + + bool ok_to_expand() { return ok_to_expand_; } + + private: + RegExpCompiler* compiler_; + int saved_expansion_factor_; + bool ok_to_expand_; +}; + +/* static */ RegExpNode* +RegExpQuantifier::ToNode(int min, + int max, + bool is_greedy, + RegExpTree* body, + RegExpCompiler* compiler, + RegExpNode* on_success, + bool not_at_start /* = false */) +{ + // x{f, t} becomes this: + // + // (r++)<-. + // | ` + // | (x) + // v ^ + // (r=0)-->(?)---/ [if r < t] + // | + // [if r >= f] \----> ... + // + + // 15.10.2.5 RepeatMatcher algorithm. + // The parser has already eliminated the case where max is 0. In the case + // where max_match is zero the parser has removed the quantifier if min was + // > 0 and removed the atom if min was 0. See AddQuantifierToAtom. + + // If we know that we cannot match zero length then things are a little + // simpler since we don't need to make the special zero length match check + // from step 2.1. If the min and max are small we can unroll a little in + // this case. + static const int kMaxUnrolledMinMatches = 3; // Unroll (foo)+ and (foo){3,} + static const int kMaxUnrolledMaxMatches = 3; // Unroll (foo)? and (foo){x,3} + + if (max == 0) + return on_success; // This can happen due to recursion. + + bool body_can_be_empty = (body->min_match() == 0); + int body_start_reg = RegExpCompiler::kNoRegister; + Interval capture_registers = body->CaptureRegisters(); + bool needs_capture_clearing = !capture_registers.is_empty(); + LifoAlloc* alloc = compiler->alloc(); + + if (body_can_be_empty) { + body_start_reg = compiler->AllocateRegister(); + } else if (!needs_capture_clearing) { + // Only unroll if there are no captures and the body can't be + // empty. + { + RegExpExpansionLimiter limiter(compiler, min + ((max != min) ? 1 : 0)); + if (min > 0 && min <= kMaxUnrolledMinMatches && limiter.ok_to_expand()) { + int new_max = (max == kInfinity) ? max : max - min; + // Recurse once to get the loop or optional matches after the fixed + // ones. + RegExpNode* answer = ToNode(0, new_max, is_greedy, body, compiler, on_success, true); + // Unroll the forced matches from 0 to min. This can cause chains of + // TextNodes (which the parser does not generate). These should be + // combined if it turns out they hinder good code generation. + for (int i = 0; i < min; i++) + answer = body->ToNode(compiler, answer); + return answer; + } + } + if (max <= kMaxUnrolledMaxMatches && min == 0) { + MOZ_ASSERT(max > 0); // Due to the 'if' above. + RegExpExpansionLimiter limiter(compiler, max); + if (limiter.ok_to_expand()) { + // Unroll the optional matches up to max. + RegExpNode* answer = on_success; + for (int i = 0; i < max; i++) { + ChoiceNode* alternation = alloc->newInfallible<ChoiceNode>(alloc, 2); + if (is_greedy) { + alternation->AddAlternative(GuardedAlternative(body->ToNode(compiler, answer))); + alternation->AddAlternative(GuardedAlternative(on_success)); + } else { + alternation->AddAlternative(GuardedAlternative(on_success)); + alternation->AddAlternative(GuardedAlternative(body->ToNode(compiler, answer))); + } + answer = alternation; + if (not_at_start) alternation->set_not_at_start(); + } + return answer; + } + } + } + bool has_min = min > 0; + bool has_max = max < RegExpTree::kInfinity; + bool needs_counter = has_min || has_max; + int reg_ctr = needs_counter + ? compiler->AllocateRegister() + : RegExpCompiler::kNoRegister; + LoopChoiceNode* center = alloc->newInfallible<LoopChoiceNode>(alloc, body->min_match() == 0); + if (not_at_start) + center->set_not_at_start(); + RegExpNode* loop_return = needs_counter + ? static_cast<RegExpNode*>(ActionNode::IncrementRegister(reg_ctr, center)) + : static_cast<RegExpNode*>(center); + if (body_can_be_empty) { + // If the body can be empty we need to check if it was and then + // backtrack. + loop_return = ActionNode::EmptyMatchCheck(body_start_reg, + reg_ctr, + min, + loop_return); + } + RegExpNode* body_node = body->ToNode(compiler, loop_return); + if (body_can_be_empty) { + // If the body can be empty we need to store the start position + // so we can bail out if it was empty. + body_node = ActionNode::StorePosition(body_start_reg, false, body_node); + } + if (needs_capture_clearing) { + // Before entering the body of this loop we need to clear captures. + body_node = ActionNode::ClearCaptures(capture_registers, body_node); + } + GuardedAlternative body_alt(body_node); + if (has_max) { + Guard* body_guard = alloc->newInfallible<Guard>(reg_ctr, Guard::LT, max); + body_alt.AddGuard(alloc, body_guard); + } + GuardedAlternative rest_alt(on_success); + if (has_min) { + Guard* rest_guard = alloc->newInfallible<Guard>(reg_ctr, Guard::GEQ, min); + rest_alt.AddGuard(alloc, rest_guard); + } + if (is_greedy) { + center->AddLoopAlternative(body_alt); + center->AddContinueAlternative(rest_alt); + } else { + center->AddContinueAlternative(rest_alt); + center->AddLoopAlternative(body_alt); + } + if (needs_counter) + return ActionNode::SetRegister(reg_ctr, 0, center); + return center; +} + +RegExpNode* +RegExpAssertion::ToNode(RegExpCompiler* compiler, + RegExpNode* on_success) +{ + NodeInfo info; + LifoAlloc* alloc = compiler->alloc(); + + switch (assertion_type()) { + case START_OF_LINE: + return AssertionNode::AfterNewline(on_success); + case START_OF_INPUT: + return AssertionNode::AtStart(on_success); + case BOUNDARY: + return AssertionNode::AtBoundary(on_success); + case NON_BOUNDARY: + return AssertionNode::AtNonBoundary(on_success); + case END_OF_INPUT: + return AssertionNode::AtEnd(on_success); + case END_OF_LINE: { + // Compile $ in multiline regexps as an alternation with a positive + // lookahead in one side and an end-of-input on the other side. + // We need two registers for the lookahead. + int stack_pointer_register = compiler->AllocateRegister(); + int position_register = compiler->AllocateRegister(); + // The ChoiceNode to distinguish between a newline and end-of-input. + ChoiceNode* result = alloc->newInfallible<ChoiceNode>(alloc, 2); + // Create a newline atom. + CharacterRangeVector* newline_ranges = alloc->newInfallible<CharacterRangeVector>(*alloc); + CharacterRange::AddClassEscape(alloc, 'n', newline_ranges); + RegExpCharacterClass* newline_atom = alloc->newInfallible<RegExpCharacterClass>('n'); + TextNode* newline_matcher = + alloc->newInfallible<TextNode>(newline_atom, + ActionNode::PositiveSubmatchSuccess(stack_pointer_register, + position_register, + 0, // No captures inside. + -1, // Ignored if no captures. + on_success)); + // Create an end-of-input matcher. + RegExpNode* end_of_line = + ActionNode::BeginSubmatch(stack_pointer_register, position_register, newline_matcher); + + // Add the two alternatives to the ChoiceNode. + GuardedAlternative eol_alternative(end_of_line); + result->AddAlternative(eol_alternative); + GuardedAlternative end_alternative(AssertionNode::AtEnd(on_success)); + result->AddAlternative(end_alternative); + return result; + } + case NOT_AFTER_LEAD_SURROGATE: + return AssertionNode::NotAfterLeadSurrogate(on_success); + case NOT_IN_SURROGATE_PAIR: + return AssertionNode::NotInSurrogatePair(on_success); + default: + MOZ_CRASH("Bad assertion type"); + } + return on_success; +} + +RegExpNode* +RegExpBackReference::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return compiler->alloc()->newInfallible<BackReferenceNode>(RegExpCapture::StartRegister(index()), + RegExpCapture::EndRegister(index()), + on_success); +} + +RegExpNode* +RegExpEmpty::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return on_success; +} + +RegExpNode* +RegExpLookahead::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + int stack_pointer_register = compiler->AllocateRegister(); + int position_register = compiler->AllocateRegister(); + + const int registers_per_capture = 2; + const int register_of_first_capture = 2; + int register_count = capture_count_ * registers_per_capture; + int register_start = + register_of_first_capture + capture_from_ * registers_per_capture; + + if (is_positive()) { + RegExpNode* bodyNode = + body()->ToNode(compiler, + ActionNode::PositiveSubmatchSuccess(stack_pointer_register, + position_register, + register_count, + register_start, + on_success)); + return ActionNode::BeginSubmatch(stack_pointer_register, + position_register, + bodyNode); + } + + // We use a ChoiceNode for a negative lookahead because it has most of + // the characteristics we need. It has the body of the lookahead as its + // first alternative and the expression after the lookahead of the second + // alternative. If the first alternative succeeds then the + // NegativeSubmatchSuccess will unwind the stack including everything the + // choice node set up and backtrack. If the first alternative fails then + // the second alternative is tried, which is exactly the desired result + // for a negative lookahead. The NegativeLookaheadChoiceNode is a special + // ChoiceNode that knows to ignore the first exit when calculating quick + // checks. + LifoAlloc* alloc = compiler->alloc(); + + RegExpNode* success = + alloc->newInfallible<NegativeSubmatchSuccess>(alloc, + stack_pointer_register, + position_register, + register_count, + register_start); + GuardedAlternative body_alt(body()->ToNode(compiler, success)); + + ChoiceNode* choice_node = + alloc->newInfallible<NegativeLookaheadChoiceNode>(alloc, body_alt, GuardedAlternative(on_success)); + + return ActionNode::BeginSubmatch(stack_pointer_register, + position_register, + choice_node); +} + +RegExpNode* +RegExpCapture::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + return ToNode(body(), index(), compiler, on_success); +} + +/* static */ RegExpNode* +RegExpCapture::ToNode(RegExpTree* body, + int index, + RegExpCompiler* compiler, + RegExpNode* on_success) +{ + int start_reg = RegExpCapture::StartRegister(index); + int end_reg = RegExpCapture::EndRegister(index); + RegExpNode* store_end = ActionNode::StorePosition(end_reg, true, on_success); + RegExpNode* body_node = body->ToNode(compiler, store_end); + return ActionNode::StorePosition(start_reg, true, body_node); +} + +RegExpNode* +RegExpAlternative::ToNode(RegExpCompiler* compiler, RegExpNode* on_success) +{ + const RegExpTreeVector& children = nodes(); + RegExpNode* current = on_success; + for (int i = children.length() - 1; i >= 0; i--) + current = children[i]->ToNode(compiler, current); + return current; +} + +// ------------------------------------------------------------------- +// BoyerMooreLookahead + +ContainedInLattice +irregexp::AddRange(ContainedInLattice containment, + const int* ranges, + int ranges_length, + Interval new_range) +{ + MOZ_ASSERT((ranges_length & 1) == 1); + MOZ_ASSERT(ranges[ranges_length - 1] == kMaxUtf16CodeUnit + 1); + if (containment == kLatticeUnknown) return containment; + bool inside = false; + int last = 0; + for (int i = 0; i < ranges_length; inside = !inside, last = ranges[i], i++) { + // Consider the range from last to ranges[i]. + // We haven't got to the new range yet. + if (ranges[i] <= new_range.from()) + continue; + + // New range is wholly inside last-ranges[i]. Note that new_range.to() is + // inclusive, but the values in ranges are not. + if (last <= new_range.from() && new_range.to() < ranges[i]) + return Combine(containment, inside ? kLatticeIn : kLatticeOut); + + return kLatticeUnknown; + } + return containment; +} + +void +BoyerMoorePositionInfo::Set(int character) +{ + SetInterval(Interval(character, character)); +} + +void +BoyerMoorePositionInfo::SetInterval(const Interval& interval) +{ + s_ = AddRange(s_, kSpaceRanges, kSpaceRangeCount, interval); + w_ = AddRange(w_, kWordRanges, kWordRangeCount, interval); + d_ = AddRange(d_, kDigitRanges, kDigitRangeCount, interval); + surrogate_ = + AddRange(surrogate_, kSurrogateRanges, kSurrogateRangeCount, interval); + if (interval.to() - interval.from() >= kMapSize - 1) { + if (map_count_ != kMapSize) { + map_count_ = kMapSize; + for (int i = 0; i < kMapSize; i++) + map_[i] = true; + } + return; + } + for (int i = interval.from(); i <= interval.to(); i++) { + int mod_character = (i & kMask); + if (!map_[mod_character]) { + map_count_++; + map_[mod_character] = true; + } + if (map_count_ == kMapSize) + return; + } +} + +void +BoyerMoorePositionInfo::SetAll() +{ + s_ = w_ = d_ = kLatticeUnknown; + if (map_count_ != kMapSize) { + map_count_ = kMapSize; + for (int i = 0; i < kMapSize; i++) + map_[i] = true; + } +} + +BoyerMooreLookahead::BoyerMooreLookahead(LifoAlloc* alloc, size_t length, RegExpCompiler* compiler) + : length_(length), compiler_(compiler), bitmaps_(*alloc) +{ + max_char_ = MaximumCharacter(compiler->ascii()); + + bitmaps_.reserve(length); + for (size_t i = 0; i < length; i++) + bitmaps_.append(alloc->newInfallible<BoyerMoorePositionInfo>(alloc)); +} + +// Find the longest range of lookahead that has the fewest number of different +// characters that can occur at a given position. Since we are optimizing two +// different parameters at once this is a tradeoff. +bool BoyerMooreLookahead::FindWorthwhileInterval(int* from, int* to) { + int biggest_points = 0; + // If more than 32 characters out of 128 can occur it is unlikely that we can + // be lucky enough to step forwards much of the time. + const int kMaxMax = 32; + for (int max_number_of_chars = 4; + max_number_of_chars < kMaxMax; + max_number_of_chars *= 2) { + biggest_points = + FindBestInterval(max_number_of_chars, biggest_points, from, to); + } + if (biggest_points == 0) return false; + return true; +} + +// Find the highest-points range between 0 and length_ where the character +// information is not too vague. 'Too vague' means that there are more than +// max_number_of_chars that can occur at this position. Calculates the number +// of points as the product of width-of-the-range and +// probability-of-finding-one-of-the-characters, where the probability is +// calculated using the frequency distribution of the sample subject string. +int +BoyerMooreLookahead::FindBestInterval(int max_number_of_chars, int old_biggest_points, + int* from, int* to) +{ + int biggest_points = old_biggest_points; + static const int kSize = RegExpMacroAssembler::kTableSize; + for (int i = 0; i < length_; ) { + while (i < length_ && Count(i) > max_number_of_chars) i++; + if (i == length_) break; + int remembered_from = i; + bool union_map[kSize]; + for (int j = 0; j < kSize; j++) union_map[j] = false; + while (i < length_ && Count(i) <= max_number_of_chars) { + BoyerMoorePositionInfo* map = bitmaps_[i]; + for (int j = 0; j < kSize; j++) union_map[j] |= map->at(j); + i++; + } + int frequency = 0; + for (int j = 0; j < kSize; j++) { + if (union_map[j]) { + // Add 1 to the frequency to give a small per-character boost for + // the cases where our sampling is not good enough and many + // characters have a frequency of zero. This means the frequency + // can theoretically be up to 2*kSize though we treat it mostly as + // a fraction of kSize. + frequency += compiler_->frequency_collator()->Frequency(j) + 1; + } + } + // We use the probability of skipping times the distance we are skipping to + // judge the effectiveness of this. Actually we have a cut-off: By + // dividing by 2 we switch off the skipping if the probability of skipping + // is less than 50%. This is because the multibyte mask-and-compare + // skipping in quickcheck is more likely to do well on this case. + bool in_quickcheck_range = ((i - remembered_from < 4) || + (compiler_->ascii() ? remembered_from <= 4 : remembered_from <= 2)); + // Called 'probability' but it is only a rough estimate and can actually + // be outside the 0-kSize range. + int probability = (in_quickcheck_range ? kSize / 2 : kSize) - frequency; + int points = (i - remembered_from) * probability; + if (points > biggest_points) { + *from = remembered_from; + *to = i - 1; + biggest_points = points; + } + } + return biggest_points; +} + +// Take all the characters that will not prevent a successful match if they +// occur in the subject string in the range between min_lookahead and +// max_lookahead (inclusive) measured from the current position. If the +// character at max_lookahead offset is not one of these characters, then we +// can safely skip forwards by the number of characters in the range. +int BoyerMooreLookahead::GetSkipTable(int min_lookahead, + int max_lookahead, + uint8_t* boolean_skip_table) +{ + const int kSize = RegExpMacroAssembler::kTableSize; + + const int kSkipArrayEntry = 0; + const int kDontSkipArrayEntry = 1; + + for (int i = 0; i < kSize; i++) + boolean_skip_table[i] = kSkipArrayEntry; + int skip = max_lookahead + 1 - min_lookahead; + + for (int i = max_lookahead; i >= min_lookahead; i--) { + BoyerMoorePositionInfo* map = bitmaps_[i]; + for (int j = 0; j < kSize; j++) { + if (map->at(j)) + boolean_skip_table[j] = kDontSkipArrayEntry; + } + } + + return skip; +} + +// See comment on the implementation of GetSkipTable. +bool +BoyerMooreLookahead::EmitSkipInstructions(RegExpMacroAssembler* masm) +{ + const int kSize = RegExpMacroAssembler::kTableSize; + + int min_lookahead = 0; + int max_lookahead = 0; + + if (!FindWorthwhileInterval(&min_lookahead, &max_lookahead)) + return false; + + bool found_single_character = false; + int single_character = 0; + for (int i = max_lookahead; i >= min_lookahead; i--) { + BoyerMoorePositionInfo* map = bitmaps_[i]; + if (map->map_count() > 1 || + (found_single_character && map->map_count() != 0)) { + found_single_character = false; + break; + } + for (int j = 0; j < kSize; j++) { + if (map->at(j)) { + found_single_character = true; + single_character = j; + break; + } + } + } + + int lookahead_width = max_lookahead + 1 - min_lookahead; + + if (found_single_character && lookahead_width == 1 && max_lookahead < 3) { + // The mask-compare can probably handle this better. + return false; + } + + if (found_single_character) { + jit::Label cont, again; + masm->Bind(&again); + masm->LoadCurrentCharacter(max_lookahead, &cont, true); + if (max_char_ > kSize) { + masm->CheckCharacterAfterAnd(single_character, + RegExpMacroAssembler::kTableMask, + &cont); + } else { + masm->CheckCharacter(single_character, &cont); + } + masm->AdvanceCurrentPosition(lookahead_width); + masm->JumpOrBacktrack(&again); + masm->Bind(&cont); + return true; + } + + uint8_t* boolean_skip_table; + { + AutoEnterOOMUnsafeRegion oomUnsafe; + boolean_skip_table = static_cast<uint8_t*>(js_malloc(kSize)); + if (!boolean_skip_table || !masm->shared->addTable(boolean_skip_table)) + oomUnsafe.crash("Table malloc"); + } + + int skip_distance = GetSkipTable(min_lookahead, max_lookahead, boolean_skip_table); + MOZ_ASSERT(skip_distance != 0); + + jit::Label cont, again; + masm->Bind(&again); + masm->LoadCurrentCharacter(max_lookahead, &cont, true); + masm->CheckBitInTable(boolean_skip_table, &cont); + masm->AdvanceCurrentPosition(skip_distance); + masm->JumpOrBacktrack(&again); + masm->Bind(&cont); + + return true; +} + +bool +BoyerMooreLookahead::CheckOverRecursed() +{ + JS_CHECK_RECURSION(compiler()->cx(), compiler()->SetRegExpTooBig(); return false); + return true; +} + +// ------------------------------------------------------------------- +// Trace + +bool Trace::DeferredAction::Mentions(int that) +{ + if (action_type() == ActionNode::CLEAR_CAPTURES) { + Interval range = static_cast<DeferredClearCaptures*>(this)->range(); + return range.Contains(that); + } + return reg() == that; +} + +bool Trace::mentions_reg(int reg) +{ + for (DeferredAction* action = actions_; action != nullptr; action = action->next()) { + if (action->Mentions(reg)) + return true; + } + return false; +} + +bool +Trace::GetStoredPosition(int reg, int* cp_offset) +{ + MOZ_ASSERT(0 == *cp_offset); + for (DeferredAction* action = actions_; action != nullptr; action = action->next()) { + if (action->Mentions(reg)) { + if (action->action_type() == ActionNode::STORE_POSITION) { + *cp_offset = static_cast<DeferredCapture*>(action)->cp_offset(); + return true; + } + return false; + } + } + return false; +} + +int +Trace::FindAffectedRegisters(LifoAlloc* alloc, OutSet* affected_registers) +{ + int max_register = RegExpCompiler::kNoRegister; + for (DeferredAction* action = actions_; action != nullptr; action = action->next()) { + if (action->action_type() == ActionNode::CLEAR_CAPTURES) { + Interval range = static_cast<DeferredClearCaptures*>(action)->range(); + for (int i = range.from(); i <= range.to(); i++) + affected_registers->Set(alloc, i); + if (range.to() > max_register) max_register = range.to(); + } else { + affected_registers->Set(alloc, action->reg()); + if (action->reg() > max_register) max_register = action->reg(); + } + } + return max_register; +} + +void +Trace::RestoreAffectedRegisters(RegExpMacroAssembler* assembler, + int max_register, + OutSet& registers_to_pop, + OutSet& registers_to_clear) +{ + for (int reg = max_register; reg >= 0; reg--) { + if (registers_to_pop.Get(reg)) assembler->PopRegister(reg); + else if (registers_to_clear.Get(reg)) { + int clear_to = reg; + while (reg > 0 && registers_to_clear.Get(reg - 1)) + reg--; + assembler->ClearRegisters(reg, clear_to); + } + } +} + +enum DeferredActionUndoType { + DEFER_IGNORE, + DEFER_RESTORE, + DEFER_CLEAR +}; + +void +Trace::PerformDeferredActions(LifoAlloc* alloc, + RegExpMacroAssembler* assembler, + int max_register, + OutSet& affected_registers, + OutSet* registers_to_pop, + OutSet* registers_to_clear) +{ + // The "+1" is to avoid a push_limit of zero if stack_limit_slack() is 1. + const int push_limit = (assembler->stack_limit_slack() + 1) / 2; + + // Count pushes performed to force a stack limit check occasionally. + int pushes = 0; + + for (int reg = 0; reg <= max_register; reg++) { + if (!affected_registers.Get(reg)) + continue; + + // The chronologically first deferred action in the trace + // is used to infer the action needed to restore a register + // to its previous state (or not, if it's safe to ignore it). + DeferredActionUndoType undo_action = DEFER_IGNORE; + + int value = 0; + bool absolute = false; + bool clear = false; + int store_position = -1; + // This is a little tricky because we are scanning the actions in reverse + // historical order (newest first). + for (DeferredAction* action = actions_; + action != nullptr; + action = action->next()) { + if (action->Mentions(reg)) { + switch (action->action_type()) { + case ActionNode::SET_REGISTER: { + Trace::DeferredSetRegister* psr = + static_cast<Trace::DeferredSetRegister*>(action); + if (!absolute) { + value += psr->value(); + absolute = true; + } + // SET_REGISTER is currently only used for newly introduced loop + // counters. They can have a significant previous value if they + // occour in a loop. TODO(lrn): Propagate this information, so + // we can set undo_action to IGNORE if we know there is no value to + // restore. + undo_action = DEFER_RESTORE; + MOZ_ASSERT(store_position == -1); + MOZ_ASSERT(!clear); + break; + } + case ActionNode::INCREMENT_REGISTER: + if (!absolute) { + value++; + } + MOZ_ASSERT(store_position == -1); + MOZ_ASSERT(!clear); + undo_action = DEFER_RESTORE; + break; + case ActionNode::STORE_POSITION: { + Trace::DeferredCapture* pc = + static_cast<Trace::DeferredCapture*>(action); + if (!clear && store_position == -1) { + store_position = pc->cp_offset(); + } + + // For captures we know that stores and clears alternate. + // Other register, are never cleared, and if the occur + // inside a loop, they might be assigned more than once. + if (reg <= 1) { + // Registers zero and one, aka "capture zero", is + // always set correctly if we succeed. There is no + // need to undo a setting on backtrack, because we + // will set it again or fail. + undo_action = DEFER_IGNORE; + } else { + undo_action = pc->is_capture() ? DEFER_CLEAR : DEFER_RESTORE; + } + MOZ_ASSERT(!absolute); + MOZ_ASSERT(value == 0); + break; + } + case ActionNode::CLEAR_CAPTURES: { + // Since we're scanning in reverse order, if we've already + // set the position we have to ignore historically earlier + // clearing operations. + if (store_position == -1) { + clear = true; + } + undo_action = DEFER_RESTORE; + MOZ_ASSERT(!absolute); + MOZ_ASSERT(value == 0); + break; + } + default: + MOZ_CRASH("Bad action"); + } + } + } + // Prepare for the undo-action (e.g., push if it's going to be popped). + if (undo_action == DEFER_RESTORE) { + pushes++; + RegExpMacroAssembler::StackCheckFlag stack_check = + RegExpMacroAssembler::kNoStackLimitCheck; + if (pushes == push_limit) { + stack_check = RegExpMacroAssembler::kCheckStackLimit; + pushes = 0; + } + + assembler->PushRegister(reg, stack_check); + registers_to_pop->Set(alloc, reg); + } else if (undo_action == DEFER_CLEAR) { + registers_to_clear->Set(alloc, reg); + } + // Perform the chronologically last action (or accumulated increment) + // for the register. + if (store_position != -1) { + assembler->WriteCurrentPositionToRegister(reg, store_position); + } else if (clear) { + assembler->ClearRegisters(reg, reg); + } else if (absolute) { + assembler->SetRegister(reg, value); + } else if (value != 0) { + assembler->AdvanceRegister(reg, value); + } + } +} + +// This is called as we come into a loop choice node and some other tricky +// nodes. It normalizes the state of the code generator to ensure we can +// generate generic code. +void Trace::Flush(RegExpCompiler* compiler, RegExpNode* successor) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + MOZ_ASSERT(!is_trivial()); + + if (actions_ == nullptr && backtrack() == nullptr) { + // Here we just have some deferred cp advances to fix and we are back to + // a normal situation. We may also have to forget some information gained + // through a quick check that was already performed. + if (cp_offset_ != 0) assembler->AdvanceCurrentPosition(cp_offset_); + // Create a new trivial state and generate the node with that. + Trace new_state; + successor->Emit(compiler, &new_state); + return; + } + + // Generate deferred actions here along with code to undo them again. + OutSet affected_registers; + + if (backtrack() != nullptr) { + // Here we have a concrete backtrack location. These are set up by choice + // nodes and so they indicate that we have a deferred save of the current + // position which we may need to emit here. + assembler->PushCurrentPosition(); + } + + int max_register = FindAffectedRegisters(compiler->alloc(), &affected_registers); + OutSet registers_to_pop; + OutSet registers_to_clear; + PerformDeferredActions(compiler->alloc(), + assembler, + max_register, + affected_registers, + ®isters_to_pop, + ®isters_to_clear); + if (cp_offset_ != 0) + assembler->AdvanceCurrentPosition(cp_offset_); + + // Create a new trivial state and generate the node with that. + jit::Label undo; + assembler->PushBacktrack(&undo); + Trace new_state; + successor->Emit(compiler, &new_state); + + // On backtrack we need to restore state. + assembler->BindBacktrack(&undo); + RestoreAffectedRegisters(assembler, + max_register, + registers_to_pop, + registers_to_clear); + if (backtrack() == nullptr) { + assembler->Backtrack(); + } else { + assembler->PopCurrentPosition(); + assembler->JumpOrBacktrack(backtrack()); + } +} + +void +Trace::InvalidateCurrentCharacter() +{ + characters_preloaded_ = 0; +} + +void +Trace::AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler) +{ + MOZ_ASSERT(by > 0); + // We don't have an instruction for shifting the current character register + // down or for using a shifted value for anything so lets just forget that + // we preloaded any characters into it. + characters_preloaded_ = 0; + // Adjust the offsets of the quick check performed information. This + // information is used to find out what we already determined about the + // characters by means of mask and compare. + quick_check_performed_.Advance(by, compiler->ascii()); + cp_offset_ += by; + if (cp_offset_ > RegExpMacroAssembler::kMaxCPOffset) { + compiler->SetRegExpTooBig(); + cp_offset_ = 0; + } + bound_checked_up_to_ = Max(0, bound_checked_up_to_ - by); +} + +void +OutSet::Set(LifoAlloc* alloc, unsigned value) +{ + if (value < kFirstLimit) { + first_ |= (1 << value); + } else { + if (remaining_ == nullptr) + remaining_ = alloc->newInfallible<RemainingVector>(*alloc); + + for (size_t i = 0; i < remaining().length(); i++) { + if (remaining()[i] == value) + return; + } + remaining().append(value); + } +} + +bool +OutSet::Get(unsigned value) +{ + if (value < kFirstLimit) + return (first_ & (1 << value)) != 0; + if (remaining_ == nullptr) + return false; + for (size_t i = 0; i < remaining().length(); i++) { + if (remaining()[i] == value) + return true; + } + return false; +} + +// ------------------------------------------------------------------- +// Graph emitting + +void +NegativeSubmatchSuccess::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + // Omit flushing the trace. We discard the entire stack frame anyway. + + if (!label()->bound()) { + // We are completely independent of the trace, since we ignore it, + // so this code can be used as the generic version. + assembler->Bind(label()); + } + + // Throw away everything on the backtrack stack since the start + // of the negative submatch and restore the character position. + assembler->ReadCurrentPositionFromRegister(current_position_register_); + assembler->ReadBacktrackStackPointerFromRegister(stack_pointer_register_); + + if (clear_capture_count_ > 0) { + // Clear any captures that might have been performed during the success + // of the body of the negative look-ahead. + int clear_capture_end = clear_capture_start_ + clear_capture_count_ - 1; + assembler->ClearRegisters(clear_capture_start_, clear_capture_end); + } + + // Now that we have unwound the stack we find at the top of the stack the + // backtrack that the BeginSubmatch node got. + assembler->Backtrack(); +} + +void +EndNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + if (!trace->is_trivial()) { + trace->Flush(compiler, this); + return; + } + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + if (!label()->bound()) { + assembler->Bind(label()); + } + switch (action_) { + case ACCEPT: + assembler->Succeed(); + return; + case BACKTRACK: + assembler->JumpOrBacktrack(trace->backtrack()); + return; + case NEGATIVE_SUBMATCH_SUCCESS: + // This case is handled in a different virtual method. + MOZ_CRASH("Bad action: NEGATIVE_SUBMATCH_SUCCESS"); + } + MOZ_CRASH("Bad action"); +} + +// Emit the code to check for a ^ in multiline mode (1-character lookbehind +// that matches newline or the start of input). +static void +EmitHat(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + // We will be loading the previous character into the current character + // register. + Trace new_trace(*trace); + new_trace.InvalidateCurrentCharacter(); + + jit::Label ok; + if (new_trace.cp_offset() == 0) { + // The start of input counts as a newline in this context, so skip to + // ok if we are at the start. + assembler->CheckAtStart(&ok); + } + + // We already checked that we are not at the start of input so it must be + // OK to load the previous character. + assembler->LoadCurrentCharacter(new_trace.cp_offset() -1, new_trace.backtrack(), false); + + if (!assembler->CheckSpecialCharacterClass('n', new_trace.backtrack())) { + // Newline means \n, \r, 0x2028 or 0x2029. + if (!compiler->ascii()) + assembler->CheckCharacterAfterAnd(0x2028, 0xfffe, &ok); + assembler->CheckCharacter('\n', &ok); + assembler->CheckNotCharacter('\r', new_trace.backtrack()); + } + assembler->Bind(&ok); + on_success->Emit(compiler, &new_trace); +} + +// Assert that the next character cannot be a part of a surrogate pair. +static void +EmitNotAfterLeadSurrogate(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + // We will be loading the previous character into the current character + // register. + Trace new_trace(*trace); + new_trace.InvalidateCurrentCharacter(); + + jit::Label ok; + if (new_trace.cp_offset() == 0) + assembler->CheckAtStart(&ok); + + // We already checked that we are not at the start of input so it must be + // OK to load the previous character. + assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, new_trace.backtrack(), false); + assembler->CheckCharacterInRange(unicode::LeadSurrogateMin, unicode::LeadSurrogateMax, + new_trace.backtrack()); + + assembler->Bind(&ok); + on_success->Emit(compiler, &new_trace); +} + +// Assert that the next character is not a trail surrogate that has a +// corresponding lead surrogate. +static void +EmitNotInSurrogatePair(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + jit::Label ok; + assembler->CheckPosition(trace->cp_offset(), &ok); + + // We will be loading the next and previous characters into the current + // character register. + Trace new_trace(*trace); + new_trace.InvalidateCurrentCharacter(); + + if (new_trace.cp_offset() == 0) + assembler->CheckAtStart(&ok); + + // First check if next character is a trail surrogate. + assembler->LoadCurrentCharacter(new_trace.cp_offset(), new_trace.backtrack(), false); + assembler->CheckCharacterNotInRange(unicode::TrailSurrogateMin, unicode::TrailSurrogateMax, + &ok); + + // Next check if previous character is a lead surrogate. + // We already checked that we are not at the start of input so it must be + // OK to load the previous character. + assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, new_trace.backtrack(), false); + assembler->CheckCharacterInRange(unicode::LeadSurrogateMin, unicode::LeadSurrogateMax, + new_trace.backtrack()); + + assembler->Bind(&ok); + on_success->Emit(compiler, &new_trace); +} + +// Check for [0-9A-Z_a-z]. +static void +EmitWordCheck(RegExpMacroAssembler* assembler, + jit::Label* word, jit::Label* non_word, bool fall_through_on_word) +{ + if (assembler->CheckSpecialCharacterClass(fall_through_on_word ? 'w' : 'W', + fall_through_on_word ? non_word : word)) + { + // Optimized implementation available. + return; + } + + assembler->CheckCharacterGT('z', non_word); + assembler->CheckCharacterLT('0', non_word); + assembler->CheckCharacterGT('a' - 1, word); + assembler->CheckCharacterLT('9' + 1, word); + assembler->CheckCharacterLT('A', non_word); + assembler->CheckCharacterLT('Z' + 1, word); + + if (fall_through_on_word) + assembler->CheckNotCharacter('_', non_word); + else + assembler->CheckCharacter('_', word); +} + +// Emit the code to handle \b and \B (word-boundary or non-word-boundary). +void +AssertionNode::EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + Trace::TriBool next_is_word_character = Trace::UNKNOWN; + bool not_at_start = (trace->at_start() == Trace::FALSE_VALUE); + BoyerMooreLookahead* lookahead = bm_info(not_at_start); + if (lookahead == nullptr) { + int eats_at_least = + Min(kMaxLookaheadForBoyerMoore, EatsAtLeast(kMaxLookaheadForBoyerMoore, + kRecursionBudget, + not_at_start)); + if (eats_at_least >= 1) { + BoyerMooreLookahead* bm = + alloc()->newInfallible<BoyerMooreLookahead>(alloc(), eats_at_least, compiler); + FillInBMInfo(0, kRecursionBudget, bm, not_at_start); + if (bm->at(0)->is_non_word()) + next_is_word_character = Trace::FALSE_VALUE; + if (bm->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE; + } + } else { + if (lookahead->at(0)->is_non_word()) + next_is_word_character = Trace::FALSE_VALUE; + if (lookahead->at(0)->is_word()) + next_is_word_character = Trace::TRUE_VALUE; + } + bool at_boundary = (assertion_type_ == AssertionNode::AT_BOUNDARY); + if (next_is_word_character == Trace::UNKNOWN) { + jit::Label before_non_word; + jit::Label before_word; + if (trace->characters_preloaded() != 1) { + assembler->LoadCurrentCharacter(trace->cp_offset(), &before_non_word); + } + // Fall through on non-word. + EmitWordCheck(assembler, &before_word, &before_non_word, false); + // Next character is not a word character. + assembler->Bind(&before_non_word); + jit::Label ok; + BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord); + assembler->JumpOrBacktrack(&ok); + + assembler->Bind(&before_word); + BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord); + assembler->Bind(&ok); + } else if (next_is_word_character == Trace::TRUE_VALUE) { + BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord); + } else { + MOZ_ASSERT(next_is_word_character == Trace::FALSE_VALUE); + BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord); + } +} + +void +AssertionNode::BacktrackIfPrevious(RegExpCompiler* compiler, + Trace* trace, + AssertionNode::IfPrevious backtrack_if_previous) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + Trace new_trace(*trace); + new_trace.InvalidateCurrentCharacter(); + + jit::Label fall_through, dummy; + + jit::Label* non_word = backtrack_if_previous == kIsNonWord ? new_trace.backtrack() : &fall_through; + jit::Label* word = backtrack_if_previous == kIsNonWord ? &fall_through : new_trace.backtrack(); + + if (new_trace.cp_offset() == 0) { + // The start of input counts as a non-word character, so the question is + // decided if we are at the start. + assembler->CheckAtStart(non_word); + } + // We already checked that we are not at the start of input so it must be + // OK to load the previous character. + assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, &dummy, false); + EmitWordCheck(assembler, word, non_word, backtrack_if_previous == kIsNonWord); + + assembler->Bind(&fall_through); + on_success()->Emit(compiler, &new_trace); +} + +void +AssertionNode::GetQuickCheckDetails(QuickCheckDetails* details, + RegExpCompiler* compiler, + int filled_in, + bool not_at_start) +{ + if (assertion_type_ == AT_START && not_at_start) { + details->set_cannot_match(); + return; + } + return on_success()->GetQuickCheckDetails(details, compiler, filled_in, not_at_start); +} + +void +AssertionNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + switch (assertion_type_) { + case AT_END: { + jit::Label ok; + assembler->CheckPosition(trace->cp_offset(), &ok); + assembler->JumpOrBacktrack(trace->backtrack()); + assembler->Bind(&ok); + break; + } + case AT_START: { + if (trace->at_start() == Trace::FALSE_VALUE) { + assembler->JumpOrBacktrack(trace->backtrack()); + return; + } + if (trace->at_start() == Trace::UNKNOWN) { + assembler->CheckNotAtStart(trace->backtrack()); + Trace at_start_trace = *trace; + at_start_trace.set_at_start(true); + on_success()->Emit(compiler, &at_start_trace); + return; + } + } + break; + case AFTER_NEWLINE: + EmitHat(compiler, on_success(), trace); + return; + case AT_BOUNDARY: + case AT_NON_BOUNDARY: { + EmitBoundaryCheck(compiler, trace); + return; + } + case NOT_AFTER_LEAD_SURROGATE: + EmitNotAfterLeadSurrogate(compiler, on_success(), trace); + return; + case NOT_IN_SURROGATE_PAIR: + EmitNotInSurrogatePair(compiler, on_success(), trace); + return; + } + on_success()->Emit(compiler, trace); +} + +static bool +DeterminedAlready(QuickCheckDetails* quick_check, int offset) +{ + if (quick_check == nullptr) + return false; + if (offset >= quick_check->characters()) + return false; + return quick_check->positions(offset)->determines_perfectly; +} + +static void +UpdateBoundsCheck(int index, int* checked_up_to) +{ + if (index > *checked_up_to) + *checked_up_to = index; +} + +static void +EmitBoundaryTest(RegExpMacroAssembler* masm, + int border, + jit::Label* fall_through, + jit::Label* above_or_equal, + jit::Label* below) +{ + if (below != fall_through) { + masm->CheckCharacterLT(border, below); + if (above_or_equal != fall_through) + masm->JumpOrBacktrack(above_or_equal); + } else { + masm->CheckCharacterGT(border - 1, above_or_equal); + } +} + +static void +EmitDoubleBoundaryTest(RegExpMacroAssembler* masm, + int first, + int last, + jit::Label* fall_through, + jit::Label* in_range, + jit::Label* out_of_range) +{ + if (in_range == fall_through) { + if (first == last) + masm->CheckNotCharacter(first, out_of_range); + else + masm->CheckCharacterNotInRange(first, last, out_of_range); + } else { + if (first == last) + masm->CheckCharacter(first, in_range); + else + masm->CheckCharacterInRange(first, last, in_range); + if (out_of_range != fall_through) + masm->JumpOrBacktrack(out_of_range); + } +} + +typedef InfallibleVector<int, 4> RangeBoundaryVector; + +// even_label is for ranges[i] to ranges[i + 1] where i - start_index is even. +// odd_label is for ranges[i] to ranges[i + 1] where i - start_index is odd. +static void +EmitUseLookupTable(RegExpMacroAssembler* masm, + RangeBoundaryVector& ranges, + int start_index, + int end_index, + int min_char, + jit::Label* fall_through, + jit::Label* even_label, + jit::Label* odd_label) +{ + static const int kSize = RegExpMacroAssembler::kTableSize; + static const int kMask = RegExpMacroAssembler::kTableMask; + + DebugOnly<int> base = (min_char & ~kMask); + + // Assert that everything is on one kTableSize page. + for (int i = start_index; i <= end_index; i++) + MOZ_ASSERT((ranges[i] & ~kMask) == base); + MOZ_ASSERT(start_index == 0 || (ranges[start_index - 1] & ~kMask) <= base); + + char templ[kSize]; + jit::Label* on_bit_set; + jit::Label* on_bit_clear; + int bit; + if (even_label == fall_through) { + on_bit_set = odd_label; + on_bit_clear = even_label; + bit = 1; + } else { + on_bit_set = even_label; + on_bit_clear = odd_label; + bit = 0; + } + for (int i = 0; i < (ranges[start_index] & kMask) && i < kSize; i++) + templ[i] = bit; + int j = 0; + bit ^= 1; + for (int i = start_index; i < end_index; i++) { + for (j = (ranges[i] & kMask); j < (ranges[i + 1] & kMask); j++) { + templ[j] = bit; + } + bit ^= 1; + } + for (int i = j; i < kSize; i++) { + templ[i] = bit; + } + + // TODO(erikcorry): Cache these. + uint8_t* ba; + { + AutoEnterOOMUnsafeRegion oomUnsafe; + ba = static_cast<uint8_t*>(js_malloc(kSize)); + if (!ba || !masm->shared->addTable(ba)) + oomUnsafe.crash("Table malloc"); + } + + for (int i = 0; i < kSize; i++) + ba[i] = templ[i]; + + masm->CheckBitInTable(ba, on_bit_set); + if (on_bit_clear != fall_through) + masm->JumpOrBacktrack(on_bit_clear); +} + +static void +CutOutRange(RegExpMacroAssembler* masm, + RangeBoundaryVector& ranges, + int start_index, + int end_index, + int cut_index, + jit::Label* even_label, + jit::Label* odd_label) +{ + bool odd = (((cut_index - start_index) & 1) == 1); + jit::Label* in_range_label = odd ? odd_label : even_label; + jit::Label dummy; + EmitDoubleBoundaryTest(masm, + ranges[cut_index], + ranges[cut_index + 1] - 1, + &dummy, + in_range_label, + &dummy); + MOZ_ASSERT(!dummy.used()); + // Cut out the single range by rewriting the array. This creates a new + // range that is a merger of the two ranges on either side of the one we + // are cutting out. The oddity of the labels is preserved. + for (int j = cut_index; j > start_index; j--) + ranges[j] = ranges[j - 1]; + for (int j = cut_index + 1; j < end_index; j++) + ranges[j] = ranges[j + 1]; +} + +// Unicode case. Split the search space into kSize spaces that are handled +// with recursion. +static void +SplitSearchSpace(RangeBoundaryVector& ranges, + int start_index, + int end_index, + int* new_start_index, + int* new_end_index, + int* border) +{ + static const int kSize = RegExpMacroAssembler::kTableSize; + static const int kMask = RegExpMacroAssembler::kTableMask; + + int first = ranges[start_index]; + int last = ranges[end_index] - 1; + + *new_start_index = start_index; + *border = (ranges[start_index] & ~kMask) + kSize; + while (*new_start_index < end_index) { + if (ranges[*new_start_index] > *border) + break; + (*new_start_index)++; + } + // new_start_index is the index of the first edge that is beyond the + // current kSize space. + + // For very large search spaces we do a binary chop search of the non-ASCII + // space instead of just going to the end of the current kSize space. The + // heuristics are complicated a little by the fact that any 128-character + // encoding space can be quickly tested with a table lookup, so we don't + // wish to do binary chop search at a smaller granularity than that. A + // 128-character space can take up a lot of space in the ranges array if, + // for example, we only want to match every second character (eg. the lower + // case characters on some Unicode pages). + int binary_chop_index = (end_index + start_index) / 2; + // The first test ensures that we get to the code that handles the ASCII + // range with a single not-taken branch, speeding up this important + // character range (even non-ASCII charset-based text has spaces and + // punctuation). + if (*border - 1 > kMaxOneByteCharCode && // ASCII case. + end_index - start_index > (*new_start_index - start_index) * 2 && + last - first > kSize * 2 && + binary_chop_index > *new_start_index && + ranges[binary_chop_index] >= first + 2 * kSize) + { + int scan_forward_for_section_border = binary_chop_index;; + int new_border = (ranges[binary_chop_index] | kMask) + 1; + + while (scan_forward_for_section_border < end_index) { + if (ranges[scan_forward_for_section_border] > new_border) { + *new_start_index = scan_forward_for_section_border; + *border = new_border; + break; + } + scan_forward_for_section_border++; + } + } + + MOZ_ASSERT(*new_start_index > start_index); + *new_end_index = *new_start_index - 1; + if (ranges[*new_end_index] == *border) + (*new_end_index)--; + if (*border >= ranges[end_index]) { + *border = ranges[end_index]; + *new_start_index = end_index; // Won't be used. + *new_end_index = end_index - 1; + } +} + +// Gets a series of segment boundaries representing a character class. If the +// character is in the range between an even and an odd boundary (counting from +// start_index) then go to even_label, otherwise go to odd_label. We already +// know that the character is in the range of min_char to max_char inclusive. +// Either label can be nullptr indicating backtracking. Either label can also be +// equal to the fall_through label. +static void +GenerateBranches(RegExpMacroAssembler* masm, + RangeBoundaryVector& ranges, + int start_index, + int end_index, + char16_t min_char, + char16_t max_char, + jit::Label* fall_through, + jit::Label* even_label, + jit::Label* odd_label) +{ + int first = ranges[start_index]; + int last = ranges[end_index] - 1; + + MOZ_ASSERT(min_char < first); + + // Just need to test if the character is before or on-or-after + // a particular character. + if (start_index == end_index) { + EmitBoundaryTest(masm, first, fall_through, even_label, odd_label); + return; + } + + // Another almost trivial case: There is one interval in the middle that is + // different from the end intervals. + if (start_index + 1 == end_index) { + EmitDoubleBoundaryTest(masm, first, last, fall_through, even_label, odd_label); + return; + } + + // It's not worth using table lookup if there are very few intervals in the + // character class. + if (end_index - start_index <= 6) { + // It is faster to test for individual characters, so we look for those + // first, then try arbitrary ranges in the second round. + static int kNoCutIndex = -1; + int cut = kNoCutIndex; + for (int i = start_index; i < end_index; i++) { + if (ranges[i] == ranges[i + 1] - 1) { + cut = i; + break; + } + } + if (cut == kNoCutIndex) cut = start_index; + CutOutRange(masm, ranges, start_index, end_index, cut, even_label, odd_label); + MOZ_ASSERT(end_index - start_index >= 2); + GenerateBranches(masm, + ranges, + start_index + 1, + end_index - 1, + min_char, + max_char, + fall_through, + even_label, + odd_label); + return; + } + + // If there are a lot of intervals in the regexp, then we will use tables to + // determine whether the character is inside or outside the character class. + static const int kBits = RegExpMacroAssembler::kTableSizeBits; + + if ((max_char >> kBits) == (min_char >> kBits)) { + EmitUseLookupTable(masm, + ranges, + start_index, + end_index, + min_char, + fall_through, + even_label, + odd_label); + return; + } + + if ((min_char >> kBits) != (first >> kBits)) { + masm->CheckCharacterLT(first, odd_label); + GenerateBranches(masm, + ranges, + start_index + 1, + end_index, + first, + max_char, + fall_through, + odd_label, + even_label); + return; + } + + int new_start_index = 0; + int new_end_index = 0; + int border = 0; + + SplitSearchSpace(ranges, + start_index, + end_index, + &new_start_index, + &new_end_index, + &border); + + jit::Label handle_rest; + jit::Label* above = &handle_rest; + if (border == last + 1) { + // We didn't find any section that started after the limit, so everything + // above the border is one of the terminal labels. + above = (end_index & 1) != (start_index & 1) ? odd_label : even_label; + MOZ_ASSERT(new_end_index == end_index - 1); + } + + MOZ_ASSERT(start_index <= new_end_index); + MOZ_ASSERT(new_start_index <= end_index); + MOZ_ASSERT(start_index < new_start_index); + MOZ_ASSERT(new_end_index < end_index); + MOZ_ASSERT(new_end_index + 1 == new_start_index || + (new_end_index + 2 == new_start_index && + border == ranges[new_end_index + 1])); + MOZ_ASSERT(min_char < border - 1); + MOZ_ASSERT(border < max_char); + MOZ_ASSERT(ranges[new_end_index] < border); + MOZ_ASSERT(border < ranges[new_start_index] || + (border == ranges[new_start_index] && + new_start_index == end_index && + new_end_index == end_index - 1 && + border == last + 1)); + MOZ_ASSERT(new_start_index == 0 || border >= ranges[new_start_index - 1]); + + masm->CheckCharacterGT(border - 1, above); + jit::Label dummy; + GenerateBranches(masm, + ranges, + start_index, + new_end_index, + min_char, + border - 1, + &dummy, + even_label, + odd_label); + if (handle_rest.used()) { + masm->Bind(&handle_rest); + bool flip = (new_start_index & 1) != (start_index & 1); + GenerateBranches(masm, + ranges, + new_start_index, + end_index, + border, + max_char, + &dummy, + flip ? odd_label : even_label, + flip ? even_label : odd_label); + } +} + +static void +EmitCharClass(LifoAlloc* alloc, + RegExpMacroAssembler* macro_assembler, + RegExpCharacterClass* cc, + bool ascii, + jit::Label* on_failure, + int cp_offset, + bool check_offset, + bool preloaded) +{ + CharacterRangeVector& ranges = cc->ranges(alloc); + if (!CharacterRange::IsCanonical(ranges)) { + CharacterRange::Canonicalize(ranges); + } + + int max_char = MaximumCharacter(ascii); + int range_count = ranges.length(); + + int last_valid_range = range_count - 1; + while (last_valid_range >= 0) { + CharacterRange& range = ranges[last_valid_range]; + if (range.from() <= max_char) { + break; + } + last_valid_range--; + } + + if (last_valid_range < 0) { + if (!cc->is_negated()) { + macro_assembler->JumpOrBacktrack(on_failure); + } + if (check_offset) { + macro_assembler->CheckPosition(cp_offset, on_failure); + } + return; + } + + if (last_valid_range == 0 && + ranges[0].IsEverything(max_char)) { + if (cc->is_negated()) { + macro_assembler->JumpOrBacktrack(on_failure); + } else { + // This is a common case hit by non-anchored expressions. + if (check_offset) { + macro_assembler->CheckPosition(cp_offset, on_failure); + } + } + return; + } + if (last_valid_range == 0 && + !cc->is_negated() && + ranges[0].IsEverything(max_char)) { + // This is a common case hit by non-anchored expressions. + if (check_offset) { + macro_assembler->CheckPosition(cp_offset, on_failure); + } + return; + } + + if (!preloaded) { + macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check_offset); + } + + if (cc->is_standard(alloc) && + macro_assembler->CheckSpecialCharacterClass(cc->standard_type(), + on_failure)) { + return; + } + + // A new list with ascending entries. Each entry is a code unit + // where there is a boundary between code units that are part of + // the class and code units that are not. Normally we insert an + // entry at zero which goes to the failure label, but if there + // was already one there we fall through for success on that entry. + // Subsequent entries have alternating meaning (success/failure). + RangeBoundaryVector* range_boundaries = + alloc->newInfallible<RangeBoundaryVector>(*alloc); + + bool zeroth_entry_is_failure = !cc->is_negated(); + + range_boundaries->reserve(last_valid_range); + for (int i = 0; i <= last_valid_range; i++) { + CharacterRange& range = ranges[i]; + if (range.from() == 0) { + MOZ_ASSERT(i == 0); + zeroth_entry_is_failure = !zeroth_entry_is_failure; + } else { + range_boundaries->append(range.from()); + } + range_boundaries->append(range.to() + 1); + } + int end_index = range_boundaries->length() - 1; + if ((*range_boundaries)[end_index] > max_char) + end_index--; + + jit::Label fall_through; + GenerateBranches(macro_assembler, + *range_boundaries, + 0, // start_index. + end_index, + 0, // min_char. + max_char, + &fall_through, + zeroth_entry_is_failure ? &fall_through : on_failure, + zeroth_entry_is_failure ? on_failure : &fall_through); + macro_assembler->Bind(&fall_through); +} + +typedef bool EmitCharacterFunction(RegExpCompiler* compiler, + char16_t c, + jit::Label* on_failure, + int cp_offset, + bool check, + bool preloaded); + +static inline bool +EmitSimpleCharacter(RegExpCompiler* compiler, + char16_t c, + jit::Label* on_failure, + int cp_offset, + bool check, + bool preloaded) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + bool bound_checked = false; + if (!preloaded) { + assembler->LoadCurrentCharacter(cp_offset, on_failure, check); + bound_checked = true; + } + assembler->CheckNotCharacter(c, on_failure); + return bound_checked; +} + +// Only emits non-letters (things that don't have case). Only used for case +// independent matches. +static inline bool +EmitAtomNonLetter(RegExpCompiler* compiler, + char16_t c, + jit::Label* on_failure, + int cp_offset, + bool check, + bool preloaded) +{ + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + bool ascii = compiler->ascii(); + char16_t chars[kEcma262UnCanonicalizeMaxWidth]; + int length = GetCaseIndependentLetters(c, ascii, compiler->unicode(), chars); + if (length < 1) { + // This can't match. Must be an ASCII subject and a non-ASCII character. + // We do not need to do anything since the ASCII pass already handled this. + return false; // Bounds not checked. + } + bool checked = false; + // We handle the length > 1 case in a later pass. + if (length == 1) { + if (ascii && c > kMaxOneByteCharCode) { + // Can't match - see above. + return false; // Bounds not checked. + } + if (!preloaded) { + macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check); + checked = check; + } + macro_assembler->CheckNotCharacter(c, on_failure); + } + return checked; +} + +static bool +ShortCutEmitCharacterPair(RegExpMacroAssembler* macro_assembler, + bool ascii, + char16_t c1, + char16_t c2, + jit::Label* on_failure) +{ + char16_t char_mask = MaximumCharacter(ascii); + + MOZ_ASSERT(c1 != c2); + if (c1 > c2) { + char16_t tmp = c1; + c1 = c2; + c2 = tmp; + } + + char16_t exor = c1 ^ c2; + // Check whether exor has only one bit set. + if (((exor - 1) & exor) == 0) { + // If c1 and c2 differ only by one bit. + char16_t mask = char_mask ^ exor; + macro_assembler->CheckNotCharacterAfterAnd(c1, mask, on_failure); + return true; + } + + char16_t diff = c2 - c1; + if (((diff - 1) & diff) == 0 && c1 >= diff) { + // If the characters differ by 2^n but don't differ by one bit then + // subtract the difference from the found character, then do the or + // trick. We avoid the theoretical case where negative numbers are + // involved in order to simplify code generation. + char16_t mask = char_mask ^ diff; + macro_assembler->CheckNotCharacterAfterMinusAnd(c1 - diff, + diff, + mask, + on_failure); + return true; + } + return false; +} + +// Only emits letters (things that have case). Only used for case independent +// matches. +static inline bool +EmitAtomLetter(RegExpCompiler* compiler, + char16_t c, + jit::Label* on_failure, + int cp_offset, + bool check, + bool preloaded) +{ + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + bool ascii = compiler->ascii(); + char16_t chars[kEcma262UnCanonicalizeMaxWidth]; + int length = GetCaseIndependentLetters(c, ascii, compiler->unicode(), chars); + if (length <= 1) return false; + // We may not need to check against the end of the input string + // if this character lies before a character that matched. + if (!preloaded) + macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check); + jit::Label ok; + MOZ_ASSERT(kEcma262UnCanonicalizeMaxWidth == 4); + switch (length) { + case 2: { + if (ShortCutEmitCharacterPair(macro_assembler, + ascii, + chars[0], + chars[1], + on_failure)) { + } else { + macro_assembler->CheckCharacter(chars[0], &ok); + macro_assembler->CheckNotCharacter(chars[1], on_failure); + macro_assembler->Bind(&ok); + } + break; + } + case 4: + macro_assembler->CheckCharacter(chars[3], &ok); + MOZ_FALLTHROUGH; + case 3: + macro_assembler->CheckCharacter(chars[0], &ok); + macro_assembler->CheckCharacter(chars[1], &ok); + macro_assembler->CheckNotCharacter(chars[2], on_failure); + macro_assembler->Bind(&ok); + break; + default: + MOZ_CRASH("Bad length"); + } + return true; +} + +// We call this repeatedly to generate code for each pass over the text node. +// The passes are in increasing order of difficulty because we hope one +// of the first passes will fail in which case we are saved the work of the +// later passes. for example for the case independent regexp /%[asdfghjkl]a/ +// we will check the '%' in the first pass, the case independent 'a' in the +// second pass and the character class in the last pass. +// +// The passes are done from right to left, so for example to test for /bar/ +// we will first test for an 'r' with offset 2, then an 'a' with offset 1 +// and then a 'b' with offset 0. This means we can avoid the end-of-input +// bounds check most of the time. In the example we only need to check for +// end-of-input when loading the putative 'r'. +// +// A slight complication involves the fact that the first character may already +// be fetched into a register by the previous node. In this case we want to +// do the test for that character first. We do this in separate passes. The +// 'preloaded' argument indicates that we are doing such a 'pass'. If such a +// pass has been performed then subsequent passes will have true in +// first_element_checked to indicate that that character does not need to be +// checked again. +// +// In addition to all this we are passed a Trace, which can +// contain an AlternativeGeneration object. In this AlternativeGeneration +// object we can see details of any quick check that was already passed in +// order to get to the code we are now generating. The quick check can involve +// loading characters, which means we do not need to recheck the bounds +// up to the limit the quick check already checked. In addition the quick +// check can have involved a mask and compare operation which may simplify +// or obviate the need for further checks at some character positions. +void +TextNode::TextEmitPass(RegExpCompiler* compiler, + TextEmitPassType pass, + bool preloaded, + Trace* trace, + bool first_element_checked, + int* checked_up_to) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + bool ascii = compiler->ascii(); + jit::Label* backtrack = trace->backtrack(); + QuickCheckDetails* quick_check = trace->quick_check_performed(); + int element_count = elements().length(); + for (int i = preloaded ? 0 : element_count - 1; i >= 0; i--) { + TextElement elm = elements()[i]; + int cp_offset = trace->cp_offset() + elm.cp_offset(); + if (elm.text_type() == TextElement::ATOM) { + const CharacterVector& quarks = elm.atom()->data(); + for (int j = preloaded ? 0 : quarks.length() - 1; j >= 0; j--) { + if (first_element_checked && i == 0 && j == 0) continue; + if (DeterminedAlready(quick_check, elm.cp_offset() + j)) continue; + EmitCharacterFunction* emit_function = nullptr; + switch (pass) { + case NON_ASCII_MATCH: + MOZ_ASSERT(ascii); + if (quarks[j] > kMaxOneByteCharCode) { + assembler->JumpOrBacktrack(backtrack); + return; + } + break; + case NON_LETTER_CHARACTER_MATCH: + emit_function = &EmitAtomNonLetter; + break; + case SIMPLE_CHARACTER_MATCH: + emit_function = &EmitSimpleCharacter; + break; + case CASE_CHARACTER_MATCH: + emit_function = &EmitAtomLetter; + break; + default: + break; + } + if (emit_function != nullptr) { + bool bound_checked = emit_function(compiler, + quarks[j], + backtrack, + cp_offset + j, + *checked_up_to < cp_offset + j, + preloaded); + if (bound_checked) UpdateBoundsCheck(cp_offset + j, checked_up_to); + } + } + } else { + MOZ_ASSERT(TextElement::CHAR_CLASS == elm.text_type()); + if (pass == CHARACTER_CLASS_MATCH) { + if (first_element_checked && i == 0) continue; + if (DeterminedAlready(quick_check, elm.cp_offset())) continue; + RegExpCharacterClass* cc = elm.char_class(); + EmitCharClass(alloc(), + assembler, + cc, + ascii, + backtrack, + cp_offset, + *checked_up_to < cp_offset, + preloaded); + UpdateBoundsCheck(cp_offset, checked_up_to); + } + } + } +} + +int +TextNode::Length() +{ + TextElement elm = elements()[elements().length() - 1]; + MOZ_ASSERT(elm.cp_offset() >= 0); + return elm.cp_offset() + elm.length(); +} + +bool +TextNode::SkipPass(int int_pass, bool ignore_case) +{ + TextEmitPassType pass = static_cast<TextEmitPassType>(int_pass); + if (ignore_case) + return pass == SIMPLE_CHARACTER_MATCH; + return pass == NON_LETTER_CHARACTER_MATCH || pass == CASE_CHARACTER_MATCH; +} + +// This generates the code to match a text node. A text node can contain +// straight character sequences (possibly to be matched in a case-independent +// way) and character classes. For efficiency we do not do this in a single +// pass from left to right. Instead we pass over the text node several times, +// emitting code for some character positions every time. See the comment on +// TextEmitPass for details. +void +TextNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + LimitResult limit_result = LimitVersions(compiler, trace); + if (limit_result == DONE) return; + MOZ_ASSERT(limit_result == CONTINUE); + + if (trace->cp_offset() + Length() > RegExpMacroAssembler::kMaxCPOffset) { + compiler->SetRegExpTooBig(); + return; + } + + if (compiler->ascii()) { + int dummy = 0; + TextEmitPass(compiler, NON_ASCII_MATCH, false, trace, false, &dummy); + } + + bool first_elt_done = false; + int bound_checked_to = trace->cp_offset() - 1; + bound_checked_to += trace->bound_checked_up_to(); + + // If a character is preloaded into the current character register then + // check that now. + if (trace->characters_preloaded() == 1) { + for (int pass = kFirstRealPass; pass <= kLastPass; pass++) { + if (!SkipPass(pass, compiler->ignore_case())) { + TextEmitPass(compiler, + static_cast<TextEmitPassType>(pass), + true, + trace, + false, + &bound_checked_to); + } + } + first_elt_done = true; + } + + for (int pass = kFirstRealPass; pass <= kLastPass; pass++) { + if (!SkipPass(pass, compiler->ignore_case())) { + TextEmitPass(compiler, + static_cast<TextEmitPassType>(pass), + false, + trace, + first_elt_done, + &bound_checked_to); + } + } + + Trace successor_trace(*trace); + successor_trace.set_at_start(false); + successor_trace.AdvanceCurrentPositionInTrace(Length(), compiler); + RecursionCheck rc(compiler); + on_success()->Emit(compiler, &successor_trace); +} + +void +LoopChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + if (trace->stop_node() == this) { + int text_length = + GreedyLoopTextLengthForAlternative(&alternatives()[0]); + MOZ_ASSERT(text_length != kNodeIsTooComplexForGreedyLoops); + // Update the counter-based backtracking info on the stack. This is an + // optimization for greedy loops (see below). + MOZ_ASSERT(trace->cp_offset() == text_length); + macro_assembler->AdvanceCurrentPosition(text_length); + macro_assembler->JumpOrBacktrack(trace->loop_label()); + return; + } + MOZ_ASSERT(trace->stop_node() == nullptr); + if (!trace->is_trivial()) { + trace->Flush(compiler, this); + return; + } + ChoiceNode::Emit(compiler, trace); +} + +/* Code generation for choice nodes. + * + * We generate quick checks that do a mask and compare to eliminate a + * choice. If the quick check succeeds then it jumps to the continuation to + * do slow checks and check subsequent nodes. If it fails (the common case) + * it falls through to the next choice. + * + * Here is the desired flow graph. Nodes directly below each other imply + * fallthrough. Alternatives 1 and 2 have quick checks. Alternative + * 3 doesn't have a quick check so we have to call the slow check. + * Nodes are marked Qn for quick checks and Sn for slow checks. The entire + * regexp continuation is generated directly after the Sn node, up to the + * next JumpOrBacktrack if we decide to reuse some already generated code. Some + * nodes expect preload_characters to be preloaded into the current + * character register. R nodes do this preloading. Vertices are marked + * F for failures and S for success (possible success in the case of quick + * nodes). L, V, < and > are used as arrow heads. + * + * ----------> R + * | + * V + * Q1 -----> S1 + * | S / + * F| / + * | F/ + * | / + * | R + * | / + * V L + * Q2 -----> S2 + * | S / + * F| / + * | F/ + * | / + * | R + * | / + * V L + * S3 + * | + * F| + * | + * R + * | + * backtrack V + * <----------Q4 + * \ F | + * \ |S + * \ F V + * \-----S4 + * + * For greedy loops we reverse our expectation and expect to match rather + * than fail. Therefore we want the loop code to look like this (U is the + * unwind code that steps back in the greedy loop). The following alternatives + * look the same as above. + * _____ + * / \ + * V | + * ----------> S1 | + * /| | + * / |S | + * F/ \_____/ + * / + * |<----------- + * | \ + * V \ + * Q2 ---> S2 \ + * | S / | + * F| / | + * | F/ | + * | / | + * | R | + * | / | + * F VL | + * <------U | + * back |S | + * \______________/ + */ + +// This class is used when generating the alternatives in a choice node. It +// records the way the alternative is being code generated. +class irregexp::AlternativeGeneration +{ + public: + AlternativeGeneration() + : possible_success(), + expects_preload(false), + after(), + quick_check_details() + {} + + jit::Label possible_success; + bool expects_preload; + jit::Label after; + QuickCheckDetails quick_check_details; +}; + +void +ChoiceNode::GenerateGuard(RegExpMacroAssembler* macro_assembler, + Guard* guard, Trace* trace) +{ + switch (guard->op()) { + case Guard::LT: + MOZ_ASSERT(!trace->mentions_reg(guard->reg())); + macro_assembler->IfRegisterGE(guard->reg(), + guard->value(), + trace->backtrack()); + break; + case Guard::GEQ: + MOZ_ASSERT(!trace->mentions_reg(guard->reg())); + macro_assembler->IfRegisterLT(guard->reg(), + guard->value(), + trace->backtrack()); + break; + } +} + +int +ChoiceNode::CalculatePreloadCharacters(RegExpCompiler* compiler, int eats_at_least) +{ + int preload_characters = Min(4, eats_at_least); + if (compiler->macro_assembler()->CanReadUnaligned()) { + bool ascii = compiler->ascii(); + if (ascii) { + if (preload_characters > 4) + preload_characters = 4; + // We can't preload 3 characters because there is no machine instruction + // to do that. We can't just load 4 because we could be reading + // beyond the end of the string, which could cause a memory fault. + if (preload_characters == 3) + preload_characters = 2; + } else { + if (preload_characters > 2) + preload_characters = 2; + } + } else { + if (preload_characters > 1) + preload_characters = 1; + } + return preload_characters; +} + +RegExpNode* +TextNode::GetSuccessorOfOmnivorousTextNode(RegExpCompiler* compiler) +{ + if (elements().length() != 1) + return nullptr; + + TextElement elm = elements()[0]; + if (elm.text_type() != TextElement::CHAR_CLASS) + return nullptr; + + RegExpCharacterClass* node = elm.char_class(); + CharacterRangeVector& ranges = node->ranges(alloc()); + + if (!CharacterRange::IsCanonical(ranges)) + CharacterRange::Canonicalize(ranges); + + if (node->is_negated()) + return ranges.length() == 0 ? on_success() : nullptr; + + if (ranges.length() != 1) + return nullptr; + + uint32_t max_char = MaximumCharacter(compiler->ascii()); + return ranges[0].IsEverything(max_char) ? on_success() : nullptr; +} + +// Finds the fixed match length of a sequence of nodes that goes from +// this alternative and back to this choice node. If there are variable +// length nodes or other complications in the way then return a sentinel +// value indicating that a greedy loop cannot be constructed. +int +ChoiceNode::GreedyLoopTextLengthForAlternative(GuardedAlternative* alternative) +{ + int length = 0; + RegExpNode* node = alternative->node(); + // Later we will generate code for all these text nodes using recursion + // so we have to limit the max number. + int recursion_depth = 0; + while (node != this) { + if (recursion_depth++ > RegExpCompiler::kMaxRecursion) { + return kNodeIsTooComplexForGreedyLoops; + } + int node_length = node->GreedyLoopTextLength(); + if (node_length == kNodeIsTooComplexForGreedyLoops) { + return kNodeIsTooComplexForGreedyLoops; + } + length += node_length; + SeqRegExpNode* seq_node = static_cast<SeqRegExpNode*>(node); + node = seq_node->on_success(); + } + return length; +} + +// Creates a list of AlternativeGenerations. If the list has a reasonable +// size then it is on the stack, otherwise the excess is on the heap. +class AlternativeGenerationList +{ + public: + AlternativeGenerationList(LifoAlloc* alloc, size_t count) + : alt_gens_(*alloc) + { + alt_gens_.reserve(count); + for (size_t i = 0; i < count && i < kAFew; i++) + alt_gens_.append(a_few_alt_gens_ + i); + for (size_t i = kAFew; i < count; i++) { + AutoEnterOOMUnsafeRegion oomUnsafe; + AlternativeGeneration* gen = js_new<AlternativeGeneration>(); + if (!gen) + oomUnsafe.crash("AlternativeGenerationList js_new"); + alt_gens_.append(gen); + } + } + + ~AlternativeGenerationList() { + for (size_t i = kAFew; i < alt_gens_.length(); i++) { + js_delete(alt_gens_[i]); + alt_gens_[i] = nullptr; + } + } + + AlternativeGeneration* at(int i) { + return alt_gens_[i]; + } + + private: + static const size_t kAFew = 10; + InfallibleVector<AlternativeGeneration*, 1> alt_gens_; + AlternativeGeneration a_few_alt_gens_[kAFew]; +}; + +void +ChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + size_t choice_count = alternatives().length(); +#ifdef DEBUG + for (size_t i = 0; i < choice_count - 1; i++) { + const GuardedAlternative& alternative = alternatives()[i]; + const GuardVector* guards = alternative.guards(); + if (guards) { + for (size_t j = 0; j < guards->length(); j++) + MOZ_ASSERT(!trace->mentions_reg((*guards)[j]->reg())); + } + } +#endif + + LimitResult limit_result = LimitVersions(compiler, trace); + if (limit_result == DONE) return; + MOZ_ASSERT(limit_result == CONTINUE); + + int new_flush_budget = trace->flush_budget() / choice_count; + if (trace->flush_budget() == 0 && trace->actions() != nullptr) { + trace->Flush(compiler, this); + return; + } + + RecursionCheck rc(compiler); + + Trace* current_trace = trace; + + int text_length = GreedyLoopTextLengthForAlternative(&alternatives()[0]); + bool greedy_loop = false; + jit::Label greedy_loop_label; + Trace counter_backtrack_trace; + counter_backtrack_trace.set_backtrack(&greedy_loop_label); + if (not_at_start()) counter_backtrack_trace.set_at_start(false); + + if (choice_count > 1 && text_length != kNodeIsTooComplexForGreedyLoops) { + // Here we have special handling for greedy loops containing only text nodes + // and other simple nodes. These are handled by pushing the current + // position on the stack and then incrementing the current position each + // time around the switch. On backtrack we decrement the current position + // and check it against the pushed value. This avoids pushing backtrack + // information for each iteration of the loop, which could take up a lot of + // space. + greedy_loop = true; + MOZ_ASSERT(trace->stop_node() == nullptr); + macro_assembler->PushCurrentPosition(); + current_trace = &counter_backtrack_trace; + jit::Label greedy_match_failed; + Trace greedy_match_trace; + if (not_at_start()) greedy_match_trace.set_at_start(false); + greedy_match_trace.set_backtrack(&greedy_match_failed); + jit::Label loop_label; + macro_assembler->Bind(&loop_label); + greedy_match_trace.set_stop_node(this); + greedy_match_trace.set_loop_label(&loop_label); + alternatives()[0].node()->Emit(compiler, &greedy_match_trace); + macro_assembler->Bind(&greedy_match_failed); + } + + jit::Label second_choice; // For use in greedy matches. + macro_assembler->Bind(&second_choice); + + size_t first_normal_choice = greedy_loop ? 1 : 0; + + bool not_at_start = current_trace->at_start() == Trace::FALSE_VALUE; + const int kEatsAtLeastNotYetInitialized = -1; + int eats_at_least = kEatsAtLeastNotYetInitialized; + + bool skip_was_emitted = false; + + if (!greedy_loop && choice_count == 2) { + GuardedAlternative alt1 = alternatives()[1]; + if (!alt1.guards() || alt1.guards()->length() == 0) { + RegExpNode* eats_anything_node = alt1.node(); + if (eats_anything_node->GetSuccessorOfOmnivorousTextNode(compiler) == this) { + // At this point we know that we are at a non-greedy loop that will eat + // any character one at a time. Any non-anchored regexp has such a + // loop prepended to it in order to find where it starts. We look for + // a pattern of the form ...abc... where we can look 6 characters ahead + // and step forwards 3 if the character is not one of abc. Abc need + // not be atoms, they can be any reasonably limited character class or + // small alternation. + MOZ_ASSERT(trace->is_trivial()); // This is the case on LoopChoiceNodes. + BoyerMooreLookahead* lookahead = bm_info(not_at_start); + if (lookahead == nullptr) { + eats_at_least = Min(kMaxLookaheadForBoyerMoore, + EatsAtLeast(kMaxLookaheadForBoyerMoore, + kRecursionBudget, + not_at_start)); + if (eats_at_least >= 1) { + BoyerMooreLookahead* bm = + alloc()->newInfallible<BoyerMooreLookahead>(alloc(), eats_at_least, compiler); + GuardedAlternative alt0 = alternatives()[0]; + alt0.node()->FillInBMInfo(0, kRecursionBudget, bm, not_at_start); + skip_was_emitted = bm->EmitSkipInstructions(macro_assembler); + } + } else { + skip_was_emitted = lookahead->EmitSkipInstructions(macro_assembler); + } + } + } + } + + if (eats_at_least == kEatsAtLeastNotYetInitialized) { + // Save some time by looking at most one machine word ahead. + eats_at_least = + EatsAtLeast(compiler->ascii() ? 4 : 2, kRecursionBudget, not_at_start); + } + int preload_characters = CalculatePreloadCharacters(compiler, eats_at_least); + + bool preload_is_current = !skip_was_emitted && + (current_trace->characters_preloaded() == preload_characters); + bool preload_has_checked_bounds = preload_is_current; + + AlternativeGenerationList alt_gens(alloc(), choice_count); + + // For now we just call all choices one after the other. The idea ultimately + // is to use the Dispatch table to try only the relevant ones. + for (size_t i = first_normal_choice; i < choice_count; i++) { + GuardedAlternative alternative = alternatives()[i]; + AlternativeGeneration* alt_gen = alt_gens.at(i); + alt_gen->quick_check_details.set_characters(preload_characters); + const GuardVector* guards = alternative.guards(); + Trace new_trace(*current_trace); + new_trace.set_characters_preloaded(preload_is_current ? + preload_characters : + 0); + if (preload_has_checked_bounds) { + new_trace.set_bound_checked_up_to(preload_characters); + } + new_trace.quick_check_performed()->Clear(); + if (not_at_start_) new_trace.set_at_start(Trace::FALSE_VALUE); + alt_gen->expects_preload = preload_is_current; + bool generate_full_check_inline = false; + if (try_to_emit_quick_check_for_alternative(i) && + alternative.node()->EmitQuickCheck(compiler, + &new_trace, + preload_has_checked_bounds, + &alt_gen->possible_success, + &alt_gen->quick_check_details, + i < choice_count - 1)) { + // Quick check was generated for this choice. + preload_is_current = true; + preload_has_checked_bounds = true; + // On the last choice in the ChoiceNode we generated the quick + // check to fall through on possible success. So now we need to + // generate the full check inline. + if (i == choice_count - 1) { + macro_assembler->Bind(&alt_gen->possible_success); + new_trace.set_quick_check_performed(&alt_gen->quick_check_details); + new_trace.set_characters_preloaded(preload_characters); + new_trace.set_bound_checked_up_to(preload_characters); + generate_full_check_inline = true; + } + } else if (alt_gen->quick_check_details.cannot_match()) { + if (i == choice_count - 1 && !greedy_loop) { + macro_assembler->JumpOrBacktrack(trace->backtrack()); + } + continue; + } else { + // No quick check was generated. Put the full code here. + // If this is not the first choice then there could be slow checks from + // previous cases that go here when they fail. There's no reason to + // insist that they preload characters since the slow check we are about + // to generate probably can't use it. + if (i != first_normal_choice) { + alt_gen->expects_preload = false; + new_trace.InvalidateCurrentCharacter(); + } + if (i < choice_count - 1) { + new_trace.set_backtrack(&alt_gen->after); + } + generate_full_check_inline = true; + } + if (generate_full_check_inline) { + if (new_trace.actions() != nullptr) + new_trace.set_flush_budget(new_flush_budget); + if (guards) { + for (size_t j = 0; j < guards->length(); j++) + GenerateGuard(macro_assembler, (*guards)[j], &new_trace); + } + alternative.node()->Emit(compiler, &new_trace); + preload_is_current = false; + } + macro_assembler->Bind(&alt_gen->after); + } + if (greedy_loop) { + macro_assembler->Bind(&greedy_loop_label); + // If we have unwound to the bottom then backtrack. + macro_assembler->CheckGreedyLoop(trace->backtrack()); + // Otherwise try the second priority at an earlier position. + macro_assembler->AdvanceCurrentPosition(-text_length); + macro_assembler->JumpOrBacktrack(&second_choice); + } + + // At this point we need to generate slow checks for the alternatives where + // the quick check was inlined. We can recognize these because the associated + // label was bound. + for (size_t i = first_normal_choice; i < choice_count - 1; i++) { + AlternativeGeneration* alt_gen = alt_gens.at(i); + Trace new_trace(*current_trace); + // If there are actions to be flushed we have to limit how many times + // they are flushed. Take the budget of the parent trace and distribute + // it fairly amongst the children. + if (new_trace.actions() != nullptr) { + new_trace.set_flush_budget(new_flush_budget); + } + EmitOutOfLineContinuation(compiler, + &new_trace, + alternatives()[i], + alt_gen, + preload_characters, + alt_gens.at(i + 1)->expects_preload); + } +} + +void +ChoiceNode::EmitOutOfLineContinuation(RegExpCompiler* compiler, + Trace* trace, + GuardedAlternative alternative, + AlternativeGeneration* alt_gen, + int preload_characters, + bool next_expects_preload) +{ + if (!alt_gen->possible_success.used()) + return; + + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + macro_assembler->Bind(&alt_gen->possible_success); + Trace out_of_line_trace(*trace); + out_of_line_trace.set_characters_preloaded(preload_characters); + out_of_line_trace.set_quick_check_performed(&alt_gen->quick_check_details); + if (not_at_start_) out_of_line_trace.set_at_start(Trace::FALSE_VALUE); + const GuardVector* guards = alternative.guards(); + if (next_expects_preload) { + jit::Label reload_current_char; + out_of_line_trace.set_backtrack(&reload_current_char); + if (guards) { + for (size_t j = 0; j < guards->length(); j++) + GenerateGuard(macro_assembler, (*guards)[j], &out_of_line_trace); + } + alternative.node()->Emit(compiler, &out_of_line_trace); + macro_assembler->Bind(&reload_current_char); + // Reload the current character, since the next quick check expects that. + // We don't need to check bounds here because we only get into this + // code through a quick check which already did the checked load. + macro_assembler->LoadCurrentCharacter(trace->cp_offset(), + nullptr, + false, + preload_characters); + macro_assembler->JumpOrBacktrack(&(alt_gen->after)); + } else { + out_of_line_trace.set_backtrack(&(alt_gen->after)); + if (guards) { + for (size_t j = 0; j < guards->length(); j++) + GenerateGuard(macro_assembler, (*guards)[j], &out_of_line_trace); + } + alternative.node()->Emit(compiler, &out_of_line_trace); + } +} + +void +ActionNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + LimitResult limit_result = LimitVersions(compiler, trace); + if (limit_result == DONE) return; + MOZ_ASSERT(limit_result == CONTINUE); + + RecursionCheck rc(compiler); + + switch (action_type_) { + case STORE_POSITION: { + Trace::DeferredCapture + new_capture(data_.u_position_register.reg, + data_.u_position_register.is_capture, + trace); + Trace new_trace = *trace; + new_trace.add_action(&new_capture); + on_success()->Emit(compiler, &new_trace); + break; + } + case INCREMENT_REGISTER: { + Trace::DeferredIncrementRegister + new_increment(data_.u_increment_register.reg); + Trace new_trace = *trace; + new_trace.add_action(&new_increment); + on_success()->Emit(compiler, &new_trace); + break; + } + case SET_REGISTER: { + Trace::DeferredSetRegister + new_set(data_.u_store_register.reg, data_.u_store_register.value); + Trace new_trace = *trace; + new_trace.add_action(&new_set); + on_success()->Emit(compiler, &new_trace); + break; + } + case CLEAR_CAPTURES: { + Trace::DeferredClearCaptures + new_capture(Interval(data_.u_clear_captures.range_from, + data_.u_clear_captures.range_to)); + Trace new_trace = *trace; + new_trace.add_action(&new_capture); + on_success()->Emit(compiler, &new_trace); + break; + } + case BEGIN_SUBMATCH: + if (!trace->is_trivial()) { + trace->Flush(compiler, this); + } else { + assembler->WriteCurrentPositionToRegister(data_.u_submatch.current_position_register, 0); + assembler->WriteBacktrackStackPointerToRegister(data_.u_submatch.stack_pointer_register); + on_success()->Emit(compiler, trace); + } + break; + case EMPTY_MATCH_CHECK: { + int start_pos_reg = data_.u_empty_match_check.start_register; + int stored_pos = 0; + int rep_reg = data_.u_empty_match_check.repetition_register; + bool has_minimum = (rep_reg != RegExpCompiler::kNoRegister); + bool know_dist = trace->GetStoredPosition(start_pos_reg, &stored_pos); + if (know_dist && !has_minimum && stored_pos == trace->cp_offset()) { + // If we know we haven't advanced and there is no minimum we + // can just backtrack immediately. + assembler->JumpOrBacktrack(trace->backtrack()); + } else if (know_dist && stored_pos < trace->cp_offset()) { + // If we know we've advanced we can generate the continuation + // immediately. + on_success()->Emit(compiler, trace); + } else if (!trace->is_trivial()) { + trace->Flush(compiler, this); + } else { + jit::Label skip_empty_check; + // If we have a minimum number of repetitions we check the current + // number first and skip the empty check if it's not enough. + if (has_minimum) { + int limit = data_.u_empty_match_check.repetition_limit; + assembler->IfRegisterLT(rep_reg, limit, &skip_empty_check); + } + // If the match is empty we bail out, otherwise we fall through + // to the on-success continuation. + assembler->IfRegisterEqPos(data_.u_empty_match_check.start_register, + trace->backtrack()); + assembler->Bind(&skip_empty_check); + on_success()->Emit(compiler, trace); + } + break; + } + case POSITIVE_SUBMATCH_SUCCESS: { + if (!trace->is_trivial()) { + trace->Flush(compiler, this); + return; + } + assembler->ReadCurrentPositionFromRegister(data_.u_submatch.current_position_register); + assembler->ReadBacktrackStackPointerFromRegister(data_.u_submatch.stack_pointer_register); + int clear_register_count = data_.u_submatch.clear_register_count; + if (clear_register_count == 0) { + on_success()->Emit(compiler, trace); + return; + } + int clear_registers_from = data_.u_submatch.clear_register_from; + jit::Label clear_registers_backtrack; + Trace new_trace = *trace; + new_trace.set_backtrack(&clear_registers_backtrack); + on_success()->Emit(compiler, &new_trace); + + assembler->Bind(&clear_registers_backtrack); + int clear_registers_to = clear_registers_from + clear_register_count - 1; + assembler->ClearRegisters(clear_registers_from, clear_registers_to); + + MOZ_ASSERT(trace->backtrack() == nullptr); + assembler->Backtrack(); + return; + } + default: + MOZ_CRASH("Bad action"); + } +} + +void +BackReferenceNode::Emit(RegExpCompiler* compiler, Trace* trace) +{ + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + if (!trace->is_trivial()) { + trace->Flush(compiler, this); + return; + } + + LimitResult limit_result = LimitVersions(compiler, trace); + if (limit_result == DONE) return; + MOZ_ASSERT(limit_result == CONTINUE); + + RecursionCheck rc(compiler); + + MOZ_ASSERT(start_reg_ + 1 == end_reg_); + if (compiler->ignore_case()) { + assembler->CheckNotBackReferenceIgnoreCase(start_reg_, + trace->backtrack(), + compiler->unicode()); + } else { + assembler->CheckNotBackReference(start_reg_, trace->backtrack()); + } + on_success()->Emit(compiler, trace); +} + +RegExpNode::LimitResult +RegExpNode::LimitVersions(RegExpCompiler* compiler, Trace* trace) +{ + // If we are generating a greedy loop then don't stop and don't reuse code. + if (trace->stop_node() != nullptr) + return CONTINUE; + + RegExpMacroAssembler* macro_assembler = compiler->macro_assembler(); + if (trace->is_trivial()) { + if (label()->bound()) { + // We are being asked to generate a generic version, but that's already + // been done so just go to it. + macro_assembler->JumpOrBacktrack(label()); + return DONE; + } + if (compiler->recursion_depth() >= RegExpCompiler::kMaxRecursion) { + // To avoid too deep recursion we push the node to the work queue and just + // generate a goto here. + compiler->AddWork(this); + macro_assembler->JumpOrBacktrack(label()); + return DONE; + } + // Generate generic version of the node and bind the label for later use. + macro_assembler->Bind(label()); + return CONTINUE; + } + + // We are being asked to make a non-generic version. Keep track of how many + // non-generic versions we generate so as not to overdo it. + trace_count_++; + if (trace_count_ < kMaxCopiesCodeGenerated && + compiler->recursion_depth() <= RegExpCompiler::kMaxRecursion) { + return CONTINUE; + } + + // If we get here code has been generated for this node too many times or + // recursion is too deep. Time to switch to a generic version. The code for + // generic versions above can handle deep recursion properly. + trace->Flush(compiler, this); + return DONE; +} + +bool +RegExpNode::EmitQuickCheck(RegExpCompiler* compiler, + Trace* trace, + bool preload_has_checked_bounds, + jit::Label* on_possible_success, + QuickCheckDetails* details, + bool fall_through_on_failure) +{ + if (details->characters() == 0) return false; + GetQuickCheckDetails( + details, compiler, 0, trace->at_start() == Trace::FALSE_VALUE); + if (details->cannot_match()) return false; + if (!details->Rationalize(compiler->ascii())) return false; + MOZ_ASSERT(details->characters() == 1 || + compiler->macro_assembler()->CanReadUnaligned()); + uint32_t mask = details->mask(); + uint32_t value = details->value(); + + RegExpMacroAssembler* assembler = compiler->macro_assembler(); + + if (trace->characters_preloaded() != details->characters()) { + assembler->LoadCurrentCharacter(trace->cp_offset(), + trace->backtrack(), + !preload_has_checked_bounds, + details->characters()); + } + + bool need_mask = true; + + if (details->characters() == 1) { + // If number of characters preloaded is 1 then we used a byte or 16 bit + // load so the value is already masked down. + uint32_t char_mask = MaximumCharacter(compiler->ascii()); + if ((mask & char_mask) == char_mask) need_mask = false; + mask &= char_mask; + } else { + // For 2-character preloads in ASCII mode or 1-character preloads in + // TWO_BYTE mode we also use a 16 bit load with zero extend. + if (details->characters() == 2 && compiler->ascii()) { + if ((mask & 0xffff) == 0xffff) need_mask = false; + } else if (details->characters() == 1 && !compiler->ascii()) { + if ((mask & 0xffff) == 0xffff) need_mask = false; + } else { + if (mask == 0xffffffff) need_mask = false; + } + } + + if (fall_through_on_failure) { + if (need_mask) { + assembler->CheckCharacterAfterAnd(value, mask, on_possible_success); + } else { + assembler->CheckCharacter(value, on_possible_success); + } + } else { + if (need_mask) { + assembler->CheckNotCharacterAfterAnd(value, mask, trace->backtrack()); + } else { + assembler->CheckNotCharacter(value, trace->backtrack()); + } + } + return true; +} + +bool +TextNode::FillInBMInfo(int initial_offset, + int budget, + BoyerMooreLookahead* bm, + bool not_at_start) +{ + if (!bm->CheckOverRecursed()) + return false; + + if (initial_offset >= bm->length()) + return true; + + int offset = initial_offset; + int max_char = bm->max_char(); + for (size_t i = 0; i < elements().length(); i++) { + if (offset >= bm->length()) { + if (initial_offset == 0) + set_bm_info(not_at_start, bm); + return true; + } + TextElement text = elements()[i]; + if (text.text_type() == TextElement::ATOM) { + RegExpAtom* atom = text.atom(); + for (int j = 0; j < atom->length(); j++, offset++) { + if (offset >= bm->length()) { + if (initial_offset == 0) + set_bm_info(not_at_start, bm); + return true; + } + char16_t character = atom->data()[j]; + if (bm->compiler()->ignore_case()) { + char16_t chars[kEcma262UnCanonicalizeMaxWidth]; + int length = GetCaseIndependentLetters(character, + bm->max_char() == kMaxOneByteCharCode, + bm->compiler()->unicode(), + chars); + for (int j = 0; j < length; j++) + bm->Set(offset, chars[j]); + } else { + if (character <= max_char) bm->Set(offset, character); + } + } + } else { + MOZ_ASSERT(TextElement::CHAR_CLASS == text.text_type()); + RegExpCharacterClass* char_class = text.char_class(); + const CharacterRangeVector& ranges = char_class->ranges(alloc()); + if (char_class->is_negated()) { + bm->SetAll(offset); + } else { + for (size_t k = 0; k < ranges.length(); k++) { + const CharacterRange& range = ranges[k]; + if (range.from() > max_char) + continue; + int to = Min(max_char, static_cast<int>(range.to())); + bm->SetInterval(offset, Interval(range.from(), to)); + } + } + offset++; + } + } + if (offset >= bm->length()) { + if (initial_offset == 0) set_bm_info(not_at_start, bm); + return true; + } + if (!on_success()->FillInBMInfo(offset, + budget - 1, + bm, + true)) // Not at start after a text node. + return false; + if (initial_offset == 0) + set_bm_info(not_at_start, bm); + return true; +} + +// ------------------------------------------------------------------- +// QuickCheckDetails + +// Takes the left-most 1-bit and smears it out, setting all bits to its right. +static inline uint32_t +SmearBitsRight(uint32_t v) +{ + v |= v >> 1; + v |= v >> 2; + v |= v >> 4; + v |= v >> 8; + v |= v >> 16; + return v; +} + +// Here is the meat of GetQuickCheckDetails (see also the comment on the +// super-class in the .h file). +// +// We iterate along the text object, building up for each character a +// mask and value that can be used to test for a quick failure to match. +// The masks and values for the positions will be combined into a single +// machine word for the current character width in order to be used in +// generating a quick check. +void +TextNode::GetQuickCheckDetails(QuickCheckDetails* details, + RegExpCompiler* compiler, + int characters_filled_in, + bool not_at_start) +{ + MOZ_ASSERT(characters_filled_in < details->characters()); + int characters = details->characters(); + int char_mask = MaximumCharacter(compiler->ascii()); + + for (size_t k = 0; k < elements().length(); k++) { + TextElement elm = elements()[k]; + if (elm.text_type() == TextElement::ATOM) { + const CharacterVector& quarks = elm.atom()->data(); + for (size_t i = 0; i < (size_t) characters && i < quarks.length(); i++) { + QuickCheckDetails::Position* pos = + details->positions(characters_filled_in); + char16_t c = quarks[i]; + if (c > char_mask) { + // If we expect a non-ASCII character from an ASCII string, + // there is no way we can match. Not even case independent + // matching can turn an ASCII character into non-ASCII or + // vice versa. + details->set_cannot_match(); + pos->determines_perfectly = false; + return; + } + if (compiler->ignore_case()) { + char16_t chars[kEcma262UnCanonicalizeMaxWidth]; + size_t length = GetCaseIndependentLetters(c, compiler->ascii(), + compiler->unicode(), chars); + MOZ_ASSERT(length != 0); // Can only happen if c > char_mask (see above). + if (length == 1) { + // This letter has no case equivalents, so it's nice and simple + // and the mask-compare will determine definitely whether we have + // a match at this character position. + pos->mask = char_mask; + pos->value = c; + pos->determines_perfectly = true; + } else { + uint32_t common_bits = char_mask; + uint32_t bits = chars[0]; + for (size_t j = 1; j < length; j++) { + uint32_t differing_bits = ((chars[j] & common_bits) ^ bits); + common_bits ^= differing_bits; + bits &= common_bits; + } + // If length is 2 and common bits has only one zero in it then + // our mask and compare instruction will determine definitely + // whether we have a match at this character position. Otherwise + // it can only be an approximate check. + uint32_t one_zero = (common_bits | ~char_mask); + if (length == 2 && ((~one_zero) & ((~one_zero) - 1)) == 0) { + pos->determines_perfectly = true; + } + pos->mask = common_bits; + pos->value = bits; + } + } else { + // Don't ignore case. Nice simple case where the mask-compare will + // determine definitely whether we have a match at this character + // position. + pos->mask = char_mask; + pos->value = c; + pos->determines_perfectly = true; + } + characters_filled_in++; + MOZ_ASSERT(characters_filled_in <= details->characters()); + if (characters_filled_in == details->characters()) { + return; + } + } + } else { + QuickCheckDetails::Position* pos = + details->positions(characters_filled_in); + RegExpCharacterClass* tree = elm.char_class(); + const CharacterRangeVector& ranges = tree->ranges(alloc()); + if (tree->is_negated()) { + // A quick check uses multi-character mask and compare. There is no + // useful way to incorporate a negative char class into this scheme + // so we just conservatively create a mask and value that will always + // succeed. + pos->mask = 0; + pos->value = 0; + } else { + size_t first_range = 0; + while (ranges[first_range].from() > char_mask) { + first_range++; + if (first_range == ranges.length()) { + details->set_cannot_match(); + pos->determines_perfectly = false; + return; + } + } + CharacterRange range = ranges[first_range]; + char16_t from = range.from(); + char16_t to = range.to(); + if (to > char_mask) { + to = char_mask; + } + uint32_t differing_bits = (from ^ to); + // A mask and compare is only perfect if the differing bits form a + // number like 00011111 with one single block of trailing 1s. + if ((differing_bits & (differing_bits + 1)) == 0 && + from + differing_bits == to) { + pos->determines_perfectly = true; + } + uint32_t common_bits = ~SmearBitsRight(differing_bits); + uint32_t bits = (from & common_bits); + for (size_t i = first_range + 1; i < ranges.length(); i++) { + CharacterRange range = ranges[i]; + char16_t from = range.from(); + char16_t to = range.to(); + if (from > char_mask) continue; + if (to > char_mask) to = char_mask; + // Here we are combining more ranges into the mask and compare + // value. With each new range the mask becomes more sparse and + // so the chances of a false positive rise. A character class + // with multiple ranges is assumed never to be equivalent to a + // mask and compare operation. + pos->determines_perfectly = false; + uint32_t new_common_bits = (from ^ to); + new_common_bits = ~SmearBitsRight(new_common_bits); + common_bits &= new_common_bits; + bits &= new_common_bits; + uint32_t differing_bits = (from & common_bits) ^ bits; + common_bits ^= differing_bits; + bits &= common_bits; + } + pos->mask = common_bits; + pos->value = bits; + } + characters_filled_in++; + MOZ_ASSERT(characters_filled_in <= details->characters()); + if (characters_filled_in == details->characters()) { + return; + } + } + } + MOZ_ASSERT(characters_filled_in != details->characters()); + if (!details->cannot_match()) { + on_success()-> GetQuickCheckDetails(details, + compiler, + characters_filled_in, + true); + } +} + +void +QuickCheckDetails::Clear() +{ + for (int i = 0; i < characters_; i++) { + positions_[i].mask = 0; + positions_[i].value = 0; + positions_[i].determines_perfectly = false; + } + characters_ = 0; +} + +void +QuickCheckDetails::Advance(int by, bool ascii) +{ + MOZ_ASSERT(by >= 0); + if (by >= characters_) { + Clear(); + return; + } + for (int i = 0; i < characters_ - by; i++) { + positions_[i] = positions_[by + i]; + } + for (int i = characters_ - by; i < characters_; i++) { + positions_[i].mask = 0; + positions_[i].value = 0; + positions_[i].determines_perfectly = false; + } + characters_ -= by; + // We could change mask_ and value_ here but we would never advance unless + // they had already been used in a check and they won't be used again because + // it would gain us nothing. So there's no point. +} + +bool +QuickCheckDetails::Rationalize(bool is_ascii) +{ + bool found_useful_op = false; + uint32_t char_mask = MaximumCharacter(is_ascii); + + mask_ = 0; + value_ = 0; + int char_shift = 0; + for (int i = 0; i < characters_; i++) { + Position* pos = &positions_[i]; + if ((pos->mask & kMaxOneByteCharCode) != 0) + found_useful_op = true; + mask_ |= (pos->mask & char_mask) << char_shift; + value_ |= (pos->value & char_mask) << char_shift; + char_shift += is_ascii ? 8 : 16; + } + return found_useful_op; +} + +void QuickCheckDetails::Merge(QuickCheckDetails* other, int from_index) +{ + MOZ_ASSERT(characters_ == other->characters_); + if (other->cannot_match_) + return; + if (cannot_match_) { + *this = *other; + return; + } + for (int i = from_index; i < characters_; i++) { + QuickCheckDetails::Position* pos = positions(i); + QuickCheckDetails::Position* other_pos = other->positions(i); + if (pos->mask != other_pos->mask || + pos->value != other_pos->value || + !other_pos->determines_perfectly) { + // Our mask-compare operation will be approximate unless we have the + // exact same operation on both sides of the alternation. + pos->determines_perfectly = false; + } + pos->mask &= other_pos->mask; + pos->value &= pos->mask; + other_pos->value &= pos->mask; + char16_t differing_bits = (pos->value ^ other_pos->value); + pos->mask &= ~differing_bits; + pos->value &= pos->mask; + } +} |