Add m-esr52 at 52.6.0

1 files changed, 3634 insertions, 0 deletions

diff --git a/js/src/jit/RangeAnalysis.cpp b/js/src/jit/RangeAnalysis.cpp
new file mode 100644
index 000000000..95484c249
--- /dev/null
+++ b/js/src/jit/RangeAnalysis.cpp
@@ -0,0 +1,3634 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/RangeAnalysis.h"
+
+#include "mozilla/MathAlgorithms.h"
+
+#include "jit/Ion.h"
+#include "jit/IonAnalysis.h"
+#include "jit/JitSpewer.h"
+#include "jit/MIR.h"
+#include "jit/MIRGenerator.h"
+#include "jit/MIRGraph.h"
+#include "js/Conversions.h"
+#include "vm/ArgumentsObject.h"
+#include "vm/TypedArrayCommon.h"
+
+#include "jsopcodeinlines.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::Abs;
+using mozilla::CountLeadingZeroes32;
+using mozilla::NumberEqualsInt32;
+using mozilla::ExponentComponent;
+using mozilla::FloorLog2;
+using mozilla::IsInfinite;
+using mozilla::IsNaN;
+using mozilla::IsNegative;
+using mozilla::IsNegativeZero;
+using mozilla::NegativeInfinity;
+using mozilla::PositiveInfinity;
+using mozilla::Swap;
+using JS::GenericNaN;
+using JS::ToInt32;
+
+// This algorithm is based on the paper "Eliminating Range Checks Using
+// Static Single Assignment Form" by Gough and Klaren.
+//
+// We associate a range object with each SSA name, and the ranges are consulted
+// in order to determine whether overflow is possible for arithmetic
+// computations.
+//
+// An important source of range information that requires care to take
+// advantage of is conditional control flow. Consider the code below:
+//
+// if (x < 0) {
+//   y = x + 2000000000;
+// } else {
+//   if (x < 1000000000) {
+//     y = x * 2;
+//   } else {
+//     y = x - 3000000000;
+//   }
+// }
+//
+// The arithmetic operations in this code cannot overflow, but it is not
+// sufficient to simply associate each name with a range, since the information
+// differs between basic blocks. The traditional dataflow approach would be
+// associate ranges with (name, basic block) pairs. This solution is not
+// satisfying, since we lose the benefit of SSA form: in SSA form, each
+// definition has a unique name, so there is no need to track information about
+// the control flow of the program.
+//
+// The approach used here is to add a new form of pseudo operation called a
+// beta node, which associates range information with a value. These beta
+// instructions take one argument and additionally have an auxiliary constant
+// range associated with them. Operationally, beta nodes are just copies, but
+// the invariant expressed by beta node copies is that the output will fall
+// inside the range given by the beta node.  Gough and Klaeren refer to SSA
+// extended with these beta nodes as XSA form. The following shows the example
+// code transformed into XSA form:
+//
+// if (x < 0) {
+//   x1 = Beta(x, [INT_MIN, -1]);
+//   y1 = x1 + 2000000000;
+// } else {
+//   x2 = Beta(x, [0, INT_MAX]);
+//   if (x2 < 1000000000) {
+//     x3 = Beta(x2, [INT_MIN, 999999999]);
+//     y2 = x3*2;
+//   } else {
+//     x4 = Beta(x2, [1000000000, INT_MAX]);
+//     y3 = x4 - 3000000000;
+//   }
+//   y4 = Phi(y2, y3);
+// }
+// y = Phi(y1, y4);
+//
+// We insert beta nodes for the purposes of range analysis (they might also be
+// usefully used for other forms of bounds check elimination) and remove them
+// after range analysis is performed. The remaining compiler phases do not ever
+// encounter beta nodes.
+
+static bool
+IsDominatedUse(MBasicBlock* block, MUse* use)
+{
+    MNode* n = use->consumer();
+    bool isPhi = n->isDefinition() && n->toDefinition()->isPhi();
+
+    if (isPhi) {
+        MPhi* phi = n->toDefinition()->toPhi();
+        return block->dominates(phi->block()->getPredecessor(phi->indexOf(use)));
+    }
+
+    return block->dominates(n->block());
+}
+
+static inline void
+SpewRange(MDefinition* def)
+{
+#ifdef JS_JITSPEW
+    if (JitSpewEnabled(JitSpew_Range) && def->type() != MIRType::None && def->range()) {
+        JitSpewHeader(JitSpew_Range);
+        Fprinter& out = JitSpewPrinter();
+        def->printName(out);
+        out.printf(" has range ");
+        def->range()->dump(out);
+    }
+#endif
+}
+
+static inline void
+SpewTruncate(MDefinition* def, MDefinition::TruncateKind kind, bool shouldClone)
+{
+#ifdef JS_JITSPEW
+    if (JitSpewEnabled(JitSpew_Range)) {
+        JitSpewHeader(JitSpew_Range);
+        Fprinter& out = JitSpewPrinter();
+        out.printf("truncating ");
+        def->printName(out);
+        out.printf(" (kind: %s, clone: %d)\n", MDefinition::TruncateKindString(kind), shouldClone);
+    }
+#endif
+}
+
+TempAllocator&
+RangeAnalysis::alloc() const
+{
+    return graph_.alloc();
+}
+
+void
+RangeAnalysis::replaceDominatedUsesWith(MDefinition* orig, MDefinition* dom,
+                                            MBasicBlock* block)
+{
+    for (MUseIterator i(orig->usesBegin()); i != orig->usesEnd(); ) {
+        MUse* use = *i++;
+        if (use->consumer() != dom && IsDominatedUse(block, use))
+            use->replaceProducer(dom);
+    }
+}
+
+bool
+RangeAnalysis::addBetaNodes()
+{
+    JitSpew(JitSpew_Range, "Adding beta nodes");
+
+    for (PostorderIterator i(graph_.poBegin()); i != graph_.poEnd(); i++) {
+        MBasicBlock* block = *i;
+        JitSpew(JitSpew_Range, "Looking at block %d", block->id());
+
+        BranchDirection branch_dir;
+        MTest* test = block->immediateDominatorBranch(&branch_dir);
+
+        if (!test || !test->getOperand(0)->isCompare())
+            continue;
+
+        MCompare* compare = test->getOperand(0)->toCompare();
+
+        if (!compare->isNumericComparison())
+            continue;
+
+        // TODO: support unsigned comparisons
+        if (compare->compareType() == MCompare::Compare_UInt32)
+            continue;
+
+        MDefinition* left = compare->getOperand(0);
+        MDefinition* right = compare->getOperand(1);
+        double bound;
+        double conservativeLower = NegativeInfinity<double>();
+        double conservativeUpper = PositiveInfinity<double>();
+        MDefinition* val = nullptr;
+
+        JSOp jsop = compare->jsop();
+
+        if (branch_dir == FALSE_BRANCH) {
+            jsop = NegateCompareOp(jsop);
+            conservativeLower = GenericNaN();
+            conservativeUpper = GenericNaN();
+        }
+
+        MConstant* leftConst = left->maybeConstantValue();
+        MConstant* rightConst = right->maybeConstantValue();
+        if (leftConst && leftConst->isTypeRepresentableAsDouble()) {
+            bound = leftConst->numberToDouble();
+            val = right;
+            jsop = ReverseCompareOp(jsop);
+        } else if (rightConst && rightConst->isTypeRepresentableAsDouble()) {
+            bound = rightConst->numberToDouble();
+            val = left;
+        } else if (left->type() == MIRType::Int32 && right->type() == MIRType::Int32) {
+            MDefinition* smaller = nullptr;
+            MDefinition* greater = nullptr;
+            if (jsop == JSOP_LT) {
+                smaller = left;
+                greater = right;
+            } else if (jsop == JSOP_GT) {
+                smaller = right;
+                greater = left;
+            }
+            if (smaller && greater) {
+                if (!alloc().ensureBallast())
+                    return false;
+
+                MBeta* beta;
+                beta = MBeta::New(alloc(), smaller,
+                                  Range::NewInt32Range(alloc(), JSVAL_INT_MIN, JSVAL_INT_MAX-1));
+                block->insertBefore(*block->begin(), beta);
+                replaceDominatedUsesWith(smaller, beta, block);
+                JitSpew(JitSpew_Range, "Adding beta node for smaller %d", smaller->id());
+                beta = MBeta::New(alloc(), greater,
+                                  Range::NewInt32Range(alloc(), JSVAL_INT_MIN+1, JSVAL_INT_MAX));
+                block->insertBefore(*block->begin(), beta);
+                replaceDominatedUsesWith(greater, beta, block);
+                JitSpew(JitSpew_Range, "Adding beta node for greater %d", greater->id());
+            }
+            continue;
+        } else {
+            continue;
+        }
+
+        // At this point, one of the operands if the compare is a constant, and
+        // val is the other operand.
+        MOZ_ASSERT(val);
+
+        Range comp;
+        switch (jsop) {
+          case JSOP_LE:
+            comp.setDouble(conservativeLower, bound);
+            break;
+          case JSOP_LT:
+            // For integers, if x < c, the upper bound of x is c-1.
+            if (val->type() == MIRType::Int32) {
+                int32_t intbound;
+                if (NumberEqualsInt32(bound, &intbound) && SafeSub(intbound, 1, &intbound))
+                    bound = intbound;
+            }
+            comp.setDouble(conservativeLower, bound);
+
+            // Negative zero is not less than zero.
+            if (bound == 0)
+                comp.refineToExcludeNegativeZero();
+            break;
+          case JSOP_GE:
+            comp.setDouble(bound, conservativeUpper);
+            break;
+          case JSOP_GT:
+            // For integers, if x > c, the lower bound of x is c+1.
+            if (val->type() == MIRType::Int32) {
+                int32_t intbound;
+                if (NumberEqualsInt32(bound, &intbound) && SafeAdd(intbound, 1, &intbound))
+                    bound = intbound;
+            }
+            comp.setDouble(bound, conservativeUpper);
+
+            // Negative zero is not greater than zero.
+            if (bound == 0)
+                comp.refineToExcludeNegativeZero();
+            break;
+          case JSOP_STRICTEQ:
+            // A strict comparison can test for things other than numeric value.
+            if (!compare->isNumericComparison())
+                continue;
+            // Otherwise fall through to handle JSOP_STRICTEQ the same as JSOP_EQ.
+            MOZ_FALLTHROUGH;
+          case JSOP_EQ:
+            comp.setDouble(bound, bound);
+            break;
+          case JSOP_STRICTNE:
+            // A strict comparison can test for things other than numeric value.
+            if (!compare->isNumericComparison())
+                continue;
+            // Otherwise fall through to handle JSOP_STRICTNE the same as JSOP_NE.
+            MOZ_FALLTHROUGH;
+          case JSOP_NE:
+            // Negative zero is not not-equal to zero.
+            if (bound == 0) {
+                comp.refineToExcludeNegativeZero();
+                break;
+            }
+            continue; // well, we could have
+                      // [-\inf, bound-1] U [bound+1, \inf] but we only use contiguous ranges.
+          default:
+            continue;
+        }
+
+        if (JitSpewEnabled(JitSpew_Range)) {
+            JitSpewHeader(JitSpew_Range);
+            Fprinter& out = JitSpewPrinter();
+            out.printf("Adding beta node for %d with range ", val->id());
+            comp.dump(out);
+        }
+
+        if (!alloc().ensureBallast())
+            return false;
+
+        MBeta* beta = MBeta::New(alloc(), val, new(alloc()) Range(comp));
+        block->insertBefore(*block->begin(), beta);
+        replaceDominatedUsesWith(val, beta, block);
+    }
+
+    return true;
+}
+
+bool
+RangeAnalysis::removeBetaNodes()
+{
+    JitSpew(JitSpew_Range, "Removing beta nodes");
+
+    for (PostorderIterator i(graph_.poBegin()); i != graph_.poEnd(); i++) {
+        MBasicBlock* block = *i;
+        for (MDefinitionIterator iter(*i); iter; ) {
+            MDefinition* def = *iter++;
+            if (def->isBeta()) {
+                MDefinition* op = def->getOperand(0);
+                JitSpew(JitSpew_Range, "Removing beta node %d for %d",
+                        def->id(), op->id());
+                def->justReplaceAllUsesWith(op);
+                block->discardDef(def);
+            } else {
+                // We only place Beta nodes at the beginning of basic
+                // blocks, so if we see something else, we can move on
+                // to the next block.
+                break;
+            }
+        }
+    }
+    return true;
+}
+
+void
+SymbolicBound::dump(GenericPrinter& out) const
+{
+    if (loop)
+        out.printf("[loop] ");
+    sum.dump(out);
+}
+
+void
+SymbolicBound::dump() const
+{
+    Fprinter out(stderr);
+    dump(out);
+    out.printf("\n");
+    out.finish();
+}
+
+// Test whether the given range's exponent tells us anything that its lower
+// and upper bound values don't.
+static bool
+IsExponentInteresting(const Range* r)
+{
+   // If it lacks either a lower or upper bound, the exponent is interesting.
+   if (!r->hasInt32Bounds())
+       return true;
+
+   // Otherwise if there's no fractional part, the lower and upper bounds,
+   // which are integers, are perfectly precise.
+   if (!r->canHaveFractionalPart())
+       return false;
+
+   // Otherwise, if the bounds are conservatively rounded across a power-of-two
+   // boundary, the exponent may imply a tighter range.
+   return FloorLog2(Max(Abs(r->lower()), Abs(r->upper()))) > r->exponent();
+}
+
+void
+Range::dump(GenericPrinter& out) const
+{
+    assertInvariants();
+
+    // Floating-point or Integer subset.
+    if (canHaveFractionalPart_)
+        out.printf("F");
+    else
+        out.printf("I");
+
+    out.printf("[");
+
+    if (!hasInt32LowerBound_)
+        out.printf("?");
+    else
+        out.printf("%d", lower_);
+    if (symbolicLower_) {
+        out.printf(" {");
+        symbolicLower_->dump(out);
+        out.printf("}");
+    }
+
+    out.printf(", ");
+
+    if (!hasInt32UpperBound_)
+        out.printf("?");
+    else
+        out.printf("%d", upper_);
+    if (symbolicUpper_) {
+        out.printf(" {");
+        symbolicUpper_->dump(out);
+        out.printf("}");
+    }
+
+    out.printf("]");
+
+    bool includesNaN = max_exponent_ == IncludesInfinityAndNaN;
+    bool includesNegativeInfinity = max_exponent_ >= IncludesInfinity && !hasInt32LowerBound_;
+    bool includesPositiveInfinity = max_exponent_ >= IncludesInfinity && !hasInt32UpperBound_;
+    bool includesNegativeZero = canBeNegativeZero_;
+
+    if (includesNaN ||
+        includesNegativeInfinity ||
+        includesPositiveInfinity ||
+        includesNegativeZero)
+    {
+        out.printf(" (");
+        bool first = true;
+        if (includesNaN) {
+            if (first)
+                first = false;
+            else
+                out.printf(" ");
+            out.printf("U NaN");
+        }
+        if (includesNegativeInfinity) {
+            if (first)
+                first = false;
+            else
+                out.printf(" ");
+            out.printf("U -Infinity");
+        }
+        if (includesPositiveInfinity) {
+            if (first)
+                first = false;
+            else
+                out.printf(" ");
+            out.printf("U Infinity");
+        }
+        if (includesNegativeZero) {
+            if (first)
+                first = false;
+            else
+                out.printf(" ");
+            out.printf("U -0");
+        }
+        out.printf(")");
+    }
+    if (max_exponent_ < IncludesInfinity && IsExponentInteresting(this))
+        out.printf(" (< pow(2, %d+1))", max_exponent_);
+}
+
+void
+Range::dump() const
+{
+    Fprinter out(stderr);
+    dump(out);
+    out.printf("\n");
+    out.finish();
+}
+
+Range*
+Range::intersect(TempAllocator& alloc, const Range* lhs, const Range* rhs, bool* emptyRange)
+{
+    *emptyRange = false;
+
+    if (!lhs && !rhs)
+        return nullptr;
+
+    if (!lhs)
+        return new(alloc) Range(*rhs);
+    if (!rhs)
+        return new(alloc) Range(*lhs);
+
+    int32_t newLower = Max(lhs->lower_, rhs->lower_);
+    int32_t newUpper = Min(lhs->upper_, rhs->upper_);
+
+    // If upper < lower, then we have conflicting constraints. Consider:
+    //
+    // if (x < 0) {
+    //   if (x > 0) {
+    //     [Some code.]
+    //   }
+    // }
+    //
+    // In this case, the block is unreachable.
+    if (newUpper < newLower) {
+        // If both ranges can be NaN, the result can still be NaN.
+        if (!lhs->canBeNaN() || !rhs->canBeNaN())
+            *emptyRange = true;
+        return nullptr;
+    }
+
+    bool newHasInt32LowerBound = lhs->hasInt32LowerBound_ || rhs->hasInt32LowerBound_;
+    bool newHasInt32UpperBound = lhs->hasInt32UpperBound_ || rhs->hasInt32UpperBound_;
+
+    FractionalPartFlag newCanHaveFractionalPart = FractionalPartFlag(lhs->canHaveFractionalPart_ &&
+                                                                     rhs->canHaveFractionalPart_);
+    NegativeZeroFlag newMayIncludeNegativeZero = NegativeZeroFlag(lhs->canBeNegativeZero_ &&
+                                                                  rhs->canBeNegativeZero_);
+
+    uint16_t newExponent = Min(lhs->max_exponent_, rhs->max_exponent_);
+
+    // NaN is a special value which is neither greater than infinity or less than
+    // negative infinity. When we intersect two ranges like [?, 0] and [0, ?], we
+    // can end up thinking we have both a lower and upper bound, even though NaN
+    // is still possible. In this case, just be conservative, since any case where
+    // we can have NaN is not especially interesting.
+    if (newHasInt32LowerBound && newHasInt32UpperBound && newExponent == IncludesInfinityAndNaN)
+        return nullptr;
+
+    // If one of the ranges has a fractional part and the other doesn't, it's
+    // possible that we will have computed a newExponent that's more precise
+    // than our newLower and newUpper. This is unusual, so we handle it here
+    // instead of in optimize().
+    //
+    // For example, consider the range F[0,1.5]. Range analysis represents the
+    // lower and upper bound as integers, so we'd actually have
+    // F[0,2] (< pow(2, 0+1)). In this case, the exponent gives us a slightly
+    // more precise upper bound than the integer upper bound.
+    //
+    // When intersecting such a range with an integer range, the fractional part
+    // of the range is dropped. The max exponent of 0 remains valid, so the
+    // upper bound needs to be adjusted to 1.
+    //
+    // When intersecting F[0,2] (< pow(2, 0+1)) with a range like F[2,4],
+    // the naive intersection is I[2,2], but since the max exponent tells us
+    // that the value is always less than 2, the intersection is actually empty.
+    if (lhs->canHaveFractionalPart() != rhs->canHaveFractionalPart() ||
+        (lhs->canHaveFractionalPart() &&
+         newHasInt32LowerBound && newHasInt32UpperBound &&
+         newLower == newUpper))
+    {
+        refineInt32BoundsByExponent(newExponent,
+                                    &newLower, &newHasInt32LowerBound,
+                                    &newUpper, &newHasInt32UpperBound);
+
+        // If we're intersecting two ranges that don't overlap, this could also
+        // push the bounds past each other, since the actual intersection is
+        // the empty set.
+        if (newLower > newUpper) {
+            *emptyRange = true;
+            return nullptr;
+        }
+    }
+
+    return new(alloc) Range(newLower, newHasInt32LowerBound, newUpper, newHasInt32UpperBound,
+                            newCanHaveFractionalPart,
+                            newMayIncludeNegativeZero,
+                            newExponent);
+}
+
+void
+Range::unionWith(const Range* other)
+{
+    int32_t newLower = Min(lower_, other->lower_);
+    int32_t newUpper = Max(upper_, other->upper_);
+
+    bool newHasInt32LowerBound = hasInt32LowerBound_ && other->hasInt32LowerBound_;
+    bool newHasInt32UpperBound = hasInt32UpperBound_ && other->hasInt32UpperBound_;
+
+    FractionalPartFlag newCanHaveFractionalPart =
+        FractionalPartFlag(canHaveFractionalPart_ ||
+                           other->canHaveFractionalPart_);
+    NegativeZeroFlag newMayIncludeNegativeZero = NegativeZeroFlag(canBeNegativeZero_ ||
+                                                                  other->canBeNegativeZero_);
+
+    uint16_t newExponent = Max(max_exponent_, other->max_exponent_);
+
+    rawInitialize(newLower, newHasInt32LowerBound, newUpper, newHasInt32UpperBound,
+                  newCanHaveFractionalPart,
+                  newMayIncludeNegativeZero,
+                  newExponent);
+}
+
+Range::Range(const MDefinition* def)
+  : symbolicLower_(nullptr),
+    symbolicUpper_(nullptr)
+{
+    if (const Range* other = def->range()) {
+        // The instruction has range information; use it.
+        *this = *other;
+
+        // Simulate the effect of converting the value to its type.
+        // Note: we cannot clamp here, since ranges aren't allowed to shrink
+        // and truncation can increase range again. So doing wrapAround to
+        // mimick a possible truncation.
+        switch (def->type()) {
+          case MIRType::Int32:
+            // MToInt32 cannot truncate. So we can safely clamp.
+            if (def->isToInt32())
+                clampToInt32();
+            else
+                wrapAroundToInt32();
+            break;
+          case MIRType::Boolean:
+            wrapAroundToBoolean();
+            break;
+          case MIRType::None:
+            MOZ_CRASH("Asking for the range of an instruction with no value");
+          default:
+            break;
+        }
+    } else {
+        // Otherwise just use type information. We can trust the type here
+        // because we don't care what value the instruction actually produces,
+        // but what value we might get after we get past the bailouts.
+        switch (def->type()) {
+          case MIRType::Int32:
+            setInt32(JSVAL_INT_MIN, JSVAL_INT_MAX);
+            break;
+          case MIRType::Boolean:
+            setInt32(0, 1);
+            break;
+          case MIRType::None:
+            MOZ_CRASH("Asking for the range of an instruction with no value");
+          default:
+            setUnknown();
+            break;
+        }
+    }
+
+    // As a special case, MUrsh is permitted to claim a result type of
+    // MIRType::Int32 while actually returning values in [0,UINT32_MAX] without
+    // bailouts. If range analysis hasn't ruled out values in
+    // (INT32_MAX,UINT32_MAX], set the range to be conservatively correct for
+    // use as either a uint32 or an int32.
+    if (!hasInt32UpperBound() &&
+        def->isUrsh() &&
+        def->toUrsh()->bailoutsDisabled() &&
+        def->type() != MIRType::Int64)
+    {
+        lower_ = INT32_MIN;
+    }
+
+    assertInvariants();
+}
+
+static uint16_t
+ExponentImpliedByDouble(double d)
+{
+    // Handle the special values.
+    if (IsNaN(d))
+        return Range::IncludesInfinityAndNaN;
+    if (IsInfinite(d))
+        return Range::IncludesInfinity;
+
+    // Otherwise take the exponent part and clamp it at zero, since the Range
+    // class doesn't track fractional ranges.
+    return uint16_t(Max(int_fast16_t(0), ExponentComponent(d)));
+}
+
+void
+Range::setDouble(double l, double h)
+{
+    MOZ_ASSERT(!(l > h));
+
+    // Infer lower_, upper_, hasInt32LowerBound_, and hasInt32UpperBound_.
+    if (l >= INT32_MIN && l <= INT32_MAX) {
+        lower_ = int32_t(::floor(l));
+        hasInt32LowerBound_ = true;
+    } else if (l >= INT32_MAX) {
+        lower_ = INT32_MAX;
+        hasInt32LowerBound_ = true;
+    } else {
+        lower_ = INT32_MIN;
+        hasInt32LowerBound_ = false;
+    }
+    if (h >= INT32_MIN && h <= INT32_MAX) {
+        upper_ = int32_t(::ceil(h));
+        hasInt32UpperBound_ = true;
+    } else if (h <= INT32_MIN) {
+        upper_ = INT32_MIN;
+        hasInt32UpperBound_ = true;
+    } else {
+        upper_ = INT32_MAX;
+        hasInt32UpperBound_ = false;
+    }
+
+    // Infer max_exponent_.
+    uint16_t lExp = ExponentImpliedByDouble(l);
+    uint16_t hExp = ExponentImpliedByDouble(h);
+    max_exponent_ = Max(lExp, hExp);
+
+    canHaveFractionalPart_ = ExcludesFractionalParts;
+    canBeNegativeZero_ = ExcludesNegativeZero;
+
+    // Infer the canHaveFractionalPart_ setting. We can have a
+    // fractional part if the range crosses through the neighborhood of zero. We
+    // won't have a fractional value if the value is always beyond the point at
+    // which double precision can't represent fractional values.
+    uint16_t minExp = Min(lExp, hExp);
+    bool includesNegative = IsNaN(l) || l < 0;
+    bool includesPositive = IsNaN(h) || h > 0;
+    bool crossesZero = includesNegative && includesPositive;
+    if (crossesZero || minExp < MaxTruncatableExponent)
+        canHaveFractionalPart_ = IncludesFractionalParts;
+
+    // Infer the canBeNegativeZero_ setting. We can have a negative zero if
+    // either bound is zero.
+    if (!(l > 0) && !(h < 0))
+        canBeNegativeZero_ = IncludesNegativeZero;
+
+    optimize();
+}
+
+void
+Range::setDoubleSingleton(double d)
+{
+    setDouble(d, d);
+
+    // The above setDouble call is for comparisons, and treats negative zero
+    // as equal to zero. We're aiming for a minimum range, so we can clear the
+    // negative zero flag if the value isn't actually negative zero.
+    if (!IsNegativeZero(d))
+        canBeNegativeZero_ = ExcludesNegativeZero;
+
+    assertInvariants();
+}
+
+static inline bool
+MissingAnyInt32Bounds(const Range* lhs, const Range* rhs)
+{
+    return !lhs->hasInt32Bounds() || !rhs->hasInt32Bounds();
+}
+
+Range*
+Range::add(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    int64_t l = (int64_t) lhs->lower_ + (int64_t) rhs->lower_;
+    if (!lhs->hasInt32LowerBound() || !rhs->hasInt32LowerBound())
+        l = NoInt32LowerBound;
+
+    int64_t h = (int64_t) lhs->upper_ + (int64_t) rhs->upper_;
+    if (!lhs->hasInt32UpperBound() || !rhs->hasInt32UpperBound())
+        h = NoInt32UpperBound;
+
+    // The exponent is at most one greater than the greater of the operands'
+    // exponents, except for NaN and infinity cases.
+    uint16_t e = Max(lhs->max_exponent_, rhs->max_exponent_);
+    if (e <= Range::MaxFiniteExponent)
+        ++e;
+
+    // Infinity + -Infinity is NaN.
+    if (lhs->canBeInfiniteOrNaN() && rhs->canBeInfiniteOrNaN())
+        e = Range::IncludesInfinityAndNaN;
+
+    return new(alloc) Range(l, h,
+                            FractionalPartFlag(lhs->canHaveFractionalPart() ||
+                                               rhs->canHaveFractionalPart()),
+                            NegativeZeroFlag(lhs->canBeNegativeZero() &&
+                                             rhs->canBeNegativeZero()),
+                            e);
+}
+
+Range*
+Range::sub(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    int64_t l = (int64_t) lhs->lower_ - (int64_t) rhs->upper_;
+    if (!lhs->hasInt32LowerBound() || !rhs->hasInt32UpperBound())
+        l = NoInt32LowerBound;
+
+    int64_t h = (int64_t) lhs->upper_ - (int64_t) rhs->lower_;
+    if (!lhs->hasInt32UpperBound() || !rhs->hasInt32LowerBound())
+        h = NoInt32UpperBound;
+
+    // The exponent is at most one greater than the greater of the operands'
+    // exponents, except for NaN and infinity cases.
+    uint16_t e = Max(lhs->max_exponent_, rhs->max_exponent_);
+    if (e <= Range::MaxFiniteExponent)
+        ++e;
+
+    // Infinity - Infinity is NaN.
+    if (lhs->canBeInfiniteOrNaN() && rhs->canBeInfiniteOrNaN())
+        e = Range::IncludesInfinityAndNaN;
+
+    return new(alloc) Range(l, h,
+                            FractionalPartFlag(lhs->canHaveFractionalPart() ||
+                                               rhs->canHaveFractionalPart()),
+                            NegativeZeroFlag(lhs->canBeNegativeZero() &&
+                                             rhs->canBeZero()),
+                            e);
+}
+
+Range*
+Range::and_(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+
+    // If both numbers can be negative, result can be negative in the whole range
+    if (lhs->lower() < 0 && rhs->lower() < 0)
+        return Range::NewInt32Range(alloc, INT32_MIN, Max(lhs->upper(), rhs->upper()));
+
+    // Only one of both numbers can be negative.
+    // - result can't be negative
+    // - Upper bound is minimum of both upper range,
+    int32_t lower = 0;
+    int32_t upper = Min(lhs->upper(), rhs->upper());
+
+    // EXCEPT when upper bound of non negative number is max value,
+    // because negative value can return the whole max value.
+    // -1 & 5 = 5
+    if (lhs->lower() < 0)
+       upper = rhs->upper();
+    if (rhs->lower() < 0)
+        upper = lhs->upper();
+
+    return Range::NewInt32Range(alloc, lower, upper);
+}
+
+Range*
+Range::or_(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+    // When one operand is always 0 or always -1, it's a special case where we
+    // can compute a fully precise result. Handling these up front also
+    // protects the code below from calling CountLeadingZeroes32 with a zero
+    // operand or from shifting an int32_t by 32.
+    if (lhs->lower() == lhs->upper()) {
+        if (lhs->lower() == 0)
+            return new(alloc) Range(*rhs);
+        if (lhs->lower() == -1)
+            return new(alloc) Range(*lhs);
+    }
+    if (rhs->lower() == rhs->upper()) {
+        if (rhs->lower() == 0)
+            return new(alloc) Range(*lhs);
+        if (rhs->lower() == -1)
+            return new(alloc) Range(*rhs);
+    }
+
+    // The code below uses CountLeadingZeroes32, which has undefined behavior
+    // if its operand is 0. We rely on the code above to protect it.
+    MOZ_ASSERT_IF(lhs->lower() >= 0, lhs->upper() != 0);
+    MOZ_ASSERT_IF(rhs->lower() >= 0, rhs->upper() != 0);
+    MOZ_ASSERT_IF(lhs->upper() < 0, lhs->lower() != -1);
+    MOZ_ASSERT_IF(rhs->upper() < 0, rhs->lower() != -1);
+
+    int32_t lower = INT32_MIN;
+    int32_t upper = INT32_MAX;
+
+    if (lhs->lower() >= 0 && rhs->lower() >= 0) {
+        // Both operands are non-negative, so the result won't be less than either.
+        lower = Max(lhs->lower(), rhs->lower());
+        // The result will have leading zeros where both operands have leading zeros.
+        // CountLeadingZeroes32 of a non-negative int32 will at least be 1 to account
+        // for the bit of sign.
+        upper = int32_t(UINT32_MAX >> Min(CountLeadingZeroes32(lhs->upper()),
+                                          CountLeadingZeroes32(rhs->upper())));
+    } else {
+        // The result will have leading ones where either operand has leading ones.
+        if (lhs->upper() < 0) {
+            unsigned leadingOnes = CountLeadingZeroes32(~lhs->lower());
+            lower = Max(lower, ~int32_t(UINT32_MAX >> leadingOnes));
+            upper = -1;
+        }
+        if (rhs->upper() < 0) {
+            unsigned leadingOnes = CountLeadingZeroes32(~rhs->lower());
+            lower = Max(lower, ~int32_t(UINT32_MAX >> leadingOnes));
+            upper = -1;
+        }
+    }
+
+    return Range::NewInt32Range(alloc, lower, upper);
+}
+
+Range*
+Range::xor_(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+    int32_t lhsLower = lhs->lower();
+    int32_t lhsUpper = lhs->upper();
+    int32_t rhsLower = rhs->lower();
+    int32_t rhsUpper = rhs->upper();
+    bool invertAfter = false;
+
+    // If either operand is negative, bitwise-negate it, and arrange to negate
+    // the result; ~((~x)^y) == x^y. If both are negative the negations on the
+    // result cancel each other out; effectively this is (~x)^(~y) == x^y.
+    // These transformations reduce the number of cases we have to handle below.
+    if (lhsUpper < 0) {
+        lhsLower = ~lhsLower;
+        lhsUpper = ~lhsUpper;
+        Swap(lhsLower, lhsUpper);
+        invertAfter = !invertAfter;
+    }
+    if (rhsUpper < 0) {
+        rhsLower = ~rhsLower;
+        rhsUpper = ~rhsUpper;
+        Swap(rhsLower, rhsUpper);
+        invertAfter = !invertAfter;
+    }
+
+    // Handle cases where lhs or rhs is always zero specially, because they're
+    // easy cases where we can be perfectly precise, and because it protects the
+    // CountLeadingZeroes32 calls below from seeing 0 operands, which would be
+    // undefined behavior.
+    int32_t lower = INT32_MIN;
+    int32_t upper = INT32_MAX;
+    if (lhsLower == 0 && lhsUpper == 0) {
+        upper = rhsUpper;
+        lower = rhsLower;
+    } else if (rhsLower == 0 && rhsUpper == 0) {
+        upper = lhsUpper;
+        lower = lhsLower;
+    } else if (lhsLower >= 0 && rhsLower >= 0) {
+        // Both operands are non-negative. The result will be non-negative.
+        lower = 0;
+        // To compute the upper value, take each operand's upper value and
+        // set all bits that don't correspond to leading zero bits in the
+        // other to one. For each one, this gives an upper bound for the
+        // result, so we can take the minimum between the two.
+        unsigned lhsLeadingZeros = CountLeadingZeroes32(lhsUpper);
+        unsigned rhsLeadingZeros = CountLeadingZeroes32(rhsUpper);
+        upper = Min(rhsUpper | int32_t(UINT32_MAX >> lhsLeadingZeros),
+                    lhsUpper | int32_t(UINT32_MAX >> rhsLeadingZeros));
+    }
+
+    // If we bitwise-negated one (but not both) of the operands above, apply the
+    // bitwise-negate to the result, completing ~((~x)^y) == x^y.
+    if (invertAfter) {
+        lower = ~lower;
+        upper = ~upper;
+        Swap(lower, upper);
+    }
+
+    return Range::NewInt32Range(alloc, lower, upper);
+}
+
+Range*
+Range::not_(TempAllocator& alloc, const Range* op)
+{
+    MOZ_ASSERT(op->isInt32());
+    return Range::NewInt32Range(alloc, ~op->upper(), ~op->lower());
+}
+
+Range*
+Range::mul(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    FractionalPartFlag newCanHaveFractionalPart = FractionalPartFlag(lhs->canHaveFractionalPart_ ||
+                                                                     rhs->canHaveFractionalPart_);
+
+    NegativeZeroFlag newMayIncludeNegativeZero =
+        NegativeZeroFlag((lhs->canHaveSignBitSet() && rhs->canBeFiniteNonNegative()) ||
+                         (rhs->canHaveSignBitSet() && lhs->canBeFiniteNonNegative()));
+
+    uint16_t exponent;
+    if (!lhs->canBeInfiniteOrNaN() && !rhs->canBeInfiniteOrNaN()) {
+        // Two finite values.
+        exponent = lhs->numBits() + rhs->numBits() - 1;
+        if (exponent > Range::MaxFiniteExponent)
+            exponent = Range::IncludesInfinity;
+    } else if (!lhs->canBeNaN() &&
+               !rhs->canBeNaN() &&
+               !(lhs->canBeZero() && rhs->canBeInfiniteOrNaN()) &&
+               !(rhs->canBeZero() && lhs->canBeInfiniteOrNaN()))
+    {
+        // Two values that multiplied together won't produce a NaN.
+        exponent = Range::IncludesInfinity;
+    } else {
+        // Could be anything.
+        exponent = Range::IncludesInfinityAndNaN;
+    }
+
+    if (MissingAnyInt32Bounds(lhs, rhs))
+        return new(alloc) Range(NoInt32LowerBound, NoInt32UpperBound,
+                                newCanHaveFractionalPart,
+                                newMayIncludeNegativeZero,
+                                exponent);
+    int64_t a = (int64_t)lhs->lower() * (int64_t)rhs->lower();
+    int64_t b = (int64_t)lhs->lower() * (int64_t)rhs->upper();
+    int64_t c = (int64_t)lhs->upper() * (int64_t)rhs->lower();
+    int64_t d = (int64_t)lhs->upper() * (int64_t)rhs->upper();
+    return new(alloc) Range(
+        Min( Min(a, b), Min(c, d) ),
+        Max( Max(a, b), Max(c, d) ),
+        newCanHaveFractionalPart,
+        newMayIncludeNegativeZero,
+        exponent);
+}
+
+Range*
+Range::lsh(TempAllocator& alloc, const Range* lhs, int32_t c)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    int32_t shift = c & 0x1f;
+
+    // If the shift doesn't loose bits or shift bits into the sign bit, we
+    // can simply compute the correct range by shifting.
+    if ((int32_t)((uint32_t)lhs->lower() << shift << 1 >> shift >> 1) == lhs->lower() &&
+        (int32_t)((uint32_t)lhs->upper() << shift << 1 >> shift >> 1) == lhs->upper())
+    {
+        return Range::NewInt32Range(alloc,
+            uint32_t(lhs->lower()) << shift,
+            uint32_t(lhs->upper()) << shift);
+    }
+
+    return Range::NewInt32Range(alloc, INT32_MIN, INT32_MAX);
+}
+
+Range*
+Range::rsh(TempAllocator& alloc, const Range* lhs, int32_t c)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    int32_t shift = c & 0x1f;
+    return Range::NewInt32Range(alloc,
+        lhs->lower() >> shift,
+        lhs->upper() >> shift);
+}
+
+Range*
+Range::ursh(TempAllocator& alloc, const Range* lhs, int32_t c)
+{
+    // ursh's left operand is uint32, not int32, but for range analysis we
+    // currently approximate it as int32. We assume here that the range has
+    // already been adjusted accordingly by our callers.
+    MOZ_ASSERT(lhs->isInt32());
+
+    int32_t shift = c & 0x1f;
+
+    // If the value is always non-negative or always negative, we can simply
+    // compute the correct range by shifting.
+    if (lhs->isFiniteNonNegative() || lhs->isFiniteNegative()) {
+        return Range::NewUInt32Range(alloc,
+            uint32_t(lhs->lower()) >> shift,
+            uint32_t(lhs->upper()) >> shift);
+    }
+
+    // Otherwise return the most general range after the shift.
+    return Range::NewUInt32Range(alloc, 0, UINT32_MAX >> shift);
+}
+
+Range*
+Range::lsh(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+    return Range::NewInt32Range(alloc, INT32_MIN, INT32_MAX);
+}
+
+Range*
+Range::rsh(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+
+    // Canonicalize the shift range to 0 to 31.
+    int32_t shiftLower = rhs->lower();
+    int32_t shiftUpper = rhs->upper();
+    if ((int64_t(shiftUpper) - int64_t(shiftLower)) >= 31) {
+        shiftLower = 0;
+        shiftUpper = 31;
+    } else {
+        shiftLower &= 0x1f;
+        shiftUpper &= 0x1f;
+        if (shiftLower > shiftUpper) {
+            shiftLower = 0;
+            shiftUpper = 31;
+        }
+    }
+    MOZ_ASSERT(shiftLower >= 0 && shiftUpper <= 31);
+
+    // The lhs bounds are signed, thus the minimum is either the lower bound
+    // shift by the smallest shift if negative or the lower bound shifted by the
+    // biggest shift otherwise.  And the opposite for the maximum.
+    int32_t lhsLower = lhs->lower();
+    int32_t min = lhsLower < 0 ? lhsLower >> shiftLower : lhsLower >> shiftUpper;
+    int32_t lhsUpper = lhs->upper();
+    int32_t max = lhsUpper >= 0 ? lhsUpper >> shiftLower : lhsUpper >> shiftUpper;
+
+    return Range::NewInt32Range(alloc, min, max);
+}
+
+Range*
+Range::ursh(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    // ursh's left operand is uint32, not int32, but for range analysis we
+    // currently approximate it as int32. We assume here that the range has
+    // already been adjusted accordingly by our callers.
+    MOZ_ASSERT(lhs->isInt32());
+    MOZ_ASSERT(rhs->isInt32());
+    return Range::NewUInt32Range(alloc, 0, lhs->isFiniteNonNegative() ? lhs->upper() : UINT32_MAX);
+}
+
+Range*
+Range::abs(TempAllocator& alloc, const Range* op)
+{
+    int32_t l = op->lower_;
+    int32_t u = op->upper_;
+    FractionalPartFlag canHaveFractionalPart = op->canHaveFractionalPart_;
+
+    // Abs never produces a negative zero.
+    NegativeZeroFlag canBeNegativeZero = ExcludesNegativeZero;
+
+    return new(alloc) Range(Max(Max(int32_t(0), l), u == INT32_MIN ? INT32_MAX : -u),
+                            true,
+                            Max(Max(int32_t(0), u), l == INT32_MIN ? INT32_MAX : -l),
+                            op->hasInt32Bounds() && l != INT32_MIN,
+                            canHaveFractionalPart,
+                            canBeNegativeZero,
+                            op->max_exponent_);
+}
+
+Range*
+Range::min(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    // If either operand is NaN, the result is NaN.
+    if (lhs->canBeNaN() || rhs->canBeNaN())
+        return nullptr;
+
+    FractionalPartFlag newCanHaveFractionalPart = FractionalPartFlag(lhs->canHaveFractionalPart_ ||
+                                                                     rhs->canHaveFractionalPart_);
+    NegativeZeroFlag newMayIncludeNegativeZero = NegativeZeroFlag(lhs->canBeNegativeZero_ ||
+                                                                  rhs->canBeNegativeZero_);
+
+    return new(alloc) Range(Min(lhs->lower_, rhs->lower_),
+                            lhs->hasInt32LowerBound_ && rhs->hasInt32LowerBound_,
+                            Min(lhs->upper_, rhs->upper_),
+                            lhs->hasInt32UpperBound_ || rhs->hasInt32UpperBound_,
+                            newCanHaveFractionalPart,
+                            newMayIncludeNegativeZero,
+                            Max(lhs->max_exponent_, rhs->max_exponent_));
+}
+
+Range*
+Range::max(TempAllocator& alloc, const Range* lhs, const Range* rhs)
+{
+    // If either operand is NaN, the result is NaN.
+    if (lhs->canBeNaN() || rhs->canBeNaN())
+        return nullptr;
+
+    FractionalPartFlag newCanHaveFractionalPart = FractionalPartFlag(lhs->canHaveFractionalPart_ ||
+                                                                     rhs->canHaveFractionalPart_);
+    NegativeZeroFlag newMayIncludeNegativeZero = NegativeZeroFlag(lhs->canBeNegativeZero_ ||
+                                                                  rhs->canBeNegativeZero_);
+
+    return new(alloc) Range(Max(lhs->lower_, rhs->lower_),
+                            lhs->hasInt32LowerBound_ || rhs->hasInt32LowerBound_,
+                            Max(lhs->upper_, rhs->upper_),
+                            lhs->hasInt32UpperBound_ && rhs->hasInt32UpperBound_,
+                            newCanHaveFractionalPart,
+                            newMayIncludeNegativeZero,
+                            Max(lhs->max_exponent_, rhs->max_exponent_));
+}
+
+Range*
+Range::floor(TempAllocator& alloc, const Range* op)
+{
+    Range* copy = new(alloc) Range(*op);
+    // Decrement lower bound of copy range if op have a factional part and lower
+    // bound is Int32 defined. Also we avoid to decrement when op have a
+    // fractional part but lower_ >= JSVAL_INT_MAX.
+    if (op->canHaveFractionalPart() && op->hasInt32LowerBound())
+        copy->setLowerInit(int64_t(copy->lower_) - 1);
+
+    // Also refine max_exponent_ because floor may have decremented int value
+    // If we've got int32 defined bounds, just deduce it using defined bounds.
+    // But, if we don't have those, value's max_exponent_ may have changed.
+    // Because we're looking to maintain an over estimation, if we can,
+    // we increment it.
+    if(copy->hasInt32Bounds())
+        copy->max_exponent_ = copy->exponentImpliedByInt32Bounds();
+    else if(copy->max_exponent_ < MaxFiniteExponent)
+        copy->max_exponent_++;
+
+    copy->canHaveFractionalPart_ = ExcludesFractionalParts;
+    copy->assertInvariants();
+    return copy;
+}
+
+Range*
+Range::ceil(TempAllocator& alloc, const Range* op)
+{
+    Range* copy = new(alloc) Range(*op);
+
+    // We need to refine max_exponent_ because ceil may have incremented the int value.
+    // If we have got int32 bounds defined, just deduce it using the defined bounds.
+    // Else we can just increment its value,
+    // as we are looking to maintain an over estimation.
+    if (copy->hasInt32Bounds())
+        copy->max_exponent_ = copy->exponentImpliedByInt32Bounds();
+    else if (copy->max_exponent_ < MaxFiniteExponent)
+        copy->max_exponent_++;
+
+    copy->canHaveFractionalPart_ = ExcludesFractionalParts;
+    copy->assertInvariants();
+    return copy;
+}
+
+Range*
+Range::sign(TempAllocator& alloc, const Range* op)
+{
+    if (op->canBeNaN())
+        return nullptr;
+
+    return new(alloc) Range(Max(Min(op->lower_, 1), -1),
+                            Max(Min(op->upper_, 1), -1),
+                            Range::ExcludesFractionalParts,
+                            NegativeZeroFlag(op->canBeNegativeZero()),
+                            0);
+}
+
+Range*
+Range::NaNToZero(TempAllocator& alloc, const Range *op)
+{
+    Range* copy = new(alloc) Range(*op);
+    if (copy->canBeNaN()) {
+        copy->max_exponent_ = Range::IncludesInfinity;
+        if (!copy->canBeZero()) {
+            Range zero;
+            zero.setDoubleSingleton(0);
+            copy->unionWith(&zero);
+        }
+    }
+    copy->refineToExcludeNegativeZero();
+    return copy;
+}
+
+bool
+Range::negativeZeroMul(const Range* lhs, const Range* rhs)
+{
+    // The result can only be negative zero if both sides are finite and they
+    // have differing signs.
+    return (lhs->canHaveSignBitSet() && rhs->canBeFiniteNonNegative()) ||
+           (rhs->canHaveSignBitSet() && lhs->canBeFiniteNonNegative());
+}
+
+bool
+Range::update(const Range* other)
+{
+    bool changed =
+        lower_ != other->lower_ ||
+        hasInt32LowerBound_ != other->hasInt32LowerBound_ ||
+        upper_ != other->upper_ ||
+        hasInt32UpperBound_ != other->hasInt32UpperBound_ ||
+        canHaveFractionalPart_ != other->canHaveFractionalPart_ ||
+        canBeNegativeZero_ != other->canBeNegativeZero_ ||
+        max_exponent_ != other->max_exponent_;
+    if (changed) {
+        lower_ = other->lower_;
+        hasInt32LowerBound_ = other->hasInt32LowerBound_;
+        upper_ = other->upper_;
+        hasInt32UpperBound_ = other->hasInt32UpperBound_;
+        canHaveFractionalPart_ = other->canHaveFractionalPart_;
+        canBeNegativeZero_ = other->canBeNegativeZero_;
+        max_exponent_ = other->max_exponent_;
+        assertInvariants();
+    }
+
+    return changed;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Range Computation for MIR Nodes
+///////////////////////////////////////////////////////////////////////////////
+
+void
+MPhi::computeRange(TempAllocator& alloc)
+{
+    if (type() != MIRType::Int32 && type() != MIRType::Double)
+        return;
+
+    Range* range = nullptr;
+    for (size_t i = 0, e = numOperands(); i < e; i++) {
+        if (getOperand(i)->block()->unreachable()) {
+            JitSpew(JitSpew_Range, "Ignoring unreachable input %d", getOperand(i)->id());
+            continue;
+        }
+
+        // Peek at the pre-bailout range so we can take a short-cut; if any of
+        // the operands has an unknown range, this phi has an unknown range.
+        if (!getOperand(i)->range())
+            return;
+
+        Range input(getOperand(i));
+
+        if (range)
+            range->unionWith(&input);
+        else
+            range = new(alloc) Range(input);
+    }
+
+    setRange(range);
+}
+
+void
+MBeta::computeRange(TempAllocator& alloc)
+{
+    bool emptyRange = false;
+
+    Range opRange(getOperand(0));
+    Range* range = Range::intersect(alloc, &opRange, comparison_, &emptyRange);
+    if (emptyRange) {
+        JitSpew(JitSpew_Range, "Marking block for inst %d unreachable", id());
+        block()->setUnreachableUnchecked();
+    } else {
+        setRange(range);
+    }
+}
+
+void
+MConstant::computeRange(TempAllocator& alloc)
+{
+    if (isTypeRepresentableAsDouble()) {
+        double d = numberToDouble();
+        setRange(Range::NewDoubleSingletonRange(alloc, d));
+    } else if (type() == MIRType::Boolean) {
+        bool b = toBoolean();
+        setRange(Range::NewInt32Range(alloc, b, b));
+    }
+}
+
+void
+MCharCodeAt::computeRange(TempAllocator& alloc)
+{
+    // ECMA 262 says that the integer will be non-negative and at most 65535.
+    setRange(Range::NewInt32Range(alloc, 0, 65535));
+}
+
+void
+MClampToUint8::computeRange(TempAllocator& alloc)
+{
+    setRange(Range::NewUInt32Range(alloc, 0, 255));
+}
+
+void
+MBitAnd::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    left.wrapAroundToInt32();
+    right.wrapAroundToInt32();
+
+    setRange(Range::and_(alloc, &left, &right));
+}
+
+void
+MBitOr::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    left.wrapAroundToInt32();
+    right.wrapAroundToInt32();
+
+    setRange(Range::or_(alloc, &left, &right));
+}
+
+void
+MBitXor::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    left.wrapAroundToInt32();
+    right.wrapAroundToInt32();
+
+    setRange(Range::xor_(alloc, &left, &right));
+}
+
+void
+MBitNot::computeRange(TempAllocator& alloc)
+{
+    Range op(getOperand(0));
+    op.wrapAroundToInt32();
+
+    setRange(Range::not_(alloc, &op));
+}
+
+void
+MLsh::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    left.wrapAroundToInt32();
+
+    MConstant* rhsConst = getOperand(1)->maybeConstantValue();
+    if (rhsConst && rhsConst->type() == MIRType::Int32) {
+        int32_t c = rhsConst->toInt32();
+        setRange(Range::lsh(alloc, &left, c));
+        return;
+    }
+
+    right.wrapAroundToShiftCount();
+    setRange(Range::lsh(alloc, &left, &right));
+}
+
+void
+MRsh::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    left.wrapAroundToInt32();
+
+    MConstant* rhsConst = getOperand(1)->maybeConstantValue();
+    if (rhsConst && rhsConst->type() == MIRType::Int32) {
+        int32_t c = rhsConst->toInt32();
+        setRange(Range::rsh(alloc, &left, c));
+        return;
+    }
+
+    right.wrapAroundToShiftCount();
+    setRange(Range::rsh(alloc, &left, &right));
+}
+
+void
+MUrsh::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+
+    // ursh can be thought of as converting its left operand to uint32, or it
+    // can be thought of as converting its left operand to int32, and then
+    // reinterpreting the int32 bits as a uint32 value. Both approaches yield
+    // the same result. Since we lack support for full uint32 ranges, we use
+    // the second interpretation, though it does cause us to be conservative.
+    left.wrapAroundToInt32();
+    right.wrapAroundToShiftCount();
+
+    MConstant* rhsConst = getOperand(1)->maybeConstantValue();
+    if (rhsConst && rhsConst->type() == MIRType::Int32) {
+        int32_t c = rhsConst->toInt32();
+        setRange(Range::ursh(alloc, &left, c));
+    } else {
+        setRange(Range::ursh(alloc, &left, &right));
+    }
+
+    MOZ_ASSERT(range()->lower() >= 0);
+}
+
+void
+MAbs::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ != MIRType::Int32 && specialization_ != MIRType::Double)
+        return;
+
+    Range other(getOperand(0));
+    Range* next = Range::abs(alloc, &other);
+    if (implicitTruncate_)
+        next->wrapAroundToInt32();
+    setRange(next);
+}
+
+void
+MFloor::computeRange(TempAllocator& alloc)
+{
+    Range other(getOperand(0));
+    setRange(Range::floor(alloc, &other));
+}
+
+void
+MCeil::computeRange(TempAllocator& alloc)
+{
+    Range other(getOperand(0));
+    setRange(Range::ceil(alloc, &other));
+}
+
+void
+MClz::computeRange(TempAllocator& alloc)
+{
+    if (type() != MIRType::Int32)
+        return;
+    setRange(Range::NewUInt32Range(alloc, 0, 32));
+}
+
+void
+MCtz::computeRange(TempAllocator& alloc)
+{
+    if (type() != MIRType::Int32)
+        return;
+    setRange(Range::NewUInt32Range(alloc, 0, 32));
+}
+
+void
+MPopcnt::computeRange(TempAllocator& alloc)
+{
+    if (type() != MIRType::Int32)
+        return;
+    setRange(Range::NewUInt32Range(alloc, 0, 32));
+}
+
+void
+MMinMax::computeRange(TempAllocator& alloc)
+{
+    if (specialization_ != MIRType::Int32 && specialization_ != MIRType::Double)
+        return;
+
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    setRange(isMax() ? Range::max(alloc, &left, &right) : Range::min(alloc, &left, &right));
+}
+
+void
+MAdd::computeRange(TempAllocator& alloc)
+{
+    if (specialization() != MIRType::Int32 && specialization() != MIRType::Double)
+        return;
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    Range* next = Range::add(alloc, &left, &right);
+    if (isTruncated())
+        next->wrapAroundToInt32();
+    setRange(next);
+}
+
+void
+MSub::computeRange(TempAllocator& alloc)
+{
+    if (specialization() != MIRType::Int32 && specialization() != MIRType::Double)
+        return;
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    Range* next = Range::sub(alloc, &left, &right);
+    if (isTruncated())
+        next->wrapAroundToInt32();
+    setRange(next);
+}
+
+void
+MMul::computeRange(TempAllocator& alloc)
+{
+    if (specialization() != MIRType::Int32 && specialization() != MIRType::Double)
+        return;
+    Range left(getOperand(0));
+    Range right(getOperand(1));
+    if (canBeNegativeZero())
+        canBeNegativeZero_ = Range::negativeZeroMul(&left, &right);
+    Range* next = Range::mul(alloc, &left, &right);
+    if (!next->canBeNegativeZero())
+        canBeNegativeZero_ = false;
+    // Truncated multiplications could overflow in both directions
+    if (isTruncated())
+        next->wrapAroundToInt32();
+    setRange(next);
+}
+
+void
+MMod::computeRange(TempAllocator& alloc)
+{
+    if (specialization() != MIRType::Int32 && specialization() != MIRType::Double)
+        return;
+    Range lhs(getOperand(0));
+    Range rhs(getOperand(1));
+
+    // If either operand is a NaN, the result is NaN. This also conservatively
+    // handles Infinity cases.
+    if (!lhs.hasInt32Bounds() || !rhs.hasInt32Bounds())
+        return;
+
+    // If RHS can be zero, the result can be NaN.
+    if (rhs.lower() <= 0 && rhs.upper() >= 0)
+        return;
+
+    // If both operands are non-negative integers, we can optimize this to an
+    // unsigned mod.
+    if (specialization() == MIRType::Int32 && rhs.lower() > 0) {
+        bool hasDoubles = lhs.lower() < 0 || lhs.canHaveFractionalPart() ||
+            rhs.canHaveFractionalPart();
+        // It is not possible to check that lhs.lower() >= 0, since the range
+        // of a ursh with rhs a 0 constant is wrapped around the int32 range in
+        // Range::Range(). However, IsUint32Type() will only return true for
+        // nodes that lie in the range [0, UINT32_MAX].
+        bool hasUint32s = IsUint32Type(getOperand(0)) &&
+            getOperand(1)->type() == MIRType::Int32 &&
+            (IsUint32Type(getOperand(1)) || getOperand(1)->isConstant());
+        if (!hasDoubles || hasUint32s)
+            unsigned_ = true;
+    }
+
+    // For unsigned mod, we have to convert both operands to unsigned.
+    // Note that we handled the case of a zero rhs above.
+    if (unsigned_) {
+        // The result of an unsigned mod will never be unsigned-greater than
+        // either operand.
+        uint32_t lhsBound = Max<uint32_t>(lhs.lower(), lhs.upper());
+        uint32_t rhsBound = Max<uint32_t>(rhs.lower(), rhs.upper());
+
+        // If either range crosses through -1 as a signed value, it could be
+        // the maximum unsigned value when interpreted as unsigned. If the range
+        // doesn't include -1, then the simple max value we computed above is
+        // correct.
+        if (lhs.lower() <= -1 && lhs.upper() >= -1)
+            lhsBound = UINT32_MAX;
+        if (rhs.lower() <= -1 && rhs.upper() >= -1)
+            rhsBound = UINT32_MAX;
+
+        // The result will never be equal to the rhs, and we shouldn't have
+        // any rounding to worry about.
+        MOZ_ASSERT(!lhs.canHaveFractionalPart() && !rhs.canHaveFractionalPart());
+        --rhsBound;
+
+        // This gives us two upper bounds, so we can take the best one.
+        setRange(Range::NewUInt32Range(alloc, 0, Min(lhsBound, rhsBound)));
+        return;
+    }
+
+    // Math.abs(lhs % rhs) == Math.abs(lhs) % Math.abs(rhs).
+    // First, the absolute value of the result will always be less than the
+    // absolute value of rhs. (And if rhs is zero, the result is NaN).
+    int64_t a = Abs<int64_t>(rhs.lower());
+    int64_t b = Abs<int64_t>(rhs.upper());
+    if (a == 0 && b == 0)
+        return;
+    int64_t rhsAbsBound = Max(a, b);
+
+    // If the value is known to be integer, less-than abs(rhs) is equivalent
+    // to less-than-or-equal abs(rhs)-1. This is important for being able to
+    // say that the result of x%256 is an 8-bit unsigned number.
+    if (!lhs.canHaveFractionalPart() && !rhs.canHaveFractionalPart())
+        --rhsAbsBound;
+
+    // Next, the absolute value of the result will never be greater than the
+    // absolute value of lhs.
+    int64_t lhsAbsBound = Max(Abs<int64_t>(lhs.lower()), Abs<int64_t>(lhs.upper()));
+
+    // This gives us two upper bounds, so we can take the best one.
+    int64_t absBound = Min(lhsAbsBound, rhsAbsBound);
+
+    // Now consider the sign of the result.
+    // If lhs is non-negative, the result will be non-negative.
+    // If lhs is non-positive, the result will be non-positive.
+    int64_t lower = lhs.lower() >= 0 ? 0 : -absBound;
+    int64_t upper = lhs.upper() <= 0 ? 0 : absBound;
+
+    Range::FractionalPartFlag newCanHaveFractionalPart =
+        Range::FractionalPartFlag(lhs.canHaveFractionalPart() ||
+                                  rhs.canHaveFractionalPart());
+
+    // If the lhs can have the sign bit set and we can return a zero, it'll be a
+    // negative zero.
+    Range::NegativeZeroFlag newMayIncludeNegativeZero =
+        Range::NegativeZeroFlag(lhs.canHaveSignBitSet());
+
+    setRange(new(alloc) Range(lower, upper,
+                              newCanHaveFractionalPart,
+                              newMayIncludeNegativeZero,
+                              Min(lhs.exponent(), rhs.exponent())));
+}
+
+void
+MDiv::computeRange(TempAllocator& alloc)
+{
+    if (specialization() != MIRType::Int32 && specialization() != MIRType::Double)
+        return;
+    Range lhs(getOperand(0));
+    Range rhs(getOperand(1));
+
+    // If either operand is a NaN, the result is NaN. This also conservatively
+    // handles Infinity cases.
+    if (!lhs.hasInt32Bounds() || !rhs.hasInt32Bounds())
+        return;
+
+    // Something simple for now: When dividing by a positive rhs, the result
+    // won't be further from zero than lhs.
+    if (lhs.lower() >= 0 && rhs.lower() >= 1) {
+        setRange(new(alloc) Range(0, lhs.upper(),
+                                  Range::IncludesFractionalParts,
+                                  Range::IncludesNegativeZero,
+                                  lhs.exponent()));
+    } else if (unsigned_ && rhs.lower() >= 1) {
+        // We shouldn't set the unsigned flag if the inputs can have
+        // fractional parts.
+        MOZ_ASSERT(!lhs.canHaveFractionalPart() && !rhs.canHaveFractionalPart());
+        // We shouldn't set the unsigned flag if the inputs can be
+        // negative zero.
+        MOZ_ASSERT(!lhs.canBeNegativeZero() && !rhs.canBeNegativeZero());
+        // Unsigned division by a non-zero rhs will return a uint32 value.
+        setRange(Range::NewUInt32Range(alloc, 0, UINT32_MAX));
+    }
+}
+
+void
+MSqrt::computeRange(TempAllocator& alloc)
+{
+    Range input(getOperand(0));
+
+    // If either operand is a NaN, the result is NaN. This also conservatively
+    // handles Infinity cases.
+    if (!input.hasInt32Bounds())
+        return;
+
+    // Sqrt of a negative non-zero value is NaN.
+    if (input.lower() < 0)
+        return;
+
+    // Something simple for now: When taking the sqrt of a positive value, the
+    // result won't be further from zero than the input.
+    // And, sqrt of an integer may have a fractional part.
+    setRange(new(alloc) Range(0, input.upper(),
+                              Range::IncludesFractionalParts,
+                              input.canBeNegativeZero(),
+                              input.exponent()));
+}
+
+void
+MToDouble::computeRange(TempAllocator& alloc)
+{
+    setRange(new(alloc) Range(getOperand(0)));
+}
+
+void
+MToFloat32::computeRange(TempAllocator& alloc)
+{
+}
+
+void
+MTruncateToInt32::computeRange(TempAllocator& alloc)
+{
+    Range* output = new(alloc) Range(getOperand(0));
+    output->wrapAroundToInt32();
+    setRange(output);
+}
+
+void
+MToInt32::computeRange(TempAllocator& alloc)
+{
+    // No clamping since this computes the range *before* bailouts.
+    setRange(new(alloc) Range(getOperand(0)));
+}
+
+void
+MLimitedTruncate::computeRange(TempAllocator& alloc)
+{
+    Range* output = new(alloc) Range(input());
+    setRange(output);
+}
+
+void
+MFilterTypeSet::computeRange(TempAllocator& alloc)
+{
+    setRange(new(alloc) Range(getOperand(0)));
+}
+
+static Range*
+GetTypedArrayRange(TempAllocator& alloc, Scalar::Type type)
+{
+    switch (type) {
+      case Scalar::Uint8Clamped:
+      case Scalar::Uint8:
+        return Range::NewUInt32Range(alloc, 0, UINT8_MAX);
+      case Scalar::Uint16:
+        return Range::NewUInt32Range(alloc, 0, UINT16_MAX);
+      case Scalar::Uint32:
+        return Range::NewUInt32Range(alloc, 0, UINT32_MAX);
+
+      case Scalar::Int8:
+        return Range::NewInt32Range(alloc, INT8_MIN, INT8_MAX);
+      case Scalar::Int16:
+        return Range::NewInt32Range(alloc, INT16_MIN, INT16_MAX);
+      case Scalar::Int32:
+        return Range::NewInt32Range(alloc, INT32_MIN, INT32_MAX);
+
+      case Scalar::Int64:
+      case Scalar::Float32:
+      case Scalar::Float64:
+      case Scalar::Float32x4:
+      case Scalar::Int8x16:
+      case Scalar::Int16x8:
+      case Scalar::Int32x4:
+      case Scalar::MaxTypedArrayViewType:
+        break;
+    }
+    return nullptr;
+}
+
+void
+MLoadUnboxedScalar::computeRange(TempAllocator& alloc)
+{
+    // We have an Int32 type and if this is a UInt32 load it may produce a value
+    // outside of our range, but we have a bailout to handle those cases.
+    setRange(GetTypedArrayRange(alloc, readType()));
+}
+
+void
+MLoadTypedArrayElementStatic::computeRange(TempAllocator& alloc)
+{
+    // We don't currently use MLoadTypedArrayElementStatic for uint32, so we
+    // don't have to worry about it returning a value outside our type.
+    MOZ_ASSERT(someTypedArray_->as<TypedArrayObject>().type() != Scalar::Uint32);
+
+    setRange(GetTypedArrayRange(alloc, someTypedArray_->as<TypedArrayObject>().type()));
+}
+
+void
+MArrayLength::computeRange(TempAllocator& alloc)
+{
+    // Array lengths can go up to UINT32_MAX, but we only create MArrayLength
+    // nodes when the value is known to be int32 (see the
+    // OBJECT_FLAG_LENGTH_OVERFLOW flag).
+    setRange(Range::NewUInt32Range(alloc, 0, INT32_MAX));
+}
+
+void
+MInitializedLength::computeRange(TempAllocator& alloc)
+{
+    setRange(Range::NewUInt32Range(alloc, 0, NativeObject::MAX_DENSE_ELEMENTS_COUNT));
+}
+
+void
+MTypedArrayLength::computeRange(TempAllocator& alloc)
+{
+    setRange(Range::NewUInt32Range(alloc, 0, INT32_MAX));
+}
+
+void
+MStringLength::computeRange(TempAllocator& alloc)
+{
+    static_assert(JSString::MAX_LENGTH <= UINT32_MAX,
+                  "NewUInt32Range requires a uint32 value");
+    setRange(Range::NewUInt32Range(alloc, 0, JSString::MAX_LENGTH));
+}
+
+void
+MArgumentsLength::computeRange(TempAllocator& alloc)
+{
+    // This is is a conservative upper bound on what |TooManyActualArguments|
+    // checks.  If exceeded, Ion will not be entered in the first place.
+    static_assert(ARGS_LENGTH_MAX <= UINT32_MAX,
+                  "NewUInt32Range requires a uint32 value");
+    setRange(Range::NewUInt32Range(alloc, 0, ARGS_LENGTH_MAX));
+}
+
+void
+MBoundsCheck::computeRange(TempAllocator& alloc)
+{
+    // Just transfer the incoming index range to the output. The length() is
+    // also interesting, but it is handled as a bailout check, and we're
+    // computing a pre-bailout range here.
+    setRange(new(alloc) Range(index()));
+}
+
+void
+MArrayPush::computeRange(TempAllocator& alloc)
+{
+    // MArrayPush returns the new array length.
+    setRange(Range::NewUInt32Range(alloc, 0, UINT32_MAX));
+}
+
+void
+MMathFunction::computeRange(TempAllocator& alloc)
+{
+    Range opRange(getOperand(0));
+    switch (function()) {
+      case Sin:
+      case Cos:
+        if (!opRange.canBeInfiniteOrNaN())
+            setRange(Range::NewDoubleRange(alloc, -1.0, 1.0));
+        break;
+      case Sign:
+        setRange(Range::sign(alloc, &opRange));
+        break;
+    default:
+        break;
+    }
+}
+
+void
+MRandom::computeRange(TempAllocator& alloc)
+{
+    Range* r = Range::NewDoubleRange(alloc, 0.0, 1.0);
+
+    // Random never returns negative zero.
+    r->refineToExcludeNegativeZero();
+
+    setRange(r);
+}
+
+void
+MNaNToZero::computeRange(TempAllocator& alloc)
+{
+    Range other(input());
+    setRange(Range::NaNToZero(alloc, &other));
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Range Analysis
+///////////////////////////////////////////////////////////////////////////////
+
+bool
+RangeAnalysis::analyzeLoop(MBasicBlock* header)
+{
+    MOZ_ASSERT(header->hasUniqueBackedge());
+
+    // Try to compute an upper bound on the number of times the loop backedge
+    // will be taken. Look for tests that dominate the backedge and which have
+    // an edge leaving the loop body.
+    MBasicBlock* backedge = header->backedge();
+
+    // Ignore trivial infinite loops.
+    if (backedge == header)
+        return true;
+
+    bool canOsr;
+    size_t numBlocks = MarkLoopBlocks(graph_, header, &canOsr);
+
+    // Ignore broken loops.
+    if (numBlocks == 0)
+        return true;
+
+    LoopIterationBound* iterationBound = nullptr;
+
+    MBasicBlock* block = backedge;
+    do {
+        BranchDirection direction;
+        MTest* branch = block->immediateDominatorBranch(&direction);
+
+        if (block == block->immediateDominator())
+            break;
+
+        block = block->immediateDominator();
+
+        if (branch) {
+            direction = NegateBranchDirection(direction);
+            MBasicBlock* otherBlock = branch->branchSuccessor(direction);
+            if (!otherBlock->isMarked()) {
+                if (!alloc().ensureBallast())
+                    return false;
+                iterationBound =
+                    analyzeLoopIterationCount(header, branch, direction);
+                if (iterationBound)
+                    break;
+            }
+        }
+    } while (block != header);
+
+    if (!iterationBound) {
+        UnmarkLoopBlocks(graph_, header);
+        return true;
+    }
+
+    if (!loopIterationBounds.append(iterationBound))
+        return false;
+
+#ifdef DEBUG
+    if (JitSpewEnabled(JitSpew_Range)) {
+        Sprinter sp(GetJitContext()->cx);
+        if (!sp.init())
+            return false;
+        iterationBound->boundSum.dump(sp);
+        JitSpew(JitSpew_Range, "computed symbolic bound on backedges: %s",
+                sp.string());
+    }
+#endif
+
+    // Try to compute symbolic bounds for the phi nodes at the head of this
+    // loop, expressed in terms of the iteration bound just computed.
+
+    for (MPhiIterator iter(header->phisBegin()); iter != header->phisEnd(); iter++)
+        analyzeLoopPhi(header, iterationBound, *iter);
+
+    if (!mir->compilingWasm()) {
+        // Try to hoist any bounds checks from the loop using symbolic bounds.
+
+        Vector<MBoundsCheck*, 0, JitAllocPolicy> hoistedChecks(alloc());
+
+        for (ReversePostorderIterator iter(graph_.rpoBegin(header)); iter != graph_.rpoEnd(); iter++) {
+            MBasicBlock* block = *iter;
+            if (!block->isMarked())
+                continue;
+
+            for (MDefinitionIterator iter(block); iter; iter++) {
+                MDefinition* def = *iter;
+                if (def->isBoundsCheck() && def->isMovable()) {
+                    if (!alloc().ensureBallast())
+                        return false;
+                    if (tryHoistBoundsCheck(header, def->toBoundsCheck())) {
+                        if (!hoistedChecks.append(def->toBoundsCheck()))
+                            return false;
+                    }
+                }
+            }
+        }
+
+        // Note: replace all uses of the original bounds check with the
+        // actual index. This is usually done during bounds check elimination,
+        // but in this case it's safe to do it here since the load/store is
+        // definitely not loop-invariant, so we will never move it before
+        // one of the bounds checks we just added.
+        for (size_t i = 0; i < hoistedChecks.length(); i++) {
+            MBoundsCheck* ins = hoistedChecks[i];
+            ins->replaceAllUsesWith(ins->index());
+            ins->block()->discard(ins);
+        }
+    }
+
+    UnmarkLoopBlocks(graph_, header);
+    return true;
+}
+
+// Unbox beta nodes in order to hoist instruction properly, and not be limited
+// by the beta nodes which are added after each branch.
+static inline MDefinition*
+DefinitionOrBetaInputDefinition(MDefinition* ins)
+{
+    while (ins->isBeta())
+        ins = ins->toBeta()->input();
+    return ins;
+}
+
+LoopIterationBound*
+RangeAnalysis::analyzeLoopIterationCount(MBasicBlock* header,
+                                         MTest* test, BranchDirection direction)
+{
+    SimpleLinearSum lhs(nullptr, 0);
+    MDefinition* rhs;
+    bool lessEqual;
+    if (!ExtractLinearInequality(test, direction, &lhs, &rhs, &lessEqual))
+        return nullptr;
+
+    // Ensure the rhs is a loop invariant term.
+    if (rhs && rhs->block()->isMarked()) {
+        if (lhs.term && lhs.term->block()->isMarked())
+            return nullptr;
+        MDefinition* temp = lhs.term;
+        lhs.term = rhs;
+        rhs = temp;
+        if (!SafeSub(0, lhs.constant, &lhs.constant))
+            return nullptr;
+        lessEqual = !lessEqual;
+    }
+
+    MOZ_ASSERT_IF(rhs, !rhs->block()->isMarked());
+
+    // Ensure the lhs is a phi node from the start of the loop body.
+    if (!lhs.term || !lhs.term->isPhi() || lhs.term->block() != header)
+        return nullptr;
+
+    // Check that the value of the lhs changes by a constant amount with each
+    // loop iteration. This requires that the lhs be written in every loop
+    // iteration with a value that is a constant difference from its value at
+    // the start of the iteration.
+
+    if (lhs.term->toPhi()->numOperands() != 2)
+        return nullptr;
+
+    // The first operand of the phi should be the lhs' value at the start of
+    // the first executed iteration, and not a value written which could
+    // replace the second operand below during the middle of execution.
+    MDefinition* lhsInitial = lhs.term->toPhi()->getLoopPredecessorOperand();
+    if (lhsInitial->block()->isMarked())
+        return nullptr;
+
+    // The second operand of the phi should be a value written by an add/sub
+    // in every loop iteration, i.e. in a block which dominates the backedge.
+    MDefinition* lhsWrite =
+        DefinitionOrBetaInputDefinition(lhs.term->toPhi()->getLoopBackedgeOperand());
+    if (!lhsWrite->isAdd() && !lhsWrite->isSub())
+        return nullptr;
+    if (!lhsWrite->block()->isMarked())
+        return nullptr;
+    MBasicBlock* bb = header->backedge();
+    for (; bb != lhsWrite->block() && bb != header; bb = bb->immediateDominator()) {}
+    if (bb != lhsWrite->block())
+        return nullptr;
+
+    SimpleLinearSum lhsModified = ExtractLinearSum(lhsWrite);
+
+    // Check that the value of the lhs at the backedge is of the form
+    // 'old(lhs) + N'. We can be sure that old(lhs) is the value at the start
+    // of the iteration, and not that written to lhs in a previous iteration,
+    // as such a previous value could not appear directly in the addition:
+    // it could not be stored in lhs as the lhs add/sub executes in every
+    // iteration, and if it were stored in another variable its use here would
+    // be as an operand to a phi node for that variable.
+    if (lhsModified.term != lhs.term)
+        return nullptr;
+
+    LinearSum iterationBound(alloc());
+    LinearSum currentIteration(alloc());
+
+    if (lhsModified.constant == 1 && !lessEqual) {
+        // The value of lhs is 'initial(lhs) + iterCount' and this will end
+        // execution of the loop if 'lhs + lhsN >= rhs'. Thus, an upper bound
+        // on the number of backedges executed is:
+        //
+        // initial(lhs) + iterCount + lhsN == rhs
+        // iterCount == rhsN - initial(lhs) - lhsN
+
+        if (rhs) {
+            if (!iterationBound.add(rhs, 1))
+                return nullptr;
+        }
+        if (!iterationBound.add(lhsInitial, -1))
+            return nullptr;
+
+        int32_t lhsConstant;
+        if (!SafeSub(0, lhs.constant, &lhsConstant))
+            return nullptr;
+        if (!iterationBound.add(lhsConstant))
+            return nullptr;
+
+        if (!currentIteration.add(lhs.term, 1))
+            return nullptr;
+        if (!currentIteration.add(lhsInitial, -1))
+            return nullptr;
+    } else if (lhsModified.constant == -1 && lessEqual) {
+        // The value of lhs is 'initial(lhs) - iterCount'. Similar to the above
+        // case, an upper bound on the number of backedges executed is:
+        //
+        // initial(lhs) - iterCount + lhsN == rhs
+        // iterCount == initial(lhs) - rhs + lhsN
+
+        if (!iterationBound.add(lhsInitial, 1))
+            return nullptr;
+        if (rhs) {
+            if (!iterationBound.add(rhs, -1))
+                return nullptr;
+        }
+        if (!iterationBound.add(lhs.constant))
+            return nullptr;
+
+        if (!currentIteration.add(lhsInitial, 1))
+            return nullptr;
+        if (!currentIteration.add(lhs.term, -1))
+            return nullptr;
+    } else {
+        return nullptr;
+    }
+
+    return new(alloc()) LoopIterationBound(header, test, iterationBound, currentIteration);
+}
+
+void
+RangeAnalysis::analyzeLoopPhi(MBasicBlock* header, LoopIterationBound* loopBound, MPhi* phi)
+{
+    // Given a bound on the number of backedges taken, compute an upper and
+    // lower bound for a phi node that may change by a constant amount each
+    // iteration. Unlike for the case when computing the iteration bound
+    // itself, the phi does not need to change the same amount every iteration,
+    // but is required to change at most N and be either nondecreasing or
+    // nonincreasing.
+
+    MOZ_ASSERT(phi->numOperands() == 2);
+
+    MDefinition* initial = phi->getLoopPredecessorOperand();
+    if (initial->block()->isMarked())
+        return;
+
+    SimpleLinearSum modified = ExtractLinearSum(phi->getLoopBackedgeOperand());
+
+    if (modified.term != phi || modified.constant == 0)
+        return;
+
+    if (!phi->range())
+        phi->setRange(new(alloc()) Range(phi));
+
+    LinearSum initialSum(alloc());
+    if (!initialSum.add(initial, 1))
+        return;
+
+    // The phi may change by N each iteration, and is either nondecreasing or
+    // nonincreasing. initial(phi) is either a lower or upper bound for the
+    // phi, and initial(phi) + loopBound * N is either an upper or lower bound,
+    // at all points within the loop, provided that loopBound >= 0.
+    //
+    // We are more interested, however, in the bound for phi at points
+    // dominated by the loop bound's test; if the test dominates e.g. a bounds
+    // check we want to hoist from the loop, using the value of the phi at the
+    // head of the loop for this will usually be too imprecise to hoist the
+    // check. These points will execute only if the backedge executes at least
+    // one more time (as the test passed and the test dominates the backedge),
+    // so we know both that loopBound >= 1 and that the phi's value has changed
+    // at most loopBound - 1 times. Thus, another upper or lower bound for the
+    // phi is initial(phi) + (loopBound - 1) * N, without requiring us to
+    // ensure that loopBound >= 0.
+
+    LinearSum limitSum(loopBound->boundSum);
+    if (!limitSum.multiply(modified.constant) || !limitSum.add(initialSum))
+        return;
+
+    int32_t negativeConstant;
+    if (!SafeSub(0, modified.constant, &negativeConstant) || !limitSum.add(negativeConstant))
+        return;
+
+    Range* initRange = initial->range();
+    if (modified.constant > 0) {
+        if (initRange && initRange->hasInt32LowerBound())
+            phi->range()->refineLower(initRange->lower());
+        phi->range()->setSymbolicLower(SymbolicBound::New(alloc(), nullptr, initialSum));
+        phi->range()->setSymbolicUpper(SymbolicBound::New(alloc(), loopBound, limitSum));
+    } else {
+        if (initRange && initRange->hasInt32UpperBound())
+            phi->range()->refineUpper(initRange->upper());
+        phi->range()->setSymbolicUpper(SymbolicBound::New(alloc(), nullptr, initialSum));
+        phi->range()->setSymbolicLower(SymbolicBound::New(alloc(), loopBound, limitSum));
+    }
+
+    JitSpew(JitSpew_Range, "added symbolic range on %d", phi->id());
+    SpewRange(phi);
+}
+
+// Whether bound is valid at the specified bounds check instruction in a loop,
+// and may be used to hoist ins.
+static inline bool
+SymbolicBoundIsValid(MBasicBlock* header, MBoundsCheck* ins, const SymbolicBound* bound)
+{
+    if (!bound->loop)
+        return true;
+    if (ins->block() == header)
+        return false;
+    MBasicBlock* bb = ins->block()->immediateDominator();
+    while (bb != header && bb != bound->loop->test->block())
+        bb = bb->immediateDominator();
+    return bb == bound->loop->test->block();
+}
+
+bool
+RangeAnalysis::tryHoistBoundsCheck(MBasicBlock* header, MBoundsCheck* ins)
+{
+    // The bounds check's length must be loop invariant.
+    MDefinition *length = DefinitionOrBetaInputDefinition(ins->length());
+    if (length->block()->isMarked())
+        return false;
+
+    // The bounds check's index should not be loop invariant (else we would
+    // already have hoisted it during LICM).
+    SimpleLinearSum index = ExtractLinearSum(ins->index());
+    if (!index.term || !index.term->block()->isMarked())
+        return false;
+
+    // Check for a symbolic lower and upper bound on the index. If either
+    // condition depends on an iteration bound for the loop, only hoist if
+    // the bounds check is dominated by the iteration bound's test.
+    if (!index.term->range())
+        return false;
+    const SymbolicBound* lower = index.term->range()->symbolicLower();
+    if (!lower || !SymbolicBoundIsValid(header, ins, lower))
+        return false;
+    const SymbolicBound* upper = index.term->range()->symbolicUpper();
+    if (!upper || !SymbolicBoundIsValid(header, ins, upper))
+        return false;
+
+    MBasicBlock* preLoop = header->loopPredecessor();
+    MOZ_ASSERT(!preLoop->isMarked());
+
+    MDefinition* lowerTerm = ConvertLinearSum(alloc(), preLoop, lower->sum);
+    if (!lowerTerm)
+        return false;
+
+    MDefinition* upperTerm = ConvertLinearSum(alloc(), preLoop, upper->sum);
+    if (!upperTerm)
+        return false;
+
+    // We are checking that index + indexConstant >= 0, and know that
+    // index >= lowerTerm + lowerConstant. Thus, check that:
+    //
+    // lowerTerm + lowerConstant + indexConstant >= 0
+    // lowerTerm >= -lowerConstant - indexConstant
+
+    int32_t lowerConstant = 0;
+    if (!SafeSub(lowerConstant, index.constant, &lowerConstant))
+        return false;
+    if (!SafeSub(lowerConstant, lower->sum.constant(), &lowerConstant))
+        return false;
+
+    // We are checking that index < boundsLength, and know that
+    // index <= upperTerm + upperConstant. Thus, check that:
+    //
+    // upperTerm + upperConstant < boundsLength
+
+    int32_t upperConstant = index.constant;
+    if (!SafeAdd(upper->sum.constant(), upperConstant, &upperConstant))
+        return false;
+
+    // Hoist the loop invariant lower bounds checks.
+    MBoundsCheckLower* lowerCheck = MBoundsCheckLower::New(alloc(), lowerTerm);
+    lowerCheck->setMinimum(lowerConstant);
+    lowerCheck->computeRange(alloc());
+    lowerCheck->collectRangeInfoPreTrunc();
+    preLoop->insertBefore(preLoop->lastIns(), lowerCheck);
+
+    // Hoist the loop invariant upper bounds checks.
+    if (upperTerm != length || upperConstant >= 0) {
+        MBoundsCheck* upperCheck = MBoundsCheck::New(alloc(), upperTerm, length);
+        upperCheck->setMinimum(upperConstant);
+        upperCheck->setMaximum(upperConstant);
+        upperCheck->computeRange(alloc());
+        upperCheck->collectRangeInfoPreTrunc();
+        preLoop->insertBefore(preLoop->lastIns(), upperCheck);
+    }
+
+    return true;
+}
+
+bool
+RangeAnalysis::analyze()
+{
+    JitSpew(JitSpew_Range, "Doing range propagation");
+
+    for (ReversePostorderIterator iter(graph_.rpoBegin()); iter != graph_.rpoEnd(); iter++) {
+        MBasicBlock* block = *iter;
+        // No blocks are supposed to be unreachable, except when we have an OSR
+        // block, in which case the Value Numbering phase add fixup blocks which
+        // are unreachable.
+        MOZ_ASSERT(!block->unreachable() || graph_.osrBlock());
+
+        // If the block's immediate dominator is unreachable, the block is
+        // unreachable. Iterating in RPO, we'll always see the immediate
+        // dominator before the block.
+        if (block->immediateDominator()->unreachable()) {
+            block->setUnreachableUnchecked();
+            continue;
+        }
+
+        for (MDefinitionIterator iter(block); iter; iter++) {
+            MDefinition* def = *iter;
+            if (!alloc().ensureBallast())
+                return false;
+
+            def->computeRange(alloc());
+            JitSpew(JitSpew_Range, "computing range on %d", def->id());
+            SpewRange(def);
+        }
+
+        // Beta node range analysis may have marked this block unreachable. If
+        // so, it's no longer interesting to continue processing it.
+        if (block->unreachable())
+            continue;
+
+        if (block->isLoopHeader()) {
+            if (!analyzeLoop(block))
+                return false;
+        }
+
+        // First pass at collecting range info - while the beta nodes are still
+        // around and before truncation.
+        for (MInstructionIterator iter(block->begin()); iter != block->end(); iter++)
+            iter->collectRangeInfoPreTrunc();
+    }
+
+    return true;
+}
+
+bool
+RangeAnalysis::addRangeAssertions()
+{
+    if (!JitOptions.checkRangeAnalysis)
+        return true;
+
+    // Check the computed range for this instruction, if the option is set. Note
+    // that this code is quite invasive; it adds numerous additional
+    // instructions for each MInstruction with a computed range, and it uses
+    // registers, so it also affects register allocation.
+    for (ReversePostorderIterator iter(graph_.rpoBegin()); iter != graph_.rpoEnd(); iter++) {
+        MBasicBlock* block = *iter;
+
+        // Do not add assertions in unreachable blocks.
+        if (block->unreachable())
+            continue;
+
+        for (MDefinitionIterator iter(block); iter; iter++) {
+            MDefinition* ins = *iter;
+
+            // Perform range checking for all numeric and numeric-like types.
+            if (!IsNumberType(ins->type()) &&
+                ins->type() != MIRType::Boolean &&
+                ins->type() != MIRType::Value)
+            {
+                continue;
+            }
+
+            // MIsNoIter is fused with the MTest that follows it and emitted as
+            // LIsNoIterAndBranch. Skip it to avoid complicating MIsNoIter
+            // lowering.
+            if (ins->isIsNoIter())
+                continue;
+
+            Range r(ins);
+
+            MOZ_ASSERT_IF(ins->type() == MIRType::Int64, r.isUnknown());
+
+            // Don't insert assertions if there's nothing interesting to assert.
+            if (r.isUnknown() || (ins->type() == MIRType::Int32 && r.isUnknownInt32()))
+                continue;
+
+            // Don't add a use to an instruction that is recovered on bailout.
+            if (ins->isRecoveredOnBailout())
+                continue;
+
+            if (!alloc().ensureBallast())
+                return false;
+            MAssertRange* guard = MAssertRange::New(alloc(), ins, new(alloc()) Range(r));
+
+            // Beta nodes and interrupt checks are required to be located at the
+            // beginnings of basic blocks, so we must insert range assertions
+            // after any such instructions.
+            MInstruction* insertAt = nullptr;
+            if (block->graph().osrBlock() == block)
+                insertAt = ins->toInstruction();
+            else
+                insertAt = block->safeInsertTop(ins);
+
+            if (insertAt == *iter)
+                block->insertAfter(insertAt,  guard);
+            else
+                block->insertBefore(insertAt, guard);
+        }
+    }
+
+    return true;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Range based Truncation
+///////////////////////////////////////////////////////////////////////////////
+
+void
+Range::clampToInt32()
+{
+    if (isInt32())
+        return;
+    int32_t l = hasInt32LowerBound() ? lower() : JSVAL_INT_MIN;
+    int32_t h = hasInt32UpperBound() ? upper() : JSVAL_INT_MAX;
+    setInt32(l, h);
+}
+
+void
+Range::wrapAroundToInt32()
+{
+    if (!hasInt32Bounds()) {
+        setInt32(JSVAL_INT_MIN, JSVAL_INT_MAX);
+    } else if (canHaveFractionalPart()) {
+        // Clearing the fractional field may provide an opportunity to refine
+        // lower_ or upper_.
+        canHaveFractionalPart_ = ExcludesFractionalParts;
+        canBeNegativeZero_ = ExcludesNegativeZero;
+        refineInt32BoundsByExponent(max_exponent_,
+                                    &lower_, &hasInt32LowerBound_,
+                                    &upper_, &hasInt32UpperBound_);
+
+        assertInvariants();
+    } else {
+        // If nothing else, we can clear the negative zero flag.
+        canBeNegativeZero_ = ExcludesNegativeZero;
+    }
+    MOZ_ASSERT(isInt32());
+}
+
+void
+Range::wrapAroundToShiftCount()
+{
+    wrapAroundToInt32();
+    if (lower() < 0 || upper() >= 32)
+        setInt32(0, 31);
+}
+
+void
+Range::wrapAroundToBoolean()
+{
+    wrapAroundToInt32();
+    if (!isBoolean())
+        setInt32(0, 1);
+    MOZ_ASSERT(isBoolean());
+}
+
+bool
+MDefinition::needTruncation(TruncateKind kind)
+{
+    // No procedure defined for truncating this instruction.
+    return false;
+}
+
+void
+MDefinition::truncate()
+{
+    MOZ_CRASH("No procedure defined for truncating this instruction.");
+}
+
+bool
+MConstant::needTruncation(TruncateKind kind)
+{
+    return IsFloatingPointType(type());
+}
+
+void
+MConstant::truncate()
+{
+    MOZ_ASSERT(needTruncation(Truncate));
+
+    // Truncate the double to int, since all uses truncates it.
+    int32_t res = ToInt32(numberToDouble());
+    payload_.asBits = 0;
+    payload_.i32 = res;
+    setResultType(MIRType::Int32);
+    if (range())
+        range()->setInt32(res, res);
+}
+
+bool
+MPhi::needTruncation(TruncateKind kind)
+{
+    if (type() == MIRType::Double || type() == MIRType::Int32) {
+        truncateKind_ = kind;
+        return true;
+    }
+
+    return false;
+}
+
+void
+MPhi::truncate()
+{
+    setResultType(MIRType::Int32);
+    if (truncateKind_ >= IndirectTruncate && range())
+        range()->wrapAroundToInt32();
+}
+
+bool
+MAdd::needTruncation(TruncateKind kind)
+{
+    // Remember analysis, needed for fallible checks.
+    setTruncateKind(kind);
+
+    return type() == MIRType::Double || type() == MIRType::Int32;
+}
+
+void
+MAdd::truncate()
+{
+    MOZ_ASSERT(needTruncation(truncateKind()));
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+    if (truncateKind() >= IndirectTruncate && range())
+        range()->wrapAroundToInt32();
+}
+
+bool
+MSub::needTruncation(TruncateKind kind)
+{
+    // Remember analysis, needed for fallible checks.
+    setTruncateKind(kind);
+
+    return type() == MIRType::Double || type() == MIRType::Int32;
+}
+
+void
+MSub::truncate()
+{
+    MOZ_ASSERT(needTruncation(truncateKind()));
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+    if (truncateKind() >= IndirectTruncate && range())
+        range()->wrapAroundToInt32();
+}
+
+bool
+MMul::needTruncation(TruncateKind kind)
+{
+    // Remember analysis, needed for fallible checks.
+    setTruncateKind(kind);
+
+    return type() == MIRType::Double || type() == MIRType::Int32;
+}
+
+void
+MMul::truncate()
+{
+    MOZ_ASSERT(needTruncation(truncateKind()));
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+    if (truncateKind() >= IndirectTruncate) {
+        setCanBeNegativeZero(false);
+        if (range())
+            range()->wrapAroundToInt32();
+    }
+}
+
+bool
+MDiv::needTruncation(TruncateKind kind)
+{
+    // Remember analysis, needed for fallible checks.
+    setTruncateKind(kind);
+
+    return type() == MIRType::Double || type() == MIRType::Int32;
+}
+
+void
+MDiv::truncate()
+{
+    MOZ_ASSERT(needTruncation(truncateKind()));
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+
+    // Divisions where the lhs and rhs are unsigned and the result is
+    // truncated can be lowered more efficiently.
+    if (unsignedOperands()) {
+        replaceWithUnsignedOperands();
+        unsigned_ = true;
+    }
+}
+
+bool
+MMod::needTruncation(TruncateKind kind)
+{
+    // Remember analysis, needed for fallible checks.
+    setTruncateKind(kind);
+
+    return type() == MIRType::Double || type() == MIRType::Int32;
+}
+
+void
+MMod::truncate()
+{
+    // As for division, handle unsigned modulus with a truncated result.
+    MOZ_ASSERT(needTruncation(truncateKind()));
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+
+    if (unsignedOperands()) {
+        replaceWithUnsignedOperands();
+        unsigned_ = true;
+    }
+}
+
+bool
+MToDouble::needTruncation(TruncateKind kind)
+{
+    MOZ_ASSERT(type() == MIRType::Double);
+    setTruncateKind(kind);
+
+    return true;
+}
+
+void
+MToDouble::truncate()
+{
+    MOZ_ASSERT(needTruncation(truncateKind()));
+
+    // We use the return type to flag that this MToDouble should be replaced by
+    // a MTruncateToInt32 when modifying the graph.
+    setResultType(MIRType::Int32);
+    if (truncateKind() >= IndirectTruncate) {
+        if (range())
+            range()->wrapAroundToInt32();
+    }
+}
+
+bool
+MLoadTypedArrayElementStatic::needTruncation(TruncateKind kind)
+{
+    // IndirectTruncate not possible, since it returns 'undefined'
+    // upon out of bounds read. Doing arithmetic on 'undefined' gives wrong
+    // results. So only set infallible if explicitly truncated.
+    if (kind == Truncate)
+        setInfallible();
+
+    return false;
+}
+
+bool
+MLimitedTruncate::needTruncation(TruncateKind kind)
+{
+    setTruncateKind(kind);
+    setResultType(MIRType::Int32);
+    if (kind >= IndirectTruncate && range())
+        range()->wrapAroundToInt32();
+    return false;
+}
+
+bool
+MCompare::needTruncation(TruncateKind kind)
+{
+    // If we're compiling wasm, don't try to optimize the comparison type, as
+    // the code presumably is already using the type it wants. Also, wasm
+    // doesn't support bailouts, so we woudn't be able to rely on
+    // TruncateAfterBailouts to convert our inputs.
+    if (block()->info().compilingWasm())
+       return false;
+
+    if (!isDoubleComparison())
+        return false;
+
+    // If both operands are naturally in the int32 range, we can convert from
+    // a double comparison to being an int32 comparison.
+    if (!Range(lhs()).isInt32() || !Range(rhs()).isInt32())
+        return false;
+
+    return true;
+}
+
+void
+MCompare::truncate()
+{
+    compareType_ = Compare_Int32;
+
+    // Truncating the operands won't change their value because we don't force a
+    // truncation, but it will change their type, which we need because we
+    // now expect integer inputs.
+    truncateOperands_ = true;
+}
+
+MDefinition::TruncateKind
+MDefinition::operandTruncateKind(size_t index) const
+{
+    // Generic routine: We don't know anything.
+    return NoTruncate;
+}
+
+MDefinition::TruncateKind
+MPhi::operandTruncateKind(size_t index) const
+{
+    // The truncation applied to a phi is effectively applied to the phi's
+    // operands.
+    return truncateKind_;
+}
+
+MDefinition::TruncateKind
+MTruncateToInt32::operandTruncateKind(size_t index) const
+{
+    // This operator is an explicit truncate to int32.
+    return Truncate;
+}
+
+MDefinition::TruncateKind
+MBinaryBitwiseInstruction::operandTruncateKind(size_t index) const
+{
+    // The bitwise operators truncate to int32.
+    return Truncate;
+}
+
+MDefinition::TruncateKind
+MLimitedTruncate::operandTruncateKind(size_t index) const
+{
+    return Min(truncateKind(), truncateLimit_);
+}
+
+MDefinition::TruncateKind
+MAdd::operandTruncateKind(size_t index) const
+{
+    // This operator is doing some arithmetic. If its result is truncated,
+    // it's an indirect truncate for its operands.
+    return Min(truncateKind(), IndirectTruncate);
+}
+
+MDefinition::TruncateKind
+MSub::operandTruncateKind(size_t index) const
+{
+    // See the comment in MAdd::operandTruncateKind.
+    return Min(truncateKind(), IndirectTruncate);
+}
+
+MDefinition::TruncateKind
+MMul::operandTruncateKind(size_t index) const
+{
+    // See the comment in MAdd::operandTruncateKind.
+    return Min(truncateKind(), IndirectTruncate);
+}
+
+MDefinition::TruncateKind
+MToDouble::operandTruncateKind(size_t index) const
+{
+    // MToDouble propagates its truncate kind to its operand.
+    return truncateKind();
+}
+
+MDefinition::TruncateKind
+MStoreUnboxedScalar::operandTruncateKind(size_t index) const
+{
+    // Some receiver objects, such as typed arrays, will truncate out of range integer inputs.
+    return (truncateInput() && index == 2 && isIntegerWrite()) ? Truncate : NoTruncate;
+}
+
+MDefinition::TruncateKind
+MStoreTypedArrayElementHole::operandTruncateKind(size_t index) const
+{
+    // An integer store truncates the stored value.
+    return index == 3 && isIntegerWrite() ? Truncate : NoTruncate;
+}
+
+MDefinition::TruncateKind
+MStoreTypedArrayElementStatic::operandTruncateKind(size_t index) const
+{
+    // An integer store truncates the stored value.
+    return index == 1 && isIntegerWrite() ? Truncate : NoTruncate;
+}
+
+MDefinition::TruncateKind
+MDiv::operandTruncateKind(size_t index) const
+{
+    return Min(truncateKind(), TruncateAfterBailouts);
+}
+
+MDefinition::TruncateKind
+MMod::operandTruncateKind(size_t index) const
+{
+    return Min(truncateKind(), TruncateAfterBailouts);
+}
+
+MDefinition::TruncateKind
+MCompare::operandTruncateKind(size_t index) const
+{
+    // If we're doing an int32 comparison on operands which were previously
+    // floating-point, convert them!
+    MOZ_ASSERT_IF(truncateOperands_, isInt32Comparison());
+    return truncateOperands_ ? TruncateAfterBailouts : NoTruncate;
+}
+
+static bool
+TruncateTest(TempAllocator& alloc, MTest* test)
+{
+    // If all possible inputs to the test are either int32 or boolean,
+    // convert those inputs to int32 so that an int32 test can be performed.
+
+    if (test->input()->type() != MIRType::Value)
+        return true;
+
+    if (!test->input()->isPhi() || !test->input()->hasOneDefUse() || test->input()->isImplicitlyUsed())
+        return true;
+
+    MPhi* phi = test->input()->toPhi();
+    for (size_t i = 0; i < phi->numOperands(); i++) {
+        MDefinition* def = phi->getOperand(i);
+        if (!def->isBox())
+            return true;
+        MDefinition* inner = def->getOperand(0);
+        if (inner->type() != MIRType::Boolean && inner->type() != MIRType::Int32)
+            return true;
+    }
+
+    for (size_t i = 0; i < phi->numOperands(); i++) {
+        MDefinition* inner = phi->getOperand(i)->getOperand(0);
+        if (inner->type() != MIRType::Int32) {
+            if (!alloc.ensureBallast())
+                return false;
+            MBasicBlock* block = inner->block();
+            inner = MToInt32::New(alloc, inner);
+            block->insertBefore(block->lastIns(), inner->toInstruction());
+        }
+        MOZ_ASSERT(inner->type() == MIRType::Int32);
+        phi->replaceOperand(i, inner);
+    }
+
+    phi->setResultType(MIRType::Int32);
+    return true;
+}
+
+// Truncating instruction result is an optimization which implies
+// knowing all uses of an instruction.  This implies that if one of
+// the uses got removed, then Range Analysis is not be allowed to do
+// any modification which can change the result, especially if the
+// result can be observed.
+//
+// This corner can easily be understood with UCE examples, but it
+// might also happen with type inference assumptions.  Note: Type
+// inference is implicitly branches where other types might be
+// flowing into.
+static bool
+CloneForDeadBranches(TempAllocator& alloc, MInstruction* candidate)
+{
+    // Compare returns a boolean so it doesn't have to be recovered on bailout
+    // because the output would remain correct.
+    if (candidate->isCompare())
+        return true;
+
+    MOZ_ASSERT(candidate->canClone());
+    if (!alloc.ensureBallast())
+        return false;
+
+    MDefinitionVector operands(alloc);
+    size_t end = candidate->numOperands();
+    if (!operands.reserve(end))
+        return false;
+    for (size_t i = 0; i < end; ++i)
+        operands.infallibleAppend(candidate->getOperand(i));
+
+    MInstruction* clone = candidate->clone(alloc, operands);
+    clone->setRange(nullptr);
+
+    // Set UseRemoved flag on the cloned instruction in order to chain recover
+    // instruction for the bailout path.
+    clone->setUseRemovedUnchecked();
+
+    candidate->block()->insertBefore(candidate, clone);
+
+    if (!candidate->maybeConstantValue()) {
+        MOZ_ASSERT(clone->canRecoverOnBailout());
+        clone->setRecoveredOnBailout();
+    }
+
+    // Replace the candidate by its recovered on bailout clone within recovered
+    // instructions and resume points operands.
+    for (MUseIterator i(candidate->usesBegin()); i != candidate->usesEnd(); ) {
+        MUse* use = *i++;
+        MNode* ins = use->consumer();
+        if (ins->isDefinition() && !ins->toDefinition()->isRecoveredOnBailout())
+            continue;
+
+        use->replaceProducer(clone);
+    }
+
+    return true;
+}
+
+// Examine all the users of |candidate| and determine the most aggressive
+// truncate kind that satisfies all of them.
+static MDefinition::TruncateKind
+ComputeRequestedTruncateKind(MDefinition* candidate, bool* shouldClone)
+{
+    bool isCapturedResult = false;   // Check if used by a recovered instruction or a resume point.
+    bool isObservableResult = false; // Check if it can be read from another frame.
+    bool isRecoverableResult = true; // Check if it can safely be reconstructed.
+    bool hasUseRemoved = candidate->isUseRemoved();
+
+    MDefinition::TruncateKind kind = MDefinition::Truncate;
+    for (MUseIterator use(candidate->usesBegin()); use != candidate->usesEnd(); use++) {
+        if (use->consumer()->isResumePoint()) {
+            // Truncation is a destructive optimization, as such, we need to pay
+            // attention to removed branches and prevent optimization
+            // destructive optimizations if we have no alternative. (see
+            // UseRemoved flag)
+            isCapturedResult = true;
+            isObservableResult = isObservableResult ||
+                use->consumer()->toResumePoint()->isObservableOperand(*use);
+            isRecoverableResult = isRecoverableResult &&
+                use->consumer()->toResumePoint()->isRecoverableOperand(*use);
+            continue;
+        }
+
+        MDefinition* consumer = use->consumer()->toDefinition();
+        if (consumer->isRecoveredOnBailout()) {
+            isCapturedResult = true;
+            hasUseRemoved = hasUseRemoved || consumer->isUseRemoved();
+            continue;
+        }
+
+        MDefinition::TruncateKind consumerKind = consumer->operandTruncateKind(consumer->indexOf(*use));
+        kind = Min(kind, consumerKind);
+        if (kind == MDefinition::NoTruncate)
+            break;
+    }
+
+    // We cannot do full trunction on guarded instructions.
+    if (candidate->isGuard() || candidate->isGuardRangeBailouts())
+        kind = Min(kind, MDefinition::TruncateAfterBailouts);
+
+    // If the value naturally produces an int32 value (before bailout checks)
+    // that needs no conversion, we don't have to worry about resume points
+    // seeing truncated values.
+    bool needsConversion = !candidate->range() || !candidate->range()->isInt32();
+
+    // If the instruction is explicitly truncated (not indirectly) by all its
+    // uses and if it has no removed uses, then we can safely encode its
+    // truncated result as part of the resume point operands.  This is safe,
+    // because even if we resume with a truncated double, the next baseline
+    // instruction operating on this instruction is going to be a no-op.
+    //
+    // Note, that if the result can be observed from another frame, then this
+    // optimization is not safe.
+    bool safeToConvert = kind == MDefinition::Truncate && !hasUseRemoved && !isObservableResult;
+
+    // If the candidate instruction appears as operand of a resume point or a
+    // recover instruction, and we have to truncate its result, then we might
+    // have to either recover the result during the bailout, or avoid the
+    // truncation.
+    if (isCapturedResult && needsConversion && !safeToConvert) {
+
+        // If the result can be recovered from all the resume points (not needed
+        // for iterating over the inlined frames), and this instruction can be
+        // recovered on bailout, then we can clone it and use the cloned
+        // instruction to encode the recover instruction.  Otherwise, we should
+        // keep the original result and bailout if the value is not in the int32
+        // range.
+        if (!JitOptions.disableRecoverIns && isRecoverableResult && candidate->canRecoverOnBailout())
+            *shouldClone = true;
+        else
+            kind = Min(kind, MDefinition::TruncateAfterBailouts);
+    }
+
+    return kind;
+}
+
+static MDefinition::TruncateKind
+ComputeTruncateKind(MDefinition* candidate, bool* shouldClone)
+{
+    // Compare operations might coerce its inputs to int32 if the ranges are
+    // correct.  So we do not need to check if all uses are coerced.
+    if (candidate->isCompare())
+        return MDefinition::TruncateAfterBailouts;
+
+    // Set truncated flag if range analysis ensure that it has no
+    // rounding errors and no fractional part. Note that we can't use
+    // the MDefinition Range constructor, because we need to know if
+    // the value will have rounding errors before any bailout checks.
+    const Range* r = candidate->range();
+    bool canHaveRoundingErrors = !r || r->canHaveRoundingErrors();
+
+    // Special case integer division and modulo: a/b can be infinite, and a%b
+    // can be NaN but cannot actually have rounding errors induced by truncation.
+    if ((candidate->isDiv() || candidate->isMod()) &&
+        static_cast<const MBinaryArithInstruction *>(candidate)->specialization() == MIRType::Int32)
+    {
+        canHaveRoundingErrors = false;
+    }
+
+    if (canHaveRoundingErrors)
+        return MDefinition::NoTruncate;
+
+    // Ensure all observable uses are truncated.
+    return ComputeRequestedTruncateKind(candidate, shouldClone);
+}
+
+static void
+RemoveTruncatesOnOutput(MDefinition* truncated)
+{
+    // Compare returns a boolean so it doen't have any output truncates.
+    if (truncated->isCompare())
+        return;
+
+    MOZ_ASSERT(truncated->type() == MIRType::Int32);
+    MOZ_ASSERT(Range(truncated).isInt32());
+
+    for (MUseDefIterator use(truncated); use; use++) {
+        MDefinition* def = use.def();
+        if (!def->isTruncateToInt32() || !def->isToInt32())
+            continue;
+
+        def->replaceAllUsesWith(truncated);
+    }
+}
+
+static void
+AdjustTruncatedInputs(TempAllocator& alloc, MDefinition* truncated)
+{
+    MBasicBlock* block = truncated->block();
+    for (size_t i = 0, e = truncated->numOperands(); i < e; i++) {
+        MDefinition::TruncateKind kind = truncated->operandTruncateKind(i);
+        if (kind == MDefinition::NoTruncate)
+            continue;
+
+        MDefinition* input = truncated->getOperand(i);
+        if (input->type() == MIRType::Int32)
+            continue;
+
+        if (input->isToDouble() && input->getOperand(0)->type() == MIRType::Int32) {
+            truncated->replaceOperand(i, input->getOperand(0));
+        } else {
+            MInstruction* op;
+            if (kind == MDefinition::TruncateAfterBailouts)
+                op = MToInt32::New(alloc, truncated->getOperand(i));
+            else
+                op = MTruncateToInt32::New(alloc, truncated->getOperand(i));
+
+            if (truncated->isPhi()) {
+                MBasicBlock* pred = block->getPredecessor(i);
+                pred->insertBefore(pred->lastIns(), op);
+            } else {
+                block->insertBefore(truncated->toInstruction(), op);
+            }
+            truncated->replaceOperand(i, op);
+        }
+    }
+
+    if (truncated->isToDouble()) {
+        truncated->replaceAllUsesWith(truncated->toToDouble()->getOperand(0));
+        block->discard(truncated->toToDouble());
+    }
+}
+
+// Iterate backward on all instruction and attempt to truncate operations for
+// each instruction which respect the following list of predicates: Has been
+// analyzed by range analysis, the range has no rounding errors, all uses cases
+// are truncating the result.
+//
+// If the truncation of the operation is successful, then the instruction is
+// queue for later updating the graph to restore the type correctness by
+// converting the operands that need to be truncated.
+//
+// We iterate backward because it is likely that a truncated operation truncates
+// some of its operands.
+bool
+RangeAnalysis::truncate()
+{
+    JitSpew(JitSpew_Range, "Do range-base truncation (backward loop)");
+
+    // Automatic truncation is disabled for wasm because the truncation logic
+    // is based on IonMonkey which assumes that we can bailout if the truncation
+    // logic fails. As wasm code has no bailout mechanism, it is safer to avoid
+    // any automatic truncations.
+    MOZ_ASSERT(!mir->compilingWasm());
+
+    Vector<MDefinition*, 16, SystemAllocPolicy> worklist;
+
+    for (PostorderIterator block(graph_.poBegin()); block != graph_.poEnd(); block++) {
+        for (MInstructionReverseIterator iter(block->rbegin()); iter != block->rend(); iter++) {
+            if (iter->isRecoveredOnBailout())
+                continue;
+
+            if (iter->type() == MIRType::None) {
+                if (iter->isTest()) {
+                    if (!TruncateTest(alloc(), iter->toTest()))
+                        return false;
+                }
+                continue;
+            }
+
+            // Remember all bitop instructions for folding after range analysis.
+            switch (iter->op()) {
+              case MDefinition::Op_BitAnd:
+              case MDefinition::Op_BitOr:
+              case MDefinition::Op_BitXor:
+              case MDefinition::Op_Lsh:
+              case MDefinition::Op_Rsh:
+              case MDefinition::Op_Ursh:
+                if (!bitops.append(static_cast<MBinaryBitwiseInstruction*>(*iter)))
+                    return false;
+                break;
+              default:;
+            }
+
+            bool shouldClone = false;
+            MDefinition::TruncateKind kind = ComputeTruncateKind(*iter, &shouldClone);
+            if (kind == MDefinition::NoTruncate)
+                continue;
+
+            // Range Analysis is sometimes eager to do optimizations, even if we
+            // are not be able to truncate an instruction. In such case, we
+            // speculatively compile the instruction to an int32 instruction
+            // while adding a guard. This is what is implied by
+            // TruncateAfterBailout.
+            //
+            // If we already experienced an overflow bailout while executing
+            // code within the current JSScript, we no longer attempt to make
+            // this kind of eager optimizations.
+            if (kind <= MDefinition::TruncateAfterBailouts && block->info().hadOverflowBailout())
+                continue;
+
+            // Truncate this instruction if possible.
+            if (!iter->needTruncation(kind))
+                continue;
+
+            SpewTruncate(*iter, kind, shouldClone);
+
+            // If needed, clone the current instruction for keeping it for the
+            // bailout path.  This give us the ability to truncate instructions
+            // even after the removal of branches.
+            if (shouldClone && !CloneForDeadBranches(alloc(), *iter))
+                return false;
+
+            iter->truncate();
+
+            // Delay updates of inputs/outputs to avoid creating node which
+            // would be removed by the truncation of the next operations.
+            iter->setInWorklist();
+            if (!worklist.append(*iter))
+                return false;
+        }
+        for (MPhiIterator iter(block->phisBegin()), end(block->phisEnd()); iter != end; ++iter) {
+            bool shouldClone = false;
+            MDefinition::TruncateKind kind = ComputeTruncateKind(*iter, &shouldClone);
+            if (kind == MDefinition::NoTruncate)
+                continue;
+
+            // Truncate this phi if possible.
+            if (shouldClone || !iter->needTruncation(kind))
+                continue;
+
+            SpewTruncate(*iter, kind, shouldClone);
+
+            iter->truncate();
+
+            // Delay updates of inputs/outputs to avoid creating node which
+            // would be removed by the truncation of the next operations.
+            iter->setInWorklist();
+            if (!worklist.append(*iter))
+                return false;
+        }
+    }
+
+    // Update inputs/outputs of truncated instructions.
+    JitSpew(JitSpew_Range, "Do graph type fixup (dequeue)");
+    while (!worklist.empty()) {
+        if (!alloc().ensureBallast())
+            return false;
+        MDefinition* def = worklist.popCopy();
+        def->setNotInWorklist();
+        RemoveTruncatesOnOutput(def);
+        AdjustTruncatedInputs(alloc(), def);
+    }
+
+    return true;
+}
+
+bool
+RangeAnalysis::removeUnnecessaryBitops()
+{
+    // Note: This operation change the semantic of the program in a way which
+    // uniquely works with Int32, Recover Instructions added by the Sink phase
+    // expects the MIR Graph to still have a valid flow as-if they were double
+    // operations instead of Int32 operations. Thus, this phase should be
+    // executed after the Sink phase, and before DCE.
+
+    // Fold any unnecessary bitops in the graph, such as (x | 0) on an integer
+    // input. This is done after range analysis rather than during GVN as the
+    // presence of the bitop can change which instructions are truncated.
+    for (size_t i = 0; i < bitops.length(); i++) {
+        MBinaryBitwiseInstruction* ins = bitops[i];
+        if (ins->isRecoveredOnBailout())
+            continue;
+
+        MDefinition* folded = ins->foldUnnecessaryBitop();
+        if (folded != ins) {
+            ins->replaceAllLiveUsesWith(folded);
+            ins->setRecoveredOnBailout();
+        }
+    }
+
+    bitops.clear();
+    return true;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+// Collect Range information of operands
+///////////////////////////////////////////////////////////////////////////////
+
+void
+MInArray::collectRangeInfoPreTrunc()
+{
+    Range indexRange(index());
+    if (indexRange.isFiniteNonNegative())
+        needsNegativeIntCheck_ = false;
+}
+
+void
+MLoadElementHole::collectRangeInfoPreTrunc()
+{
+    Range indexRange(index());
+    if (indexRange.isFiniteNonNegative()) {
+        needsNegativeIntCheck_ = false;
+        setNotGuard();
+    }
+}
+
+void
+MLoadTypedArrayElementStatic::collectRangeInfoPreTrunc()
+{
+    Range range(ptr());
+
+    if (range.hasInt32LowerBound() && range.hasInt32UpperBound()) {
+        int64_t offset = this->offset();
+        int64_t lower = range.lower() + offset;
+        int64_t upper = range.upper() + offset;
+        int64_t length = this->length();
+        if (lower >= 0 && upper < length)
+            setNeedsBoundsCheck(false);
+    }
+}
+
+void
+MStoreTypedArrayElementStatic::collectRangeInfoPreTrunc()
+{
+    Range range(ptr());
+
+    if (range.hasInt32LowerBound() && range.hasInt32UpperBound()) {
+        int64_t offset = this->offset();
+        int64_t lower = range.lower() + offset;
+        int64_t upper = range.upper() + offset;
+        int64_t length = this->length();
+        if (lower >= 0 && upper < length)
+            setNeedsBoundsCheck(false);
+    }
+}
+
+void
+MClz::collectRangeInfoPreTrunc()
+{
+    Range inputRange(input());
+    if (!inputRange.canBeZero())
+        operandIsNeverZero_ = true;
+}
+
+void
+MCtz::collectRangeInfoPreTrunc()
+{
+    Range inputRange(input());
+    if (!inputRange.canBeZero())
+        operandIsNeverZero_ = true;
+}
+
+void
+MDiv::collectRangeInfoPreTrunc()
+{
+    Range lhsRange(lhs());
+    Range rhsRange(rhs());
+
+    // Test if Dividend is non-negative.
+    if (lhsRange.isFiniteNonNegative())
+        canBeNegativeDividend_ = false;
+
+    // Try removing divide by zero check.
+    if (!rhsRange.canBeZero())
+        canBeDivideByZero_ = false;
+
+    // If lhsRange does not contain INT32_MIN in its range,
+    // negative overflow check can be skipped.
+    if (!lhsRange.contains(INT32_MIN))
+        canBeNegativeOverflow_ = false;
+
+    // If rhsRange does not contain -1 likewise.
+    if (!rhsRange.contains(-1))
+        canBeNegativeOverflow_ = false;
+
+    // If lhsRange does not contain a zero,
+    // negative zero check can be skipped.
+    if (!lhsRange.canBeZero())
+        canBeNegativeZero_ = false;
+
+    // If rhsRange >= 0 negative zero check can be skipped.
+    if (rhsRange.isFiniteNonNegative())
+        canBeNegativeZero_ = false;
+}
+
+void
+MMul::collectRangeInfoPreTrunc()
+{
+    Range lhsRange(lhs());
+    Range rhsRange(rhs());
+
+    // If lhsRange contains only positive then we can skip negative zero check.
+    if (lhsRange.isFiniteNonNegative() && !lhsRange.canBeZero())
+        setCanBeNegativeZero(false);
+
+    // Likewise rhsRange.
+    if (rhsRange.isFiniteNonNegative() && !rhsRange.canBeZero())
+        setCanBeNegativeZero(false);
+
+    // If rhsRange and lhsRange contain Non-negative integers only,
+    // We skip negative zero check.
+    if (rhsRange.isFiniteNonNegative() && lhsRange.isFiniteNonNegative())
+        setCanBeNegativeZero(false);
+
+    //If rhsRange and lhsRange < 0. Then we skip negative zero check.
+    if (rhsRange.isFiniteNegative() && lhsRange.isFiniteNegative())
+        setCanBeNegativeZero(false);
+}
+
+void
+MMod::collectRangeInfoPreTrunc()
+{
+    Range lhsRange(lhs());
+    Range rhsRange(rhs());
+    if (lhsRange.isFiniteNonNegative())
+        canBeNegativeDividend_ = false;
+    if (!rhsRange.canBeZero())
+        canBeDivideByZero_ = false;
+
+}
+
+void
+MToInt32::collectRangeInfoPreTrunc()
+{
+    Range inputRange(input());
+    if (!inputRange.canBeNegativeZero())
+        canBeNegativeZero_ = false;
+}
+
+void
+MBoundsCheck::collectRangeInfoPreTrunc()
+{
+    Range indexRange(index());
+    Range lengthRange(length());
+    if (!indexRange.hasInt32LowerBound() || !indexRange.hasInt32UpperBound())
+        return;
+    if (!lengthRange.hasInt32LowerBound() || lengthRange.canBeNaN())
+        return;
+
+    int64_t indexLower = indexRange.lower();
+    int64_t indexUpper = indexRange.upper();
+    int64_t lengthLower = lengthRange.lower();
+    int64_t min = minimum();
+    int64_t max = maximum();
+
+    if (indexLower + min >= 0 && indexUpper + max < lengthLower)
+        fallible_ = false;
+}
+
+void
+MBoundsCheckLower::collectRangeInfoPreTrunc()
+{
+    Range indexRange(index());
+    if (indexRange.hasInt32LowerBound() && indexRange.lower() >= minimum_)
+        fallible_ = false;
+}
+
+void
+MCompare::collectRangeInfoPreTrunc()
+{
+    if (!Range(lhs()).canBeNaN() && !Range(rhs()).canBeNaN())
+        operandsAreNeverNaN_ = true;
+}
+
+void
+MNot::collectRangeInfoPreTrunc()
+{
+    if (!Range(input()).canBeNaN())
+        operandIsNeverNaN_ = true;
+}
+
+void
+MPowHalf::collectRangeInfoPreTrunc()
+{
+    Range inputRange(input());
+    if (!inputRange.canBeInfiniteOrNaN() || inputRange.hasInt32LowerBound())
+        operandIsNeverNegativeInfinity_ = true;
+    if (!inputRange.canBeNegativeZero())
+        operandIsNeverNegativeZero_ = true;
+    if (!inputRange.canBeNaN())
+        operandIsNeverNaN_ = true;
+}
+
+void
+MUrsh::collectRangeInfoPreTrunc()
+{
+    if (specialization_ == MIRType::Int64)
+        return;
+
+    Range lhsRange(lhs()), rhsRange(rhs());
+
+    // As in MUrsh::computeRange(), convert the inputs.
+    lhsRange.wrapAroundToInt32();
+    rhsRange.wrapAroundToShiftCount();
+
+    // If the most significant bit of our result is always going to be zero,
+    // we can optimize by disabling bailout checks for enforcing an int32 range.
+    if (lhsRange.lower() >= 0 || rhsRange.lower() >= 1)
+        bailoutsDisabled_ = true;
+}
+
+static bool
+DoesMaskMatchRange(int32_t mask, Range& range)
+{
+    // Check if range is positive, because the bitand operator in `(-3) & 0xff` can't be
+    // eliminated.
+    if (range.lower() >= 0) {
+        MOZ_ASSERT(range.isInt32());
+        // Check that the mask value has all bits set given the range upper bound. Note that the
+        // upper bound does not have to be exactly the mask value. For example, consider `x &
+        // 0xfff` where `x` is a uint8. That expression can still be optimized to `x`.
+        int bits = 1 + FloorLog2(range.upper());
+        uint32_t maskNeeded = (bits == 32) ? 0xffffffff : (uint32_t(1) << bits) - 1;
+        if ((mask & maskNeeded) == maskNeeded)
+            return true;
+    }
+
+    return false;
+}
+
+void
+MBinaryBitwiseInstruction::collectRangeInfoPreTrunc()
+{
+    Range lhsRange(lhs());
+    Range rhsRange(rhs());
+
+    if (lhs()->isConstant() && lhs()->type() == MIRType::Int32 &&
+        DoesMaskMatchRange(lhs()->toConstant()->toInt32(), rhsRange))
+    {
+        maskMatchesRightRange = true;
+    }
+
+    if (rhs()->isConstant() && rhs()->type() == MIRType::Int32 &&
+        DoesMaskMatchRange(rhs()->toConstant()->toInt32(), lhsRange))
+    {
+        maskMatchesLeftRange = true;
+    }
+}
+
+void
+MNaNToZero::collectRangeInfoPreTrunc()
+{
+    Range inputRange(input());
+
+    if (!inputRange.canBeNaN())
+        operandIsNeverNaN_ = true;
+    if (!inputRange.canBeNegativeZero())
+        operandIsNeverNegativeZero_ = true;
+}
+
+bool
+RangeAnalysis::prepareForUCE(bool* shouldRemoveDeadCode)
+{
+    *shouldRemoveDeadCode = false;
+
+    for (ReversePostorderIterator iter(graph_.rpoBegin()); iter != graph_.rpoEnd(); iter++) {
+        MBasicBlock* block = *iter;
+
+        if (!block->unreachable())
+            continue;
+
+        // Filter out unreachable fake entries.
+        if (block->numPredecessors() == 0) {
+            // Ignore fixup blocks added by the Value Numbering phase, in order
+            // to keep the dominator tree as-is when we have OSR Block which are
+            // no longer reachable from the main entry point of the graph.
+            MOZ_ASSERT(graph_.osrBlock());
+            continue;
+        }
+
+        MControlInstruction* cond = block->getPredecessor(0)->lastIns();
+        if (!cond->isTest())
+            continue;
+
+        // Replace the condition of the test control instruction by a constant
+        // chosen based which of the successors has the unreachable flag which is
+        // added by MBeta::computeRange on its own block.
+        MTest* test = cond->toTest();
+        MDefinition* condition = test->input();
+
+        // If the false-branch is unreachable, then the test condition must be true.
+        // If the true-branch is unreachable, then the test condition must be false.
+        MOZ_ASSERT(block == test->ifTrue() || block == test->ifFalse());
+        bool value = block == test->ifFalse();
+        MConstant* constant = MConstant::New(alloc().fallible(), BooleanValue(value));
+        if (!constant)
+            return false;
+
+        condition->setGuardRangeBailoutsUnchecked();
+
+        test->block()->insertBefore(test, constant);
+
+        test->replaceOperand(0, constant);
+        JitSpew(JitSpew_Range, "Update condition of %d to reflect unreachable branches.",
+                test->id());
+
+        *shouldRemoveDeadCode = true;
+    }
+
+    return tryRemovingGuards();
+}
+
+bool RangeAnalysis::tryRemovingGuards()
+{
+    MDefinitionVector guards(alloc());
+
+    for (ReversePostorderIterator block = graph_.rpoBegin(); block != graph_.rpoEnd(); block++) {
+        for (MDefinitionIterator iter(*block); iter; iter++) {
+            if (!iter->isGuardRangeBailouts())
+                continue;
+
+            iter->setInWorklist();
+            if (!guards.append(*iter))
+                return false;
+        }
+    }
+
+    // Flag all fallible instructions which were indirectly used in the
+    // computation of the condition, such that we do not ignore
+    // bailout-paths which are used to shrink the input range of the
+    // operands of the condition.
+    for (size_t i = 0; i < guards.length(); i++) {
+        MDefinition* guard = guards[i];
+
+        // If this ins is a guard even without guardRangeBailouts,
+        // there is no reason in trying to hoist the guardRangeBailouts check.
+        guard->setNotGuardRangeBailouts();
+        if (!DeadIfUnused(guard)) {
+            guard->setGuardRangeBailouts();
+            continue;
+        }
+        guard->setGuardRangeBailouts();
+
+        if (!guard->isPhi()) {
+            if (!guard->range())
+                continue;
+
+            // Filter the range of the instruction based on its MIRType.
+            Range typeFilteredRange(guard);
+
+            // If the output range is updated by adding the inner range,
+            // then the MIRType act as an effectful filter. As we do not know if
+            // this filtered Range might change or not the result of the
+            // previous comparison, we have to keep this instruction as a guard
+            // because it has to bailout in order to restrict the Range to its
+            // MIRType.
+            if (typeFilteredRange.update(guard->range()))
+                continue;
+        }
+
+        guard->setNotGuardRangeBailouts();
+
+        // Propagate the guard to its operands.
+        for (size_t op = 0, e = guard->numOperands(); op < e; op++) {
+            MDefinition* operand = guard->getOperand(op);
+
+            // Already marked.
+            if (operand->isInWorklist())
+                continue;
+
+            MOZ_ASSERT(!operand->isGuardRangeBailouts());
+
+            operand->setInWorklist();
+            operand->setGuardRangeBailouts();
+            if (!guards.append(operand))
+                return false;
+        }
+    }
+
+    for (size_t i = 0; i < guards.length(); i++) {
+        MDefinition* guard = guards[i];
+        guard->setNotInWorklist();
+    }
+
+    return true;
+}