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authorjanekptacijarabaci <janekptacijarabaci@seznam.cz>2018-03-25 13:32:14 +0200
committerjanekptacijarabaci <janekptacijarabaci@seznam.cz>2018-03-25 13:32:14 +0200
commite2853b8a8fc05a7526d933a62828c26747b4580a (patch)
treeee01d2ebdc14c1c80b0c3f9749fa599745b5bbcf /js/src/frontend
parente641a2c53a857141042ca62f1fe0b63b55a130af (diff)
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Bug 1322069 - Add TryEmitter
Issue #74
Diffstat (limited to 'js/src/frontend')
-rw-r--r--js/src/frontend/BytecodeEmitter.cpp510
1 files changed, 341 insertions, 169 deletions
diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 76f1f75b5..b1b0055e2 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -1563,6 +1563,318 @@ BytecodeEmitter::TDZCheckCache::noteTDZCheck(BytecodeEmitter* bce, JSAtom* name,
return true;
}
+class MOZ_STACK_CLASS TryEmitter
+{
+ public:
+ enum Kind {
+ TryCatch,
+ TryCatchFinally,
+ TryFinally
+ };
+ enum ShouldUseRetVal {
+ UseRetVal,
+ DontUseRetVal
+ };
+ enum ShouldUseControl {
+ UseControl,
+ DontUseControl,
+ };
+
+ private:
+ BytecodeEmitter* bce_;
+ Kind kind_;
+ ShouldUseRetVal retValKind_;
+
+ // Track jumps-over-catches and gosubs-to-finally for later fixup.
+ //
+ // When a finally block is active, non-local jumps (including
+ // jumps-over-catches) result in a GOSUB being written into the bytecode
+ // stream and fixed-up later.
+ //
+ // If ShouldUseControl is DontUseControl, all that handling is skipped.
+ // DontUseControl is used by yield*, that matches to the following:
+ // * has only one catch block
+ // * has no catch guard
+ // * has JSOP_GOTO at the end of catch-block
+ // * has no non-local-jump
+ // * doesn't use finally block for normal completion of try-block and
+ // catch-block
+ Maybe<TryFinallyControl> controlInfo_;
+
+ int depth_;
+ unsigned noteIndex_;
+ ptrdiff_t tryStart_;
+ JumpList catchAndFinallyJump_;
+ JumpTarget tryEnd_;
+ JumpTarget finallyStart_;
+
+ enum State {
+ Start,
+ Try,
+ TryEnd,
+ Catch,
+ CatchEnd,
+ Finally,
+ FinallyEnd,
+ End
+ };
+ State state_;
+
+ bool hasCatch() const {
+ return kind_ == TryCatch || kind_ == TryCatchFinally;
+ }
+ bool hasFinally() const {
+ return kind_ == TryCatchFinally || kind_ == TryFinally;
+ }
+
+ public:
+ TryEmitter(BytecodeEmitter* bce, Kind kind, ShouldUseRetVal retValKind = UseRetVal,
+ ShouldUseControl controlKind = UseControl)
+ : bce_(bce),
+ kind_(kind),
+ retValKind_(retValKind),
+ depth_(0),
+ noteIndex_(0),
+ tryStart_(0),
+ state_(Start)
+ {
+ if (controlKind == UseControl)
+ controlInfo_.emplace(bce_, hasFinally() ? StatementKind::Finally : StatementKind::Try);
+ finallyStart_.offset = 0;
+ }
+
+ bool emitJumpOverCatchAndFinally() {
+ if (!bce_->emitJump(JSOP_GOTO, &catchAndFinallyJump_))
+ return false;
+ return true;
+ }
+
+ bool emitTry() {
+ MOZ_ASSERT(state_ == Start);
+
+ // Since an exception can be thrown at any place inside the try block,
+ // we need to restore the stack and the scope chain before we transfer
+ // the control to the exception handler.
+ //
+ // For that we store in a try note associated with the catch or
+ // finally block the stack depth upon the try entry. The interpreter
+ // uses this depth to properly unwind the stack and the scope chain.
+ depth_ = bce_->stackDepth;
+
+ // Record the try location, then emit the try block.
+ if (!bce_->newSrcNote(SRC_TRY, &noteIndex_))
+ return false;
+ if (!bce_->emit1(JSOP_TRY))
+ return false;
+ tryStart_ = bce_->offset();
+
+ state_ = Try;
+ return true;
+ }
+
+ private:
+ bool emitTryEnd() {
+ MOZ_ASSERT(state_ == Try);
+ MOZ_ASSERT(depth_ == bce_->stackDepth);
+
+ // GOSUB to finally, if present.
+ if (hasFinally() && controlInfo_) {
+ if (!bce_->emitJump(JSOP_GOSUB, &controlInfo_->gosubs))
+ return false;
+ }
+
+ // Source note points to the jump at the end of the try block.
+ if (!bce_->setSrcNoteOffset(noteIndex_, 0, bce_->offset() - tryStart_ + JSOP_TRY_LENGTH))
+ return false;
+
+ // Emit jump over catch and/or finally.
+ if (!bce_->emitJump(JSOP_GOTO, &catchAndFinallyJump_))
+ return false;
+
+ if (!bce_->emitJumpTarget(&tryEnd_))
+ return false;
+
+ return true;
+ }
+
+ public:
+ bool emitCatch() {
+ if (state_ == Try) {
+ if (!emitTryEnd())
+ return false;
+ } else {
+ MOZ_ASSERT(state_ == Catch);
+ if (!emitCatchEnd(true))
+ return false;
+ }
+
+ MOZ_ASSERT(bce_->stackDepth == depth_);
+
+ if (retValKind_ == UseRetVal) {
+ // Clear the frame's return value that might have been set by the
+ // try block:
+ //
+ // eval("try { 1; throw 2 } catch(e) {}"); // undefined, not 1
+ if (!bce_->emit1(JSOP_UNDEFINED))
+ return false;
+ if (!bce_->emit1(JSOP_SETRVAL))
+ return false;
+ }
+
+ state_ = Catch;
+ return true;
+ }
+
+ private:
+ bool emitCatchEnd(bool hasNext) {
+ MOZ_ASSERT(state_ == Catch);
+
+ if (!controlInfo_)
+ return true;
+
+ // gosub <finally>, if required.
+ if (hasFinally()) {
+ if (!bce_->emitJump(JSOP_GOSUB, &controlInfo_->gosubs))
+ return false;
+ MOZ_ASSERT(bce_->stackDepth == depth_);
+ }
+
+ // Jump over the remaining catch blocks. This will get fixed
+ // up to jump to after catch/finally.
+ if (!bce_->emitJump(JSOP_GOTO, &catchAndFinallyJump_))
+ return false;
+
+ // If this catch block had a guard clause, patch the guard jump to
+ // come here.
+ if (controlInfo_->guardJump.offset != -1) {
+ if (!bce_->emitJumpTargetAndPatch(controlInfo_->guardJump))
+ return false;
+ controlInfo_->guardJump.offset = -1;
+
+ // If this catch block is the last one, rethrow, delegating
+ // execution of any finally block to the exception handler.
+ if (!hasNext) {
+ if (!bce_->emit1(JSOP_EXCEPTION))
+ return false;
+ if (!bce_->emit1(JSOP_THROW))
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ public:
+ bool emitFinally(Maybe<uint32_t> finallyPos = Nothing()) {
+ MOZ_ASSERT(hasFinally());
+
+ if (state_ == Try) {
+ if (!emitTryEnd())
+ return false;
+ } else {
+ MOZ_ASSERT(state_ == Catch);
+ if (!emitCatchEnd(false))
+ return false;
+ }
+
+ MOZ_ASSERT(bce_->stackDepth == depth_);
+
+ if (!bce_->emitJumpTarget(&finallyStart_))
+ return false;
+
+ if (controlInfo_) {
+ // Fix up the gosubs that might have been emitted before non-local
+ // jumps to the finally code.
+ bce_->patchJumpsToTarget(controlInfo_->gosubs, finallyStart_);
+
+ // Indicate that we're emitting a subroutine body.
+ controlInfo_->setEmittingSubroutine();
+ }
+ if (finallyPos) {
+ if (!bce_->updateSourceCoordNotes(finallyPos.value()))
+ return false;
+ }
+ if (!bce_->emit1(JSOP_FINALLY))
+ return false;
+
+ if (retValKind_ == UseRetVal) {
+ if (!bce_->emit1(JSOP_GETRVAL))
+ return false;
+
+ // Clear the frame's return value to make break/continue return
+ // correct value even if there's no other statement before them:
+ //
+ // eval("x: try { 1 } finally { break x; }"); // undefined, not 1
+ if (!bce_->emit1(JSOP_UNDEFINED))
+ return false;
+ if (!bce_->emit1(JSOP_SETRVAL))
+ return false;
+ }
+
+ state_ = Finally;
+ return true;
+ }
+
+ private:
+ bool emitFinallyEnd() {
+ MOZ_ASSERT(state_ == Finally);
+
+ if (retValKind_ == UseRetVal) {
+ if (!bce_->emit1(JSOP_SETRVAL))
+ return false;
+ }
+
+ if (!bce_->emit1(JSOP_RETSUB))
+ return false;
+
+ bce_->hasTryFinally = true;
+ return true;
+ }
+
+ public:
+ bool emitEnd() {
+ if (state_ == Catch) {
+ MOZ_ASSERT(!hasFinally());
+ if (!emitCatchEnd(false))
+ return false;
+ } else {
+ MOZ_ASSERT(state_ == Finally);
+ MOZ_ASSERT(hasFinally());
+ if (!emitFinallyEnd())
+ return false;
+ }
+
+ MOZ_ASSERT(bce_->stackDepth == depth_);
+
+ // ReconstructPCStack needs a NOP here to mark the end of the last
+ // catch block.
+ if (!bce_->emit1(JSOP_NOP))
+ return false;
+
+ // Fix up the end-of-try/catch jumps to come here.
+ if (!bce_->emitJumpTargetAndPatch(catchAndFinallyJump_))
+ return false;
+
+ // Add the try note last, to let post-order give us the right ordering
+ // (first to last for a given nesting level, inner to outer by level).
+ if (hasCatch()) {
+ if (!bce_->tryNoteList.append(JSTRY_CATCH, depth_, tryStart_, tryEnd_.offset))
+ return false;
+ }
+
+ // If we've got a finally, mark try+catch region with additional
+ // trynote to catch exceptions (re)thrown from a catch block or
+ // for the try{}finally{} case.
+ if (hasFinally()) {
+ if (!bce_->tryNoteList.append(JSTRY_FINALLY, depth_, tryStart_, finallyStart_.offset))
+ return false;
+ }
+
+ state_ = End;
+ return true;
+ }
+};
+
class MOZ_STACK_CLASS IfThenElseEmitter
{
BytecodeEmitter* bce_;
@@ -6073,57 +6385,28 @@ BytecodeEmitter::emitCatch(ParseNode* pn)
MOZ_NEVER_INLINE bool
BytecodeEmitter::emitTry(ParseNode* pn)
{
- // Track jumps-over-catches and gosubs-to-finally for later fixup.
- //
- // When a finally block is active, non-local jumps (including
- // jumps-over-catches) result in a GOSUB being written into the bytecode
- // stream and fixed-up later.
- //
- TryFinallyControl controlInfo(this, pn->pn_kid3 ? StatementKind::Finally : StatementKind::Try);
-
- // Since an exception can be thrown at any place inside the try block,
- // we need to restore the stack and the scope chain before we transfer
- // the control to the exception handler.
- //
- // For that we store in a try note associated with the catch or
- // finally block the stack depth upon the try entry. The interpreter
- // uses this depth to properly unwind the stack and the scope chain.
- //
- int depth = stackDepth;
-
- // Record the try location, then emit the try block.
- unsigned noteIndex;
- if (!newSrcNote(SRC_TRY, &noteIndex))
- return false;
- if (!emit1(JSOP_TRY))
- return false;
-
- ptrdiff_t tryStart = offset();
- if (!emitTree(pn->pn_kid1))
- return false;
- MOZ_ASSERT(depth == stackDepth);
+ ParseNode* catchList = pn->pn_kid2;
+ ParseNode* finallyNode = pn->pn_kid3;
- // GOSUB to finally, if present.
- if (pn->pn_kid3) {
- if (!emitJump(JSOP_GOSUB, &controlInfo.gosubs))
- return false;
+ TryEmitter::Kind kind;
+ if (catchList) {
+ if (finallyNode)
+ kind = TryEmitter::TryCatchFinally;
+ else
+ kind = TryEmitter::TryCatch;
+ } else {
+ MOZ_ASSERT(finallyNode);
+ kind = TryEmitter::TryFinally;
}
+ TryEmitter tryCatch(this, kind);
- // Source note points to the jump at the end of the try block.
- if (!setSrcNoteOffset(noteIndex, 0, offset() - tryStart + JSOP_TRY_LENGTH))
- return false;
-
- // Emit jump over catch and/or finally.
- JumpList catchJump;
- if (!emitJump(JSOP_GOTO, &catchJump))
+ if (!tryCatch.emitTry())
return false;
- JumpTarget tryEnd;
- if (!emitJumpTarget(&tryEnd))
+ if (!emitTree(pn->pn_kid1))
return false;
// If this try has a catch block, emit it.
- ParseNode* catchList = pn->pn_kid2;
if (catchList) {
MOZ_ASSERT(catchList->isKind(PNK_CATCHLIST));
@@ -6153,110 +6436,26 @@ BytecodeEmitter::emitTry(ParseNode* pn)
// capturing exceptions thrown from catch{} blocks.
//
for (ParseNode* pn3 = catchList->pn_head; pn3; pn3 = pn3->pn_next) {
- MOZ_ASSERT(this->stackDepth == depth);
-
- // Clear the frame's return value that might have been set by the
- // try block:
- //
- // eval("try { 1; throw 2 } catch(e) {}"); // undefined, not 1
- if (!emit1(JSOP_UNDEFINED))
- return false;
- if (!emit1(JSOP_SETRVAL))
+ if (!tryCatch.emitCatch())
return false;
// Emit the lexical scope and catch body.
MOZ_ASSERT(pn3->isKind(PNK_LEXICALSCOPE));
if (!emitTree(pn3))
return false;
-
- // gosub <finally>, if required.
- if (pn->pn_kid3) {
- if (!emitJump(JSOP_GOSUB, &controlInfo.gosubs))
- return false;
- MOZ_ASSERT(this->stackDepth == depth);
- }
-
- // Jump over the remaining catch blocks. This will get fixed
- // up to jump to after catch/finally.
- if (!emitJump(JSOP_GOTO, &catchJump))
- return false;
-
- // If this catch block had a guard clause, patch the guard jump to
- // come here.
- if (controlInfo.guardJump.offset != -1) {
- if (!emitJumpTargetAndPatch(controlInfo.guardJump))
- return false;
- controlInfo.guardJump.offset = -1;
-
- // If this catch block is the last one, rethrow, delegating
- // execution of any finally block to the exception handler.
- if (!pn3->pn_next) {
- if (!emit1(JSOP_EXCEPTION))
- return false;
- if (!emit1(JSOP_THROW))
- return false;
- }
- }
}
}
- MOZ_ASSERT(this->stackDepth == depth);
-
// Emit the finally handler, if there is one.
- JumpTarget finallyStart{ 0 };
- if (pn->pn_kid3) {
- if (!emitJumpTarget(&finallyStart))
- return false;
-
- // Fix up the gosubs that might have been emitted before non-local
- // jumps to the finally code.
- patchJumpsToTarget(controlInfo.gosubs, finallyStart);
-
- // Indicate that we're emitting a subroutine body.
- controlInfo.setEmittingSubroutine();
- if (!updateSourceCoordNotes(pn->pn_kid3->pn_pos.begin))
- return false;
- if (!emit1(JSOP_FINALLY))
- return false;
- if (!emit1(JSOP_GETRVAL))
- return false;
-
- // Clear the frame's return value to make break/continue return
- // correct value even if there's no other statement before them:
- //
- // eval("x: try { 1 } finally { break x; }"); // undefined, not 1
- if (!emit1(JSOP_UNDEFINED))
- return false;
- if (!emit1(JSOP_SETRVAL))
+ if (finallyNode) {
+ if (!tryCatch.emitFinally(Some(finallyNode->pn_pos.begin)))
return false;
- if (!emitTree(pn->pn_kid3))
- return false;
- if (!emit1(JSOP_SETRVAL))
- return false;
- if (!emit1(JSOP_RETSUB))
+ if (!emitTree(finallyNode))
return false;
- hasTryFinally = true;
- MOZ_ASSERT(this->stackDepth == depth);
}
- // ReconstructPCStack needs a NOP here to mark the end of the last catch block.
- if (!emit1(JSOP_NOP))
- return false;
-
- // Fix up the end-of-try/catch jumps to come here.
- if (!emitJumpTargetAndPatch(catchJump))
- return false;
-
- // Add the try note last, to let post-order give us the right ordering
- // (first to last for a given nesting level, inner to outer by level).
- if (catchList && !tryNoteList.append(JSTRY_CATCH, depth, tryStart, tryEnd.offset))
- return false;
-
- // If we've got a finally, mark try+catch region with additional
- // trynote to catch exceptions (re)thrown from a catch block or
- // for the try{}finally{} case.
- if (pn->pn_kid3 && !tryNoteList.append(JSTRY_FINALLY, depth, tryStart, finallyStart.offset))
+ if (!tryCatch.emitEnd())
return false;
return true;
@@ -8040,17 +8239,15 @@ BytecodeEmitter::emitYieldStar(ParseNode* iter, ParseNode* gen)
int depth = stackDepth;
MOZ_ASSERT(depth >= 2);
- JumpList send;
- if (!emitJump(JSOP_GOTO, &send)) // goto send
+ TryEmitter tryCatch(this, TryEmitter::TryCatchFinally, TryEmitter::DontUseRetVal,
+ TryEmitter::DontUseControl);
+ if (!tryCatch.emitJumpOverCatchAndFinally()) // ITER RESULT
return false;
- // Try prologue. // ITER RESULT
- unsigned noteIndex;
- if (!newSrcNote(SRC_TRY, &noteIndex))
- return false;
JumpTarget tryStart{ offset() };
- if (!emit1(JSOP_TRY)) // tryStart:
+ if (!tryCatch.emitTry()) // ITER RESULT
return false;
+
MOZ_ASSERT(this->stackDepth == depth);
// Load the generator object.
@@ -8061,17 +8258,9 @@ BytecodeEmitter::emitYieldStar(ParseNode* iter, ParseNode* gen)
if (!emitYieldOp(JSOP_YIELD)) // ITER RECEIVED
return false;
- // Try epilogue.
- if (!setSrcNoteOffset(noteIndex, 0, offset() - tryStart.offset))
- return false;
- if (!emitJump(JSOP_GOTO, &send)) // goto send
- return false;
-
- JumpTarget tryEnd;
- if (!emitJumpTarget(&tryEnd)) // tryEnd:
+ if (!tryCatch.emitCatch()) // ITER RESULT
return false;
- // Catch location.
stackDepth = uint32_t(depth); // ITER RESULT
if (!emit1(JSOP_EXCEPTION)) // ITER RESULT EXCEPTION
return false;
@@ -8118,36 +8307,19 @@ BytecodeEmitter::emitYieldStar(ParseNode* iter, ParseNode* gen)
if (!emitJump(JSOP_GOTO, &checkResult)) // goto checkResult
return false;
- // The finally block, IteratorClose logic.
+ // IteratorClose logic.
+ if (!tryCatch.emitFinally())
+ return false;
- JumpTarget finallyStart{ 0 };
- if (!emitJumpTarget(&finallyStart))
- return false;
- if (!emit1(JSOP_FINALLY)) // ITER RESULT FTYPE FVALUE
- return false;
if (!emitDupAt(3)) // ITER RESULT FTYPE FVALUE ITER
return false;
if (!emitIteratorClose(Some(tryStart))) // ITER RESULT FTYPE FVALUE
return false;
- if (!emit1(JSOP_RETSUB)) // ITER RESULT
- return false;
-
- // Catch and finally epilogue.
- // This is a peace offering to ReconstructPCStack. See the note in EmitTry.
- if (!emit1(JSOP_NOP))
- return false;
- size_t tryStartOffset = tryStart.offset + JSOP_TRY_LENGTH;
- if (!tryNoteList.append(JSTRY_CATCH, depth, tryStartOffset, tryEnd.offset))
- return false;
- if (!tryNoteList.append(JSTRY_FINALLY, depth, tryStartOffset, finallyStart.offset))
+ if (!tryCatch.emitEnd())
return false;
// After the try-catch-finally block: send the received value to the iterator.
- if (!emitJumpTargetAndPatch(send)) // send:
- return false;
-
- // Send location.
// result = iter.next(received) // ITER RECEIVED
if (!emit1(JSOP_SWAP)) // RECEIVED ITER
return false;