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-rw-r--r--js/src/frontend/BytecodeEmitter.cpp70
-rw-r--r--js/src/frontend/BytecodeEmitter.h4
-rw-r--r--js/src/tests/ecma_6/Generators/yield-iterator-close.js58
3 files changed, 123 insertions, 9 deletions
diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 4d3b60c2f..c7c615ccf 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -1534,13 +1534,19 @@ class MOZ_STACK_CLASS TryEmitter
// 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
+ // DontUseControl is used by yield* and the internal try-catch around
+ // IteratorClose. These internal uses must:
+ // * have only one catch block
+ // * have no catch guard
+ // * have JSOP_GOTO at the end of catch-block
+ // * have no non-local-jump
+ // * don't use finally block for normal completion of try-block and
// catch-block
+ //
+ // Additionally, a finally block may be emitted when ShouldUseControl is
+ // DontUseControl, even if the kind is not TryCatchFinally or TryFinally,
+ // because GOSUBs are not emitted. This internal use shares the
+ // requirements as above.
Maybe<TryFinallyControl> controlInfo_;
int depth_;
@@ -1708,7 +1714,17 @@ class MOZ_STACK_CLASS TryEmitter
public:
bool emitFinally(Maybe<uint32_t> finallyPos = Nothing()) {
- MOZ_ASSERT(hasFinally());
+ // If we are using controlInfo_ (i.e., emitting a syntactic try
+ // blocks), we must have specified up front if there will be a finally
+ // close. For internal try blocks, like those emitted for yield* and
+ // IteratorClose inside for-of loops, we can emitFinally even without
+ // specifying up front, since the internal try blocks emit no GOSUBs.
+ if (!controlInfo_) {
+ if (kind_ == TryCatch)
+ kind_ = TryCatchFinally;
+ } else {
+ MOZ_ASSERT(hasFinally());
+ }
if (state_ == Try) {
if (!emitTryEnd())
@@ -2004,21 +2020,31 @@ class ForOfLoopControl : public LoopControl
// }
Maybe<TryEmitter> tryCatch_;
+ // Used to track if any yields were emitted between calls to to
+ // emitBeginCodeNeedingIteratorClose and emitEndCodeNeedingIteratorClose.
+ uint32_t numYieldsAtBeginCodeNeedingIterClose_;
+
bool allowSelfHosted_;
public:
ForOfLoopControl(BytecodeEmitter* bce, int32_t iterDepth, bool allowSelfHosted)
: LoopControl(bce, StatementKind::ForOfLoop),
iterDepth_(iterDepth),
+ numYieldsAtBeginCodeNeedingIterClose_(UINT32_MAX),
allowSelfHosted_(allowSelfHosted)
{
}
bool emitBeginCodeNeedingIteratorClose(BytecodeEmitter* bce) {
- tryCatch_.emplace(bce, TryEmitter::TryCatch, TryEmitter::DontUseRetVal);
+ tryCatch_.emplace(bce, TryEmitter::TryCatch, TryEmitter::DontUseRetVal,
+ TryEmitter::DontUseControl);
if (!tryCatch_->emitTry())
return false;
+
+ MOZ_ASSERT(numYieldsAtBeginCodeNeedingIterClose_ == UINT32_MAX);
+ numYieldsAtBeginCodeNeedingIterClose_ = bce->yieldOffsetList.numYields;
+
return true;
}
@@ -2056,10 +2082,33 @@ class ForOfLoopControl : public LoopControl
if (!bce->emit1(JSOP_THROW)) // ITER ...
return false;
+ // If any yields were emitted, then this for-of loop is inside a star
+ // generator and must handle the case of Generator.return. Like in
+ // yield*, it is handled with a finally block.
+ uint32_t numYieldsEmitted = bce->yieldOffsetList.numYields;
+ if (numYieldsEmitted > numYieldsAtBeginCodeNeedingIterClose_) {
+ if (!tryCatch_->emitFinally())
+ return false;
+
+ IfThenElseEmitter ifGeneratorClosing(bce);
+ if (!bce->emit1(JSOP_ISGENCLOSING)) // ITER ... FTYPE FVALUE CLOSING
+ return false;
+ if (!ifGeneratorClosing.emitIf()) // ITER ... FTYPE FVALUE
+ return false;
+ if (!bce->emitDupAt(slotFromTop + 1)) // ITER ... FTYPE FVALUE ITER
+ return false;
+ if (!emitIteratorClose(bce, CompletionKind::Normal)) // ITER ... FTYPE FVALUE
+ return false;
+ if (!ifGeneratorClosing.emitEnd()) // ITER ... FTYPE FVALUE
+ return false;
+ }
+
if (!tryCatch_->emitEnd())
return false;
tryCatch_.reset();
+ numYieldsAtBeginCodeNeedingIterClose_ = UINT32_MAX;
+
return true;
}
@@ -4748,6 +4797,11 @@ BytecodeEmitter::emitYieldOp(JSOp op)
return false;
}
+ if (op == JSOP_YIELD)
+ yieldOffsetList.numYields++;
+ else
+ yieldOffsetList.numAwaits++;
+
SET_UINT24(code(off), yieldIndex);
if (!yieldOffsetList.append(offset()))
diff --git a/js/src/frontend/BytecodeEmitter.h b/js/src/frontend/BytecodeEmitter.h
index 7ac9e540b..04307c8c1 100644
--- a/js/src/frontend/BytecodeEmitter.h
+++ b/js/src/frontend/BytecodeEmitter.h
@@ -100,7 +100,9 @@ struct CGScopeNoteList {
struct CGYieldOffsetList {
Vector<uint32_t> list;
- explicit CGYieldOffsetList(ExclusiveContext* cx) : list(cx) {}
+ uint32_t numYields;
+ uint32_t numAwaits;
+ explicit CGYieldOffsetList(ExclusiveContext* cx) : list(cx), numYields(0), numAwaits(0) {}
MOZ_MUST_USE bool append(uint32_t offset) { return list.append(offset); }
size_t length() const { return list.length(); }
diff --git a/js/src/tests/ecma_6/Generators/yield-iterator-close.js b/js/src/tests/ecma_6/Generators/yield-iterator-close.js
new file mode 100644
index 000000000..970ad494d
--- /dev/null
+++ b/js/src/tests/ecma_6/Generators/yield-iterator-close.js
@@ -0,0 +1,58 @@
+// Test that IteratorClose is called when a Generator is abruptly completed by
+// Generator.return.
+
+var returnCalled = 0;
+function* wrapNoThrow() {
+ let iter = {
+ [Symbol.iterator]() {
+ return this;
+ },
+ next() {
+ return { value: 10, done: false };
+ },
+ return() {
+ returnCalled++;
+ return {};
+ }
+ };
+ for (const i of iter) {
+ yield i;
+ }
+}
+
+// Breaking calls Generator.return, which causes the yield above to resume with
+// an abrupt completion of kind "return", which then calls
+// iter.return.
+for (const i of wrapNoThrow()) {
+ break;
+}
+assertEq(returnCalled, 1);
+
+function* wrapThrow() {
+ let iter = {
+ [Symbol.iterator]() {
+ return this;
+ },
+ next() {
+ return { value: 10, done: false };
+ },
+ return() {
+ throw 42;
+ }
+ };
+ for (const i of iter) {
+ yield i;
+ }
+}
+
+// Breaking calls Generator.return, which, like above, calls iter.return. If
+// iter.return throws, since the yield is resuming with an abrupt completion of
+// kind "return", the newly thrown value takes precedence over returning.
+assertThrowsValue(() => {
+ for (const i of wrapThrow()) {
+ break;
+ }
+}, 42);
+
+if (typeof reportCompare === "function")
+ reportCompare(0, 0);
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-11 22:18:07 +0000