Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 224 insertions, 0 deletions

diff --git a/js/src/frontend/ForOfEmitter.cpp b/js/src/frontend/ForOfEmitter.cpp
new file mode 100644
index 0000000000..0fd0cfbe36
--- /dev/null
+++ b/js/src/frontend/ForOfEmitter.cpp
@@ -0,0 +1,224 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * 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 "frontend/ForOfEmitter.h"
+
+#include "frontend/BytecodeEmitter.h"
+#include "frontend/EmitterScope.h"
+#include "frontend/ParserAtom.h"  // TaggedParserAtomIndex
+#include "vm/Opcodes.h"
+#include "vm/StencilEnums.h"  // TryNoteKind
+
+using namespace js;
+using namespace js::frontend;
+
+using mozilla::Nothing;
+
+ForOfEmitter::ForOfEmitter(BytecodeEmitter* bce,
+                           const EmitterScope* headLexicalEmitterScope,
+                           SelfHostedIter selfHostedIter, IteratorKind iterKind)
+    : bce_(bce),
+      selfHostedIter_(selfHostedIter),
+      iterKind_(iterKind),
+      headLexicalEmitterScope_(headLexicalEmitterScope) {}
+
+bool ForOfEmitter::emitIterated() {
+  MOZ_ASSERT(state_ == State::Start);
+
+  // Evaluate the expression being iterated. The forHeadExpr should use a
+  // distinct TDZCheckCache to evaluate since (abstractly) it runs in its
+  // own LexicalEnvironment.
+  tdzCacheForIteratedValue_.emplace(bce_);
+
+#ifdef DEBUG
+  state_ = State::Iterated;
+#endif
+  return true;
+}
+
+bool ForOfEmitter::emitInitialize(uint32_t forPos) {
+  MOZ_ASSERT(state_ == State::Iterated);
+
+  tdzCacheForIteratedValue_.reset();
+
+  //                [stack] # if AllowContentWithNext
+  //                [stack] NEXT ITER
+  //                [stack] # elif AllowContentWith
+  //                [stack] ITERABLE ITERFN SYNC_ITERFN?
+  //                [stack] # else
+  //                [stack] ITERABLE
+
+  if (iterKind_ == IteratorKind::Async) {
+    if (!bce_->emitAsyncIterator(selfHostedIter_)) {
+      //            [stack] NEXT ITER
+      return false;
+    }
+  } else {
+    if (!bce_->emitIterator(selfHostedIter_)) {
+      //            [stack] NEXT ITER
+      return false;
+    }
+  }
+
+  // For-of loops have the iterator next method and the iterator itself on the
+  // stack.
+
+  int32_t iterDepth = bce_->bytecodeSection().stackDepth();
+  loopInfo_.emplace(bce_, iterDepth, selfHostedIter_, iterKind_);
+
+  if (!loopInfo_->emitLoopHead(bce_, Nothing())) {
+    //              [stack] NEXT ITER
+    return false;
+  }
+
+  // If the loop had an escaping lexical declaration, replace the current
+  // environment with an dead zoned one to implement TDZ semantics.
+  if (headLexicalEmitterScope_) {
+    // The environment chain only includes an environment for the for-of
+    // loop head *if* a scope binding is captured, thereby requiring
+    // recreation each iteration. If a lexical scope exists for the head,
+    // it must be the innermost one. If that scope has closed-over
+    // bindings inducing an environment, recreate the current environment.
+    MOZ_ASSERT(headLexicalEmitterScope_ == bce_->innermostEmitterScope());
+    MOZ_ASSERT(headLexicalEmitterScope_->scope(bce_).kind() ==
+               ScopeKind::Lexical);
+
+    if (headLexicalEmitterScope_->hasEnvironment()) {
+      if (!bce_->emitInternedScopeOp(headLexicalEmitterScope_->index(),
+                                     JSOp::RecreateLexicalEnv)) {
+        //          [stack] NEXT ITER
+        return false;
+      }
+    }
+
+    // For uncaptured bindings, put them back in TDZ.
+    if (!headLexicalEmitterScope_->deadZoneFrameSlots(bce_)) {
+      return false;
+    }
+  }
+
+#ifdef DEBUG
+  loopDepth_ = bce_->bytecodeSection().stackDepth();
+#endif
+
+  // Make sure this code is attributed to the "for".
+  if (!bce_->updateSourceCoordNotes(forPos)) {
+    return false;
+  }
+
+  if (!bce_->emit1(JSOp::Dup2)) {
+    //              [stack] NEXT ITER NEXT ITER
+    return false;
+  }
+
+  if (!bce_->emitIteratorNext(mozilla::Some(forPos), iterKind_,
+                              selfHostedIter_)) {
+    //              [stack] NEXT ITER RESULT
+    return false;
+  }
+
+  if (!bce_->emit1(JSOp::Dup)) {
+    //              [stack] NEXT ITER RESULT RESULT
+    return false;
+  }
+  if (!bce_->emitAtomOp(JSOp::GetProp,
+                        TaggedParserAtomIndex::WellKnown::done())) {
+    //              [stack] NEXT ITER RESULT DONE
+    return false;
+  }
+
+  // if (done) break;
+  MOZ_ASSERT(bce_->innermostNestableControl == loopInfo_.ptr(),
+             "must be at the top-level of the loop");
+  if (!bce_->emitJump(JSOp::JumpIfTrue, &loopInfo_->breaks)) {
+    //              [stack] NEXT ITER RESULT
+    return false;
+  }
+
+  // Emit code to assign result.value to the iteration variable.
+  //
+  // Note that ES 13.7.5.13, step 5.c says getting result.value does not
+  // call IteratorClose, so start TryNoteKind::ForOfIterClose after the GetProp.
+  if (!bce_->emitAtomOp(JSOp::GetProp,
+                        TaggedParserAtomIndex::WellKnown::value())) {
+    //              [stack] NEXT ITER VALUE
+    return false;
+  }
+
+  if (!loopInfo_->emitBeginCodeNeedingIteratorClose(bce_)) {
+    return false;
+  }
+
+#ifdef DEBUG
+  state_ = State::Initialize;
+#endif
+  return true;
+}
+
+bool ForOfEmitter::emitBody() {
+  MOZ_ASSERT(state_ == State::Initialize);
+
+  MOZ_ASSERT(bce_->bytecodeSection().stackDepth() == loopDepth_ + 1,
+             "the stack must be balanced around the initializing "
+             "operation");
+
+#ifdef DEBUG
+  state_ = State::Body;
+#endif
+  return true;
+}
+
+bool ForOfEmitter::emitEnd(uint32_t iteratedPos) {
+  MOZ_ASSERT(state_ == State::Body);
+
+  MOZ_ASSERT(bce_->bytecodeSection().stackDepth() == loopDepth_ + 1,
+             "the stack must be balanced around the for-of body");
+
+  if (!loopInfo_->emitEndCodeNeedingIteratorClose(bce_)) {
+    //              [stack] NEXT ITER VALUE
+    return false;
+  }
+
+  if (!loopInfo_->emitContinueTarget(bce_)) {
+    //              [stack] NEXT ITER VALUE
+    return false;
+  }
+
+  // We use the iterated value's position to attribute the backedge,
+  // which corresponds to the iteration protocol.
+  // This is a bit misleading for 2nd and later iterations and might need
+  // some fix (bug 1482003).
+  if (!bce_->updateSourceCoordNotes(iteratedPos)) {
+    return false;
+  }
+
+  if (!bce_->emit1(JSOp::Pop)) {
+    //              [stack] NEXT ITER
+    return false;
+  }
+
+  if (!loopInfo_->emitLoopEnd(bce_, JSOp::Goto, TryNoteKind::ForOf)) {
+    //              [stack] NEXT ITER
+    return false;
+  }
+
+  // All jumps/breaks to this point still have an extra value on the stack.
+  MOZ_ASSERT(bce_->bytecodeSection().stackDepth() == loopDepth_);
+  bce_->bytecodeSection().setStackDepth(bce_->bytecodeSection().stackDepth() +
+                                        1);
+
+  if (!bce_->emitPopN(3)) {
+    //              [stack]
+    return false;
+  }
+
+  loopInfo_.reset();
+
+#ifdef DEBUG
+  state_ = State::End;
+#endif
+  return true;
+}