Reviewers: Sven Panne, danno,
Description:
X87: Skip write barriers in the fast case when setting up local context.
Port r21481 (5973b48)
Original commit message:
The FastNewContextStub always allocates in new space, so we don't
need to update the write barrier when copying the parameters to
the newly allocated context.
BUG=
Please review this at https://codereview.chromium.org/307433004/
SVN Base: git://github.com/v8/v8.git@master
Affected files (+28, -8 lines):
M src/x87/full-codegen-x87.cc
M src/x87/lithium-codegen-x87.cc
Index: src/x87/full-codegen-x87.cc
diff --git a/src/x87/full-codegen-x87.cc b/src/x87/full-codegen-x87.cc
index
06eaa21f311b8e4ab839e56a0976ca1d1d4ac457..006383d4d1974087dbbd62f8d2cd11a2b48395ad
100644
--- a/src/x87/full-codegen-x87.cc
+++ b/src/x87/full-codegen-x87.cc
@@ -198,6 +198,7 @@ void FullCodeGenerator::Generate() {
int heap_slots = info->scope()->num_heap_slots() -
Context::MIN_CONTEXT_SLOTS;
if (heap_slots > 0) {
Comment cmnt(masm_, "[ Allocate context");
+ bool need_write_barrier = true;
// Argument to NewContext is the function, which is still in edi.
if (FLAG_harmony_scoping && info->scope()->is_global_scope()) {
__ push(edi);
@@ -206,6 +207,8 @@ void FullCodeGenerator::Generate() {
} else if (heap_slots <= FastNewContextStub::kMaximumSlots) {
FastNewContextStub stub(isolate(), heap_slots);
__ CallStub(&stub);
+ // Result of FastNewContextStub is always in new space.
+ need_write_barrier = false;
} else {
__ push(edi);
__ CallRuntime(Runtime::kHiddenNewFunctionContext, 1);
@@ -229,10 +232,17 @@ void FullCodeGenerator::Generate() {
int context_offset = Context::SlotOffset(var->index());
__ mov(Operand(esi, context_offset), eax);
// Update the write barrier. This clobbers eax and ebx.
- __ RecordWriteContextSlot(esi,
- context_offset,
- eax,
- ebx);
+ if (need_write_barrier) {
+ __ RecordWriteContextSlot(esi,
+ context_offset,
+ eax,
+ ebx);
+ } else if (FLAG_debug_code) {
+ Label done;
+ __ JumpIfInNewSpace(esi, eax, &done, Label::kNear);
+ __ Abort(kExpectedNewSpaceObject);
+ __ bind(&done);
+ }
}
}
}
Index: src/x87/lithium-codegen-x87.cc
diff --git a/src/x87/lithium-codegen-x87.cc b/src/x87/lithium-codegen-x87.cc
index
8b370710fd88d5868be904272fbff9c1f590cb53..60fe7254e987831003e00667d5cac32b77eff0cc
100644
--- a/src/x87/lithium-codegen-x87.cc
+++ b/src/x87/lithium-codegen-x87.cc
@@ -221,10 +221,13 @@ bool LCodeGen::GeneratePrologue() {
int heap_slots = info_->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
if (heap_slots > 0) {
Comment(";;; Allocate local context");
+ bool need_write_barrier = true;
// Argument to NewContext is the function, which is still in edi.
if (heap_slots <= FastNewContextStub::kMaximumSlots) {
FastNewContextStub stub(isolate(), heap_slots);
__ CallStub(&stub);
+ // Result of FastNewContextStub is always in new space.
+ need_write_barrier = false;
} else {
__ push(edi);
__ CallRuntime(Runtime::kHiddenNewFunctionContext, 1);
@@ -248,10 +251,17 @@ bool LCodeGen::GeneratePrologue() {
int context_offset = Context::SlotOffset(var->index());
__ mov(Operand(esi, context_offset), eax);
// Update the write barrier. This clobbers eax and ebx.
- __ RecordWriteContextSlot(esi,
- context_offset,
- eax,
- ebx);
+ if (need_write_barrier) {
+ __ RecordWriteContextSlot(esi,
+ context_offset,
+ eax,
+ ebx);
+ } else if (FLAG_debug_code) {
+ Label done;
+ __ JumpIfInNewSpace(esi, eax, &done, Label::kNear);
+ __ Abort(kExpectedNewSpaceObject);
+ __ bind(&done);
+ }
}
}
Comment(";;; End allocate local context");
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