Reviewers: Benedikt Meurer,
Description:
X87: Improve write barriers in optimized code.
Port r21630 (a21ff10)
Original commit message:
Use a cheaper RecordWriteForMap() to update the
write barrier for maps. And skip the value check
in RecordWriteField() when we statically know that
the value is in new space (and therefore has "pointers
to here are interesting" flag set).
BUG=
Please review this at https://codereview.chromium.org/314983002/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+56, -43 lines):
M src/x87/lithium-codegen-x87.cc
M src/x87/macro-assembler-x87.h
M src/x87/macro-assembler-x87.cc
Index: src/x87/lithium-codegen-x87.cc
diff --git a/src/x87/lithium-codegen-x87.cc b/src/x87/lithium-codegen-x87.cc
index
a88613bc2ee3f394ede80474f4ede53e4f4e3f00..9fb1216e97449b35507ab2f5e269f9c8f2ddf5b9
100644
--- a/src/x87/lithium-codegen-x87.cc
+++ b/src/x87/lithium-codegen-x87.cc
@@ -3904,20 +3904,14 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField*
instr) {
if (instr->hydrogen()->has_transition()) {
Handle<Map> transition = instr->hydrogen()->transition_map();
AddDeprecationDependency(transition);
- if (!instr->hydrogen()->NeedsWriteBarrierForMap()) {
- __ mov(FieldOperand(object, HeapObject::kMapOffset), transition);
- } else {
+ __ mov(FieldOperand(object, HeapObject::kMapOffset), transition);
+ if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
Register temp = ToRegister(instr->temp());
Register temp_map = ToRegister(instr->temp_map());
__ mov(temp_map, transition);
__ mov(FieldOperand(object, HeapObject::kMapOffset), temp_map);
// Update the write barrier for the map field.
- __ RecordWriteField(object,
- HeapObject::kMapOffset,
- temp_map,
- temp,
- OMIT_REMEMBERED_SET,
- OMIT_SMI_CHECK);
+ __ RecordWriteForMap(object, transition, temp_map, temp);
}
}
@@ -3957,7 +3951,8 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField*
instr) {
value,
temp,
EMIT_REMEMBERED_SET,
- instr->hydrogen()->SmiCheckForWriteBarrier());
+ instr->hydrogen()->SmiCheckForWriteBarrier(),
+ instr->hydrogen()->PointersToHereCheckForValue());
}
}
@@ -4155,7 +4150,8 @@ void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed*
instr) {
key,
value,
EMIT_REMEMBERED_SET,
- check_needed);
+ check_needed,
+ instr->hydrogen()->PointersToHereCheckForValue());
}
}
Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index
30dd02d1c9b72039d3d6c95ecdf240e8cd4aeee9..06bd774a552c991ea53b0360c162e24e85c82199
100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -315,11 +315,13 @@ void MacroAssembler::LoadUint32NoSSE2(Register src) {
}
-void MacroAssembler::RecordWriteArray(Register object,
- Register value,
- Register index,
- RememberedSetAction
remembered_set_action,
- SmiCheck smi_check) {
+void MacroAssembler::RecordWriteArray(
+ Register object,
+ Register value,
+ Register index,
+ RememberedSetAction remembered_set_action,
+ SmiCheck smi_check,
+ PointersToHereCheck pointers_to_here_check_for_value) {
// First, check if a write barrier is even needed. The tests below
// catch stores of Smis.
Label done;
@@ -338,8 +340,8 @@ void MacroAssembler::RecordWriteArray(Register object,
lea(dst, Operand(object, index, times_half_pointer_size,
FixedArray::kHeaderSize - kHeapObjectTag));
- RecordWrite(
- object, dst, value, remembered_set_action, OMIT_SMI_CHECK);
+ RecordWrite(object, dst, value, remembered_set_action, OMIT_SMI_CHECK,
+ pointers_to_here_check_for_value);
bind(&done);
@@ -358,7 +360,8 @@ void MacroAssembler::RecordWriteField(
Register value,
Register dst,
RememberedSetAction remembered_set_action,
- SmiCheck smi_check) {
+ SmiCheck smi_check,
+ PointersToHereCheck pointers_to_here_check_for_value) {
// First, check if a write barrier is even needed. The tests below
// catch stores of Smis.
Label done;
@@ -381,8 +384,8 @@ void MacroAssembler::RecordWriteField(
bind(&ok);
}
- RecordWrite(
- object, dst, value, remembered_set_action, OMIT_SMI_CHECK);
+ RecordWrite(object, dst, value, remembered_set_action, OMIT_SMI_CHECK,
+ pointers_to_here_check_for_value);
bind(&done);
@@ -422,6 +425,9 @@ void MacroAssembler::RecordWriteForMap(
return;
}
+ // Compute the address.
+ lea(address, FieldOperand(object, HeapObject::kMapOffset));
+
// Count number of write barriers in generated code.
isolate()->counters()->write_barriers_static()->Increment();
IncrementCounter(isolate()->counters()->write_barriers_dynamic(), 1);
@@ -437,12 +443,6 @@ void MacroAssembler::RecordWriteForMap(
&done,
Label::kNear);
- // Delay the initialization of |address| and |value| for the stub until
it's
- // known that the will be needed. Up until this point their values are
not
- // needed since they are embedded in the operands of instructions that
need
- // them.
- lea(address, FieldOperand(object, HeapObject::kMapOffset));
- mov(value, Immediate(map));
RecordWriteStub stub(isolate(), object, value, address,
OMIT_REMEMBERED_SET);
CallStub(&stub);
@@ -458,11 +458,13 @@ void MacroAssembler::RecordWriteForMap(
}
-void MacroAssembler::RecordWrite(Register object,
- Register address,
- Register value,
- RememberedSetAction remembered_set_action,
- SmiCheck smi_check) {
+void MacroAssembler::RecordWrite(
+ Register object,
+ Register address,
+ Register value,
+ RememberedSetAction remembered_set_action,
+ SmiCheck smi_check,
+ PointersToHereCheck pointers_to_here_check_for_value) {
ASSERT(!object.is(value));
ASSERT(!object.is(address));
ASSERT(!value.is(address));
@@ -494,12 +496,14 @@ void MacroAssembler::RecordWrite(Register object,
JumpIfSmi(value, &done, Label::kNear);
}
- CheckPageFlag(value,
- value, // Used as scratch.
- MemoryChunk::kPointersToHereAreInterestingMask,
- zero,
- &done,
- Label::kNear);
+ if (pointers_to_here_check_for_value !=
kPointersToHereAreAlwaysInteresting) {
+ CheckPageFlag(value,
+ value, // Used as scratch.
+ MemoryChunk::kPointersToHereAreInterestingMask,
+ zero,
+ &done,
+ Label::kNear);
+ }
CheckPageFlag(object,
value, // Used as scratch.
MemoryChunk::kPointersFromHereAreInterestingMask,
Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index
e98502a130a00c12874a0c2edbafd65d7eae2997..84141e6bc36a721a91475405677d10ddb876aa85
100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -18,6 +18,10 @@ typedef Operand MemOperand;
enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };
enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };
+enum PointersToHereCheck {
+ kPointersToHereMaybeInteresting,
+ kPointersToHereAreAlwaysInteresting
+};
enum RegisterValueType {
@@ -138,7 +142,9 @@ class MacroAssembler: public Assembler {
Register value,
Register scratch,
RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
- SmiCheck smi_check = INLINE_SMI_CHECK);
+ SmiCheck smi_check = INLINE_SMI_CHECK,
+ PointersToHereCheck pointers_to_here_check_for_value =
+ kPointersToHereMaybeInteresting);
// As above, but the offset has the tag presubtracted. For use with
// Operand(reg, off).
@@ -148,13 +154,16 @@ class MacroAssembler: public Assembler {
Register value,
Register scratch,
RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
- SmiCheck smi_check = INLINE_SMI_CHECK) {
+ SmiCheck smi_check = INLINE_SMI_CHECK,
+ PointersToHereCheck pointers_to_here_check_for_value =
+ kPointersToHereMaybeInteresting) {
RecordWriteField(context,
offset + kHeapObjectTag,
value,
scratch,
remembered_set_action,
- smi_check);
+ smi_check,
+ pointers_to_here_check_for_value);
}
// Notify the garbage collector that we wrote a pointer into a fixed
array.
@@ -168,7 +177,9 @@ class MacroAssembler: public Assembler {
Register value,
Register index,
RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
- SmiCheck smi_check = INLINE_SMI_CHECK);
+ SmiCheck smi_check = INLINE_SMI_CHECK,
+ PointersToHereCheck pointers_to_here_check_for_value =
+ kPointersToHereMaybeInteresting);
// For page containing |object| mark region covering |address|
// dirty. |object| is the object being stored into, |value| is the
@@ -180,7 +191,9 @@ class MacroAssembler: public Assembler {
Register address,
Register value,
RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
- SmiCheck smi_check = INLINE_SMI_CHECK);
+ SmiCheck smi_check = INLINE_SMI_CHECK,
+ PointersToHereCheck pointers_to_here_check_for_value =
+ kPointersToHereMaybeInteresting);
// For page containing |object| mark the region covering the object's map
// dirty. |object| is the object being stored into, |map| is the Map
object
--
--
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