Revision: 21657
Author: [email protected]
Date: Tue Jun 3 19:23:10 2014 UTC
Log: MIPS: 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=
[email protected]
Review URL: https://codereview.chromium.org/315653002
Patch from Balazs Kilvady <[email protected]>.
http://code.google.com/p/v8/source/detail?r=21657
Modified:
/branches/bleeding_edge/src/mips/lithium-codegen-mips.cc
/branches/bleeding_edge/src/mips/macro-assembler-mips.cc
/branches/bleeding_edge/src/mips/macro-assembler-mips.h
=======================================
--- /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Tue Jun 3
15:45:38 2014 UTC
+++ /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Tue Jun 3
19:23:10 2014 UTC
@@ -4077,14 +4077,11 @@
if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
Register temp = ToRegister(instr->temp());
// Update the write barrier for the map field.
- __ RecordWriteField(object,
- HeapObject::kMapOffset,
- scratch,
- temp,
- GetRAState(),
- kSaveFPRegs,
- OMIT_REMEMBERED_SET,
- OMIT_SMI_CHECK);
+ __ RecordWriteForMap(object,
+ scratch,
+ temp,
+ GetRAState(),
+ kSaveFPRegs);
}
}
@@ -4102,7 +4099,8 @@
GetRAState(),
kSaveFPRegs,
EMIT_REMEMBERED_SET,
- instr->hydrogen()->SmiCheckForWriteBarrier());
+ instr->hydrogen()->SmiCheckForWriteBarrier(),
+
instr->hydrogen()->PointersToHereCheckForValue());
}
} else {
__ lw(scratch, FieldMemOperand(object, JSObject::kPropertiesOffset));
@@ -4118,7 +4116,8 @@
GetRAState(),
kSaveFPRegs,
EMIT_REMEMBERED_SET,
- instr->hydrogen()->SmiCheckForWriteBarrier());
+ instr->hydrogen()->SmiCheckForWriteBarrier(),
+
instr->hydrogen()->PointersToHereCheckForValue());
}
}
}
@@ -4338,7 +4337,8 @@
GetRAState(),
kSaveFPRegs,
EMIT_REMEMBERED_SET,
- check_needed);
+ check_needed,
+ instr->hydrogen()->PointersToHereCheckForValue());
}
}
@@ -4386,8 +4386,11 @@
__ li(new_map_reg, Operand(to_map));
__ sw(new_map_reg, FieldMemOperand(object_reg,
HeapObject::kMapOffset));
// Write barrier.
- __ RecordWriteField(object_reg, HeapObject::kMapOffset, new_map_reg,
- scratch, GetRAState(), kDontSaveFPRegs);
+ __ RecordWriteForMap(object_reg,
+ new_map_reg,
+ scratch,
+ GetRAState(),
+ kDontSaveFPRegs);
} else {
ASSERT(object_reg.is(a0));
ASSERT(ToRegister(instr->context()).is(cp));
=======================================
--- /branches/bleeding_edge/src/mips/macro-assembler-mips.cc Tue Jun 3
08:12:43 2014 UTC
+++ /branches/bleeding_edge/src/mips/macro-assembler-mips.cc Tue Jun 3
19:23:10 2014 UTC
@@ -194,7 +194,8 @@
RAStatus ra_status,
SaveFPRegsMode save_fp,
RememberedSetAction remembered_set_action,
- SmiCheck smi_check) {
+ SmiCheck smi_check,
+ PointersToHereCheck pointers_to_here_check_for_value) {
ASSERT(!AreAliased(value, dst, t8, object));
// First, check if a write barrier is even needed. The tests below
// catch stores of Smis.
@@ -224,7 +225,8 @@
ra_status,
save_fp,
remembered_set_action,
- OMIT_SMI_CHECK);
+ OMIT_SMI_CHECK,
+ pointers_to_here_check_for_value);
bind(&done);
@@ -235,18 +237,95 @@
li(dst, Operand(BitCast<int32_t>(kZapValue + 8)));
}
}
+
+
+// Will clobber 4 registers: object, map, dst, ip. The
+// register 'object' contains a heap object pointer.
+void MacroAssembler::RecordWriteForMap(Register object,
+ Register map,
+ Register dst,
+ RAStatus ra_status,
+ SaveFPRegsMode fp_mode) {
+ if (emit_debug_code()) {
+ ASSERT(!dst.is(at));
+ lw(dst, FieldMemOperand(map, HeapObject::kMapOffset));
+ Check(eq,
+ kWrongAddressOrValuePassedToRecordWrite,
+ dst,
+ Operand(isolate()->factory()->meta_map()));
+ }
+
+ if (!FLAG_incremental_marking) {
+ return;
+ }
+
+ // Count number of write barriers in generated code.
+ isolate()->counters()->write_barriers_static()->Increment();
+ // TODO(mstarzinger): Dynamic counter missing.
+
+ if (emit_debug_code()) {
+ lw(at, FieldMemOperand(object, HeapObject::kMapOffset));
+ Check(eq,
+ kWrongAddressOrValuePassedToRecordWrite,
+ map,
+ Operand(at));
+ }
+
+ Label done;
+
+ // A single check of the map's pages interesting flag suffices, since it
is
+ // only set during incremental collection, and then it's also guaranteed
that
+ // the from object's page's interesting flag is also set. This
optimization
+ // relies on the fact that maps can never be in new space.
+ CheckPageFlag(map,
+ map, // Used as scratch.
+ MemoryChunk::kPointersToHereAreInterestingMask,
+ eq,
+ &done);
+
+ Addu(dst, object, Operand(HeapObject::kMapOffset - kHeapObjectTag));
+ if (emit_debug_code()) {
+ Label ok;
+ And(at, dst, Operand((1 << kPointerSizeLog2) - 1));
+ Branch(&ok, eq, at, Operand(zero_reg));
+ stop("Unaligned cell in write barrier");
+ bind(&ok);
+ }
+
+ // Record the actual write.
+ if (ra_status == kRAHasNotBeenSaved) {
+ push(ra);
+ }
+ RecordWriteStub stub(isolate(), object, map, dst, OMIT_REMEMBERED_SET,
+ fp_mode);
+ CallStub(&stub);
+ if (ra_status == kRAHasNotBeenSaved) {
+ pop(ra);
+ }
+
+ bind(&done);
+
+ // Clobber clobbered registers when running with the debug-code flag
+ // turned on to provoke errors.
+ if (emit_debug_code()) {
+ li(dst, Operand(BitCast<int32_t>(kZapValue + 12)));
+ li(map, Operand(BitCast<int32_t>(kZapValue + 16)));
+ }
+}
// Will clobber 4 registers: object, address, scratch, ip. The
// register 'object' contains a heap object pointer. The heap object
// tag is shifted away.
-void MacroAssembler::RecordWrite(Register object,
- Register address,
- Register value,
- RAStatus ra_status,
- SaveFPRegsMode fp_mode,
- RememberedSetAction remembered_set_action,
- SmiCheck smi_check) {
+void MacroAssembler::RecordWrite(
+ Register object,
+ Register address,
+ Register value,
+ RAStatus ra_status,
+ SaveFPRegsMode fp_mode,
+ RememberedSetAction remembered_set_action,
+ SmiCheck smi_check,
+ PointersToHereCheck pointers_to_here_check_for_value) {
ASSERT(!AreAliased(object, address, value, t8));
ASSERT(!AreAliased(object, address, value, t9));
@@ -255,6 +334,11 @@
Assert(
eq, kWrongAddressOrValuePassedToRecordWrite, at, Operand(value));
}
+
+ if (remembered_set_action == OMIT_REMEMBERED_SET &&
+ !FLAG_incremental_marking) {
+ return;
+ }
// Count number of write barriers in generated code.
isolate()->counters()->write_barriers_static()->Increment();
@@ -269,11 +353,13 @@
JumpIfSmi(value, &done);
}
- CheckPageFlag(value,
- value, // Used as scratch.
- MemoryChunk::kPointersToHereAreInterestingMask,
- eq,
- &done);
+ if (pointers_to_here_check_for_value !=
kPointersToHereAreAlwaysInteresting) {
+ CheckPageFlag(value,
+ value, // Used as scratch.
+ MemoryChunk::kPointersToHereAreInterestingMask,
+ eq,
+ &done);
+ }
CheckPageFlag(object,
value, // Used as scratch.
MemoryChunk::kPointersFromHereAreInterestingMask,
=======================================
--- /branches/bleeding_edge/src/mips/macro-assembler-mips.h Tue Jun 3
08:12:43 2014 UTC
+++ /branches/bleeding_edge/src/mips/macro-assembler-mips.h Tue Jun 3
19:23:10 2014 UTC
@@ -71,6 +71,10 @@
enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };
enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };
+enum PointersToHereCheck {
+ kPointersToHereMaybeInteresting,
+ kPointersToHereAreAlwaysInteresting
+};
enum RAStatus { kRAHasNotBeenSaved, kRAHasBeenSaved };
Register GetRegisterThatIsNotOneOf(Register reg1,
@@ -365,7 +369,9 @@
RAStatus ra_status,
SaveFPRegsMode save_fp,
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
// MemOperand(reg, off).
@@ -377,7 +383,9 @@
RAStatus ra_status,
SaveFPRegsMode save_fp,
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,
@@ -385,8 +393,16 @@
ra_status,
save_fp,
remembered_set_action,
- smi_check);
+ smi_check,
+ pointers_to_here_check_for_value);
}
+
+ void RecordWriteForMap(
+ Register object,
+ Register map,
+ Register dst,
+ RAStatus ra_status,
+ SaveFPRegsMode save_fp);
// For a given |object| notify the garbage collector that the slot |
address|
// has been written. |value| is the object being stored. The value and
@@ -398,7 +414,9 @@
RAStatus ra_status,
SaveFPRegsMode save_fp,
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);
//
---------------------------------------------------------------------------
--
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