Reviewers: Toon Verwaest, danno, Paul Lind, kisg,
Description:
MIPS: Swapped transition array and descriptor array.
Port r12298 (7b39ef67)
Original commit message:
Now a map points to a transition array which contains the descriptor array.
The
descriptor array is now immutable. The next step is to share the descriptor
array with all back-pointed maps as long as there is a single line of
extension.
Maps that require a descriptor array but don't need transitions will still
need
a pseudo-empty transition array to contain the descriptor array.
BUG=
TEST=
Please review this at https://chromiumcodereview.appspot.com/10827335/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/mips/macro-assembler-mips.cc
Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc
b/src/mips/macro-assembler-mips.cc
index
cd6d7dc108b868b11ad482ca0c4609b154b3f8ff..349937d716813fe604f15ea714fcd87c690be21b
100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -5293,15 +5293,16 @@ void MacroAssembler::EnsureNotWhite(
void MacroAssembler::LoadInstanceDescriptors(Register map,
Register descriptors,
Register scratch) {
- lw(descriptors,
- FieldMemOperand(map, Map::kInstanceDescriptorsOrBackPointerOffset));
+ Register temp = descriptors;
+ lw(temp, FieldMemOperand(map, Map::kTransitionsOrBackPointerOffset));
Label ok, fail;
- CheckMap(descriptors,
+ CheckMap(temp,
scratch,
isolate()->factory()->fixed_array_map(),
&fail,
DONT_DO_SMI_CHECK);
+ lw(descriptors, FieldMemOperand(temp,
TransitionArray::kDescriptorsOffset));
jmp(&ok);
bind(&fail);
LoadRoot(descriptors, Heap::kEmptyDescriptorArrayRootIndex);
@@ -5314,9 +5315,6 @@ void MacroAssembler::CheckEnumCache(Register
null_value, Label* call_runtime) {
// Preload a couple of values used in the loop.
Register empty_fixed_array_value = t2;
LoadRoot(empty_fixed_array_value, Heap::kEmptyFixedArrayRootIndex);
- Register empty_descriptor_array_value = t3;
- LoadRoot(empty_descriptor_array_value,
- Heap::kEmptyDescriptorArrayRootIndex);
mov(a1, a0);
bind(&next);
@@ -5329,7 +5327,7 @@ void MacroAssembler::CheckEnumCache(Register
null_value, Label* call_runtime) {
// check for an enum cache. Leave the map in a2 for the subsequent
// prototype load.
lw(a2, FieldMemOperand(a1, HeapObject::kMapOffset));
- lw(a3, FieldMemOperand(a2,
Map::kInstanceDescriptorsOrBackPointerOffset));
+ lw(a3, FieldMemOperand(a2, Map::kTransitionsOrBackPointerOffset));
CheckMap(a3,
t3,
@@ -5337,6 +5335,10 @@ void MacroAssembler::CheckEnumCache(Register
null_value, Label* call_runtime) {
call_runtime,
DONT_DO_SMI_CHECK);
+ LoadRoot(t3, Heap::kEmptyDescriptorArrayRootIndex);
+ lw(a3, FieldMemOperand(a3, TransitionArray::kDescriptorsOffset));
+ Branch(call_runtime, eq, a3, Operand(t3));
+
// Check that there is an enum cache in the non-empty instance
// descriptors (a3). This is the case if the next enumeration
// index field does not contain a smi.
--
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