Reviewers: jochen, ulan,
Description:
A64: Minor code generation improvement: only load the object map if needed.
Please review this at https://codereview.chromium.org/170503004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+7, -3 lines):
M src/a64/stub-cache-a64.cc
Index: src/a64/stub-cache-a64.cc
diff --git a/src/a64/stub-cache-a64.cc b/src/a64/stub-cache-a64.cc
index
3cf2a29cc33c63c9c32d31e07771d6ea59d54c38..57c03e8b9667067955680288c03c057f7c6969d2
100644
--- a/src/a64/stub-cache-a64.cc
+++ b/src/a64/stub-cache-a64.cc
@@ -888,9 +888,13 @@ Register
StubCompiler::CheckPrototypes(Handle<HeapType> type,
reg = holder_reg; // From now on the object will be in holder_reg.
__ Ldr(reg, FieldMemOperand(scratch1, Map::kPrototypeOffset));
} else {
- Register map_reg = scratch1;
- // TODO(jbramley): Skip this load when we don't need the map.
- __ Ldr(map_reg, FieldMemOperand(reg, HeapObject::kMapOffset));
+ bool need_map = (depth != 1 || check == CHECK_ALL_MAPS) ||
+ heap()->InNewSpace(*prototype);
+ Register map_reg = NoReg;
+ if (need_map) {
+ map_reg = scratch1;
+ __ Ldr(map_reg, FieldMemOperand(reg, HeapObject::kMapOffset));
+ }
if (depth != 1 || check == CHECK_ALL_MAPS) {
__ CheckMap(map_reg, current_map, miss, DONT_DO_SMI_CHECK);
--
--
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