AuroraMiddleware/v8
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[turbofan] We don't need write barriers for immortal immovable maps.

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WriteBarrierKindFor would always return kMapWriteBarrier in
SimplifiedLowering even if the map that's to be stored is part
of the immortal immovable roots which don't need write barriers
ever.

Bug: v8:7310
Change-Id: I0a87a1c3ddd7f71ccf8ebacba8409067dc00cd1c
Reviewed-on: https://chromium-review.googlesource.com/928564
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51431}
This commit is contained in:
Benedikt Meurer 2018-02-21 13:24:02 +01:00 committed by Commit Bot
parent 7badc3f0c4
commit a98c889313
1 changed files with 9 additions and 5 deletions
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14
src/compiler/simplified-lowering.cc
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@ -1237,12 +1237,16 @@ class RepresentationSelector {
MachineRepresentation field_representation, int field_offset,
Type* field_type, MachineRepresentation value_representation,
Node* value) {
if (base_taggedness == kTaggedBase &&
field_offset == HeapObject::kMapOffset) {
return kMapWriteBarrier;
WriteBarrierKind write_barrier_kind =
WriteBarrierKindFor(base_taggedness, field_representation, field_type,
value_representation, value);
if (write_barrier_kind != kNoWriteBarrier) {
if (base_taggedness == kTaggedBase &&
field_offset == HeapObject::kMapOffset) {
write_barrier_kind = kMapWriteBarrier;
}
}
return WriteBarrierKindFor(base_taggedness, field_representation,
field_type, value_representation, value);
return write_barrier_kind;
}
Graph* graph() const { return jsgraph_->graph(); }