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[turbofan] Propagate tenuring decisions to child object allocations.

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When an allocation for a parent object is pretenured, also propagate
that to all allocations for objects that are (potentially) stored into
the parent object.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2348293003
Cr-Commit-Position: refs/heads/master@{#39534}
This commit is contained in:
bmeurer 2016-09-20 02:57:43 -07:00 committed by Commit bot
parent b36c60cce8
commit 825f506fab
1 changed files with 31 additions and 0 deletions
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31
src/compiler/memory-optimizer.cc
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@ -109,6 +109,37 @@ void MemoryOptimizer::VisitAllocate(Node* node, AllocationState const* state) {
Node* control = node->InputAt(2);
PretenureFlag pretenure = OpParameter<PretenureFlag>(node->op());
// Propagate tenuring from outer allocations to inner allocations, i.e.
// when we allocate an object in old space and store a newly allocated
// child object into the pretenured object, then the newly allocated
// child object also should get pretenured to old space.
if (pretenure == TENURED) {
for (Edge const edge : node->use_edges()) {
Node* const user = edge.from();
if (user->opcode() == IrOpcode::kStoreField && edge.index() == 0) {
Node* const child = user->InputAt(1);
if (child->opcode() == IrOpcode::kAllocate &&
OpParameter<PretenureFlag>(child) == NOT_TENURED) {
NodeProperties::ChangeOp(child, node->op());
break;
}
}
}
} else {
DCHECK_EQ(NOT_TENURED, pretenure);
for (Edge const edge : node->use_edges()) {
Node* const user = edge.from();
if (user->opcode() == IrOpcode::kStoreField && edge.index() == 1) {
Node* const parent = user->InputAt(0);
if (parent->opcode() == IrOpcode::kAllocate &&
OpParameter<PretenureFlag>(parent) == TENURED) {
pretenure = TENURED;
break;
}
}
}
}
// Determine the top/limit addresses.
Node* top_address = jsgraph()->ExternalConstant(
pretenure == NOT_TENURED