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[turbofan] Refine CsaLoadElimination::ComputeLoopState

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Avoid killing the whole mutable state in the following two cases:
- When we encounter a mutable object store operation, we can only kill
  the respective object/field pair in the mutable state.
- When we encounter an immutable initialization operation, we do not
  have to modify the state. A DCHECK ensures we do not initialize the
  same field twice.

Drive-by: Avoid zone-allocating data structures for frame-local
variables.

Bug: v8:11510
Change-Id: I1c655f619cf620923256f460b30dc7371de571de
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3452022
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79035}
This commit is contained in:
Manos Koukoutos 2022-02-10 14:16:37 +00:00 committed by V8 LUCI CQ
parent 3cd68b1c13
commit ca849f24ab
1 changed files with 19 additions and 3 deletions
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22
src/compiler/csa-load-elimination.cc
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@ -497,8 +497,8 @@ Reduction CsaLoadElimination::PropagateInputState(Node* node) {
CsaLoadElimination::AbstractState const* CsaLoadElimination::ComputeLoopState(
Node* node, AbstractState const* state) const {
DCHECK_EQ(node->opcode(), IrOpcode::kEffectPhi);
ZoneQueue<Node*> queue(zone());
ZoneSet<Node*> visited(zone());
std::queue<Node*> queue;
std::unordered_set<Node*> visited;
visited.insert(node);
for (int i = 1; i < node->InputCount() - 1; ++i) {
queue.push(node->InputAt(i));
@ -507,7 +507,23 @@ CsaLoadElimination::AbstractState const* CsaLoadElimination::ComputeLoopState(
Node* const current = queue.front();
queue.pop();
if (visited.insert(current).second) {
if (!current->op()->HasProperty(Operator::kNoWrite)) {
if (current->opcode() == IrOpcode::kStoreToObject) {
Node* object = NodeProperties::GetValueInput(current, 0);
Node* offset = NodeProperties::GetValueInput(current, 1);
MachineRepresentation repr =
ObjectAccessOf(current->op()).machine_type.representation();
const HalfState* new_mutable_state =
state->mutable_state.KillField(object, offset, repr);
state = zone()->New<AbstractState>(*new_mutable_state,
state->immutable_state);
} else if (current->opcode() == IrOpcode::kInitializeImmutableInObject) {
#if DEBUG
// We are not allowed to reset an immutable (object, offset) pair.
Node* object = NodeProperties::GetValueInput(current, 0);
Node* offset = NodeProperties::GetValueInput(current, 1);
CHECK(state->immutable_state.Lookup(object, offset).IsEmpty());
#endif
} else if (!current->op()->HasProperty(Operator::kNoWrite)) {
return zone()->New<AbstractState>(HalfState(zone()),
state->immutable_state);
}