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[turbofan] Restrict redundancy elimination from widening types

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This CL prevents redundancy elimination from widening types, which
can cause problems if the input of a DeadValue (which has type None)
is replaced by an equivalent node that does not have type None. This
can happen because load elimination does not re-type nodes, for
example.

Bug: chromium:919340
Change-Id: I89e872412edbcdc610e70ae160cde56cd045006c
Reviewed-on: https://chromium-review.googlesource.com/c/1397709
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58617}
This commit is contained in:
Sigurd Schneider 2019-01-07 15:11:31 +01:00 committed by Commit Bot
parent 9525443498
commit 5a9fa8f304
2 changed files with 29 additions and 1 deletions
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13
src/compiler/redundancy-elimination.cc
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@ -200,11 +200,22 @@ bool CheckSubsumes(Node const* a, Node const* b) {
return true;
}
bool TypeSubsumes(Node* node, Node* replacement) {
if (!NodeProperties::IsTyped(node) || !NodeProperties::IsTyped(replacement)) {
// If either node is untyped, we are running during an untyped optimization
// phase, and replacement is OK.
return true;
}
Type node_type = NodeProperties::GetType(node);
Type replacement_type = NodeProperties::GetType(replacement);
return replacement_type.Is(node_type);
}
} // namespace
Node* RedundancyElimination::EffectPathChecks::LookupCheck(Node* node) const {
for (Check const* check = head_; check != nullptr; check = check->next) {
if (CheckSubsumes(check->node, node)) {
if (CheckSubsumes(check->node, node) && TypeSubsumes(node, check->node)) {
DCHECK(!check->node->IsDead());
return check->node;
}

17
test/mjsunit/regress/regress-919340.js Normal file
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@ -0,0 +1,17 @@
// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --allow-natives-syntax --opt
var E = 'Σ';
var PI = 123;
function f() {
print(E = 2, /b/.test(E) || /b/.test(E = 2));
((E = 3) * PI);
}
f();
f();
%OptimizeFunctionOnNextCall(f);
f();