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[turbofan] fix dead code elimination: propagate DeadValue along Frame…

…State inputs

Bug: chromium:788539
Change-Id: I75b6ef7e486b578f123747d79f52c9eb45a0370e
Reviewed-on: https://chromium-review.googlesource.com/792050
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49654}
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tebbi authored and Commit Bot committed Nov 27, 2017
1 parent aa7d143 commit 904c3a1f091d3ff6f19451fced343392a5ec944a
Showing with 39 additions and 6 deletions.
  1. +2 −6 src/compiler/dead-code-elimination.cc
  2. +37 −0 test/mjsunit/compiler/regress-788539.js
@@ -218,12 +218,8 @@ Reduction DeadCodeElimination::ReducePhi(Node* node) {

Reduction DeadCodeElimination::ReducePureNode(Node* node) {
DCHECK_EQ(0, node->op()->EffectInputCount());
int input_count = node->op()->ValueInputCount();
for (int i = 0; i < input_count; ++i) {
Node* input = NodeProperties::GetValueInput(node, i);
if (NoReturn(input)) {
return Replace(dead_value());
}
if (HasDeadInput(node)) {
return Replace(dead_value());
}
return NoChange();
}
@@ -0,0 +1,37 @@
// Copyright 2017 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 --turbo-verify

// This test creates a FrameState node with a DeadValue parent framestate.
// Ensure that deadness is propagated along FrameState edges.

function f1() {
return this;
}

function f2(x, value, type) {
x instanceof type
}

function f3(a) {
a.x = 0;
if (a.x === 0) {
a[1] = 0.1;
}
class B {
}
class C extends B {
bar() {
return super.foo()
}
}
B.prototype.foo = f1;
f2(new C().bar.call(), Object(), String);
}

f3(new Array(1));
f3(new Array(1));
%OptimizeFunctionOnNextCall(f3);
f3(new Array(1));

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