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Check elimination now sets known successor branch of HCompareObjectEqAndBranch (correctness fix).

Browse Source 
BUG=chromium:352058
LOG=N
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/196383018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19964 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
ishell@chromium.org 2014-03-17 09:11:38 +00:00
parent fac6b67b2c
commit f77c51b0a6
4 changed files with 52 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/hydrogen-check-elimination.cc
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@ -88,6 +88,10 @@ class HCheckTable : public ZoneObject {
ReduceCompareMap(HCompareMap::cast(instr));
break;
}
case HValue::kCompareObjectEqAndBranch: {
ReduceCompareObjectEqAndBranch(HCompareObjectEqAndBranch::cast(instr));
break;
}
case HValue::kTransitionElementsKind: {
ReduceTransitionElementsKind(
HTransitionElementsKind::cast(instr));
@ -479,6 +483,23 @@ class HCheckTable : public ZoneObject {
instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
}
void ReduceCompareObjectEqAndBranch(HCompareObjectEqAndBranch* instr) {
MapSet maps_left = FindMaps(instr->left()->ActualValue());
if (maps_left == NULL) return;
MapSet maps_right = FindMaps(instr->right()->ActualValue());
if (maps_right == NULL) return;
MapSet intersection = maps_left->Intersect(maps_right, phase_->zone());
if (intersection->size() > 0) return;
TRACE(("Marking redundant CompareObjectEqAndBranch #%d at B%d as false\n",
instr->id(), instr->block()->block_id()));
int succ = 1;
instr->set_known_successor_index(succ);
int unreachable_succ = 1 - succ;
instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
}
void ReduceTransitionElementsKind(HTransitionElementsKind* instr) {
MapSet maps = FindMaps(instr->object()->ActualValue());
// Can only learn more about an object that already has a known set of maps.

4
src/hydrogen-instructions.cc
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@ -3098,6 +3098,10 @@ void HCompareObjectEqAndBranch::PrintDataTo(StringStream* stream) {
bool HCompareObjectEqAndBranch::KnownSuccessorBlock(HBasicBlock** block) {
if (known_successor_index() != kNoKnownSuccessorIndex) {
*block = SuccessorAt(known_successor_index());
return true;
}
if (FLAG_fold_constants && left()->IsConstant() && right()->IsConstant()) {
*block = HConstant::cast(left())->DataEquals(HConstant::cast(right()))
? FirstSuccessor() : SecondSuccessor();

11
src/hydrogen-instructions.h
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@ -4288,6 +4288,12 @@ class HCompareObjectEqAndBranch : public HTemplateControlInstruction<2, 2> {
virtual bool KnownSuccessorBlock(HBasicBlock** block) V8_OVERRIDE;
static const int kNoKnownSuccessorIndex = -1;
int known_successor_index() const { return known_successor_index_; }
void set_known_successor_index(int known_successor_index) {
known_successor_index_ = known_successor_index;
}
HValue* left() { return OperandAt(0); }
HValue* right() { return OperandAt(1); }
@ -4307,7 +4313,8 @@ class HCompareObjectEqAndBranch : public HTemplateControlInstruction<2, 2> {
HCompareObjectEqAndBranch(HValue* left,
HValue* right,
HBasicBlock* true_target = NULL,
HBasicBlock* false_target = NULL) {
HBasicBlock* false_target = NULL)
: known_successor_index_(kNoKnownSuccessorIndex) {
ASSERT(!left->IsConstant() ||
(!HConstant::cast(left)->HasInteger32Value() ||
HConstant::cast(left)->HasSmiValue()));
@ -4319,6 +4326,8 @@ class HCompareObjectEqAndBranch : public HTemplateControlInstruction<2, 2> {
SetSuccessorAt(0, true_target);
SetSuccessorAt(1, false_target);
}
int known_successor_index_;
};

17
test/mjsunit/regress/regress-crbug-352058.js Normal file
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@ -0,0 +1,17 @@
// Copyright 2014 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 --check-elimination --stress-opt
var v0 = this;
var v2 = this;
function f() {
v2 = [1.2, 2.3];
v0 = [12, 23];
}
f();
f();
%OptimizeFunctionOnNextCall(f);
f();