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Revert "Re-land Clusterfuzz identified overflow check needed in dehoisting."

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This reverts commit r21712

TBR=danno@chromium.org

Review URL: https://codereview.chromium.org/315843005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21715 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mvstanton@chromium.org 2014-06-06 13:16:24 +00:00
parent c0cb82274c
commit 2714fd2399
3 changed files with 20 additions and 58 deletions
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20
src/hydrogen-dehoist.cc
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@ -28,25 +28,15 @@ static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
if (!constant->HasInteger32Value()) return;
int32_t sign = binary_operation->IsSub() ? -1 : 1;
int32_t value = constant->Integer32Value() * sign;
if (value < 0) return;
// Check for overflow.
// TODO(mvstanton): replace with safe_math.h operations when that code is
// integrated.
int32_t shift_amount =
1 << ElementsKindToShiftSize(array_operation->elements_kind());
int32_t multiplication_result = value * shift_amount;
if ((multiplication_result >> shift_amount) != value) return;
value = multiplication_result;
// Ensure that the array operation can add value to existing base offset
// without overflowing.
if (!array_operation->CanIncreaseBaseOffset(value)) return;
// We limit offset values to 30 bits because we want to avoid the risk of
// overflows when the offset is added to the object header size.
if (value >= 1 << array_operation->MaxBaseOffsetBits() || value < 0) return;
array_operation->SetKey(subexpression);
if (binary_operation->HasNoUses()) {
binary_operation->DeleteAndReplaceWith(NULL);
}
array_operation->IncreaseBaseOffset(value);
value <<= ElementsKindToShiftSize(array_operation->elements_kind());
array_operation->IncreaseBaseOffset(static_cast<uint32_t>(value));
array_operation->SetDehoisted(true);
}

44
src/hydrogen-instructions.h
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@ -6404,9 +6404,8 @@ class ArrayInstructionInterface {
virtual HValue* GetKey() = 0;
virtual void SetKey(HValue* key) = 0;
virtual ElementsKind elements_kind() const = 0;
// increase_by_value should be non-negative
virtual bool CanIncreaseBaseOffset(int32_t increase_by_value) = 0;
virtual void IncreaseBaseOffset(int32_t increase_by_value) = 0;
virtual void IncreaseBaseOffset(uint32_t base_offset) = 0;
virtual int MaxBaseOffsetBits() = 0;
virtual bool IsDehoisted() = 0;
virtual void SetDehoisted(bool is_dehoisted) = 0;
virtual ~ArrayInstructionInterface() { }
@ -6452,20 +6451,13 @@ class HLoadKeyed V8_FINAL
return OperandAt(2);
}
bool HasDependency() const { return OperandAt(0) != OperandAt(2); }
uint32_t base_offset() {
int32_t base_offset_value = BaseOffsetField::decode(bit_field_);
ASSERT(base_offset_value >= 0);
return static_cast<uint32_t>(base_offset_value);
uint32_t base_offset() { return BaseOffsetField::decode(bit_field_); }
void IncreaseBaseOffset(uint32_t base_offset) {
base_offset += BaseOffsetField::decode(bit_field_);
bit_field_ = BaseOffsetField::update(bit_field_, base_offset);
}
bool CanIncreaseBaseOffset(int32_t increase_by_value) {
ASSERT(increase_by_value >= 0);
int32_t new_value = BaseOffsetField::decode(bit_field_) + increase_by_value;
return (new_value >= 0 && BaseOffsetField::is_valid(new_value));
}
void IncreaseBaseOffset(int32_t increase_by_value) {
ASSERT(increase_by_value >= 0);
increase_by_value += BaseOffsetField::decode(bit_field_);
bit_field_ = BaseOffsetField::update(bit_field_, increase_by_value);
virtual int MaxBaseOffsetBits() {
return kBitsForBaseOffset;
}
HValue* GetKey() { return key(); }
void SetKey(HValue* key) { SetOperandAt(1, key); }
@ -6615,7 +6607,7 @@ class HLoadKeyed V8_FINAL
public BitField<LoadKeyedHoleMode, kStartHoleMode, kBitsForHoleMode>
{}; // NOLINT
class BaseOffsetField:
public BitField<int32_t, kStartBaseOffset, kBitsForBaseOffset>
public BitField<uint32_t, kStartBaseOffset, kBitsForBaseOffset>
{}; // NOLINT
class IsDehoistedField:
public BitField<bool, kStartIsDehoisted, kBitsForIsDehoisted>
@ -6929,18 +6921,12 @@ class HStoreKeyed V8_FINAL
}
StoreFieldOrKeyedMode store_mode() const { return store_mode_; }
ElementsKind elements_kind() const { return elements_kind_; }
uint32_t base_offset() {
ASSERT(base_offset_ >= 0);
return static_cast<uint32_t>(base_offset_);
uint32_t base_offset() { return base_offset_; }
void IncreaseBaseOffset(uint32_t base_offset) {
base_offset_ += base_offset;
}
bool CanIncreaseBaseOffset(int32_t increase_by_value) {
ASSERT(increase_by_value >= 0);
// Guard against overflow
return (increase_by_value + base_offset_) >= 0;
}
void IncreaseBaseOffset(int32_t increase_by_value) {
ASSERT(increase_by_value >= 0);
base_offset_ += increase_by_value;
virtual int MaxBaseOffsetBits() {
return 31 - ElementsKindToShiftSize(elements_kind_);
}
HValue* GetKey() { return key(); }
void SetKey(HValue* key) { SetOperandAt(1, key); }
@ -7031,7 +7017,7 @@ class HStoreKeyed V8_FINAL
}
ElementsKind elements_kind_;
int32_t base_offset_;
uint32_t base_offset_;
bool is_dehoisted_ : 1;
bool is_uninitialized_ : 1;
StoreFieldOrKeyedMode store_mode_: 1;

14
test/mjsunit/regress/regress-380092.js
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@ -1,14 +0,0 @@
// 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
function many_hoist(o, index) {
return o[index + 33554427];
}
var obj = {};
many_hoist(obj, 0);
%OptimizeFunctionOnNextCall(many_hoist);
many_hoist(obj, 5);