Reviewers: danno,
Message:
Committed patchset #1 manually as r21715 (tree was closed).
Description:
Revert "Re-land Clusterfuzz identified overflow check needed in dehoisting."
This reverts commit r21712
[email protected]
Committed: https://code.google.com/p/v8/source/detail?r=21715
Please review this at https://codereview.chromium.org/315843005/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+20, -58 lines):
M src/hydrogen-dehoist.cc
M src/hydrogen-instructions.h
D test/mjsunit/regress/regress-380092.js
Index: test/mjsunit/regress/regress-380092.js
diff --git a/test/mjsunit/regress/regress-380092.js
b/test/mjsunit/regress/regress-380092.js
deleted file mode 100644
index
a7634355ca5d0db9a867cb691b05129b984911f8..0000000000000000000000000000000000000000
--- a/test/mjsunit/regress/regress-380092.js
+++ /dev/null
@@ -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);
Index: src/hydrogen-dehoist.cc
diff --git a/src/hydrogen-dehoist.cc b/src/hydrogen-dehoist.cc
index
b377498cac3f7d58711fba6561f9c41ded13fbb8..fe0ae764ad63dcf3fc6c3ca625ebd90cdea7fcf7
100644
--- a/src/hydrogen-dehoist.cc
+++ b/src/hydrogen-dehoist.cc
@@ -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);
}
Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index
1fc800e6ffd6b6e8857c7b86bca00e1858566cf3..d1f2372db689de8059d55f532d8ad26bf3bd661a
100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -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_);
- }
- bool CanIncreaseBaseOffset(int32_t increase_by_value) {
- ASSERT(increase_by_value >= 0);
- // Guard against overflow
- return (increase_by_value + base_offset_) >= 0;
+ uint32_t base_offset() { return base_offset_; }
+ void IncreaseBaseOffset(uint32_t base_offset) {
+ base_offset_ += base_offset;
}
- 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;
--
--
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