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Make keyed operations use the unchecked index but still depend on the checked one.

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BUG=

Review URL: https://chromiumcodereview.appspot.com/11445016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13176 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mmassi@chromium.org 2012-12-10 08:56:24 +00:00
parent a1d10c69a1
commit 1aa2891ca4
2 changed files with 124 additions and 92 deletions
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198
src/hydrogen-instructions.h
View File

@ -348,6 +348,13 @@ class Representation {
}
const char* Mnemonic() const;
Representation KeyedAccessIndexRequirement() {
// This is intended to be used in RequiredInputRepresentation for keyed
// loads and stores to avoid inserting unneeded HChange instructions:
// keyed loads and stores can work on both int32 and tagged indexes.
return IsInteger32() ? Integer32() : Tagged();
}
private:
explicit Representation(Kind k) : kind_(k) { }
@ -2827,6 +2834,65 @@ class HWrapReceiver: public HTemplateInstruction<2> {
};
enum BoundsCheckKeyMode {
DONT_ALLOW_SMI_KEY,
ALLOW_SMI_KEY
};
class HBoundsCheck: public HTemplateInstruction<2> {
public:
HBoundsCheck(HValue* index, HValue* length,
BoundsCheckKeyMode key_mode = DONT_ALLOW_SMI_KEY)
: key_mode_(key_mode) {
SetOperandAt(0, index);
SetOperandAt(1, length);
set_representation(Representation::Integer32());
SetFlag(kUseGVN);
}
virtual Representation RequiredInputRepresentation(int arg_index) {
if (key_mode_ == DONT_ALLOW_SMI_KEY ||
!length()->representation().IsTagged()) {
return Representation::Integer32();
}
// If the index is tagged and isn't constant, then allow the length
// to be tagged, since it is usually already tagged from loading it out of
// the length field of a JSArray. This allows for direct comparison without
// untagging.
if (index()->representation().IsTagged() && !index()->IsConstant()) {
return Representation::Tagged();
}
// Also allow the length to be tagged if the index is constant, because
// it can be tagged to allow direct comparison.
if (index()->IsConstant() &&
index()->representation().IsInteger32() &&
arg_index == 1) {
return Representation::Tagged();
}
return Representation::Integer32();
}
virtual Representation observed_input_representation(int index) {
return Representation::Integer32();
}
virtual void PrintDataTo(StringStream* stream);
HValue* index() { return OperandAt(0); }
HValue* length() { return OperandAt(1); }
DECLARE_CONCRETE_INSTRUCTION(BoundsCheck)
static HValue* ExtractUncheckedIndex(HValue* index) {
return index->IsBoundsCheck() ? HBoundsCheck::cast(index)->index() : index;
}
protected:
virtual bool DataEquals(HValue* other) { return true; }
BoundsCheckKeyMode key_mode_;
};
class HApplyArguments: public HTemplateInstruction<4> {
public:
HApplyArguments(HValue* function,
@ -2905,28 +2971,41 @@ class HArgumentsLength: public HUnaryOperation {
};
class HAccessArgumentsAt: public HTemplateInstruction<3> {
class HAccessArgumentsAt: public HTemplateInstruction<4> {
public:
HAccessArgumentsAt(HValue* arguments, HValue* length, HValue* index) {
HAccessArgumentsAt(HValue* arguments,
HValue* length,
HValue* checked_index) {
set_representation(Representation::Tagged());
SetFlag(kUseGVN);
SetOperandAt(0, arguments);
SetOperandAt(1, length);
SetOperandAt(2, index);
SetOperandAt(2, HBoundsCheck::ExtractUncheckedIndex(checked_index));
SetOperandAt(3, checked_index);
}
virtual void PrintDataTo(StringStream* stream);
virtual Representation RequiredInputRepresentation(int index) {
// The arguments elements is considered tagged.
return index == 0
? Representation::Tagged()
: Representation::Integer32();
switch (index) {
// The arguments elements is considered tagged.
case 0: return Representation::Tagged();
case 1: return Representation::Integer32();
case 2: return Representation::Integer32();
// The checked index is a control flow dependency to avoid hoisting
// and therefore it has no representation requirements.
case 3: return Representation::None();
default: {
UNREACHABLE();
return Representation::None();
}
}
}
HValue* arguments() { return OperandAt(0); }
HValue* length() { return OperandAt(1); }
HValue* index() { return OperandAt(2); }
HValue* checked_index() { return OperandAt(3); }
DECLARE_CONCRETE_INSTRUCTION(AccessArgumentsAt)
@ -2934,61 +3013,6 @@ class HAccessArgumentsAt: public HTemplateInstruction<3> {
};
enum BoundsCheckKeyMode {
DONT_ALLOW_SMI_KEY,
ALLOW_SMI_KEY
};
class HBoundsCheck: public HTemplateInstruction<2> {
public:
HBoundsCheck(HValue* index, HValue* length,
BoundsCheckKeyMode key_mode = DONT_ALLOW_SMI_KEY)
: key_mode_(key_mode) {
SetOperandAt(0, index);
SetOperandAt(1, length);
set_representation(Representation::Integer32());
SetFlag(kUseGVN);
}
virtual Representation RequiredInputRepresentation(int arg_index) {
if (key_mode_ == DONT_ALLOW_SMI_KEY ||
!length()->representation().IsTagged()) {
return Representation::Integer32();
}
// If the index is tagged and isn't constant, then allow the length
// to be tagged, since it is usually already tagged from loading it out of
// the length field of a JSArray. This allows for direct comparison without
// untagging.
if (index()->representation().IsTagged() && !index()->IsConstant()) {
return Representation::Tagged();
}
// Also allow the length to be tagged if the index is constant, because
// it can be tagged to allow direct comparison.
if (index()->IsConstant() &&
index()->representation().IsInteger32() &&
arg_index == 1) {
return Representation::Tagged();
}
return Representation::Integer32();
}
virtual Representation observed_input_representation(int index) {
return Representation::Integer32();
}
virtual void PrintDataTo(StringStream* stream);
HValue* index() { return OperandAt(0); }
HValue* length() { return OperandAt(1); }
DECLARE_CONCRETE_INSTRUCTION(BoundsCheck)
protected:
virtual bool DataEquals(HValue* other) { return true; }
BoundsCheckKeyMode key_mode_;
};
class HBitwiseBinaryOperation: public HBinaryOperation {
public:
HBitwiseBinaryOperation(HValue* context, HValue* left, HValue* right)
@ -4343,18 +4367,18 @@ class ArrayInstructionInterface {
class HLoadKeyed
: public HTemplateInstruction<3>, public ArrayInstructionInterface {
: public HTemplateInstruction<4>, public ArrayInstructionInterface {
public:
HLoadKeyed(HValue* obj,
HValue* key,
HValue* checked_key,
HValue* dependency,
ElementsKind elements_kind)
: bit_field_(0) {
bit_field_ = ElementsKindField::encode(elements_kind);
SetOperandAt(0, obj);
SetOperandAt(1, key);
SetOperandAt(1, HBoundsCheck::ExtractUncheckedIndex(checked_key));
SetOperandAt(2, dependency);
SetOperandAt(3, checked_key);
if (!is_external()) {
// I can detect the case between storing double (holey and fast) and
@ -4396,6 +4420,7 @@ class HLoadKeyed
HValue* elements() { return OperandAt(0); }
HValue* key() { return OperandAt(1); }
HValue* dependency() { return OperandAt(2); }
HValue* checked_key() { return OperandAt(3); }
uint32_t index_offset() { return IndexOffsetField::decode(bit_field_); }
void SetIndexOffset(uint32_t index_offset) {
bit_field_ = IndexOffsetField::update(bit_field_, index_offset);
@ -4418,7 +4443,9 @@ class HLoadKeyed
return is_external() ? Representation::External()
: Representation::Tagged();
}
if (index == 1) return Representation::Integer32();
if (index == 1) {
return OperandAt(1)->representation().KeyedAccessIndexRequirement();
}
return Representation::None();
}
@ -4600,14 +4627,15 @@ class HStoreNamedGeneric: public HTemplateInstruction<3> {
class HStoreKeyed
: public HTemplateInstruction<3>, public ArrayInstructionInterface {
: public HTemplateInstruction<4>, public ArrayInstructionInterface {
public:
HStoreKeyed(HValue* obj, HValue* key, HValue* val,
HStoreKeyed(HValue* obj, HValue* checked_key, HValue* val,
ElementsKind elements_kind)
: elements_kind_(elements_kind), index_offset_(0), is_dehoisted_(false) {
SetOperandAt(0, obj);
SetOperandAt(1, key);
SetOperandAt(1, HBoundsCheck::ExtractUncheckedIndex(checked_key));
SetOperandAt(2, val);
SetOperandAt(3, checked_key);
if (is_external()) {
SetGVNFlag(kChangesSpecializedArrayElements);
@ -4633,7 +4661,9 @@ class HStoreKeyed
return is_external() ? Representation::External()
: Representation::Tagged();
} else if (index == 1) {
return Representation::Integer32();
return OperandAt(1)->representation().KeyedAccessIndexRequirement();
} else if (index == 3) {
return Representation::None();
}
ASSERT_EQ(index, 2);
@ -4664,6 +4694,7 @@ class HStoreKeyed
HValue* elements() { return OperandAt(0); }
HValue* key() { return OperandAt(1); }
HValue* value() { return OperandAt(2); }
HValue* checked_key() { return OperandAt(3); }
bool value_is_smi() const {
return IsFastSmiElementsKind(elements_kind_);
}
@ -4806,12 +4837,13 @@ class HStringAdd: public HBinaryOperation {
};
class HStringCharCodeAt: public HTemplateInstruction<3> {
class HStringCharCodeAt: public HTemplateInstruction<4> {
public:
HStringCharCodeAt(HValue* context, HValue* string, HValue* index) {
HStringCharCodeAt(HValue* context, HValue* string, HValue* checked_index) {
SetOperandAt(0, context);
SetOperandAt(1, string);
SetOperandAt(2, index);
SetOperandAt(2, HBoundsCheck::ExtractUncheckedIndex(checked_index));
SetOperandAt(3, checked_index);
set_representation(Representation::Integer32());
SetFlag(kUseGVN);
SetGVNFlag(kDependsOnMaps);
@ -4819,15 +4851,25 @@ class HStringCharCodeAt: public HTemplateInstruction<3> {
}
virtual Representation RequiredInputRepresentation(int index) {
// The index is supposed to be Integer32.
return index == 2
? Representation::Integer32()
: Representation::Tagged();
switch (index) {
case 0: return Representation::Tagged();
case 1: return Representation::Tagged();
// The index is supposed to be Integer32.
case 2: return Representation::Integer32();
// The checked index is a control flow dependency to avoid hoisting
// and therefore it has no representation requirements.
case 3: return Representation::None();
default: {
UNREACHABLE();
return Representation::None();
}
}
}
HValue* context() { return OperandAt(0); }
HValue* string() { return OperandAt(1); }
HValue* index() { return OperandAt(2); }
HValue* checked_index() { return OperandAt(3); }
DECLARE_CONCRETE_INSTRUCTION(StringCharCodeAt)

18
src/hydrogen.cc
View File

@ -3499,8 +3499,8 @@ bool HGraph::Optimize(SmartArrayPointer<char>* bailout_reason) {
HStackCheckEliminator sce(this);
sce.Process();
EliminateRedundantBoundsChecks();
DehoistSimpleArrayIndexComputations();
if (FLAG_array_bounds_checks_elimination) EliminateRedundantBoundsChecks();
if (FLAG_array_index_dehoisting) DehoistSimpleArrayIndexComputations();
if (FLAG_dead_code_elimination) DeadCodeElimination();
return true;
@ -3657,7 +3657,7 @@ class BoundsCheckBbData: public ZoneObject {
}
if (!keep_new_check) {
new_check->DeleteAndReplaceWith(NULL);
new_check->DeleteAndReplaceWith(new_check->index());
}
}
@ -3764,21 +3764,13 @@ class BoundsCheckTable : private ZoneHashMap {
// Eliminates checks in bb and recursively in the dominated blocks.
// Also replace the results of check instructions with the original value, if
// the result is used. This is safe now, since we don't do code motion after
// this point. It enables better register allocation since the value produced
// by check instructions is really a copy of the original value.
void HGraph::EliminateRedundantBoundsChecks(HBasicBlock* bb,
BoundsCheckTable* table) {
BoundsCheckBbData* bb_data_list = NULL;
for (HInstruction* i = bb->first(); i != NULL; i = i->next()) {
if (!i->IsBoundsCheck()) continue;
HBoundsCheck* check = HBoundsCheck::cast(i);
check->ReplaceAllUsesWith(check->index());
if (!FLAG_array_bounds_checks_elimination) continue;
int32_t offset;
BoundsCheckKey* key =
@ -3797,7 +3789,7 @@ void HGraph::EliminateRedundantBoundsChecks(HBasicBlock* bb,
NULL);
*data_p = bb_data_list;
} else if (data->OffsetIsCovered(offset)) {
check->DeleteAndReplaceWith(NULL);
check->DeleteAndReplaceWith(check->index());
} else if (data->BasicBlock() == bb) {
data->CoverCheck(check, offset);
} else {
@ -3892,8 +3884,6 @@ static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
void HGraph::DehoistSimpleArrayIndexComputations() {
if (!FLAG_array_index_dehoisting) return;
HPhase phase("H_Dehoist index computations", this);
for (int i = 0; i < blocks()->length(); ++i) {
for (HInstruction* instr = blocks()->at(i)->first();