Revision: 13176
Author: [email protected]
Date: Mon Dec 10 00:56:24 2012
Log: Make keyed operations use the unchecked index but still depend on
the checked one.
BUG=
Review URL: https://chromiumcodereview.appspot.com/11445016
http://code.google.com/p/v8/source/detail?r=13176
Modified:
/branches/bleeding_edge/src/hydrogen-instructions.h
/branches/bleeding_edge/src/hydrogen.cc
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.h Wed Dec 5 07:49:22
2012
+++ /branches/bleeding_edge/src/hydrogen-instructions.h Mon Dec 10 00:56:24
2012
@@ -348,6 +348,13 @@
}
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 @@
};
+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 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 @@
};
-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 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 @@
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 @@
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 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 @@
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 @@
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 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 @@
}
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)
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Wed Dec 5 07:49:22 2012
+++ /branches/bleeding_edge/src/hydrogen.cc Mon Dec 10 00:56:24 2012
@@ -3499,8 +3499,8 @@
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 @@
}
if (!keep_new_check) {
- new_check->DeleteAndReplaceWith(NULL);
+ new_check->DeleteAndReplaceWith(new_check->index());
}
}
@@ -3764,21 +3764,13 @@
// 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 @@
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 @@
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();
--
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