Revision: 4056
Author: [email protected]
Date: Mon Mar 8 07:28:57 2010
Log: Add AST analysis that flags expressions that will have ToInt32 applied
to them.
Simplify AST analysis of side-effect-free int32 expressions.
Review URL: http://codereview.chromium.org/668256
http://code.google.com/p/v8/source/detail?r=4056
Modified:
/branches/bleeding_edge/src/ast.h
/branches/bleeding_edge/src/flag-definitions.h
/branches/bleeding_edge/src/rewriter.cc
=======================================
--- /branches/bleeding_edge/src/ast.h Mon Mar 8 05:01:24 2010
+++ /branches/bleeding_edge/src/ast.h Mon Mar 8 07:28:57 2010
@@ -237,27 +237,19 @@
// side-effect free compiler.
bool side_effect_free() { return
SideEffectFreeField::decode(bitfields_); }
void set_side_effect_free(bool is_side_effect_free) {
- bitfields_ = (bitfields_ & ~SideEffectFreeField::mask()) |
- SideEffectFreeField::encode(is_side_effect_free);
+ bitfields_ &= ~SideEffectFreeField::mask();
+ bitfields_ |= SideEffectFreeField::encode(is_side_effect_free);
}
- // The number of unary and binary operations contained in the expression
- // rooted at this node. Valid only if side_effect_free() is true.
- int expression_size() { return ExpressionSizeField::decode(bitfields_); }
- void set_expression_size(int expression_size) {
- bitfields_ = (bitfields_ & ~ExpressionSizeField::mask()) |
- ExpressionSizeField::encode(Min(expression_size,
ExpressionSizeMax));
+ // Will ToInt32 ECMA 262-3 9.5) or ToUunt32 (ECMA 262-3 9.6)
+ // be applied to the value of this expression?
+ // If so, we may be able to optimize the calculation of the value.
+ bool to_int32() { return ToInt32Field::decode(bitfields_); }
+ void set_to_int32(bool to_int32) {
+ bitfields_ &= ~ToInt32Field::mask();
+ bitfields_ |= ToInt32Field::encode(to_int32);
}
- // The number of expression stack slots needed to compute the expression
- // rooted at this node. Does not count the slot needed by the value
- // computed by this expression. Valid only if side_effect_free() is true.
- int stack_height() { return StackHeightField::decode(bitfields_); }
- void set_stack_height(int stack_height) {
- bitfields_ &= ~StackHeightField::mask();
- bitfields_ |=
- StackHeightField::encode(Min(stack_height, StackHeightMax));
- }
private:
uint32_t bitfields_;
@@ -266,30 +258,9 @@
DefinitionInfo* def_;
ZoneList<DefinitionInfo*>* defined_vars_;
- static const int SideEffectFreeFieldStart = 0;
- static const int SideEffectFreeFieldLength = 1;
- class SideEffectFreeField: public BitField<bool,
- SideEffectFreeFieldStart,
- SideEffectFreeFieldLength> {
- };
-
- static const int ExpressionSizeFieldStart =
- SideEffectFreeFieldStart + SideEffectFreeFieldLength;
- static const int ExpressionSizeFieldLength = 5;
- static const int ExpressionSizeMax = (1 << ExpressionSizeFieldLength) -
1;
- class ExpressionSizeField: public BitField<int,
- ExpressionSizeFieldStart,
- ExpressionSizeFieldLength> {
- };
-
- static const int StackHeightFieldStart =
- ExpressionSizeFieldStart + ExpressionSizeFieldLength;
- static const int StackHeightFieldLength = 5;
- static const int StackHeightMax = (1 << StackHeightFieldLength) - 1;
- class StackHeightField: public BitField<int,
- StackHeightFieldStart,
- StackHeightFieldLength> {
- };
+ // Using template BitField<type, start, size>.
+ class SideEffectFreeField : public BitField<bool, 0, 1> {};
+ class ToInt32Field : public BitField<bool, 1, 1> {};
};
=======================================
--- /branches/bleeding_edge/src/flag-definitions.h Mon Mar 8 05:01:24 2010
+++ /branches/bleeding_edge/src/flag-definitions.h Mon Mar 8 07:28:57 2010
@@ -153,6 +153,8 @@
"try to use the speculative optimizing backend for all code")
DEFINE_bool(trace_bailout, false,
"print reasons for falling back to using the classic V8
backend")
+DEFINE_bool(safe_int32_compiler, false,
+ "enable optimized side-effect-free int32 expressions.")
DEFINE_bool(use_flow_graph, false, "perform flow-graph based
optimizations")
// compilation-cache.cc
=======================================
--- /branches/bleeding_edge/src/rewriter.cc Tue Mar 2 06:32:31 2010
+++ /branches/bleeding_edge/src/rewriter.cc Mon Mar 8 07:28:57 2010
@@ -245,12 +245,13 @@
func_name_inferrer_.PushName(var->name());
}
- if (var->slot() != NULL) {
+ if (FLAG_safe_int32_compiler) {
Slot* slot = var->slot();
- node->set_side_effect_free(
- (slot->type() == Slot::LOCAL && !slot->is_arguments()) ||
- slot->type() == Slot::PARAMETER);
- // stack_height and expression_size remain 0.
+ if (slot != NULL) {
+ node->set_side_effect_free(
+ (slot->type() == Slot::LOCAL && !slot->is_arguments()) ||
+ slot->type() == Slot::PARAMETER);
+ }
}
}
}
@@ -261,7 +262,6 @@
if (literal->IsSmi()) {
node->type()->SetAsLikelySmi();
node->set_side_effect_free(true);
- // stack_height and expression_size remain 0.
} else if (literal->IsString()) {
Handle<String> lit_str(Handle<String>::cast(literal));
if (!Heap::prototype_symbol()->Equals(*lit_str)) {
@@ -269,7 +269,6 @@
}
} else if (literal->IsHeapNumber()) {
node->set_side_effect_free(true);
- // stack_height and expression_size remain 0.
}
}
@@ -427,22 +426,26 @@
void AstOptimizer::VisitUnaryOperation(UnaryOperation* node) {
Visit(node->expression());
- switch (node->op()) {
- case Token::ADD:
- case Token::SUB:
- node->set_side_effect_free(node->expression()->side_effect_free());
- node->set_expression_size(node->expression()->expression_size() + 1);
- node->set_stack_height(node->expression()->stack_height());
- break;
- case Token::DELETE:
- case Token::TYPEOF:
- case Token::VOID:
- case Token::BIT_NOT:
- case Token::NOT:
- break;
- default:
- UNREACHABLE();
- break;
+ if (FLAG_safe_int32_compiler) {
+ switch (node->op()) {
+ case Token::BIT_NOT:
+ node->expression()->set_to_int32(true);
+ // Fall through.
+ case Token::ADD:
+ case Token::SUB:
+ case Token::NOT:
+ node->set_side_effect_free(node->expression()->side_effect_free());
+ break;
+ case Token::DELETE:
+ case Token::TYPEOF:
+ case Token::VOID:
+ break;
+ default:
+ UNREACHABLE();
+ break;
+ }
+ } else if (node->op() == Token::BIT_NOT) {
+ node->expression()->set_to_int32(true);
}
}
@@ -472,6 +475,8 @@
node->type()->SetAsLikelySmiIfUnknown();
node->left()->type()->SetAsLikelySmiIfUnknown();
node->right()->type()->SetAsLikelySmiIfUnknown();
+ node->left()->set_to_int32(true);
+ node->right()->set_to_int32(true);
break;
case Token::ADD:
case Token::SUB:
@@ -513,32 +518,31 @@
}
}
}
- switch (node->op()) {
- case Token::COMMA:
- case Token::OR:
- case Token::AND:
- case Token::BIT_OR:
- case Token::BIT_XOR:
- case Token::BIT_AND:
- case Token::SHL:
- case Token::SAR:
- case Token::SHR:
- case Token::MOD:
- break;
- case Token::ADD:
- case Token::SUB:
- case Token::MUL:
- case Token::DIV:
- node->set_side_effect_free(node->left()->side_effect_free() &&
- node->right()->side_effect_free());
- node->set_expression_size(node->left()->expression_size() +
- node->right()->expression_size() + 1);
- node->set_stack_height(Max(node->left()->stack_height(),
- node->right()->stack_height() + 1));
- break;
- default:
- UNREACHABLE();
- break;
+
+ if (FLAG_safe_int32_compiler) {
+ switch (node->op()) {
+ case Token::COMMA:
+ case Token::OR:
+ case Token::AND:
+ break;
+ case Token::BIT_OR:
+ case Token::BIT_XOR:
+ case Token::BIT_AND:
+ case Token::SHL:
+ case Token::SAR:
+ case Token::SHR:
+ case Token::ADD:
+ case Token::SUB:
+ case Token::MUL:
+ case Token::DIV:
+ case Token::MOD:
+ node->set_side_effect_free(node->left()->side_effect_free() &&
+ node->right()->side_effect_free());
+ break;
+ default:
+ UNREACHABLE();
+ break;
+ }
}
}
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