Revision: 3998
Author: [email protected]
Date: Tue Mar 2 06:00:59 2010
Log: Add syntax checker for side-effect-free expressions to AstOptimizer in
rewriter.cc. Add bit fields for syntax checker results to Expression in
ast.h.
Review URL: http://codereview.chromium.org/660372
http://code.google.com/p/v8/source/detail?r=3998
Modified:
/branches/bleeding_edge/src/ast.h
/branches/bleeding_edge/src/rewriter.cc
=======================================
--- /branches/bleeding_edge/src/ast.h Tue Mar 2 03:58:10 2010
+++ /branches/bleeding_edge/src/ast.h Tue Mar 2 06:00:59 2010
@@ -183,7 +183,11 @@
static const int kNoLabel = -1;
- Expression() : num_(kNoLabel), def_(NULL), defined_vars_(NULL) {}
+ Expression()
+ : bitfields_(0),
+ num_(kNoLabel),
+ def_(NULL),
+ defined_vars_(NULL) {}
virtual Expression* AsExpression() { return this; }
@@ -224,12 +228,67 @@
void set_defined_vars(ZoneList<DefinitionInfo*>* defined_vars) {
defined_vars_ = defined_vars;
}
+
+ // AST analysis results
+
+ // True if the expression rooted at this node can be compiled by the
+ // 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);
+ }
+
+ // 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));
+ }
+
+ // 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_;
StaticType type_;
+
int num_;
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> {
+ };
};
=======================================
--- /branches/bleeding_edge/src/rewriter.cc Wed Dec 16 22:21:50 2009
+++ /branches/bleeding_edge/src/rewriter.cc Tue Mar 2 06:00:59 2010
@@ -244,6 +244,14 @@
!Heap::result_symbol()->Equals(*var->name())) {
func_name_inferrer_.PushName(var->name());
}
+
+ if (var->slot() != NULL) {
+ 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.
+ }
}
}
@@ -252,11 +260,16 @@
Handle<Object> literal = node->handle();
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)) {
func_name_inferrer_.PushName(lit_str);
}
+ } else if (literal->IsHeapNumber()) {
+ node->set_side_effect_free(true);
+ // stack_height and expression_size remain 0.
}
}
@@ -414,6 +427,23 @@
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;
+ }
}
@@ -483,6 +513,33 @@
}
}
}
+ 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;
+ }
}
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