Better codegen for '<expression> === void <literal>'.

src/ast.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 319 matching lines @@
     case Token::DIV:
     case Token::MOD:
       return true;
     default:
       UNREACHABLE();
   }
   return false;
 }
 
 
+bool CompareOperation::IsLiteralCompareTypeof(Expression** expr,
+                                              Handle<String>* check) {
+  if (op_ != Token::EQ && op_ != Token::EQ_STRICT) return false;
+
+  UnaryOperation* left_unary = left_->AsUnaryOperation();
+  UnaryOperation* right_unary = right_->AsUnaryOperation();
+  Literal* left_literal = left_->AsLiteral();
+  Literal* right_literal = right_->AsLiteral();
+
+  // Check for the pattern: typeof <expression> == <string literal>.
+  if (left_unary != NULL && left_unary->op() == Token::TYPEOF &&
+      right_literal != NULL && right_literal->handle()->IsString()) {
+    *expr = left_unary->expression();
+    *check = Handle<String>::cast(right_literal->handle());
+    return true;
+  }
+
+  // Check for the pattern: <string literal> == typeof <expression>.
+  if (right_unary != NULL && right_unary->op() == Token::TYPEOF &&
+      left_literal != NULL && left_literal->handle()->IsString()) {
+    *expr = right_unary->expression();
+    *check = Handle<String>::cast(left_literal->handle());
+    return true;
+  }
+
+  return false;
+}
+
+
+bool CompareOperation::IsLiteralCompareUndefined(Expression **expr) {

[fschneider, 2011/06/24 12:04:42]

For consistency:

Expression** expr

[Steven, 2011/06/24 14:33:29]

Done.

+  if (op_ != Token::EQ_STRICT) return false;
+
+  UnaryOperation* left_unary = left_->AsUnaryOperation();
+  UnaryOperation* right_unary = right_->AsUnaryOperation();
+
+  // Check for the pattern: <expression> === void <literal>.
+  if (right_unary != NULL && right_unary->op() == Token::VOID &&
+      right_unary->expression()->AsLiteral() != NULL) {
+    *expr = left_;
+    return true;
+  }
+
+  // Check for the pattern: void <literal> === <expression>.
+  if (left_unary != NULL && left_unary->op() == Token::VOID &&
+      left_unary->expression()->AsLiteral() != NULL) {
+    *expr = right_;
+    return true;
+  }
+
+  return false;
+}
+
+
 // ----------------------------------------------------------------------------
 // Inlining support
 
 bool Declaration::IsInlineable() const {
   return proxy()->var()->IsStackAllocated() && fun() == NULL;
 }
 
 
 bool TargetCollector::IsInlineable() const {
   UNREACHABLE();
@@ skipping 792 matching lines @@
                        int pos)
     : label_(label),
       statements_(statements),
       position_(pos),
       compare_type_(NONE),
       compare_id_(AstNode::GetNextId()),
       entry_id_(AstNode::GetNextId()) {
 }
 
 } }  // namespace v8::internal