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

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index fba6cc20434d30295c35c1e4675930248a152606..f8da7e82a0d8f56c861a8516767b1553d28e0354 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -3907,25 +3907,13 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
 }
 
 
-bool FullCodeGenerator::TryLiteralCompare(Token::Value op,
-                                          Expression* left,
-                                          Expression* right,
-                                          Label* if_true,
-                                          Label* if_false,
-                                          Label* fall_through) {
-  if (op != Token::EQ && op != Token::EQ_STRICT) return false;
-
-  // Check for the pattern: typeof <expression> == <string literal>.
-  Literal* right_literal = right->AsLiteral();
-  if (right_literal == NULL) return false;
-  Handle<Object> right_literal_value = right_literal->handle();
-  if (!right_literal_value->IsString()) return false;
-  UnaryOperation* left_unary = left->AsUnaryOperation();
-  if (left_unary == NULL || left_unary->op() != Token::TYPEOF) return false;
-  Handle<String> check = Handle<String>::cast(right_literal_value);
-
+void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
+                                                 Handle<String> check,
+                                                 Label* if_true,
+                                                 Label* if_false,
+                                                 Label* fall_through) {
   { AccumulatorValueContext context(this);
-    VisitForTypeofValue(left_unary->expression());
+    VisitForTypeofValue(expr);
   }
   PrepareForBailoutBeforeSplit(TOS_REG, true, if_true, if_false);
 
@@ -3976,8 +3964,20 @@ bool FullCodeGenerator::TryLiteralCompare(Token::Value op,
   } else {
     if (if_false != fall_through) __ jmp(if_false);
   }
+}
+
 
-  return true;
+void FullCodeGenerator::EmitLiteralCompareUndefined(Expression* expr,
+                                                    Label* if_true,
+                                                    Label* if_false,
+                                                    Label* fall_through) {
+  { AccumulatorValueContext context(this);

[fschneider, 2011/06/21 11:36:08]

Same comment as on the ARM file.

[Steven, 2011/06/22 10:00:53]

Done.

+    VisitForTypeofValue(expr);
+  }
+  PrepareForBailoutBeforeSplit(TOS_REG, true, if_true, if_false);
+
+  __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
+  Split(equal, if_true, if_false, fall_through);
 }