Recognize special comparisons via pattern matching on the hydrogen graph, 2nd attempt.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 9687)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -787,6 +787,16 @@
 }
 
 
+HValue* HConstant::Canonicalize() {
+  return HasNoUses()&& !IsBlockEntry() ? NULL : this;

[Kevin Millikin (Chromium), 2011/10/19 07:24:41]

Missing a space before &&, also below.

[Sven Panne, 2011/10/19 07:33:32]

Done.

+}
+
+
+HValue* HTypeof::Canonicalize() {
+  return HasNoUses()&& !IsBlockEntry() ? NULL : this;
+}
+
+
 void HTypeof::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
 }