Calls to HCheckFunction can be eliminated if the value is an HConstant

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 041ef8b37408f11fcb8cdc68e26abbf3c479966e..a670011b6032a4396b690ebf21310bb71ad13deb 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1690,6 +1690,14 @@ void HCheckFunction::PrintDataTo(StringStream* stream) {
 }
 
 
+HValue* HCheckFunction::Canonicalize() {
+  return (value()->IsConstant() &&
+          HConstant::cast(value())->Hashcode() == target_unique_id_.Hashcode())

[Michael Starzinger, 2013/07/05 13:09:07]

This might lead to hash collisions for values that are actually not equal.
Better introduce a HConstant::IsUniqueValue(UniqueValueId id) that does a real
comparison of the ids or returns false if the HConstant doesn't have an id.

+      ? NULL
+      : this;
+}
+
+
 const char* HCheckInstanceType::GetCheckName() {
   switch (check_) {
     case IS_SPEC_OBJECT: return "object";