Improve and simplify removal of unreachable code

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 307ed80415b324c476a0b1fc31806ac488db2b8a..29dbf8304fc2abeaa9a268c8b09b3feb8e280c92 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -3390,6 +3390,13 @@ class HConstant: public HTemplateInstruction<0> {
         unique_id_ == other;
   }
 
+  bool SameConstantObject(HConstant* other) {

[Michael Starzinger, 2013/08/16 15:02:20]

nit: Let's rename this to just "SameConstant", it doesn't look specific to
objects.

[Jakob Kummerow, 2013/08/20 08:46:56]

This seems to cover a subset of the functionality of DataEquals() below. Maybe
re-use that instead? If you actually need the specialized behavior then that's
fine of course.

[danno, 2013/10/01 10:43:18]

Actually, I use DataEquals now. Makes it even simpler.

+    if (HasSmiValue() && other->HasSmiValue()) {

[Michael Starzinger, 2013/08/16 15:02:20]

Shouldn't this be HasInteger32Value in these checks? Also what about
HasDoubleValue?

[danno, 2013/10/01 10:43:18]

See above.

+      return int32_value_ == other->int32_value_;
+    }
+    return UniqueValueIdsMatch(other->unique_id_);
+  }
+
 #ifdef DEBUG
   virtual void Verify() { }
 #endif
@@ -4011,6 +4018,12 @@ class HCompareObjectEqAndBranch: public HTemplateControlInstruction<2, 2> {
   // control flow instructions.
   HCompareObjectEqAndBranch(HValue* left,
                             HValue* right) {
+    ASSERT(!left->IsConstant() ||
+           (!HConstant::cast(left)->HasInteger32Value() ||
+            HConstant::cast(left)->HasSmiValue()));
+    ASSERT(!right->IsConstant() ||
+           (!HConstant::cast(right)->HasInteger32Value() ||
+            HConstant::cast(right)->HasSmiValue()));
     SetOperandAt(0, left);
     SetOperandAt(1, right);
   }