Improve alias analysis for HConstants (and fix small snafu in MustAlias).

src/hydrogen-alias-analysis.h

Index: src/hydrogen-alias-analysis.h
diff --git a/src/hydrogen-alias-analysis.h b/src/hydrogen-alias-analysis.h
index 447850123cd415174fc7885e6246262c3ecf4db8..73e116e63e171e9a4fd8e1478a53ff1bb45e8236 100644
--- a/src/hydrogen-alias-analysis.h
+++ b/src/hydrogen-alias-analysis.h
@@ -65,7 +65,11 @@ class HAliasAnalyzer : public ZoneObject {
       if (a->IsConstant()) return kNoAlias;
     }
 
-    // TODO(titzer): return MustAlias for two equivalent constants.
+    // Constant objects can be distinguished statically.
+    if (a->IsConstant()) {
+      // TODO(titzer): DataEquals() is more efficient, but that's protected.
+      return a->Equals(b) ? kMustAlias : kNoAlias;
+    }
     return kMayAlias;
   }
 
@@ -78,7 +82,7 @@ class HAliasAnalyzer : public ZoneObject {
   }
 
   inline bool MustAlias(HValue* a, HValue* b) {
-    return Query(a, b) == kMayAlias;
+    return Query(a, b) == kMustAlias;
   }
 
   inline bool NoAlias(HValue* a, HValue* b) {