Improve precision of range analysis by allowing it to track ranges across all int typed phis.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index c0a4f039a25d4b5e34924d59808fd7a33b2e1c88..fbc492221942fa0a6d9e85cae6f73b59a8f3280c 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -1260,11 +1260,41 @@ bool BinaryIntegerOpInstr::RightIsPowerOfTwoConstant() const {
 }
 
 
+static intptr_t RepresentationBits(Representation r) {
+  switch (r) {
+    case kTagged:
+      return kBitsPerWord - 1;
+    case kUnboxedInt32:
+    case kUnboxedUint32:
+      return 32;
+    case kUnboxedMint:
+      return 64;
+    default:
+      UNREACHABLE();
+      return 0;
+  }
+}
+
+
+static int64_t RepresentationMask(Representation r) {
+  return static_cast<int64_t>(
+      static_cast<uint64_t>(-1) >> (64 - RepresentationBits(r)));
+}
+
+
 static bool ToIntegerConstant(Value* value, int64_t* result) {
   if (!value->BindsToConstant()) {
     UnboxInstr* unbox = value->definition()->AsUnbox();
-    if ((unbox != NULL) && (unbox->representation() == kUnboxedDouble)) {
-      return ToIntegerConstant(unbox->value(), result);
+    if (unbox != NULL) {
+      if (unbox->representation() == kUnboxedDouble) {
+        return ToIntegerConstant(unbox->value(), result);
+      } else if (unbox->representation() == kUnboxedUint32) {

[Florian Schneider, 2014/11/10 16:10:47]

Why are kUnboxedInt32 and kInboxedMint not handled here?

+        if (ToIntegerConstant(unbox->value(), result)) {
+          *result &= RepresentationMask(kUnboxedUint32);
+          return true;
+        }
+        return false;
+      }
     }
     return false;
   }
@@ -1392,28 +1422,6 @@ static bool IsCommutative(Token::Kind op) {
 }
 
 
-static intptr_t RepresentationBits(Representation r) {
-  switch (r) {
-    case kTagged:
-      return kBitsPerWord - 1;
-    case kUnboxedInt32:
-    case kUnboxedUint32:
-      return 32;
-    case kUnboxedMint:
-      return 64;
-    default:
-      UNREACHABLE();
-      return 0;
-  }
-}
-
-
-static int64_t RepresentationMask(Representation r) {
-  return static_cast<int64_t>(
-      static_cast<uint64_t>(-1) >> (64 - RepresentationBits(r)));
-}
-
-
 UnaryIntegerOpInstr* UnaryIntegerOpInstr::Make(Representation representation,
                                                Token::Kind op_kind,
                                                Value* value,