Add support for adding an external and a tagged pointer

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 7a3c373a452e48a71237d074a1e9854785cd095c..ca88ef8e7e879addd21db71db199df4ff86cc316 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1630,7 +1630,10 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
     return DoArithmeticD(Token::ADD, instr);
   } else if (instr->representation().IsExternal()) {
     DCHECK(instr->left()->representation().IsExternal());
-    DCHECK(instr->right()->representation().IsInteger32());
+    DCHECK((instr->external_add_type() == AddOfExternalAndInt32 &&
+            instr->right()->representation().IsInteger32()) ||
+           (instr->external_add_type() == AddOfExternalAndTagged &&
+            instr->right()->representation().IsTagged()));

[Jarin, 2015/07/20 14:17:56]

Maybe you want to factor out the two DCHECK into a separate method, up to you.

Something like 

bool HAdd::IsConsistentExternalRepresentation() {
  return  left()->representation().IsExternal() && 
         ((external_add_type() == AddOfExternalAndInt32 &&
          right()->representation().IsInteger32()) ||
         (external_add_type() == AddOfExternalAndTagged &&
          right()->representation().IsTagged()));
}

     DCHECK(!instr->CheckFlag(HValue::kCanOverflow));
     bool use_lea = LAddI::UseLea(instr);
     LOperand* left = UseRegisterAtStart(instr->left());