Support use of external strings as inputs to LoadCodeUnitsInstr.

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
diff --git a/runtime/vm/intermediate_language_ia32.cc b/runtime/vm/intermediate_language_ia32.cc
index ccf4a25ee3494cd324e7b04d0327546e73522cf0..0f5304beb7c535a5ecfe876cd961973ddc8f2ddb 100644
--- a/runtime/vm/intermediate_language_ia32.cc
+++ b/runtime/vm/intermediate_language_ia32.cc
@@ -939,9 +939,13 @@ LocationSummary* LoadUntaggedInstr::MakeLocationSummary(Isolate* isolate,
 
 
 void LoadUntaggedInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register object = locs()->in(0).reg();
+  Register obj = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
-  __ movl(result, FieldAddress(object, offset()));
+  if (object()->definition()->representation() == kUntagged) {
+    __ movl(result, Address(obj, offset()));
+  } else {
+    __ movl(result, FieldAddress(obj, offset()));

[Vyacheslav Egorov (Google), 2014/11/27 14:27:43]

ASSERT(representation == kTagged)

+  }
 }
 
 
@@ -3725,6 +3729,7 @@ LocationSummary* LoadCodeUnitsInstr::MakeLocationSummary(Isolate* isolate,
 
 
 void LoadCodeUnitsInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  // The array register points to the backing store for external arrays.
   const Register array = locs()->in(0).reg();
   const Location index = locs()->in(1);