Fix vm code base so that it can be built for --arch=simarm (no snapshot yet).

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
===================================================================
--- runtime/vm/flow_graph_optimizer.cc	(revision 17110)
+++ runtime/vm/flow_graph_optimizer.cc	(working copy)
@@ -1311,9 +1311,14 @@
     }
     if ((recognized_kind == MethodRecognizer::kDoubleTruncate) ||
         (recognized_kind == MethodRecognizer::kDoubleRound)) {
+#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)

[srdjan, 2013/01/16 19:06:30]

Instead of ifdef, use a shared e.g.,  SuportsDoubleTruncRound.

[regis, 2013/01/16 23:14:42]

As soon as we implement the arm version, there will be many more differences.
The cleaner solution is to split this file into architecture dependent files, as
noted by the TODO. But if you think it will be possible to keep this file
architecture independent, I will revisit.

[srdjan, 2013/01/16 23:57:56]

I think that the optimizer will remain machine independent.

[regis, 2013/01/17 01:02:07]

Alright. I have added a double_truncate_round_supported() static method to keep
the same style.

+      // TODO(regis): FlowGraphOptimizer should be architecture dependent.
       if (!CPUFeatures::sse4_1_supported()) {
         return false;
       }
+#else
+      return false;
+#endif
       AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
       DoubleToDoubleInstr* d2d_instr =
           new DoubleToDoubleInstr(call->ArgumentAt(0)->value(),