Fix an undetected Smi overflow on ARM.

runtime/vm/intermediate_language_mips.cc

Index: runtime/vm/intermediate_language_mips.cc
===================================================================
--- runtime/vm/intermediate_language_mips.cc	(revision 36182)
+++ runtime/vm/intermediate_language_mips.cc	(working copy)
@@ -2675,24 +2675,24 @@
   if (locs()->in(1).IsConstant()) {
     const Object& constant = locs()->in(1).constant();
     ASSERT(constant.IsSmi());
-    int32_t imm = reinterpret_cast<int32_t>(constant.raw());
+    const int32_t imm = reinterpret_cast<int32_t>(constant.raw());
     switch (op_kind()) {
-      case Token::kSUB: {
-        __ TraceSimMsg("kSUB imm");
+      case Token::kADD: {
         if (deopt == NULL) {
-          __ AddImmediate(result, left, -imm);
+          __ AddImmediate(result, left, imm);
         } else {
-          __ SubImmediateDetectOverflow(result, left, imm, CMPRES1);
+          Register temp = locs()->temp(0).reg();
+          __ AddImmediateDetectOverflow(result, left, imm, CMPRES1, temp);
           __ bltz(CMPRES1, deopt);
         }
         break;
       }
-      case Token::kADD: {
+      case Token::kSUB: {
+        __ TraceSimMsg("kSUB imm");
         if (deopt == NULL) {
-          __ AddImmediate(result, left, imm);
+          __ AddImmediate(result, left, -imm);
         } else {
-          Register temp = locs()->temp(0).reg();
-          __ AddImmediateDetectOverflow(result, left, imm, CMPRES1, temp);
+          __ SubImmediateDetectOverflow(result, left, imm, CMPRES1);
           __ bltz(CMPRES1, deopt);
         }
         break;