On Ia32 optimistically assume that results from int32 and uint32 array loads fit into Smi. Only if …

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
===================================================================
--- runtime/vm/intermediate_language_ia32.cc	(revision 17771)
+++ runtime/vm/intermediate_language_ia32.cc	(working copy)
@@ -1114,7 +1114,9 @@
     case kInt32ArrayCid:
     case kUint32ArrayCid:
       // Result can be smi or mint when boxed.
-      return kDynamicCid;
+      // Optimistic assumption that result is Smi means that the instruction
+      // can deoptimize.
+      return CanDeoptimize() ? kSmiCid : kDynamicCid;
     default:
       UNIMPLEMENTED();
       return kDynamicCid;
@@ -1137,7 +1139,9 @@
       return kTagged;
     case kInt32ArrayCid:
     case kUint32ArrayCid:
-      return kUnboxedMint;
+      // Optimistic assumption that result is Smi means that the instruction
+      // can deoptimize.
+      return CanDeoptimize() ? kTagged : kUnboxedMint;
     case kFloat32ArrayCid :
     case kFloat64ArrayCid :
       return kUnboxedDouble;
@@ -1253,6 +1257,24 @@
       __ movzxw(result, element_address);
       __ SmiTag(result);
       break;
+    case kInt32ArrayCid: {
+        Label* deopt = compiler->AddDeoptStub(deopt_id(), kDeoptInt32Load);
+        __ movl(result, element_address);
+        // Verify that the signed value in 'result' can fit inside a Smi.
+        __ cmpl(result, Immediate(0xC0000000));
+        __ j(NEGATIVE, deopt);
+        __ SmiTag(result);
+      }
+      break;
+    case kUint32ArrayCid: {
+        Label* deopt = compiler->AddDeoptStub(deopt_id(), kDeoptUint32Load);
+        __ movl(result, element_address);
+        // Verify that the unsigned value in 'result' can fit inside a Smi.
+        __ testl(result, Immediate(0xC0000000));
+        __ j(NOT_ZERO, deopt);
+        __ SmiTag(result);
+      }
+      break;
     default:
       ASSERT((class_id() == kArrayCid) || (class_id() == kImmutableArrayCid));
       __ movl(result, element_address);