Speculate on bitwise operators.

runtime/vm/intermediate_language_arm.cc

Index: runtime/vm/intermediate_language_arm.cc
diff --git a/runtime/vm/intermediate_language_arm.cc b/runtime/vm/intermediate_language_arm.cc
index fd50a1423bf24310b76107a56fbf73f46c8b8f5f..6826b63feca0bd503c7a74949ad79423e56bd76b 100644
--- a/runtime/vm/intermediate_language_arm.cc
+++ b/runtime/vm/intermediate_language_arm.cc
@@ -3259,6 +3259,32 @@ void CheckedSmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     case Token::kBIT_XOR:
       __ eor(result, left, Operand(right));
       break;
+    case Token::kSHL:
+      ASSERT(result != left);
+      ASSERT(result != right);
+      __ CompareImmediate(right, Smi::RawValue(Smi::kBits));
+      __ b(slow_path->entry_label(), HI);
+
+      __ SmiUntag(TMP, right);
+      // Check for overflow by shifting left and shifting back arithmetically.
+      // If the result is different from the original, there was overflow.
+      __ mov(result, Operand(left, LSL, TMP));

[Florian Schneider, 2016/11/11 18:12:20]

Can Assembler::LsL be used here as well?

[rmacnak, 2016/11/11 21:29:02]

Done.

+      __ cmp(left, Operand(result, ASR, TMP));
+      __ b(slow_path->entry_label(), NE);
+      break;
+    case Token::kSHR:
+      ASSERT(result != left);
+      ASSERT(result != right);
+      __ CompareImmediate(right, 0);
+      __ b(slow_path->entry_label(), LT);
+
+      __ SmiUntag(result, right);
+      __ CompareImmediate(result, 0x1F);
+      __ LoadImmediate(result, 0x1F, GT);
+      __ SmiUntag(TMP, left);
+      __ mov(result, Operand(TMP, ASR, result));

[Florian Schneider, 2016/11/11 18:12:20]

Use Asr?

[rmacnak, 2016/11/11 21:29:02]

Done.

+      __ SmiTag(result);
+      break;
     default:
       UNREACHABLE();
   }