Speculate on bitwise operators.

runtime/vm/intermediate_language_arm.cc

 
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intermediate_language.h"
 
@@ skipping 3241 matching lines @@
       if (!combined_smi_check) {
         __ orr(result, left, Operand(right));
       }
       break;
     case Token::kBIT_AND:
       __ and_(result, left, Operand(right));
       break;
     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();
   }
   __ Bind(slow_path->exit_label());
 }
 
 
 class CheckedSmiComparisonSlowPath : public SlowPathCode {
  public:
   CheckedSmiComparisonSlowPath(CheckedSmiComparisonInstr* instruction,
@@ skipping 4009 matching lines @@
                                 1,
                                 locs());
   __ Drop(1);
   __ Pop(result);
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM