Add range to kBIT_AND with positive constants. Use that range to eliminate compares in left shifts.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2012, 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_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 1651 matching lines @@
       __ SmiUntag(left);
       __ sarq(left, right);
       __ SmiTag(left);
       break;
     }
     case Token::kSHL: {
       Register temp = locs()->temp(0).reg();
       Label call_method, done;
       // Check if count too large for handling it inlined.
       __ movq(temp, left);
-      __ cmpq(right,
-          Immediate(reinterpret_cast<int64_t>(Smi::New(Smi::kBits))));
-      __ j(ABOVE_EQUAL, &call_method, Assembler::kNearJump);
+      Range* right_range = this->right()->definition()->range();
+      const bool right_needs_check =
+          (right_range == NULL) || !right_range->IsWithin(0, (Smi::kBits - 1));
+      if (right_needs_check) {
+        __ cmpq(right,
+            Immediate(reinterpret_cast<int64_t>(Smi::New(Smi::kBits))));
+        __ j(ABOVE_EQUAL, &call_method, Assembler::kNearJump);
+      }
       Register right_temp = locs()->temp(1).reg();
       ASSERT(right_temp == RCX);  // Count must be in RCX
       __ movq(right_temp, right);
       __ SmiUntag(right_temp);
       // Overflow test (preserve temp and right);
       __ shlq(left, right_temp);
       __ sarq(left, right_temp);
       __ cmpq(left, temp);
       __ j(NOT_EQUAL, &call_method, Assembler::kNearJump);  // Overflow.
       // Shift for result now we know there is no overflow.
@@ skipping 585 matching lines @@
 
 void ShiftMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64