Eliminate overflow check for non-overflowing smi << operations.

runtime/vm/intermediate_language_x64.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_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 2555 matching lines @@
     __ CompareImmediate(result, Immediate(-0x20000000000000LL), PP);
     __ j(LESS, overflow);
     __ CompareImmediate(result, Immediate(0x20000000000000LL), PP);
     __ j(GREATER, overflow);
   }
 }
 
 
 static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
                              BinarySmiOpInstr* shift_left) {
-  const bool is_truncating = shift_left->is_truncating();
+  const bool is_truncating = shift_left->IsTruncating();
   const LocationSummary& locs = *shift_left->locs();
   Register left = locs.in(0).reg();
   Register result = locs.out(0).reg();
   ASSERT(left == result);
   Label* deopt = shift_left->CanDeoptimize() ?
       compiler->AddDeoptStub(shift_left->deopt_id(), ICData::kDeoptBinarySmiOp)
       : NULL;
   if (locs.in(1).IsConstant()) {
     const Object& constant = locs.in(1).constant();
     ASSERT(constant.IsSmi());
     // shlq operation masks the count to 6 bits.
     const intptr_t kCountLimit = 0x3F;
     const intptr_t value = Smi::Cast(constant).Value();
     if (value == 0) {
       // No code needed.
     } else if ((value < 0) || (value >= kCountLimit)) {
       // This condition may not be known earlier in some cases because
       // of constant propagation, inlining, etc.
-      if ((value >=kCountLimit) && is_truncating) {
+      if ((value >= kCountLimit) && is_truncating) {
         __ xorq(result, result);
       } else {
         // Result is Mint or exception.
         __ jmp(deopt);
       }
     } else {
       if (!is_truncating) {
         // Check for overflow.
         Register temp = locs.temp(0).reg();
         __ movq(temp, left);
@@ skipping 153 matching lines @@
     return summary;
   } else if (op_kind() == Token::kSHR) {
     const intptr_t kNumTemps = 0;
     LocationSummary* summary = new(isolate) LocationSummary(
         isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresRegister());
     summary->set_in(1, Location::FixedRegisterOrSmiConstant(right(), RCX));
     summary->set_out(0, Location::SameAsFirstInput());
     return summary;
   } else if (op_kind() == Token::kSHL) {
-    const intptr_t kNumTemps = !is_truncating() ? 1 : 0;
+    const intptr_t kNumTemps = !IsTruncating() ? 1 : 0;
     LocationSummary* summary = new(isolate) LocationSummary(
         isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresRegister());
     summary->set_in(1, Location::FixedRegisterOrSmiConstant(right(), RCX));
-    if (!is_truncating()) {
+    if (!IsTruncating()) {
       summary->set_temp(0, Location::RequiresRegister());
     }
     summary->set_out(0, Location::SameAsFirstInput());
     return summary;
   } else {
     const intptr_t kNumTemps = 0;
     LocationSummary* summary = new(isolate) LocationSummary(
         isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresRegister());
     ConstantInstr* constant = right()->definition()->AsConstant();
     if (constant != NULL) {
       summary->set_in(1, Location::RegisterOrSmiConstant(right()));
     } else {
       summary->set_in(1, Location::PrefersRegister());
     }
     summary->set_out(0, Location::SameAsFirstInput());
     return summary;
   }
 }
 
 void BinarySmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (op_kind() == Token::kSHL) {
     EmitSmiShiftLeft(compiler, this);
     return;
   }
 
-  ASSERT(!is_truncating());
   Register left = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
   ASSERT(left == result);
   Label* deopt = NULL;
   if (CanDeoptimize()) {
     deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptBinarySmiOp);
   }
 
   if (locs()->in(1).IsConstant()) {
     const Object& constant = locs()->in(1).constant();
@@ skipping 3024 matching lines @@
   __ movq(R10, Immediate(kInvalidObjectPointer));
   __ movq(RBX, Immediate(kInvalidObjectPointer));
 #endif
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64