Revise assertions and fix bug in the implementation of shifts

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"
 
 #include "vm/compiler.h"
@@ skipping 6528 matching lines @@
 
   Label* deopt = NULL;
   if (CanDeoptimize()) {
     deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptBinaryMintOp);
   }
   if (locs()->in(1).IsConstant()) {
     // Code for a constant shift amount.
     ASSERT(locs()->in(1).constant().IsSmi());
     const int32_t shift =
         reinterpret_cast<int32_t>(locs()->in(1).constant().raw()) >> 1;
-    // TODO(alexmarkov): revise and uncomment the following assertions
-    // ASSERT(!has_shift_count_check());
-    // ASSERT(shift >= 0);
+    ASSERT(shift >= 0);
     switch (op_kind()) {
       case Token::kSHR: {
         if (shift < 32) {
           __ Lsl(out_lo, left_hi, Operand(32 - shift));
           __ orr(out_lo, out_lo, Operand(left_lo, LSR, shift));
           __ Asr(out_hi, left_hi, Operand(shift));
         } else {
           if (shift == 32) {
             __ mov(out_lo, Operand(left_hi));
           } else if (shift < 64) {
@@ skipping 41 matching lines @@
         UNREACHABLE();
     }
   } else {
     // Code for a variable shift amount.
     Register shift = locs()->in(1).reg();
 
     // Untag shift count.
     __ SmiUntag(shift);
 
     // Deopt if shift is larger than 63 or less than 0.
-    if (has_shift_count_check()) {
+    if (!IsShiftCountInRange()) {
       __ CompareImmediate(shift, kMintShiftCountLimit);
       __ b(deopt, HI);
     }
 
     switch (op_kind()) {
       case Token::kSHR: {
         __ rsbs(IP, shift, Operand(32));
         __ sub(IP, shift, Operand(32), MI);
         __ mov(out_lo, Operand(left_hi, ASR, IP), MI);
         __ mov(out_lo, Operand(left_lo, LSR, shift), PL);
@@ skipping 528 matching lines @@
   ASSERT(!compiler->is_optimizing());
   __ BranchLinkPatchable(*StubCode::DebugStepCheck_entry());
   compiler->AddCurrentDescriptor(stub_kind_, deopt_id_, token_pos());
   compiler->RecordSafepoint(locs());
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM