Replace manual untagging of smi with proper Smi methods

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 6525 matching lines @@
   PairLocation* out_pair = locs()->out(0).AsPairLocation();
   Register out_lo = out_pair->At(0).reg();
   Register out_hi = out_pair->At(1).reg();
 
   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());

[Vyacheslav Egorov (Google), 2017/07/12 16:56:27]

I think this ASSERT can be deleted because Smi::Cast(...) contains the same
assert.

[alexmarkov, 2017/07/12 17:37:37]

You are right, it can be deleted. However, I think the explicit ASSERT makes
this code a little bit more readable. Also, it is more convenient to get an
assertion failure message at a more specific place rather than inside generic
Smi::Cast() which is called from many other places.

So I would prefer to leave it here, if you don't mind.

-    const int32_t shift =
-        reinterpret_cast<int32_t>(locs()->in(1).constant().raw()) >> 1;
+    const int32_t shift = Smi::Cast(locs()->in(1).constant()).Value();
     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));
@@ skipping 591 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