Remove dead code from IfThenElse and StrictCompare in the compiler.

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 118 matching lines @@
          (Utils::IsPowerOfTwo(v2) && (v1 == 0));
 }
 
 
 LocationSummary* IfThenElseInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RegisterOrConstant(left()));
-  locs->set_in(1, Location::RegisterOrConstant(right()));
+  // Only one of the inputs can be a constant. Choose register if the first one
+  // is a constant.
+  locs->set_in(1, locs->in(0).IsConstant()
+                      ? Location::RequiresRegister()
+                      : Location::RegisterOrConstant(right()));
   // TODO(vegorov): support byte register constraints in the register allocator.
   locs->set_out(Location::RegisterLocation(RDX));
   return locs;
 }
 
 
 void IfThenElseInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   ASSERT(locs()->out().reg() == RDX);
   ASSERT(Token::IsEqualityOperator(kind()));
 
   Location left = locs()->in(0);
   Location right = locs()->in(1);
-  if (left.IsConstant() && right.IsConstant()) {
-    // TODO(srdjan): Determine why this instruction was not eliminated.
-    bool result = (left.constant().raw() == right.constant().raw());
-    if ((kind_ == Token::kNE_STRICT) || (kind_ == Token::kNE)) {
-      result = !result;
-    }
-    __ LoadImmediate(locs()->out().reg(),
-            Immediate(reinterpret_cast<int64_t>(
-                Smi::New(result ? if_true_ : if_false_))), PP);
-    return;
-  }
-
   ASSERT(!left.IsConstant() || !right.IsConstant());
 
   // Clear upper part of the out register. We are going to use setcc on it
   // which is a byte move.
   __ xorq(RDX, RDX);
 
   // Compare left and right. For now only equality comparison is supported.
   // TODO(vegorov): reuse code from the other comparison instructions instead of
   // generating it inline here.
   if (left.IsConstant()) {
@@ skipping 4406 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64