Support Int32 representation for selected binary operations.

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 393 matching lines @@
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
           // A canonicalization pass to remove e.g. smi checks on smi constants.
           optimizer.Canonicalize();
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
           // Canonicalization introduced more opportunities for constant
           // propagation.
           ConstantPropagator::Optimize(flow_graph);
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
         }
 
+        // Optimistically convert loop phis that have a single non-smi input
+        // coming from the loop pre-header into smi-phis.
+        if (FLAG_loop_invariant_code_motion) {
+          LICM licm(flow_graph);
+          licm.OptimisticallySpecializeSmiPhis();
+          DEBUG_ASSERT(flow_graph->VerifyUseLists());
+        }
+
         // Propagate types and eliminate even more type tests.
         // Recompute types after constant propagation to infer more precise
         // types for uses that were previously reached by now eliminated phis.
         FlowGraphTypePropagator::Propagate(flow_graph);
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
+        // Where beneficial convert Smi operations into Int32 operations.
+        // Only meanigful for 32bit platforms right now.
+        optimizer.WidenSmiToInt32();
+
         // Unbox doubles. Performed after constant propagation to minimize
         // interference from phis merging double values and tagged
         // values coming from dead paths.
         optimizer.SelectRepresentations();
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
         if (FLAG_common_subexpression_elimination ||
             FLAG_loop_invariant_code_motion) {
           flow_graph->ComputeBlockEffects();
         }
@@ skipping 591 matching lines @@
     const Object& result =
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart