Polymorphic inlining for some recognized methods in the optimizing compiler.

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/code_generator.h"
@@ skipping 320 matching lines @@
         optimizer.ApplyICData();
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
         // Optimize (a << b) & c patterns. Must occur before
         // 'SelectRepresentations' which inserts conversion nodes.
         // TODO(srdjan): Moved before inlining until environment use list can
         // be used to detect when shift-left is outside the scope of bit-and.
         optimizer.TryOptimizeLeftShiftWithBitAndPattern();
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
+        // Propagate types and eliminate more type tests.
+        if (FLAG_propagate_types) {
+          FlowGraphTypePropagator propagator(flow_graph);
+          propagator.Propagate();

[Kevin Millikin (Google), 2013/08/13 11:47:40]

Why?

We compute this five times.  The other four have a comment explaining why they
are called there, this one just has the same comment as the next one.

I'm guessing that it is necessary now for inlining?  If that's the case, can't
it be moved inside if (FLAG_use_inlining)?  (When !FLAG_use_inlining, we
propagate types and apply class ids twice in a row).

[Florian Schneider, 2013/08/14 12:30:24]

Without this I get some performance regressions where propagating types before
inlining helps. I'll move it inside the if-statement.

+          DEBUG_ASSERT(flow_graph->VerifyUseLists());
+        }
+
+        // Use propagated class-ids to optimize further.
+        optimizer.ApplyClassIds();
+        DEBUG_ASSERT(flow_graph->VerifyUseLists());
+
         // Inlining (mutates the flow graph)
         if (FLAG_use_inlining) {
           TimerScope timer(FLAG_compiler_stats,
                            &CompilerStats::graphinliner_timer);
           FlowGraphInliner inliner(flow_graph, &guarded_fields);
           inliner.Inline();
           // Use lists are maintained and validated by the inliner.
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
         }
 
@@ skipping 557 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart