Control static type propagation with a flag in 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"
 #include "vm/code_patcher.h"
@@ skipping 21 matching lines @@
 namespace dart {
 
 DEFINE_FLAG(bool, disassemble, false, "Disassemble dart code.");
 DEFINE_FLAG(bool, disassemble_optimized, false, "Disassemble optimized code.");
 DEFINE_FLAG(bool, trace_bailout, false, "Print bailout from ssa compiler.");
 DEFINE_FLAG(bool, trace_compiler, false, "Trace compiler operations.");
 DEFINE_FLAG(bool, cp, true,
     "Do conditional constant propagation/unreachable code elimination.");
 DEFINE_FLAG(bool, cse, true, "Do common subexpression elimination.");
 DEFINE_FLAG(bool, licm, true, "Do loop invariant code motion.");
+DEFINE_FLAG(bool, propagate_types, true, "Do static type propagation.");
 DEFINE_FLAG(int, deoptimization_counter_threshold, 5,
     "How many times we allow deoptimization before we disallow"
     " certain optimizations");
 DEFINE_FLAG(bool, use_inlining, true, "Enable call-site inlining");
 DECLARE_FLAG(bool, print_flow_graph);
 
 
 // Compile a function. Should call only if the function has not been compiled.
 //   Arg0: function object.
 DEFINE_RUNTIME_ENTRY(CompileFunction, 1) {
@@ skipping 122 matching lines @@
 
         // Inlining (mutates the flow graph)
         if (FLAG_use_inlining) {
           FlowGraphInliner inliner(flow_graph);
           inliner.Inline();
           // Verify that the use lists are still valid.
           DEBUG_ASSERT(flow_graph->ValidateUseLists());
         }
 
         // Propagate types and eliminate more type tests.
-        FlowGraphTypePropagator propagator(flow_graph);
-        propagator.PropagateTypes();
+        if (FLAG_propagate_types) {
+          FlowGraphTypePropagator propagator(flow_graph);
+          propagator.PropagateTypes();
+        }
 
         // Verify that the use lists are still valid.
         DEBUG_ASSERT(flow_graph->ValidateUseLists());
 
         // Propagate sminess from CheckSmi to phis.
         optimizer.PropagateSminess();
 
         // Do optimizations that depend on the propagated type information.
         optimizer.OptimizeComputations();
 
@@ skipping 363 matching lines @@
     result = 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