VM: Add flag to specify number of precompiler iterations.

runtime/vm/precompiler.cc

 // Copyright (c) 2015, 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/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 36 matching lines @@
 
 #define T (thread())
 #define I (isolate())
 #define Z (zone())
 
 
 DEFINE_FLAG(bool, print_unique_targets, false, "Print unique dynaic targets");
 DEFINE_FLAG(bool, trace_precompiler, false, "Trace precompiler.");
 DEFINE_FLAG(int, max_speculative_inlining_attempts, 1,
     "Max number of attempts with speculative inlining (precompilation only)");
+DEFINE_FLAG(int, precompiler_rounds, 1, "Number of precompiler iterations");
 
 DECLARE_FLAG(bool, allocation_sinking);
 DECLARE_FLAG(bool, common_subexpression_elimination);
 DECLARE_FLAG(bool, constant_propagation);
 DECLARE_FLAG(bool, loop_invariant_code_motion);
 DECLARE_FLAG(bool, print_flow_graph);
 DECLARE_FLAG(bool, print_flow_graph_optimized);
 DECLARE_FLAG(bool, range_analysis);
 DECLARE_FLAG(bool, trace_compiler);
 DECLARE_FLAG(bool, trace_optimizing_compiler);
@@ skipping 94 matching lines @@
 
   {
     StackZone stack_zone(T);
     zone_ = stack_zone.GetZone();
 
     // Make sure class hierarchy is stable before compilation so that CHA
     // can be used. Also ensures lookup of entry points won't miss functions
     // because their class hasn't been finalized yet.
     FinalizeAllClasses();
 
-    const intptr_t kPrecompilerRounds = 1;
-    for (intptr_t round = 0; round < kPrecompilerRounds; round++) {
+    for (intptr_t round = 0; round < FLAG_precompiler_rounds; round++) {
       if (FLAG_trace_precompiler) {
         THR_Print("Precompiler round %" Pd "\n", round);
       }
 
       if (round > 0) {
         ResetPrecompilerState();
       }
 
       // TODO(rmacnak): We should be able to do a more thorough job and drop
       // some
@@ skipping 2575 matching lines @@
       CompilationPipeline::New(thread->zone(), function);
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   return PrecompileFunctionHelper(pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart