Pattern match on generated code to find edge counters.

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 289 matching lines @@
       if (FLAG_print_flow_graph ||
           (optimized && FLAG_print_flow_graph_optimized)) {
         if (osr_id == Isolate::kNoDeoptId) {
           FlowGraphPrinter::PrintGraph("Before Optimizations", flow_graph);
         } else {
           FlowGraphPrinter::PrintGraph("For OSR", flow_graph);
         }
       }
 
       BlockScheduler block_scheduler(flow_graph);
-      if (optimized && FLAG_reorder_basic_blocks) {
+      const bool reorder_blocks =
+          FlowGraph::ShouldReorderBlocks(function, optimized);
+      if (reorder_blocks) {
         block_scheduler.AssignEdgeWeights();
       }
 
       if (optimized) {
         TimerScope timer(FLAG_compiler_stats,
                          &CompilerStats::ssa_timer,
                          isolate);
         // Transform to SSA (virtual register 0 and no inlining arguments).
         flow_graph->ComputeSSA(0, NULL);
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
@@ skipping 180 matching lines @@
           // Remove all MaterializeObject instructions inserted by allocation
           // sinking from the flow graph and let them float on the side
           // referenced only from environments. Register allocator will consider
           // them as part of a deoptimization environment.
           sinking->DetachMaterializations();
         }
 
         // Perform register allocation on the SSA graph.
         FlowGraphAllocator allocator(*flow_graph);
         allocator.AllocateRegisters();
-        if (FLAG_reorder_basic_blocks) block_scheduler.ReorderBlocks();
+        if (reorder_blocks) block_scheduler.ReorderBlocks();
 
         if (FLAG_print_flow_graph || FLAG_print_flow_graph_optimized) {
           FlowGraphPrinter::PrintGraph("After Optimizations", flow_graph);
         }
       }
 
       Assembler assembler(use_far_branches);
       FlowGraphCompiler graph_compiler(&assembler, flow_graph, optimized);
       {
         TimerScope timer(FLAG_compiler_stats,
@@ skipping 402 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