Pattern match on generated code to find edge counters.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index d9f1a537efe366f8b38790337a081f4d3e193c2e..4d81db0d9449a6685548a37337815ec9b754a975 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -307,7 +307,9 @@ static bool CompileParsedFunctionHelper(ParsedFunction* parsed_function,
       }
 
       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();
       }
 
@@ -508,7 +510,7 @@ static bool CompileParsedFunctionHelper(ParsedFunction* parsed_function,
         // 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);