Collect edge count profiling data and reorder basic blocks.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index ee9a5a08fb47a0d655796c53545688108e517585..3761087398b89f2a29da14a60e20b7c2b4fa7871 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -7,6 +7,7 @@
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
+#include "vm/block_scheduler.h"
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
 #include "vm/dart_entry.h"
@@ -294,6 +295,11 @@ static bool CompileParsedFunctionHelper(ParsedFunction* parsed_function,
       }
     }
 
+    BlockScheduler block_scheduler(flow_graph);

[Florian Schneider, 2013/08/12 11:30:09]

Maybe add a flag FLAG_reorder_basic_blocks to control reordering.

[Kevin Millikin (Google), 2013/08/13 11:14:57]

Done.

+    if (optimized) {
+      block_scheduler.AssignEdgeWeights();
+    }
+
     if (optimized) {
       TimerScope timer(FLAG_compiler_stats,
                        &CompilerStats::ssa_timer,
@@ -306,7 +312,6 @@ static bool CompileParsedFunctionHelper(ParsedFunction* parsed_function,
       }
     }
 
-
     // Collect all instance fields that are loaded in the graph and
     // have non-generic type feedback attached to them that can
     // potentially affect optimizations.
@@ -481,15 +486,15 @@ static bool CompileParsedFunctionHelper(ParsedFunction* parsed_function,
       FlowGraphAllocator allocator(*flow_graph);
       allocator.AllocateRegisters();
 
+      block_scheduler.ReorderBlocks();
+
       if (FLAG_print_flow_graph || FLAG_print_flow_graph_optimized) {
         FlowGraphPrinter::PrintGraph("After Optimizations", flow_graph);
       }
     }
 
     Assembler assembler;
-    FlowGraphCompiler graph_compiler(&assembler,
-                                     *flow_graph,
-                                     optimized);
+    FlowGraphCompiler graph_compiler(&assembler, flow_graph, optimized);
     {
       TimerScope timer(FLAG_compiler_stats,
                        &CompilerStats::graphcompiler_timer,