Implement a simple register allocator that tries to keep instruction results in registers.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index 725858bc713d7946dc32cfd15bbd7e4fc34e102f..ef724d289ba89b3ff30e7139f0b84e90bfd3f018 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -32,6 +32,7 @@ DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, trace_type_checks);
 DECLARE_FLAG(bool, report_usage_count);
 DECLARE_FLAG(int, deoptimization_counter_threshold);
+DEFINE_FLAG(charp, optimization_filter, NULL, "Optimize only named function");
 
 
 bool CodeGenerator::CanOptimize() {
@@ -1341,6 +1342,13 @@ DEFINE_RUNTIME_ENTRY(OptimizeInvokedFunction, 1) {
     function.set_usage_counter(kLowInvocationCount);
     return;
   }
+  if ((FLAG_optimization_filter != NULL) &&
+      (strncmp(function.ToFullyQualifiedCString(),
+               FLAG_optimization_filter,
+               strlen(FLAG_optimization_filter)) != 0)) {
+    function.set_usage_counter(kLowInvocationCount);

[srdjan, 2012/06/18 16:33:20]

Why not doing this in the compiler and "Bailout" from optimizing this function?

[Vyacheslav Egorov (Google), 2012/06/18 17:51:16]

I don't see any profit in bailing out so late in the pipeline compared to
bailing out later. This is a purely debug flag.

+    return;
+  }
   if (function.is_optimizable()) {
     ASSERT(!function.HasOptimizedCode());
     const Code& unoptimized_code = Code::Handle(function.unoptimized_code());