Count-based profiling for primitive functions (hidden behind a flag)

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index a4fabe2ac1a06fd032d52ad8330a02f3cb99a462..8e44660ac506b9d85e07451ece50548210135d93 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -139,6 +139,28 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
   }
 #endif
 
+  // Primitive functions are unlikely to be picked up by the stack-walking
+  // profiler, so they trigger their own optimization when they're called
+  // for the SharedFunctionInfo::kCallsUntilPrimitiveOptimization-th time.

[Erik Corry, 2012/02/09 09:43:33]

I think this comment should be moved into ShouldSelfOptimize, where it actually
describes the logic used to make the decision.  Then it is in the right place
for when we change the heuristic.

Here we should have a more generic comment like:

// We can optionally optimize based on counters rather than statistical
sampling.

[Jakob Kummerow, 2012/02/09 10:13:20]

Done.

+  if (info->ShouldSelfOptimize()) {
+    if (FLAG_trace_opt) {

[Erik Corry, 2012/02/09 09:43:33]

I think this might be annoyingly verbose, but we can add a trace-opt-verbose
flag later if we need to.

[Jakob Kummerow, 2012/02/09 10:13:20]

As discussed, let's leave it for now. We can always remove it later.

+      PrintF("[adding self-optimization header to %s]\n",
+             *info->function()->debug_name()->ToCString());
+    }
+    MaybeObject* maybe_cell = isolate()->heap()->AllocateJSGlobalPropertyCell(
+        Smi::FromInt(Compiler::kCallsUntilPrimitiveOpt));
+    JSGlobalPropertyCell* cell;
+    if (maybe_cell->To(&cell)) {
+      __ mov(r2, Operand(Handle<JSGlobalPropertyCell>(cell)));
+      __ ldr(r3, FieldMemOperand(r2, JSGlobalPropertyCell::kValueOffset));
+      __ sub(r3, r3, Operand(Smi::FromInt(1)), SetCC);
+      __ str(r3, FieldMemOperand(r2, JSGlobalPropertyCell::kValueOffset));
+      Handle<Code> compile_stub(
+          isolate()->builtins()->builtin(Builtins::kLazyRecompile));
+      __ Jump(compile_stub, RelocInfo::CODE_TARGET, eq);
+    }
+  }
+
   // Strict mode functions and builtins need to replace the receiver
   // with undefined when called as functions (without an explicit
   // receiver object). r5 is zero for method calls and non-zero for