Allow running mjsunit/manual-parallel-recompile on single-core systems.

- Add an %IsParallelSupported() builtin function to  make possible to check support of parallel processing from JavaScripts.
- Change the test script that if parallel recompilation is forced on a single core CPU, expect that it won't be recompiled in parallel.
- Change the  JSFunction::MarkForParallelRecompilation() to fall back gracefully if parallel recompilation is not supported.

BUG=v8:2733
TEST=mjsunit/manual-parallel-recompile

Review URL: https://codereview.chromium.org/17277002
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15184 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -9198,7 +9198,10 @@ void JSFunction::MarkForLazyRecompilation() {
 void JSFunction::MarkForParallelRecompilation() {
   ASSERT(is_compiled() && !IsOptimized());
   ASSERT(shared()->allows_lazy_compilation() || code()->optimizable());
-  ASSERT(FLAG_parallel_recompilation);
+  if (!FLAG_parallel_recompilation) {
+    JSFunction::MarkForLazyRecompilation();
+    return;
+  }
   if (FLAG_trace_parallel_recompilation) {
     PrintF("  ** Marking ");
     PrintName();

src/runtime.cc

@@ -8070,6 +8070,13 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_RunningInSimulator) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_IsParallelRecompilationSupported) {
+  HandleScope scope(isolate);
+  return FLAG_parallel_recompilation
+      ? isolate->heap()->true_value() : isolate->heap()->false_value();
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_OptimizeFunctionOnNextCall) {
   HandleScope scope(isolate);
   RUNTIME_ASSERT(args.length() == 1 || args.length() == 2);

src/runtime.h

@@ -95,6 +95,7 @@ namespace internal {
   F(DeoptimizeFunction, 1, 1) \
   F(ClearFunctionTypeFeedback, 1, 1) \
   F(RunningInSimulator, 0, 1) \
+  F(IsParallelRecompilationSupported, 0, 1) \
   F(OptimizeFunctionOnNextCall, -1, 1) \
   F(CompleteOptimization, 1, 1) \
   F(GetOptimizationStatus, 1, 1) \

test/mjsunit/manual-parallel-recompile.js

@@ -60,8 +60,10 @@ assertUnoptimized(g);
 %OptimizeFunctionOnNextCall(g, "parallel");
 f(g(2));  // Trigger optimization.
 
-assertUnoptimized(f);  // Not yet optimized.
-assertUnoptimized(g);
+if (%IsParallelRecompilationSupported()) {
+  assertUnoptimized(f);  // Not yet optimized.
+  assertUnoptimized(g);
+}
 
 %CompleteOptimization(f);  // Wait till optimized code is installed.
 %CompleteOptimization(g);