[Compiler] Enable use of seperate zones for parsing and compiling.

src/crankshaft/hydrogen.h

Index: src/crankshaft/hydrogen.h
diff --git a/src/crankshaft/hydrogen.h b/src/crankshaft/hydrogen.h
index 09817400fceef55719067eb59d4d0c69116887a4..aaff4c7f109f352319527c3fa2c1dc0d75b04e03 100644
--- a/src/crankshaft/hydrogen.h
+++ b/src/crankshaft/hydrogen.h
@@ -38,7 +38,8 @@ class HCompilationJob final : public CompilationJob {
   explicit HCompilationJob(Handle<JSFunction> function)
       : CompilationJob(function->GetIsolate(), &info_, "Crankshaft"),
         parse_info_(handle(function->shared())),
-        info_(&parse_info_, function),
+        compile_zone_(function->GetIsolate()->allocator(), ZONE_NAME),

[Toon Verwaest, 2017/01/26 21:24:47]

Is there value to creating separate zones if we can't parallelize anyway?
Allocating zones incurs runtime and memory overhead.

[rmcilroy, 2017/02/07 12:41:53]

Changed to only seperate zones when required and reuse the parse zone otherwise.

+        info_(&compile_zone_, &parse_info_, function),
         graph_(nullptr),
         chunk_(nullptr) {}
 
@@ -49,6 +50,7 @@ class HCompilationJob final : public CompilationJob {
 
  private:
   ParseInfo parse_info_;
+  Zone compile_zone_;
   CompilationInfo info_;
   HGraph* graph_;
   LChunk* chunk_;