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

src/crankshaft/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_CRANKSHAFT_HYDROGEN_H_
 #define V8_CRANKSHAFT_HYDROGEN_H_
 
 #include "src/accessors.h"
 #include "src/allocation.h"
 #include "src/ast/ast-type-bounds.h"
@@ skipping 20 matching lines @@
 class HTracer;
 class LAllocator;
 class LChunk;
 class LiveRange;
 
 class HCompilationJob final : public CompilationJob {
  public:
   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) {}
 
  protected:
   virtual Status PrepareJobImpl();
   virtual Status ExecuteJobImpl();
   virtual Status FinalizeJobImpl();
 
  private:
   ParseInfo parse_info_;
+  Zone compile_zone_;
   CompilationInfo info_;
   HGraph* graph_;
   LChunk* chunk_;
 };
 
 class HBasicBlock final : public ZoneObject {
  public:
   explicit HBasicBlock(HGraph* graph);
   ~HBasicBlock() { }
 
@@ skipping 2932 matching lines @@
   }
 
  private:
   HOptimizedGraphBuilder* builder_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_HYDROGEN_H_