[wasm] Split the wasm compilation into two phases for parallel compilation.

src/compiler/wasm-compiler.h

 // Copyright 2015 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_COMPILER_WASM_COMPILER_H_
 #define V8_COMPILER_WASM_COMPILER_H_
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
 // Do not include anything from src/compiler here!
 #include "src/wasm/wasm-opcodes.h"
@@ skipping 37 matching lines @@
                                     wasm::WasmName function_name);
 
 // Wraps a given wasm code object, producing a JSFunction that can be called
 // from JavaScript.
 Handle<JSFunction> CompileJSToWasmWrapper(
     Isolate* isolate, wasm::ModuleEnv* module, Handle<String> name,
     Handle<Code> wasm_code, Handle<JSObject> module_object, uint32_t index);
 
 WasmCompilationUnit* CreateWasmCompilationUnit(
     wasm::ErrorThrower* thrower, Isolate* isolate, wasm::ModuleEnv* module_env,
-    const wasm::WasmFunction* function);
+    const wasm::WasmFunction* function, uint32_t index);
 
 void ExecuteCompilation(WasmCompilationUnit* unit);
 
-int GetIndexOfWasmCompilationUnit(WasmCompilationUnit* unit);
+Handle<Code> FinishCompilation(WasmCompilationUnit* unit);
 
-Handle<Code> FinishCompilation(WasmCompilationUnit* unit);
+uint32_t GetIndexOfWasmCompilationUnit(WasmCompilationUnit* unit);
 
 // Abstracts details of building TurboFan graph nodes for WASM to separate
 // the WASM decoder from the internal details of TurboFan.
 class WasmTrapHelper;
 class WasmGraphBuilder {
  public:
   WasmGraphBuilder(
       Zone* z, JSGraph* g, wasm::FunctionSig* function_signature,
       compiler::SourcePositionTable* source_position_table = nullptr);
 
@@ skipping 220 matching lines @@
     Node** buf = Buffer(new_count);
     if (buf != buffer) memcpy(buf, buffer, old_count * sizeof(Node*));
     return buf;
   }
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_WASM_COMPILER_H_