[wasm] cloning compiled module before instantiation

src/wasm/wasm-module.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_WASM_MODULE_H_
 #define V8_WASM_MODULE_H_
 
 #include "src/api.h"
 #include "src/handles.h"
 #include "src/wasm/wasm-opcodes.h"
@@ skipping 147 matching lines @@
   static const uint32_t kPageSize = 0x10000;    // Page size, 64kb.
   static const uint32_t kMinMemPages = 1;       // Minimum memory size = 64kb
   static const uint32_t kMaxMemPages = 16384;   // Maximum memory size =  1gb
 
   const byte* module_start;   // starting address for the module bytes.
   const byte* module_end;     // end address for the module bytes.
   uint32_t min_mem_pages;     // minimum size of the memory in 64k pages.
   uint32_t max_mem_pages;     // maximum size of the memory in 64k pages.
   bool mem_export;            // true if the memory is exported.
   bool mem_external;          // true if the memory is external.
+  // TODO(wasm): model the start_function_index as a uint32_t, to be able
+  // to represent any valid index in the wasm function table. Model its
+  // presence/absence separately, as a bool.

[titzer, 2016/07/12 15:45:52]

Can you remove this TODO? I'd rather keep the current behavior. We'll need to
establish a limit on the number of functions in the decoder and the range of an
int seems reasonable to me.

[Mircea Trofin, 2016/07/12 16:12:23]

Reworded it, we do have a problem, so I'd be remiss if I just removed it. 

   int start_function_index;   // start function, if any.
   ModuleOrigin origin;        // origin of the module
 
   std::vector<WasmGlobal> globals;             // globals in this module.
   uint32_t globals_size;                       // size of globals table.
   uint32_t indirect_table_size;                // size of indirect function
                                                //     table (includes padding).
   std::vector<FunctionSig*> signatures;        // signatures in this module.
   std::vector<WasmFunction> functions;         // functions in this module.
   std::vector<WasmDataSegment> data_segments;  // data segments in this module.
@@ skipping 174 matching lines @@
 // Return the binary source bytes of a wasm module.
 SeqOneByteString* GetWasmBytes(JSObject* wasm);
 
 // Get the debug info associated with the given wasm object.
 // If no debug info exists yet, it is created automatically.
 Handle<WasmDebugInfo> GetDebugInfo(Handle<JSObject> wasm);
 
 // Return the number of functions in the given wasm object.
 int GetNumberOfFunctions(JSObject* wasm);
 
+// Create an export JSFunction

[titzer, 2016/07/12 15:45:52]

s/an/and/

[Mircea Trofin, 2016/07/12 16:12:23]

Done.

+Handle<JSFunction> CreateExport(Isolate* isolate, Handle<Code> export_code,
+                                Handle<String> name, int arity,
+                                Handle<JSObject> module_instance);
+
 // Check whether the given object is a wasm object.
 // This checks the number and type of internal fields, so it's not 100 percent
 // secure. If it turns out that we need more complete checks, we could add a
 // special marker as internal field, which will definitely never occur anywhere
 // else.
 bool IsWasmObject(Object* object);
 
 // Update memory references of code objects associated with the module
 bool UpdateWasmModuleMemory(Handle<JSObject> object, Address old_start,
                             Address new_start, uint32_t old_size,
                             uint32_t new_size);
 
 namespace testing {
 
 // Decode, verify, and run the function labeled "main" in the
 // given encoded module. The module should have no imports.
 int32_t CompileAndRunWasmModule(Isolate* isolate, const byte* module_start,
                                 const byte* module_end, bool asm_js = false);
 
 }  // namespace testing
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MODULE_H_