[wasm] Move the semaphore for parallel compilation to the wasm module.

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 160 matching lines @@
   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.
   std::vector<uint16_t> function_table;        // function table.
   std::vector<WasmImport> import_table;        // import table.
   std::vector<WasmExport> export_table;        // export table.
+  // We store the semaphore here to extend its lifetime. In <libc-2.21, which we
+  // use on the try bots, semaphore::Wait() can return while some compilation
+  // tasks are still executing semaphore::Signal(). If the semaphore is cleaned
+  // up right after semaphore::Wait() returns, then this can cause an
+  // invalid-semaphore error in the compilation tasks.
+  // TODO(wasm): Move this semaphore back to CompileInParallel when the try bots
+  // switch to libc-2.21 or higher.
+  base::SmartPointer<base::Semaphore> pending_tasks;
 
   WasmModule();
 
   // Get a string stored in the module bytes representing a name.
   WasmName GetName(uint32_t offset, uint32_t length) const {
     if (length == 0) return {"<?>", 3};  // no name.
     CHECK(BoundsCheck(offset, offset + length));
     DCHECK_GE(static_cast<int>(length), 0);
     return {reinterpret_cast<const char*>(module_start + offset),
             static_cast<int>(length)};
@@ skipping 169 matching lines @@
 // 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);
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MODULE_H_