[cleanup] Templatize the EnableFlagScope

The EnableFlagScope is useful also for non-boolean flags. With the
template we can use if for example in the wasm fuzzers to reduce the
maximum memory size of a wasm module.

In addition I put the EnableFlagScope into the v8::internal namespace,
and I fixed a small typo.

BUG=v8:6474
R=clemensh@chromium.org

Change-Id: Iae5d5c058c334cd0f9e09d20adfd229fc2d6c585
Reviewed-on: https://chromium-review.googlesource.com/531005
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45862}

test/common/wasm/flag-utils.h

@@ -5,20 +5,26 @@
 #ifndef V8_TEST_COMMON_FLAG_UTILS_H
 #define V8_TEST_COMMON_FLAG_UTILS_H
 
-class EnableFlagScope {
+namespace v8 {
+namespace internal {
+
+template <typename T>
+class FlagScope {
  public:
-  EnableFlagScope(bool* flag, bool new_value = true)
-      : flag_(flag), previous_value_(flag) {
+  FlagScope(T* flag, T new_value) : flag_(flag), previous_value_(*flag) {
     *flag = new_value;
   }
-  ~EnableFlagScope() { *flag_ = previous_value_; }
+  ~FlagScope() { *flag_ = previous_value_; }
 
  private:
-  bool* flag_;
-  bool previous_value_;
+  T* flag_;
+  T previous_value_;
 };
 
 #define EXPERIMENTAL_FLAG_SCOPE(flag) \
-  EnableFlagScope __flag_scope_##__LINE__(&FLAG_experimental_wasm_##flag)
+  FlagScope<bool> __scope_##__LINE__(&FLAG_experimental_wasm_##flag, true)
+
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_TEST_COMMON_FLAG_UTILS_H

test/fuzzer/wasm-asmjs.cc

@@ -13,14 +13,15 @@
 #include "src/objects-inl.h"
 #include "src/objects.h"
 #include "src/wasm/wasm-module.h"
+#include "test/common/wasm/flag-utils.h"
 #include "test/common/wasm/wasm-module-runner.h"
 #include "test/fuzzer/fuzzer-support.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  unsigned int max_mem_flag_value = v8::internal::FLAG_wasm_max_mem_pages;
-  unsigned int max_table_flag_value = v8::internal::FLAG_wasm_max_table_size;
-  v8::internal::FLAG_wasm_max_mem_pages = 32;
-  v8::internal::FLAG_wasm_max_table_size = 100;
+  v8::internal::FlagScope<uint32_t> max_mem_flag_scope(
+      &v8::internal::FLAG_wasm_max_mem_pages, 32);
+  v8::internal::FlagScope<uint32_t> max_table_size_scope(
+      &v8::internal::FLAG_wasm_max_table_size, 100);
   v8_fuzzer::FuzzerSupport* support = v8_fuzzer::FuzzerSupport::Get();
   v8::Isolate* isolate = support->GetIsolate();
   v8::internal::Isolate* i_isolate =
@@ -38,7 +39,5 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   v8::internal::wasm::testing::SetupIsolateForWasmModule(i_isolate);
   v8::internal::wasm::testing::CompileAndRunAsmWasmModule(i_isolate, data,
                                                           data + size);
-  v8::internal::FLAG_wasm_max_mem_pages = max_mem_flag_value;
-  v8::internal::FLAG_wasm_max_table_size = max_table_flag_value;
   return 0;
 }

test/fuzzer/wasm.cc

@@ -13,14 +13,15 @@
 #include "src/objects-inl.h"
 #include "src/objects.h"
 #include "src/wasm/wasm-module.h"
+#include "test/common/wasm/flag-utils.h"
 #include "test/common/wasm/wasm-module-runner.h"
 #include "test/fuzzer/fuzzer-support.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  unsigned int max_mem_flag_value = v8::internal::FLAG_wasm_max_mem_pages;
-  unsigned int max_table_flag_value = v8::internal::FLAG_wasm_max_table_size;
-  v8::internal::FLAG_wasm_max_mem_pages = 32;
-  v8::internal::FLAG_wasm_max_table_size = 100;
+  v8::internal::FlagScope<uint32_t> max_mem_flag_scope(
+      &v8::internal::FLAG_wasm_max_mem_pages, 32);
+  v8::internal::FlagScope<uint32_t> max_table_size_scope(
+      &v8::internal::FLAG_wasm_max_table_size, 100);
   v8_fuzzer::FuzzerSupport* support = v8_fuzzer::FuzzerSupport::Get();
   v8::Isolate* isolate = support->GetIsolate();
   v8::internal::Isolate* i_isolate =
@@ -38,7 +39,5 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   v8::internal::wasm::testing::SetupIsolateForWasmModule(i_isolate);
   v8::internal::wasm::testing::CompileAndRunWasmModule(i_isolate, data,
                                                        data + size);
-  v8::internal::FLAG_wasm_max_mem_pages = max_mem_flag_value;
-  v8::internal::FLAG_wasm_max_table_size = max_table_flag_value;
   return 0;
 }

test/unittests/wasm/module-decoder-unittest.cc

@@ -835,7 +835,7 @@ TEST_F(WasmSignatureDecodeTest, TooManyParams) {
 
 TEST_F(WasmSignatureDecodeTest, TooManyReturns) {
   for (int i = 0; i < 2; i++) {
-    EnableFlagScope flag_scope(&FLAG_experimental_wasm_mv, i != 0);
+    FlagScope<bool> flag_scope(&FLAG_experimental_wasm_mv, i != 0);
     const int max_return_count = static_cast<int>(
         FLAG_experimental_wasm_mv ? kV8MaxWasmFunctionMultiReturns
                                   : kV8MaxWasmFunctionReturns);