Revert "Remove --win64-unwinding-info flag and always generate unwind info on Win/x64"

This reverts commit efd8c2d9.

Reason for revert: Performance regressions (chromium:958035)

Original change's description:
> Remove --win64-unwinding-info flag and always generate unwind info on Win/x64
>
> The generation of unwind info to enable stack walking on Windows/x64
> (https://chromium-review.googlesource.com/c/v8/v8/+/1469329) was implemented
> behind a temporary flag, in order to coordinate these changes with the
> corresponding changes in Chromium.
>
> The required changes to Chromium
> (https://chromium-review.googlesource.com/c/chromium/src/+/1474703) have also
> been merged, so we can now remove the flag and enable the generation of stack
> unwinding info by default on Windows/x64.
>
> Bug: v8:3598
> Change-Id: I88814aaeabecc007f5262227aa0681a1d16156d5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1573138
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Paolo Severini <paolosev@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#61020}

TBR=ulan@chromium.org,mstarzinger@chromium.org,jgruber@chromium.org,paolosev@microsoft.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Tbr: ulan@chromium.org,mstarzinger@chromium.org,paolosev@microsoft.com
Bug: v8:3598, chromium:958035
Change-Id: Ia86a230ee83080ed8ace43e4641c8c1013043df4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1598748
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61259}

BUILD.gn

@@ -89,7 +89,7 @@ declare_args() {
   v8_enable_embedded_builtins = true
 
   # Enable the registration of unwinding info for Windows/x64.
-  v8_win64_unwinding_info = true
+  v8_win64_unwinding_info = false
 
   # Enable code comments for builtins in the snapshot (impacts performance).
   v8_enable_snapshot_code_comments = false
@@ -1180,6 +1180,10 @@ template("run_mksnapshot") {
 
     args += invoker.args
 
+    if (v8_win64_unwinding_info) {
+      args += [ "--win64-unwinding-info" ]
+    }
+
     if (v8_enable_embedded_builtins) {
       outputs += [ "$target_gen_dir/embedded${suffix}.S" ]
       args += [

src/flag-definitions.h

@@ -1400,7 +1400,8 @@ DEFINE_STRING(redirect_code_traces_to, nullptr,
 DEFINE_BOOL(print_opt_source, false,
             "print source code of optimized and inlined functions")
 
-DEFINE_BOOL(win64_unwinding_info, true, "Enable unwinding info for Windows/x64")
+DEFINE_BOOL(win64_unwinding_info, false,
+            "Enable unwinding info for Windows/x64 (experimental).")
 
 #ifdef V8_TARGET_ARCH_ARM
 // Unsupported on arm. See https://crbug.com/v8/8713.

src/wasm/wasm-code-manager.cc

@@ -429,8 +429,8 @@ NativeModule::NativeModule(WasmEngine* engine, const WasmFeatures& enabled,
   // See src/heap/spaces.cc, MemoryAllocator::InitializeCodePageAllocator() and
   // https://cs.chromium.org/chromium/src/components/crash/content/app/crashpad_win.cc?rcl=fd680447881449fba2edcf0589320e7253719212&l=204
   // for details.
-  if (engine_->code_manager()
-          ->CanRegisterUnwindInfoForNonABICompliantCodeRange()) {
+  if (win64_unwindinfo::CanRegisterUnwindInfoForNonABICompliantCodeRange() &&
+      FLAG_win64_unwinding_info) {
     AllocateForCode(Heap::GetCodeRangeReservedAreaSize());
   }
 #endif
@@ -1038,22 +1038,11 @@ WasmCodeManager::WasmCodeManager(WasmMemoryTracker* memory_tracker,
                                  size_t max_committed)
     : memory_tracker_(memory_tracker),
       max_committed_code_space_(max_committed),
-#if defined(V8_OS_WIN_X64)
-      is_win64_unwind_info_disabled_for_testing_(false),
-#endif
       total_committed_code_space_(0),
       critical_committed_code_space_(max_committed / 2) {
   DCHECK_LE(max_committed, kMaxWasmCodeMemory);
 }
 
-#if defined(V8_OS_WIN_X64)
-bool WasmCodeManager::CanRegisterUnwindInfoForNonABICompliantCodeRange() const {
-  return win64_unwindinfo::CanRegisterUnwindInfoForNonABICompliantCodeRange() &&
-         FLAG_win64_unwinding_info &&
-         !is_win64_unwind_info_disabled_for_testing_;
-}
-#endif
-
 bool WasmCodeManager::Commit(Address start, size_t size) {
   // TODO(v8:8462) Remove eager commit once perf supports remapping.
   if (FLAG_perf_prof) return true;
@@ -1207,7 +1196,8 @@ std::shared_ptr<NativeModule> WasmCodeManager::NewNativeModule(
              size);
 
 #if defined(V8_OS_WIN_X64)
-  if (CanRegisterUnwindInfoForNonABICompliantCodeRange()) {
+  if (win64_unwindinfo::CanRegisterUnwindInfoForNonABICompliantCodeRange() &&
+      FLAG_win64_unwinding_info) {
     win64_unwindinfo::RegisterNonABICompliantCodeRange(
         reinterpret_cast<void*>(start), size);
   }
@@ -1393,7 +1383,8 @@ void WasmCodeManager::FreeNativeModule(NativeModule* native_module) {
                code_space.address(), code_space.end(), code_space.size());
 
 #if defined(V8_OS_WIN_X64)
-    if (CanRegisterUnwindInfoForNonABICompliantCodeRange()) {
+    if (win64_unwindinfo::CanRegisterUnwindInfoForNonABICompliantCodeRange() &&
+        FLAG_win64_unwinding_info) {
       win64_unwindinfo::UnregisterNonABICompliantCodeRange(
           reinterpret_cast<void*>(code_space.address()));
     }

src/wasm/wasm-code-manager.h

@@ -561,10 +561,6 @@ class V8_EXPORT_PRIVATE WasmCodeManager final {
   }
 #endif
 
-#if defined(V8_OS_WIN_X64)
-  bool CanRegisterUnwindInfoForNonABICompliantCodeRange() const;
-#endif
-
   NativeModule* LookupNativeModule(Address pc) const;
   WasmCode* LookupCode(Address pc) const;
   size_t committed_code_space() const {
@@ -573,12 +569,6 @@ class V8_EXPORT_PRIVATE WasmCodeManager final {
 
   void SetMaxCommittedMemoryForTesting(size_t limit);
 
-#if defined(V8_OS_WIN_X64)
-  void DisableWin64UnwindInfoForTesting() {
-    is_win64_unwind_info_disabled_for_testing_ = true;
-  }
-#endif
-
   static size_t EstimateNativeModuleCodeSize(const WasmModule* module);
   static size_t EstimateNativeModuleNonCodeSize(const WasmModule* module);
 
@@ -606,10 +596,6 @@ class V8_EXPORT_PRIVATE WasmCodeManager final {
 
   size_t max_committed_code_space_;
 
-#if defined(V8_OS_WIN_X64)
-  bool is_win64_unwind_info_disabled_for_testing_;
-#endif
-
   std::atomic<size_t> total_committed_code_space_;
   // If the committed code space exceeds {critical_committed_code_space_}, then
   // we trigger a GC before creating the next module. This value is set to the

test/unittests/wasm/wasm-code-manager-unittest.cc

@@ -193,12 +193,6 @@ class WasmCodeManagerTest : public TestWithContext,
   void SetMaxCommittedMemory(size_t limit) {
     manager()->SetMaxCommittedMemoryForTesting(limit);
   }
-
-  void DisableWin64UnwindInfoForTesting() {
-#if defined(V8_OS_WIN_X64)
-    manager()->DisableWin64UnwindInfoForTesting();
-#endif
-  }
 };
 
 // static
@@ -218,8 +212,6 @@ TEST_P(WasmCodeManagerTest, EmptyCase) {
 
 TEST_P(WasmCodeManagerTest, AllocateAndGoOverLimit) {
   SetMaxCommittedMemory(page_size);
-  DisableWin64UnwindInfoForTesting();
-
   CHECK_EQ(0, manager()->committed_code_space());
   NativeModulePtr native_module = AllocModule(page_size, GetParam());
   CHECK(native_module);
@@ -249,8 +241,6 @@ TEST_P(WasmCodeManagerTest, AllocateAndGoOverLimit) {
 
 TEST_P(WasmCodeManagerTest, TotalLimitIrrespectiveOfModuleCount) {
   SetMaxCommittedMemory(3 * page_size);
-  DisableWin64UnwindInfoForTesting();
-
   NativeModulePtr nm1 = AllocModule(2 * page_size, GetParam());
   NativeModulePtr nm2 = AllocModule(2 * page_size, GetParam());
   CHECK(nm1);
@@ -265,8 +255,6 @@ TEST_P(WasmCodeManagerTest, TotalLimitIrrespectiveOfModuleCount) {
 
 TEST_P(WasmCodeManagerTest, GrowingVsFixedModule) {
   SetMaxCommittedMemory(3 * page_size);
-  DisableWin64UnwindInfoForTesting();
-
   NativeModulePtr nm = AllocModule(page_size, GetParam());
   size_t module_size = GetParam() == Fixed ? kMaxWasmCodeMemory : page_size;
   size_t remaining_space_in_module = module_size - kJumpTableSize;
@@ -287,8 +275,6 @@ TEST_P(WasmCodeManagerTest, GrowingVsFixedModule) {
 
 TEST_P(WasmCodeManagerTest, CommitIncrements) {
   SetMaxCommittedMemory(10 * page_size);
-  DisableWin64UnwindInfoForTesting();
-
   NativeModulePtr nm = AllocModule(3 * page_size, GetParam());
   WasmCodeRefScope code_ref_scope;
   WasmCode* code = AddCode(nm.get(), 0, kCodeAlignment);
@@ -304,7 +290,6 @@ TEST_P(WasmCodeManagerTest, CommitIncrements) {
 
 TEST_P(WasmCodeManagerTest, Lookup) {
   SetMaxCommittedMemory(2 * page_size);
-  DisableWin64UnwindInfoForTesting();
 
   NativeModulePtr nm1 = AllocModule(page_size, GetParam());
   NativeModulePtr nm2 = AllocModule(page_size, GetParam());
@@ -350,7 +335,6 @@ TEST_P(WasmCodeManagerTest, Lookup) {
 
 TEST_P(WasmCodeManagerTest, LookupWorksAfterRewrite) {
   SetMaxCommittedMemory(2 * page_size);
-  DisableWin64UnwindInfoForTesting();
 
   NativeModulePtr nm1 = AllocModule(page_size, GetParam());