[wasm] Keep new module in tiered down upon "debugger.enable"

Store a flag per isolate whether new modules should be kept in
tiered-down state from the beginning. Adjust initial compilation if flag
is set.

Bug: v8:9654
Change-Id: I5aae435fb807f3eaa7efafe9af60451ad3c7e14d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2028452
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66321}

src/wasm/module-compiler.cc

@@ -1202,10 +1202,15 @@ void InitializeCompilationUnits(Isolate* isolate, NativeModule* native_module) {
   ModuleWireBytes wire_bytes(native_module->wire_bytes());
   CompilationUnitBuilder builder(native_module);
   auto* module = native_module->module();
+  const bool prefer_liftoff = native_module->IsTieredDown();
 
   uint32_t start = module->num_imported_functions;
   uint32_t end = start + module->num_declared_functions;
   for (uint32_t func_index = start; func_index < end; func_index++) {
+    if (prefer_liftoff) {
+      builder.AddBaselineUnit(func_index);
+      continue;
+    }
     CompileStrategy strategy = GetCompileStrategy(
         module, native_module->enabled_features(), func_index, lazy_module);
     if (strategy == CompileStrategy::kLazy) {
@@ -2472,7 +2477,21 @@ void CompilationStateImpl::InitializeCompilationProgress(bool lazy_module,
   compilation_progress_.reserve(module->num_declared_functions);
   int start = module->num_imported_functions;
   int end = start + module->num_declared_functions;
+
+  const bool prefer_liftoff = native_module_->IsTieredDown();
   for (int func_index = start; func_index < end; func_index++) {
+    if (prefer_liftoff) {
+      constexpr uint8_t kLiftoffOnlyFunctionProgress =
+          RequiredTopTierField::update(
+              RequiredBaselineTierField::update(
+                  ReachedTierField::encode(ExecutionTier::kNone),
+                  ExecutionTier::kLiftoff),
+              ExecutionTier::kLiftoff);
+      compilation_progress_.push_back(kLiftoffOnlyFunctionProgress);
+      outstanding_baseline_units_++;
+      outstanding_top_tier_functions_++;
+      continue;
+    }
     ExecutionTierPair requested_tiers = GetRequestedExecutionTiers(
         module, compile_mode(), enabled_features, func_index);
     CompileStrategy strategy =

src/wasm/wasm-code-manager.cc

@@ -1043,7 +1043,7 @@ WasmCode* NativeModule::PublishCodeLocked(std::unique_ptr<WasmCode> code) {
     // TODO(clemensb): Revisit this logic once tier down is fully working.
     const bool prefer_liftoff = tier_down_ || debug_info_;
     const bool update_code_table =
-        prefer_liftoff ? code->tier() == ExecutionTier::kLiftoff
+        prefer_liftoff ? !prior_code || code->tier() == ExecutionTier::kLiftoff
                        : !prior_code || prior_code->tier() < code->tier();
     if (update_code_table) {
       code_table_[slot_idx] = code.get();
@@ -1799,15 +1799,28 @@ bool NativeModule::IsRedirectedToInterpreter(uint32_t func_index) {
   return has_interpreter_redirection(func_index);
 }
 
-void NativeModule::TierDown(Isolate* isolate) {
+bool NativeModule::SetTieredDown() {
   // Do not tier down asm.js.
-  if (module()->origin != kWasmOrigin) return;
-  // Set the flag.
-  {
+  if (module()->origin != kWasmOrigin) return false;
+
   base::MutexGuard lock(&allocation_mutex_);
-    if (tier_down_) return;
+  if (tier_down_) return true;
   tier_down_ = true;
-  }
+  return false;
+}
+
+bool NativeModule::IsTieredDown() {
+  base::MutexGuard lock(&allocation_mutex_);
+  return tier_down_;
+}
+
+void NativeModule::TierDown(Isolate* isolate) {
+  // Do not tier down asm.js.
+  if (module()->origin != kWasmOrigin) return;
+
+  // Set the flag. Return if it is already set.
+  if (SetTieredDown()) return;
+
   // Tier down all functions.
   isolate->wasm_engine()->RecompileAllFunctions(isolate, this,
                                                 ExecutionTier::kLiftoff);

src/wasm/wasm-code-manager.h

@@ -549,6 +549,10 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // by publishing an entry stub with the {Kind::kInterpreterEntry} code kind.
   bool IsRedirectedToInterpreter(uint32_t func_index);
 
+  // Set {tier_down_} flag. Return previous state.
+  bool SetTieredDown();
+  bool IsTieredDown();
+
   // Sets the flag, triggers recompilation of all methods to tier down or up,
   // waits for that to complete.
   void TierDown(Isolate* isolate);

src/wasm/wasm-engine.cc

@@ -331,6 +331,9 @@ struct WasmEngine::IsolateInfo {
   std::shared_ptr<v8::TaskRunner> foreground_task_runner;
 
   const std::shared_ptr<Counters> async_counters;
+
+  // Keep new modules in tiered down state.
+  bool keep_tiered_down = false;
 };
 
 struct WasmEngine::NativeModuleInfo {
@@ -577,6 +580,8 @@ void WasmEngine::TierDownAllModulesPerIsolate(Isolate* isolate) {
   std::vector<NativeModule*> native_modules;
   {
     base::MutexGuard lock(&mutex_);
+    if (isolates_[isolate]->keep_tiered_down) return;
+    isolates_[isolate]->keep_tiered_down = true;
     for (auto* native_module : isolates_[isolate]->native_modules) {
       native_modules.push_back(native_module);
     }
@@ -841,6 +846,9 @@ std::shared_ptr<NativeModule> WasmEngine::NewNativeModule(
   DCHECK(pair.second);  // inserted new entry.
   pair.first->second.get()->isolates.insert(isolate);
   isolates_[isolate]->native_modules.insert(native_module.get());
+  if (isolates_[isolate]->keep_tiered_down) {
+    native_module->SetTieredDown();
+  }
   return native_module;
 }
 

test/debugger/debug/wasm/debug-enabled-tier-down-wasm-unsupported-liftoff.js

@@ -7,33 +7,36 @@
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 // Create a simple Wasm module.
-function create_builder() {
+function create_builder(i) {
   const builder = new WasmModuleBuilder();
-  builder.addFunction('main', kSig_r_v)
-      .addBody([kExprRefNull])
+  builder.addFunction('main', kSig_i_r)
+  .addBody([
+    kExprLocalGet, 0, kExprRefIsNull,
+    ...wasmI32Const(i),
+    kExprI32Add])
   .exportFunc();
   return builder;
 }
 
-const instance = create_builder().instantiate();
+const instance = create_builder(0).instantiate();
 
 // Test recompilation.
 const Debug = new DebugWrapper();
 Debug.enable();
 assertFalse(%IsLiftoffFunction(instance.exports.main));
+const newInstance = create_builder(1).instantiate();
+assertFalse(%IsLiftoffFunction(newInstance.exports.main));
 
 // Async.
 async function testTierDownToLiftoffAsync() {
   Debug.disable();
-  const builder = new WasmModuleBuilder();
-  builder.addFunction('main', kSig_i_r)
-      .addBody([kExprLocalGet, 0, kExprRefIsNull])
-      .exportFunc();
-  const asyncInstance = await builder.asyncInstantiate();
+  const asyncInstance = await create_builder(2).asyncInstantiate();
 
   // Test recompilation.
   Debug.enable();
-  assertFalse(%IsLiftoffFunction(instance.exports.main));
+  assertFalse(%IsLiftoffFunction(asyncInstance.exports.main));
+  const newAsyncInstance = await create_builder(3).asyncInstantiate();
+  assertFalse(%IsLiftoffFunction(newAsyncInstance.exports.main));
 }
 
 assertPromiseResult(testTierDownToLiftoffAsync());

test/debugger/debug/wasm/debug-enabled-tier-down-wasm.js

@@ -27,6 +27,8 @@ const instance = create_builder().instantiate();
 const Debug = new DebugWrapper();
 Debug.enable();
 check(instance);
+const newInstance = create_builder(num_functions*2).instantiate();
+check(newInstance);
 
 // Async.
 async function testTierDownToLiftoffAsync() {
@@ -34,6 +36,8 @@ async function testTierDownToLiftoffAsync() {
   const asyncInstance = await create_builder(num_functions).asyncInstantiate();
   Debug.enable();
   check(asyncInstance);
+  const newAsyncInstance = await create_builder(num_functions*3).asyncInstantiate();
+  check(newAsyncInstance);
 }
 
 assertPromiseResult(testTierDownToLiftoffAsync());

test/inspector/debugger/wasm-scope-info-expected.txt

@@ -21,6 +21,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -38,6 +40,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -55,6 +59,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -72,6 +78,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -89,6 +97,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -106,6 +116,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -123,6 +135,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -140,6 +154,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -157,6 +173,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -174,6 +192,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -191,6 +211,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -208,6 +230,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -225,6 +249,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -242,6 +268,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -259,6 +287,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -276,6 +306,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 0 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals
@@ -293,6 +325,8 @@ at call_func (0:58):
  - scope (global):
    globals: "global#0": 15 (number)
  - scope (local):
+   locals: "arg#0": 4 (number), "local#1": 7.199999809265137 (number)
+   stack:
 at (anonymous) (0:17):
  - scope (global):
    -- skipped globals