Revert "[wasm] Add support to tier down/up Wasm NativeModule"

This reverts commit 6ce3046e.

Reason for revert: Flaky test failures, see flako run: https://ci.chromium.org/p/v8/builders/try.triggered/v8_flako/b8893085619399726256

Original change's description:
> [wasm] Add support to tier down/up Wasm NativeModule
>
> This is the first part of switching between Liftoff and Turbofan in
> debugging Wasm. In this CL, we implemented the logic to tier down/up all
> functions in module.
>
> Bug: v8:9654
> Change-Id: Ia25103ca29963afa103c124ff5f159f197c2b2b0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1970470
> Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65529}

TBR=clemensb@chromium.org,bmeurer@chromium.org,duongn@microsoft.com

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

Bug: v8:9654, v8:10086
Change-Id: I44a4c2bde87ba5e4e83859e3e3c96103249b585f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1981501
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65573}

src/runtime/runtime-test.cc

@@ -1377,26 +1377,6 @@ RUNTIME_FUNCTION(Runtime_WasmTierUpFunction) {
   return ReadOnlyRoots(isolate).undefined_value();
 }
 
-RUNTIME_FUNCTION(Runtime_WasmTierDownModule) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(1, args.length());
-  CONVERT_ARG_HANDLE_CHECKED(WasmInstanceObject, instance, 0);
-  auto* native_module = instance->module_object().native_module();
-  native_module->TierDown(isolate);
-  CHECK(!native_module->compilation_state()->failed());
-  return ReadOnlyRoots(isolate).undefined_value();
-}
-
-RUNTIME_FUNCTION(Runtime_WasmTierUpModule) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(1, args.length());
-  CONVERT_ARG_HANDLE_CHECKED(WasmInstanceObject, instance, 0);
-  auto* native_module = instance->module_object().native_module();
-  native_module->TierUp(isolate);
-  CHECK(!native_module->compilation_state()->failed());
-  return ReadOnlyRoots(isolate).undefined_value();
-}
-
 RUNTIME_FUNCTION(Runtime_IsLiftoffFunction) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());

src/runtime/runtime.h

@@ -536,9 +536,7 @@ namespace internal {
   F(WasmGetNumberOfInstances, 1, 1)           \
   F(WasmNumInterpretedCalls, 1, 1)            \
   F(WasmNumCodeSpaces, 1, 1)                  \
-  F(WasmTierDownModule, 1, 1)                 \
   F(WasmTierUpFunction, 2, 1)                 \
-  F(WasmTierUpModule, 1, 1)                   \
   F(WasmTraceMemory, 1, 1)                    \
   I(DeoptimizeNow, 0, 1)
 

src/wasm/wasm-code-manager.cc

@@ -1047,14 +1047,11 @@ WasmCode* NativeModule::PublishCodeLocked(std::unique_ptr<WasmCode> code) {
                       ExecutionTier::kLiftoff < ExecutionTier::kTurbofan,
                   "Assume an order on execution tiers");
 
-    // Unless tier down to Liftoff: update code table but avoid to fall back to
-    // less optimized code. We use the new code if it was compiled with a higher
-    // tier.
+    // Update code table but avoid to fall back to less optimized code. We use
+    // the new code if it was compiled with a higher tier.
     uint32_t slot_idx = code->index() - module_->num_imported_functions;
     WasmCode* prior_code = code_table_[slot_idx];
-    bool update_code_table =
-        tier_down_ ? !prior_code || code->tier() == ExecutionTier::kLiftoff
-                   : !prior_code || prior_code->tier() < code->tier();
+    bool update_code_table = !prior_code || prior_code->tier() < code->tier();
     if (update_code_table) {
       code_table_[slot_idx] = code.get();
       if (prior_code) {
@@ -1811,34 +1808,6 @@ bool NativeModule::IsRedirectedToInterpreter(uint32_t func_index) {
   return has_interpreter_redirection(func_index);
 }
 
-void NativeModule::TierDown(Isolate* isolate) {
-  // Set the flag.
-  tier_down_ = true;
-
-  // Tier down all functions.
-  // TODO(duongn): parallelize this eventually.
-  for (uint32_t index = module_->num_imported_functions;
-       index < num_functions(); index++) {
-    isolate->wasm_engine()->CompileFunction(isolate, this, index,
-                                            ExecutionTier::kLiftoff);
-    DCHECK(!compilation_state()->failed());
-  }
-}
-
-void NativeModule::TierUp(Isolate* isolate) {
-  // Set the flag.
-  tier_down_ = false;
-
-  // Tier up all functions.
-  // TODO(duongn): parallelize this eventually.
-  for (uint32_t index = module_->num_imported_functions;
-       index < num_functions(); index++) {
-    isolate->wasm_engine()->CompileFunction(isolate, this, index,
-                                            ExecutionTier::kTurbofan);
-    DCHECK(!compilation_state()->failed());
-  }
-}
-
 void NativeModule::FreeCode(Vector<WasmCode* const> codes) {
   // Free the code space.
   code_allocator_.FreeCode(codes);

src/wasm/wasm-code-manager.h

@@ -552,11 +552,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // by publishing an entry stub with the {Kind::kInterpreterEntry} code kind.
   bool IsRedirectedToInterpreter(uint32_t func_index);
 
-  // Sets the flag, triggers recompilation of all methods to tier down or up,
-  // waits for that to complete.
-  void TierDown(Isolate* isolate);
-  void TierUp(Isolate* isolate);
-
   // Free a set of functions of this module. Uncommits whole pages if possible.
   // The given vector must be ordered by the instruction start address, and all
   // {WasmCode} objects must not be used any more.
@@ -695,9 +690,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // Data (especially jump table) per code space.
   std::vector<CodeSpaceData> code_space_data_;
 
-  // Whether we want all code to be Liftoff for debugging.
-  bool tier_down_ = false;
-
   // Debug information for this module. You only need to hold the allocation
   // mutex while getting the {DebugInfo} pointer, or initializing this field.
   // Further accesses to the {DebugInfo} do not need to be protected by the

test/mjsunit/mjsunit.status

@@ -1096,7 +1096,6 @@
 ['arch != x64 and arch != ia32 and arch != arm64 and arch != arm', {
   'wasm/liftoff': [SKIP],
   'wasm/tier-up-testing-flag': [SKIP],
-  'wasm/tier-down-to-liftoff': [SKIP],
 }], # arch != x64 and arch != ia32 and arch != arm64 and arch != arm
 
 ##############################################################################

test/mjsunit/wasm/tier-down-to-liftoff.js

-// Copyright 2019 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.
-
-// Flags: --allow-natives-syntax --wasm-tier-up
-
-load('test/mjsunit/wasm/wasm-module-builder.js');
-
-const num_functions = 2;
-
-function create_builder() {
-  const builder = new WasmModuleBuilder();
-  for (let i = 0; i < num_functions; ++i) {
-    builder.addFunction('f' + i, kSig_i_v)
-        .addBody(wasmI32Const(i))
-        .exportFunc();
-  }
-  return builder;
-}
-
-function check(instance) {
-  for (let i = 0; i < num_functions; ++i) {
-    %WasmTierUpFunction(instance, i);
-    assertFalse(%IsLiftoffFunction(instance.exports['f' + i]));
-  }
-
-  %WasmTierDownModule(instance);
-  for (let i = 0; i < num_functions; ++i) {
-    assertTrue(%IsLiftoffFunction(instance.exports['f' + i]));
-  }
-
-  for (let i = 0; i < num_functions; ++i) {
-    %WasmTierUpFunction(instance, i);
-    assertTrue(%IsLiftoffFunction(instance.exports['f' + i]));
-  }
-
-  %WasmTierUpModule(instance);
-  for (let i = 0; i < num_functions; ++i) {
-    assertFalse(%IsLiftoffFunction(instance.exports['f' + i]));
-  }
-}
-
-(function testTierDownToLiftoff() {
-  print(arguments.callee.name);
-  const instance = create_builder().instantiate();
-  check(instance);
-})();
-
-
-async function testTierDownToLiftoffAsync() {
-  print(arguments.callee.name);
-  const instance = await create_builder().asyncInstantiate();
-  check(instance);
-}
-
-assertPromiseResult(testTierDownToLiftoffAsync());