[testing] Prevent heuristics from triggering optimization in tests

This CL adds a mechanism that prevents the RuntimeProfiler from
triggering optimization of a function after
%PrepareFunctionForOptimization has been called. This is useful to
prevent flakiness in tests, as sometimes a function that already
got deoptimized would receive a new code object from a concurrent
compile that was triggered by a heuristic just in the right moment
for the assertUnoptimized test to fail. For example, the following
was happening:

PrepareFunctionForOptimization
[marking `testAdd` for optimized recompilation, reason: small function]
[concurrently compiling method `testAdd` using TurboFan]
[manually marking `testAdd` for non-concurrent optimization]
[synchonously compiling method `testAdd` using TurboFan]
[synchonously optimizing `testAdd` produced code object 0xAAAA - took 1.638 ms]
Runtime_GetOptimizationStatus OPTIMIZED `testAdd` (code object 0xAAAA)
DeoptimizeFunction `testAdd` with Code Object 0xAAAA
[concurrently optimizing `testAdd` produced code object 0xBBBB - took 3.377 ms]
Runtime_GetOptimizationStatus OPTIMIZED `testAdd` (code object 0xBBBB)

Bug: v8:9563
Change-Id: Ia4c846aba95281589317d43b82383e70fe0a35f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1763546Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63343}

src/codegen/pending-optimization-table.cc

@@ -4,6 +4,7 @@
 
 #include "src/codegen/pending-optimization-table.h"
 
+#include "src/base/flags.h"
 #include "src/execution/isolate-inl.h"
 #include "src/heap/heap-inl.h"
 #include "src/objects/hash-table.h"
@@ -12,12 +13,24 @@
 namespace v8 {
 namespace internal {
 
-enum class FunctionStatus { kPrepareForOptimize, kMarkForOptimize };
+enum class FunctionStatus : int {
+  kPrepareForOptimize = 1 << 0,
+  kMarkForOptimize = 1 << 1,
+  kAllowHeuristicOptimization = 1 << 2,
+};
+
+using FunctionStatusFlags = base::Flags<FunctionStatus>;
 
 void PendingOptimizationTable::PreparedForOptimization(
-    Isolate* isolate, Handle<JSFunction> function) {
+    Isolate* isolate, Handle<JSFunction> function,
+    bool allow_heuristic_optimization) {
   DCHECK(FLAG_testing_d8_test_runner);
 
+  FunctionStatusFlags status = FunctionStatus::kPrepareForOptimize;
+  if (allow_heuristic_optimization) {
+    status |= FunctionStatus::kAllowHeuristicOptimization;
+  }
+
   Handle<ObjectHashTable> table =
       isolate->heap()->pending_optimize_for_test_bytecode().IsUndefined()
           ? ObjectHashTable::New(isolate, 1)
@@ -26,15 +39,33 @@ void PendingOptimizationTable::PreparedForOptimization(
                    isolate);
   Handle<Tuple2> tuple = isolate->factory()->NewTuple2(
       handle(function->shared().GetBytecodeArray(), isolate),
-      handle(
-          Smi::FromInt(static_cast<int>(FunctionStatus::kPrepareForOptimize)),
-          isolate),
-      AllocationType::kYoung);
+      handle(Smi::FromInt(status), isolate), AllocationType::kYoung);
   table =
       ObjectHashTable::Put(table, handle(function->shared(), isolate), tuple);
   isolate->heap()->SetPendingOptimizeForTestBytecode(*table);
 }
 
+bool PendingOptimizationTable::IsHeuristicOptimizationAllowed(
+    Isolate* isolate, JSFunction function) {
+  DCHECK(FLAG_testing_d8_test_runner);
+
+  Handle<Object> table =
+      handle(isolate->heap()->pending_optimize_for_test_bytecode(), isolate);
+  Handle<Object> entry =
+      table->IsUndefined()
+          ? handle(ReadOnlyRoots(isolate).the_hole_value(), isolate)
+          : handle(Handle<ObjectHashTable>::cast(table)->Lookup(
+                       handle(function.shared(), isolate)),
+                   isolate);
+  if (entry->IsTheHole()) {
+    return true;
+  }
+  DCHECK(entry->IsTuple2());
+  DCHECK(Handle<Tuple2>::cast(entry)->value2().IsSmi());
+  FunctionStatusFlags status(Smi::ToInt(Handle<Tuple2>::cast(entry)->value2()));
+  return status & FunctionStatus::kAllowHeuristicOptimization;
+}
+
 void PendingOptimizationTable::MarkedForOptimization(
     Isolate* isolate, Handle<JSFunction> function) {
   DCHECK(FLAG_testing_d8_test_runner);
@@ -58,8 +89,11 @@ void PendingOptimizationTable::MarkedForOptimization(
   }
 
   DCHECK(entry->IsTuple2());
-  Handle<Tuple2>::cast(entry)->set_value2(
-      Smi::FromInt(static_cast<int>(FunctionStatus::kMarkForOptimize)));
+  DCHECK(Handle<Tuple2>::cast(entry)->value2().IsSmi());
+  FunctionStatusFlags status(Smi::ToInt(Handle<Tuple2>::cast(entry)->value2()));
+  status = status.without(FunctionStatus::kPrepareForOptimize) |
+           FunctionStatus::kMarkForOptimize;
+  Handle<Tuple2>::cast(entry)->set_value2(Smi::FromInt(status));
   table = ObjectHashTable::Put(Handle<ObjectHashTable>::cast(table),
                                handle(function->shared(), isolate), entry);
   isolate->heap()->SetPendingOptimizeForTestBytecode(*table);

src/codegen/pending-optimization-table.h

@@ -21,7 +21,8 @@ class PendingOptimizationTable {
   // strongly in pending optimization table preventing the bytecode to be
   // flushed.
   static void PreparedForOptimization(Isolate* isolate,
-                                      Handle<JSFunction> function);
+                                      Handle<JSFunction> function,
+                                      bool allow_heuristic_optimization);
 
   // This function should be called when the function is marked for optimization
   // via the intrinsics. This will update the state of the bytecode array in the
@@ -36,6 +37,12 @@ class PendingOptimizationTable {
   // then this function removes the entry from pending optimization table.
   static void FunctionWasOptimized(Isolate* isolate,
                                    Handle<JSFunction> function);
+
+  // This function returns whether a heuristic is allowed to trigger
+  // optimization the function. This mechanism is used in tests to prevent
+  // heuristics from interfering with manually triggered optimization.
+  static bool IsHeuristicOptimizationAllowed(Isolate* isolate,
+                                             JSFunction function);
 };
 
 }  // namespace internal

src/execution/runtime-profiler.cc

@@ -8,6 +8,7 @@
 #include "src/codegen/assembler.h"
 #include "src/codegen/compilation-cache.h"
 #include "src/codegen/compiler.h"
+#include "src/codegen/pending-optimization-table.h"
 #include "src/execution/execution.h"
 #include "src/execution/frames-inl.h"
 #include "src/handles/global-handles.h"
@@ -119,6 +120,17 @@ void RuntimeProfiler::MaybeOptimize(JSFunction function,
     }
     return;
   }
+  if (FLAG_testing_d8_test_runner) {
+    if (!PendingOptimizationTable::IsHeuristicOptimizationAllowed(isolate_,
+                                                                  function)) {
+      if (FLAG_trace_opt_verbose) {
+        PrintF("[function ");
+        function.PrintName();
+        PrintF(" has been marked manually for optimization]\n");
+      }
+      return;
+    }
+  }
 
   if (FLAG_always_osr) {
     AttemptOnStackReplacement(frame, AbstractCode::kMaxLoopNestingMarker);

src/runtime/runtime-test.cc

@@ -349,12 +349,24 @@ RUNTIME_FUNCTION(Runtime_EnsureFeedbackVectorForFunction) {
 
 RUNTIME_FUNCTION(Runtime_PrepareFunctionForOptimization) {
   HandleScope scope(isolate);
-  DCHECK_EQ(1, args.length());
+  DCHECK(args.length() == 1 || args.length() == 2);
   if (!args[0].IsJSFunction()) {
     return ReadOnlyRoots(isolate).undefined_value();
   }
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
 
+  bool allow_heuristic_optimization = false;
+  if (args.length() == 2) {
+    CONVERT_ARG_HANDLE_CHECKED(Object, sync_object, 1);
+    if (!sync_object->IsString())
+      return ReadOnlyRoots(isolate).undefined_value();
+    Handle<String> sync = Handle<String>::cast(sync_object);
+    if (sync->IsOneByteEqualTo(
+            StaticCharVector("allow heuristic optimization"))) {
+      allow_heuristic_optimization = true;
+    }
+  }
+
   if (!EnsureFeedbackVector(function)) {
     return ReadOnlyRoots(isolate).undefined_value();
   }
@@ -375,7 +387,8 @@ RUNTIME_FUNCTION(Runtime_PrepareFunctionForOptimization) {
   // Hold onto the bytecode array between marking and optimization to ensure
   // it's not flushed.
   if (FLAG_testing_d8_test_runner) {
-    PendingOptimizationTable::PreparedForOptimization(isolate, function);
+    PendingOptimizationTable::PreparedForOptimization(
+        isolate, function, allow_heuristic_optimization);
   }
 
   return ReadOnlyRoots(isolate).undefined_value();

src/runtime/runtime.h

@@ -502,7 +502,7 @@ namespace internal {
   F(NotifyContextDisposed, 0, 1)              \
   F(OptimizeFunctionOnNextCall, -1, 1)        \
   F(OptimizeOsr, -1, 1)                       \
-  F(PrepareFunctionForOptimization, 1, 1)     \
+  F(PrepareFunctionForOptimization, -1, 1)    \
   F(PrintWithNameForAssert, 2, 1)             \
   F(RedirectToWasmInterpreter, 2, 1)          \
   F(RunningInSimulator, 0, 1)                 \

test/mjsunit/interrupt-budget-override.js

@@ -12,7 +12,7 @@ function f() {
   return s;
 }
 
-%PrepareFunctionForOptimization(f);
+%PrepareFunctionForOptimization(f, "allow heuristic optimization");
 f();
 f();
 f();