Introduce %IsBeingInterpreted

A call to this intrinsic will produce true in the interpreter and false
in optimized code. This is useful for writing tests.

Change-Id: I64d06ed062027e723eca82d6f879202244f21fdf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1939750
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65240}

src/compiler/js-intrinsic-lowering.cc

@@ -31,8 +31,12 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
   if (node->opcode() != IrOpcode::kJSCallRuntime) return NoChange();
   const Runtime::Function* const f =
       Runtime::FunctionForId(CallRuntimeParametersOf(node->op()).id());
-  if (f->function_id == Runtime::kTurbofanStaticAssert)
+  if (f->function_id == Runtime::kTurbofanStaticAssert) {
     return ReduceTurbofanStaticAssert(node);
+  }
+  if (f->function_id == Runtime::kIsBeingInterpreted) {
+    return ReduceIsBeingInterpreted(node);
+  }
   if (f->intrinsic_type != Runtime::IntrinsicType::INLINE) return NoChange();
   switch (f->function_id) {
     case Runtime::kInlineCopyDataProperties:
@@ -284,6 +288,11 @@ Reduction JSIntrinsicLowering::ReduceTurbofanStaticAssert(Node* node) {
   return Changed(jsgraph_->UndefinedConstant());
 }
 
+Reduction JSIntrinsicLowering::ReduceIsBeingInterpreted(Node* node) {
+  RelaxEffectsAndControls(node);
+  return Changed(jsgraph_->FalseConstant());
+}
+
 Reduction JSIntrinsicLowering::Change(Node* node, const Operator* op) {
   // Replace all effect uses of {node} with the effect dependency.
   RelaxEffectsAndControls(node);

src/compiler/js-intrinsic-lowering.h

@@ -58,6 +58,7 @@ class V8_EXPORT_PRIVATE JSIntrinsicLowering final
   Reduction ReduceIsInstanceType(Node* node, InstanceType instance_type);
   Reduction ReduceIsJSReceiver(Node* node);
   Reduction ReduceIsSmi(Node* node);
+  Reduction ReduceIsBeingInterpreted(Node* node);
   Reduction ReduceTurbofanStaticAssert(Node* node);
   Reduction ReduceToLength(Node* node);
   Reduction ReduceToObject(Node* node);

src/runtime/runtime-test.cc

@@ -1413,11 +1413,17 @@ RUNTIME_FUNCTION(Runtime_FreezeWasmLazyCompilation) {
 
 RUNTIME_FUNCTION(Runtime_TurbofanStaticAssert) {
   SealHandleScope shs(isolate);
-  // Always lowered to StaticAssert node in Turbofan, so we should never get
-  // here in compiled code.
+  // Always lowered to StaticAssert node in Turbofan, so we never get here in
+  // compiled code.
   return ReadOnlyRoots(isolate).undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_IsBeingInterpreted) {
+  SealHandleScope shs(isolate);
+  // Always lowered to false in Turbofan, so we never get here in compiled code.
+  return ReadOnlyRoots(isolate).true_value();
+}
+
 RUNTIME_FUNCTION(Runtime_EnableCodeLoggingForTesting) {
   // The {NoopListener} currently does nothing on any callback, but reports
   // {true} on {is_listening_to_code_events()}. Feel free to add assertions to

src/runtime/runtime.h

@@ -33,7 +33,7 @@ namespace internal {
 // * Each compiler has an explicit list of intrisics it supports, falling back
 //   to a simple runtime call if necessary.
 
-// Entries have the form F(name, number of arguments, number of values):
+// Entries have the form F(name, number of arguments, number of return values):
 // A variable number of arguments is specified by a -1, additional restrictions
 // are specified by inline comments. To declare only the runtime version (no
 // inline), use the F macro below. To declare the runtime version and the inline
@@ -500,6 +500,7 @@ namespace internal {
   F(ICsAreEnabled, 0, 1)                      \
   F(InYoungGeneration, 1, 1)                  \
   F(IsAsmWasmCode, 1, 1)                      \
+  F(IsBeingInterpreted, 0, 1)                 \
   F(IsConcurrentRecompilationSupported, 0, 1) \
   F(IsLiftoffFunction, 1, 1)                  \
   F(IsThreadInWasm, 0, 1)                     \

test/mjsunit/compiler/is-being-interpreted-1.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 --opt --no-always-opt
+
+
+function bar() { return foo(); }
+function foo() { return %IsBeingInterpreted(); }
+
+%PrepareFunctionForOptimization(bar);
+%PrepareFunctionForOptimization(foo);
+
+assertTrue(bar());
+assertTrue(bar());
+%OptimizeFunctionOnNextCall(bar);
+assertFalse(bar());

test/mjsunit/compiler/is-being-interpreted-2.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 --no-turbo-inlining --opt --no-always-opt
+
+
+function bar() { return foo(); }
+function foo() { return %IsBeingInterpreted(); }
+
+%PrepareFunctionForOptimization(bar);
+%PrepareFunctionForOptimization(foo);
+
+assertTrue(bar());
+assertTrue(bar());
+%OptimizeFunctionOnNextCall(bar);
+assertTrue(bar());

test/mjsunit/compiler/serializer-accessors.js

@@ -2,13 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax
+// Flags: --allow-natives-syntax --opt --no-always-opt
+
+var expect_interpreted = true;
 
 class C {
   get prop() {
     return 42;
   }
   set prop(v) {
+    assertEquals(expect_interpreted, %IsBeingInterpreted());
     %TurbofanStaticAssert(v === 43);
   }
 }
@@ -16,6 +19,7 @@ class C {
 const c = new C();
 
 function foo() {
+  assertEquals(expect_interpreted, %IsBeingInterpreted());
   %TurbofanStaticAssert(c.prop === 42);
   c.prop = 43;
 }
@@ -25,7 +29,9 @@ function foo() {
 %PrepareFunctionForOptimization(
     Object.getOwnPropertyDescriptor(C.prototype, 'prop').set);
 %PrepareFunctionForOptimization(foo);
+
 foo();
 foo();
 %OptimizeFunctionOnNextCall(foo);
+expect_interpreted = false;
 foo();

test/mjsunit/compiler/serializer-transition-propagation.js

@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax
+// Flags: --allow-natives-syntax --opt --no-always-opt
+
+var expect_interpreted = true;
 
 function C() {
   this.a = 1;
+  assertEquals(expect_interpreted, %IsBeingInterpreted());
   %TurbofanStaticAssert(this.x == 42);
 };
 
@@ -47,4 +50,5 @@ new G;
 foo();
 foo();
 %OptimizeFunctionOnNextCall(foo);
+expect_interpreted = false;
 foo();

test/mjsunit/mjsunit.status

@@ -404,6 +404,11 @@
   'regexp-tier-up-multiple': [SKIP],
   'regress/regress-996234': [SKIP],
 
+  # Tests that depend on optimization (beyond doing assertOptimized).
+  'compiler/is-being-interpreted-*': [SKIP],
+  'compiler/serializer-accessors': [SKIP],
+  'compiler/serializer-transition-propagation': [SKIP],
+
   # These tests check that we can trace the compiler.
   'tools/compiler-trace-flags': [SKIP],
   'tools/compiler-trace-flags-wasm': [SKIP],
@@ -1082,11 +1087,13 @@
   # phases.
   'compiler/concurrent-inlining-1': [SKIP],
   'compiler/concurrent-inlining-2': [SKIP],
+  'compiler/constant-fold-add-static': [SKIP],
   'compiler/diamond-followedby-branch': [SKIP],
+  'compiler/is-being-interpreted-*': [SKIP],
   'compiler/load-elimination-const-field': [SKIP],
-  'compiler/constant-fold-add-static': [SKIP],
-  'compiler/serializer-feedback-propagation-*': [SKIP],
   'compiler/serializer-accessors': [SKIP],
+  'compiler/serializer-feedback-propagation-*': [SKIP],
+  'compiler/serializer-transition-propagation': [SKIP],
 
   # Some tests rely on inlining.
   'compiler/opt-higher-order-functions': [SKIP],