[compiler] Tolerate failing ConsistentJSFunctionViewDep post-GC

GC may change heap state and make this dependency fail. That's okay -
it passed once before, meaning that compilation saw a self-consistent
JSFunctionRef state.

Bug: chromium:1230930
Change-Id: I367b10e4aa88101f1ca83a46f596c5f289f6cab2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3040838
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75802}

src/compiler/compilation-dependencies.cc

@@ -355,6 +355,10 @@ class ConsistentJSFunctionViewDependency final : public CompilationDependency {
 
   void Install(Handle<Code> code) const override {}
 
+#ifdef DEBUG
+  bool IsConsistentJSFunctionViewDependency() const override { return true; }
+#endif
+
  private:
   const JSFunctionRef function_;
 };
@@ -832,17 +836,27 @@ bool CompilationDependencies::Commit(Handle<Code> code) {
   }
 
   // It is even possible that a GC during the above installations invalidated
-  // one of the dependencies. However, this should only affect pretenure mode
+  // one of the dependencies. However, this should only affect
-  // dependencies, which we assert below. It is safe to return successfully in
+  //
-  // these cases, because once the code gets executed it will do a stack check
+  // 1. pretenure mode dependencies, or
-  // that triggers its deoptimization.
+  // 2. function consistency dependencies,
+  //
+  // which we assert below. It is safe to return successfully in these cases,
+  // because
+  //
+  // 1. once the code gets executed it will do a stack check that triggers its
+  //    deoptimization.
+  // 2. since the function state was deemed consistent above, that means the
+  //    compilation saw a self-consistent state of the jsfunction.
   if (FLAG_stress_gc_during_compilation) {
     broker_->isolate()->heap()->PreciseCollectAllGarbage(
         Heap::kForcedGC, GarbageCollectionReason::kTesting, kNoGCCallbackFlags);
   }
 #ifdef DEBUG
   for (auto dep : dependencies_) {
-    CHECK_IMPLIES(!dep->IsValid(), dep->IsPretenureModeDependency());
+    CHECK_IMPLIES(!dep->IsValid(),
+                  dep->IsPretenureModeDependency() ||
+                      dep->IsConsistentJSFunctionViewDependency());
   }
 #endif
 

src/compiler/compilation-dependency.h

@@ -26,6 +26,7 @@ class CompilationDependency : public ZoneObject {
       Handle<Map> const& receiver_map) const {
     return false;
   }
+  virtual bool IsConsistentJSFunctionViewDependency() const { return false; }
 #endif
 };
 

test/mjsunit/regress/regress-1230930.js

@@ -0,0 +1,19 @@
+// Copyright 2021 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 --stress-gc-during-compilation
+
+const __v_0 = class __c_0 extends Array {
+  constructor() {
+    super();
+    this.y = 1;
+  }
+};
+function __f_1() {
+  var __v_2 = new __v_0();
+}
+  %PrepareFunctionForOptimization(__f_1);
+__f_1();
+%OptimizeFunctionOnNextCall(__f_1);
+__f_1();