Reland "cppgc, heap: Don't eagerly allocate worklist segments"

This is a reland of c99147c6

Original change's description:
> cppgc, heap: Don't eagerly allocate worklist segments
>
> Bug: chromium:1056170
> Change-Id: I75a6b5f52bfe8dd71abc086e5d1e060759ad7fc0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2391254
> Commit-Queue: Omer Katz <omerkatz@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69778}

Bug: chromium:1056170
Change-Id: I4633da065976a6b2710d2f23b946fd2af0e65c83
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2401425Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69806}

BUILD.gn

@@ -4256,6 +4256,7 @@ v8_source_set("v8_cppgc_shared") {
   sources = [
     "src/heap/base/stack.cc",
     "src/heap/base/stack.h",
+    "src/heap/base/worklist.cc",
     "src/heap/base/worklist.h",
   ]
 

src/heap/base/worklist.cc

+// Copyright 2020 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.
+
+#include "src/heap/base/worklist.h"
+
+namespace heap {
+namespace base {
+namespace internal {
+SegmentBase SegmentBase::kSentinelSegment(0);
+}  // namespace internal
+}  // namespace base
+}  // namespace heap

test/unittests/BUILD.gn

@@ -69,6 +69,7 @@ v8_executable("cppgc_unittests") {
 
   deps = [
     ":cppgc_unittests_sources",
+    ":v8_cppgc_shared_unittests_sources",
     "../..:cppgc_for_testing",
     "//testing/gmock",
     "//testing/gtest",
@@ -136,6 +137,7 @@ v8_executable("unittests") {
   deps = [
     ":cppgc_unittests_sources",
     ":unittests_sources",
+    ":v8_cppgc_shared_unittests_sources",
     "../..:v8_for_testing",
     "../..:v8_libbase",
     "../..:v8_libplatform",

test/unittests/heap/base/worklist-unittest.cc

@@ -4,7 +4,7 @@
 
 #include "src/heap/base/worklist.h"
 
-#include "test/unittests/heap/cppgc/tests.h"
+#include "testing/gtest/include/gtest/gtest.h"
 
 namespace heap {
 namespace base {
@@ -23,17 +23,17 @@ TEST(CppgcWorkListTest, SegmentCreate) {
 TEST(CppgcWorkListTest, SegmentPush) {
   TestWorklist::Segment segment;
   EXPECT_EQ(0u, segment.Size());
-  EXPECT_TRUE(segment.Push(nullptr));
+  segment.Push(nullptr);
   EXPECT_EQ(1u, segment.Size());
 }
 
 TEST(CppgcWorkListTest, SegmentPushPop) {
   TestWorklist::Segment segment;
-  EXPECT_TRUE(segment.Push(nullptr));
+  segment.Push(nullptr);
   EXPECT_EQ(1u, segment.Size());
   SomeObject dummy;
   SomeObject* object = &dummy;
-  EXPECT_TRUE(segment.Pop(&object));
+  segment.Pop(&object);
   EXPECT_EQ(0u, segment.Size());
   EXPECT_EQ(nullptr, object);
 }
@@ -41,7 +41,7 @@ TEST(CppgcWorkListTest, SegmentPushPop) {
 TEST(CppgcWorkListTest, SegmentIsEmpty) {
   TestWorklist::Segment segment;
   EXPECT_TRUE(segment.IsEmpty());
-  EXPECT_TRUE(segment.Push(nullptr));
+  segment.Push(nullptr);
   EXPECT_FALSE(segment.IsEmpty());
 }
 
@@ -49,44 +49,27 @@ TEST(CppgcWorkListTest, SegmentIsFull) {
   TestWorklist::Segment segment;
   EXPECT_FALSE(segment.IsFull());
   for (size_t i = 0; i < TestWorklist::Segment::kSize; i++) {
-    EXPECT_TRUE(segment.Push(nullptr));
+    segment.Push(nullptr);
   }
   EXPECT_TRUE(segment.IsFull());
 }
 
 TEST(CppgcWorkListTest, SegmentClear) {
   TestWorklist::Segment segment;
-  EXPECT_TRUE(segment.Push(nullptr));
+  segment.Push(nullptr);
   EXPECT_FALSE(segment.IsEmpty());
   segment.Clear();
   EXPECT_TRUE(segment.IsEmpty());
   for (size_t i = 0; i < TestWorklist::Segment::kSize; i++) {
-    EXPECT_TRUE(segment.Push(nullptr));
+    segment.Push(nullptr);
   }
 }
 
-TEST(CppgcWorkListTest, SegmentFullPushFails) {
-  TestWorklist::Segment segment;
-  EXPECT_FALSE(segment.IsFull());
-  for (size_t i = 0; i < TestWorklist::Segment::kSize; i++) {
-    EXPECT_TRUE(segment.Push(nullptr));
-  }
-  EXPECT_TRUE(segment.IsFull());
-  EXPECT_FALSE(segment.Push(nullptr));
-}
-
-TEST(CppgcWorkListTest, SegmentEmptyPopFails) {
-  TestWorklist::Segment segment;
-  EXPECT_TRUE(segment.IsEmpty());
-  SomeObject* object;
-  EXPECT_FALSE(segment.Pop(&object));
-}
-
 TEST(CppgcWorkListTest, SegmentUpdateFalse) {
   TestWorklist::Segment segment;
   SomeObject* object;
   object = reinterpret_cast<SomeObject*>(&object);
-  EXPECT_TRUE(segment.Push(object));
+  segment.Push(object);
   segment.Update([](SomeObject* object, SomeObject** out) { return false; });
   EXPECT_TRUE(segment.IsEmpty());
 }
@@ -97,13 +80,13 @@ TEST(CppgcWorkListTest, SegmentUpdate) {
   objectA = reinterpret_cast<SomeObject*>(&objectA);
   SomeObject* objectB;
   objectB = reinterpret_cast<SomeObject*>(&objectB);
-  EXPECT_TRUE(segment.Push(objectA));
+  segment.Push(objectA);
   segment.Update([objectB](SomeObject* object, SomeObject** out) {
     *out = objectB;
     return true;
   });
   SomeObject* object;
-  EXPECT_TRUE(segment.Pop(&object));
+  segment.Pop(&object);
   EXPECT_EQ(object, objectB);
 }
 
@@ -324,5 +307,26 @@ TEST(CppgcWorkListTest, MergeGlobalPool) {
   EXPECT_TRUE(worklist2.IsEmpty());
 }
 
+#ifdef DEBUG
+
+TEST(CppgcWorkListDeathTest, DiesOnPushToFullSegment) {
+  TestWorklist::Segment segment;
+  EXPECT_FALSE(segment.IsFull());
+  for (size_t i = 0; i < TestWorklist::Segment::kSize; i++) {
+    segment.Push(nullptr);
+  }
+  EXPECT_TRUE(segment.IsFull());
+  EXPECT_DEATH_IF_SUPPORTED(segment.Push(nullptr), "");
+}
+
+TEST(CppgcWorkListDeathTest, DiesOnPopFromEmptySegment) {
+  TestWorklist::Segment segment;
+  EXPECT_TRUE(segment.IsEmpty());
+  SomeObject* object;
+  EXPECT_DEATH_IF_SUPPORTED(segment.Pop(&object), "");
+}
+
+#endif  // DEBUG
+
 }  // namespace base
 }  // namespace heap