[heap] Enable --huge_max_old_generation_size by default and add tests

Now ResourceConstraints::ConfigureDefaults sets the heap limit to 4GB
if the physical memory size is greater or equal to 16GB on 64-bit
platforms.

This CL also adds tests for configuring heap limits from the physical
memory size.

Bug: chromium:1045034
Change-Id: If0d5a237b2db31309a9a2a6456d950ef70dc71af
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2043833
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66174}

src/flags/flag-definitions.h

@@ -810,7 +810,7 @@ DEFINE_SIZE_T(
     "both max_semi_space_size and max_old_space_size take precedence. "
     "All three flags cannot be specified at the same time.")
 DEFINE_SIZE_T(initial_heap_size, 0, "initial size of the heap (in Mbytes)")
-DEFINE_BOOL(huge_max_old_generation_size, false,
+DEFINE_BOOL(huge_max_old_generation_size, true,
             "Increase max size of the old space to 4 GB for x64 systems with"
             "the physical memory bigger than 16 GB")
 DEFINE_SIZE_T(initial_old_space_size, 0, "initial old space size (in Mbytes)")

test/cctest/heap/test-heap.cc

@@ -6891,6 +6891,41 @@ TEST(Regress9701) {
   CHECK_EQ(mark_sweep_count_before, mark_sweep_count_after);
 }
 
+#if defined(V8_TARGET_ARCH_64_BIT) && !defined(V8_OS_ANDROID)
+UNINITIALIZED_TEST(HugeHeapLimit) {
+  uint64_t kMemoryGB = 16;
+  v8::Isolate::CreateParams create_params;
+  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
+  create_params.constraints.ConfigureDefaults(kMemoryGB * GB, kMemoryGB * GB);
+  v8::Isolate* isolate = v8::Isolate::New(create_params);
+  Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
+#ifdef V8_COMPRESS_POINTERS
+  // Fix this once the fix for crbug.com/1049816 lands.
+  size_t kExpectedHeapLimit = size_t{2} * GB;
+#else
+  size_t kExpectedHeapLimit = size_t{4} * GB;
+#endif
+  CHECK_EQ(kExpectedHeapLimit, i_isolate->heap()->MaxOldGenerationSize());
+  isolate->Dispose();
+}
+#endif
+
+UNINITIALIZED_TEST(HeapLimit) {
+  uint64_t kMemoryGB = 15;
+  v8::Isolate::CreateParams create_params;
+  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
+  create_params.constraints.ConfigureDefaults(kMemoryGB * GB, kMemoryGB * GB);
+  v8::Isolate* isolate = v8::Isolate::New(create_params);
+  Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
+#if defined(V8_TARGET_ARCH_64_BIT) && !defined(V8_OS_ANDROID)
+  size_t kExpectedHeapLimit = size_t{2} * GB;
+#else
+  size_t kExpectedHeapLimit = size_t{1} * GB;
+#endif
+  CHECK_EQ(kExpectedHeapLimit, i_isolate->heap()->MaxOldGenerationSize());
+  isolate->Dispose();
+}
+
 }  // namespace heap
 }  // namespace internal
 }  // namespace v8