[heap] Provide --max-heap-size flag

The flag configures both the young and old generation limits.

Bug: v8:9306
Change-Id: Ib94dcb6dc014864248a5926f585b54a83db28063
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1679500Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62440}

src/flags/flag-definitions.h

@@ -742,6 +742,11 @@ DEFINE_BOOL(experimental_new_space_growth_heuristic, false,
             "Grow the new space based on the percentage of survivors instead "
             "of their absolute value.")
 DEFINE_SIZE_T(max_old_space_size, 0, "max size of the old space (in Mbytes)")
+DEFINE_SIZE_T(
+    max_heap_size, 0,
+    "max size of the heap (in Mbytes) "
+    "both max_semi_space_size and max_old_space_size take precedence. "
+    "All three flags cannot be specified at the same time.")
 DEFINE_BOOL(huge_max_old_generation_size, false,
             "Increase max size of the old space to 4 GB for x64 systems with"
             "the physical memory bigger than 16 GB")

src/heap/heap.cc

@@ -4409,7 +4409,7 @@ void Heap::IterateBuiltins(RootVisitor* v) {
 }
 
 void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) {
-  // Initialize  max_semi_space_size_.
+  // Initialize max_semi_space_size_.
   {
     if (constraints.max_young_generation_size_in_bytes() > 0) {
       max_semi_space_size_ = SemiSpaceSizeFromYoungGenerationSize(
@@ -4417,6 +4417,20 @@ void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) {
     }
     if (FLAG_max_semi_space_size > 0) {
       max_semi_space_size_ = static_cast<size_t>(FLAG_max_semi_space_size) * MB;
+    } else if (FLAG_max_heap_size > 0) {
+      size_t max_heap_size = static_cast<size_t>(FLAG_max_heap_size) * MB;
+      size_t young_generation_size, old_generation_size;
+      if (FLAG_max_old_space_size > 0) {
+        old_generation_size = static_cast<size_t>(FLAG_max_old_space_size) * MB;
+        young_generation_size = max_heap_size > old_generation_size
+                                    ? max_heap_size - old_generation_size
+                                    : 0;
+      } else {
+        GenerationSizesFromHeapSize(max_heap_size, &young_generation_size,
+                                    &old_generation_size);
+      }
+      max_semi_space_size_ =
+          SemiSpaceSizeFromYoungGenerationSize(young_generation_size);
     }
     if (FLAG_stress_compaction) {
       // This will cause more frequent GCs when stressing.
@@ -4440,6 +4454,13 @@ void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) {
     if (FLAG_max_old_space_size > 0) {
       max_old_generation_size_ =
           static_cast<size_t>(FLAG_max_old_space_size) * MB;
+    } else if (FLAG_max_heap_size > 0) {
+      size_t max_heap_size = static_cast<size_t>(FLAG_max_heap_size) * MB;
+      size_t young_generation_size =
+          YoungGenerationSizeFromSemiSpaceSize(max_semi_space_size_);
+      max_old_generation_size_ = max_heap_size > young_generation_size
+                                     ? max_heap_size - young_generation_size
+                                     : 0;
     }
     max_old_generation_size_ =
         Max(max_old_generation_size_, MinOldGenerationSize());
@@ -4447,6 +4468,9 @@ void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) {
         RoundDown<Page::kPageSize>(max_old_generation_size_);
   }
 
+  CHECK_IMPLIES(FLAG_max_heap_size > 0,
+                FLAG_max_semi_space_size == 0 || FLAG_max_old_space_size == 0);
+
   // Initialize initial_semispace_size_.
   {
     if (max_semi_space_size_ == kMaxSemiSpaceSize) {