[heap] Allow semi space sizes above kMaxSemiSpaceSize

Maximum semispace size was capped at kMaxSemiSpaceSize. Also allow
non-power-of-2 sizes.

Change-Id: I3385674a13455b47802a3f6e62ac5b9ed3987264
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1962863Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65445}

src/heap/heap.cc

@@ -4468,14 +4468,7 @@ void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) {
       // This will cause more frequent GCs when stressing.
       max_semi_space_size_ = MB;
     }
-    // The new space size must be a power of two to support single-bit testing
-    // for containment.
-    // TODO(ulan): Rounding to a power of 2 is not longer needed. Remove it.
-    max_semi_space_size_ =
-        static_cast<size_t>(base::bits::RoundUpToPowerOfTwo64(
-            static_cast<uint64_t>(max_semi_space_size_)));
     max_semi_space_size_ = Max(max_semi_space_size_, kMinSemiSpaceSize);
-    max_semi_space_size_ = Min(max_semi_space_size_, kMaxSemiSpaceSize);
     max_semi_space_size_ = RoundDown<Page::kPageSize>(max_semi_space_size_);
   }
 

src/heap/spaces.cc

@@ -2245,8 +2245,6 @@ NewSpace::NewSpace(Heap* heap, v8::PageAllocator* page_allocator,
       to_space_(heap, kToSpace),
       from_space_(heap, kFromSpace) {
   DCHECK(initial_semispace_capacity <= max_semispace_capacity);
-  DCHECK(
-      base::bits::IsPowerOfTwo(static_cast<uint32_t>(max_semispace_capacity)));
 
   to_space_.SetUp(initial_semispace_capacity, max_semispace_capacity);
   from_space_.SetUp(initial_semispace_capacity, max_semispace_capacity);

tools/v8heapconst.py

@@ -415,8 +415,8 @@ KNOWN_OBJECTS = {
 
 # Lower 32 bits of first page addresses for various heap spaces.
 HEAP_FIRST_PAGES = {
-  0x08180000: "old_space",
-  0x081c0000: "map_space",
+  0x08100000: "old_space",
+  0x08140000: "map_space",
   0x08040000: "read_only_space",
 }