[heap] Reduce regular heap object size limit to half of the page size

This CL removes PPC specific constants and makes the regular heap
object size limit a power of two.

Bug: chromium:852420
Change-Id: I5f4000f76d029d689d22112877eea124774b29d2
Reviewed-on: https://chromium-review.googlesource.com/c/1496367Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60011}

src/globals.h

@@ -236,13 +236,8 @@ constexpr int kExternalAllocationSoftLimit =
 // migrated from new space to large object space. Takes double alignment into
 // account.
 //
-// Current value: Page::kAllocatableMemory (on 32-bit arch) - 512 (slack).
-#ifdef V8_HOST_ARCH_PPC
-// Reduced kMaxRegularHeapObjectSize due to larger page size(64k) on ppc64le
-constexpr int kMaxRegularHeapObjectSize = 327680;
-#else
-constexpr int kMaxRegularHeapObjectSize = 507136;
-#endif
+// Current value: half of the page size.
+constexpr int kMaxRegularHeapObjectSize = (1 << (kPageSizeBits - 1));
 
 constexpr int kBitsPerByte = 8;
 constexpr int kBitsPerByteLog2 = 3;

src/heap/spaces.h

@@ -1948,7 +1948,7 @@ class V8_EXPORT_PRIVATE FreeList {
   static const size_t kTinyListMax = 0x1f * kTaggedSize;
   static const size_t kSmallListMax = 0xff * kTaggedSize;
   static const size_t kMediumListMax = 0x7ff * kTaggedSize;
-  static const size_t kLargeListMax = 0x3fff * kTaggedSize;
+  static const size_t kLargeListMax = 0x2fff * kTaggedSize;
   static const size_t kTinyAllocationMax = kTiniestListMax;
   static const size_t kSmallAllocationMax = kTinyListMax;
   static const size_t kMediumAllocationMax = kSmallListMax;

src/objects/hash-table.h

@@ -176,13 +176,7 @@ class HashTable : public HashTableBase {
   // Don't shrink a HashTable below this capacity.
   static const int kMinShrinkCapacity = 16;
 
-  // Maximum length to create a regular HashTable (aka. non large object).
-#if V8_HOST_ARCH_PPC
-  // Reduced kMaxRegularCapacity due to reduced kMaxRegularHeapObjectSize
-  static const int kMaxRegularCapacity = 16384 / 2;
-#else
-  static const int kMaxRegularCapacity = 16384;
-#endif
+  static const int kMaxRegularCapacity = kMaxRegularHeapObjectSize / 32;
 
   // Returns the index for an entry (of the key)
   static constexpr inline int EntryToIndex(int entry) {