1 files changed, 25 insertions, 1 deletions
diff --git a/deps/v8/src/heap/memory-chunk-layout.cc b/deps/v8/src/heap/memory-chunk-layout.cc
index e81aaec8f3..1fb265f39f 100644
--- a/deps/v8/src/heap/memory-chunk-layout.cc
+++ b/deps/v8/src/heap/memory-chunk-layout.cc
@@ -24,6 +24,12 @@ size_t MemoryChunkLayout::CodePageGuardSize() {
 }
 
 intptr_t MemoryChunkLayout::ObjectStartOffsetInCodePage() {
+  // The first page also includes padding for code alignment.
+  return ObjectPageOffsetInCodePage() +
+         InstructionStream::kCodeAlignmentMinusCodeHeader;
+}
+
+intptr_t MemoryChunkLayout::ObjectPageOffsetInCodePage() {
   // We are guarding code pages: the first OS page after the header
   // will be protected as non-writable.
   return CodePageGuardStartOffset() + CodePageGuardSize();
@@ -46,11 +52,19 @@ intptr_t MemoryChunkLayout::ObjectStartOffsetInDataPage() {
                  ALIGN_TO_ALLOCATION_ALIGNMENT(kDoubleSize));
 }
 
+intptr_t MemoryChunkLayout::ObjectStartOffsetInReadOnlyPage() {
+  return RoundUp(BasicMemoryChunk::kHeaderSize,
+                 ALIGN_TO_ALLOCATION_ALIGNMENT(kDoubleSize));
+}
+
 size_t MemoryChunkLayout::ObjectStartOffsetInMemoryChunk(
     AllocationSpace space) {
   if (space == CODE_SPACE || space == CODE_LO_SPACE) {
     return ObjectStartOffsetInCodePage();
   }
+  if (space == RO_SPACE) {
+    return ObjectStartOffsetInReadOnlyPage();
+  }
   return ObjectStartOffsetInDataPage();
 }
 
@@ -60,16 +74,26 @@ size_t MemoryChunkLayout::AllocatableMemoryInDataPage() {
   return memory;
 }
 
+size_t MemoryChunkLayout::AllocatableMemoryInReadOnlyPage() {
+  size_t memory = MemoryChunk::kPageSize - ObjectStartOffsetInReadOnlyPage();
+  DCHECK_LE(kMaxRegularHeapObjectSize, memory);
+  return memory;
+}
+
 size_t MemoryChunkLayout::AllocatableMemoryInMemoryChunk(
     AllocationSpace space) {
   if (space == CODE_SPACE) {
     return AllocatableMemoryInCodePage();
   }
+  if (space == RO_SPACE) {
+    return AllocatableMemoryInReadOnlyPage();
+  }
   return AllocatableMemoryInDataPage();
 }
 
 int MemoryChunkLayout::MaxRegularCodeObjectSize() {
-  int size = static_cast<int>(AllocatableMemoryInCodePage() / 2);
+  int size = static_cast<int>(
+      RoundDown(AllocatableMemoryInCodePage() / 2, kTaggedSize));
   DCHECK_LE(size, kMaxRegularHeapObjectSize);
   return size;
 }