Remove usages of Heap::NewSpaceStart and its external reference

src/x87/macro-assembler-x87.cc

Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index 5607426171f8bcb15bf83f2744697e7c48dd2c90..5d9f9bd33deb0acb7eca747a49fb04e4d84d6594 100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -3174,18 +3174,36 @@ void MacroAssembler::TestJSArrayForAllocationMemento(
     Register receiver_reg,
     Register scratch_reg,
     Label* no_memento_found) {
-  ExternalReference new_space_start =
-      ExternalReference::new_space_start(isolate());
+  Label map_check;
   ExternalReference new_space_allocation_top =
       ExternalReference::new_space_allocation_top_address(isolate());
-
-  lea(scratch_reg, Operand(receiver_reg,
-      JSArray::kSize + AllocationMemento::kSize - kHeapObjectTag));
-  cmp(scratch_reg, Immediate(new_space_start));
-  j(less, no_memento_found);
+  const int kMementoMapOffset = JSArray::kSize - kHeapObjectTag;
+  const int kMementoEndOffset = kMementoMapOffset + AllocationMemento::kSize;
+
+  // Bail out if the object sits on the page boundary as no memento can follow
+  // and we cannot touch the memory following it.
+  lea(scratch_reg, Operand(receiver_reg, kMementoEndOffset));
+  xor_(scratch_reg, receiver_reg);
+  cmp(scratch_reg, Immediate(Page::kPageSize));
+  j(greater, no_memento_found);
+  // Bail out if the object is not in new space.
+  lea(scratch_reg, Operand(receiver_reg, kMementoEndOffset));
+  JumpIfNotInNewSpace(scratch_reg, scratch_reg, no_memento_found);
+  // If the object is in new space, we need to check whether it is on the same
+  // page as the current top.
+  lea(scratch_reg, Operand(receiver_reg, kMementoEndOffset));
+  xor_(scratch_reg, Operand::StaticVariable(new_space_allocation_top));
+  test(scratch_reg, Immediate(~Page::kPageAlignmentMask));
+  // If top is not on the same page as the current object, we can just continue
+  // with the map check.
+  j(not_zero, &map_check);
+  // Otherwise, we have to check whether we are still below top, to ensure that
+  // we are not checking against a stale memento.
+  lea(scratch_reg, Operand(receiver_reg, kMementoEndOffset));
   cmp(scratch_reg, Operand::StaticVariable(new_space_allocation_top));
   j(greater, no_memento_found);
-  cmp(MemOperand(scratch_reg, -AllocationMemento::kSize),
+  bind(&map_check);
+  cmp(MemOperand(receiver_reg, kMementoMapOffset),
       Immediate(isolate()->factory()->allocation_memento_map()));
 }