PPC: Remove usages of Heap::NewSpaceStart and its external reference

src/ppc/macro-assembler-ppc.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <assert.h>  // For assert
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_PPC
 
 #include "src/base/bits.h"
@@ skipping 4454 matching lines @@
   int offset = mem.offset();
 
   if (!is_int16(offset)) {
     mov(scratch, Operand(offset));
     stfdx(src, MemOperand(base, scratch));
   } else {
     stfd(src, mem);
   }
 }
 
-
 void MacroAssembler::TestJSArrayForAllocationMemento(Register receiver_reg,
                                                      Register scratch_reg,
+                                                     Register scratch2_reg,
                                                      Label* no_memento_found) {
-  ExternalReference new_space_start =
-      ExternalReference::new_space_start(isolate());
+  Label map_check;
+  Label top_check;
   ExternalReference new_space_allocation_top =
       ExternalReference::new_space_allocation_top_address(isolate());
-  addi(scratch_reg, receiver_reg,
-       Operand(JSArray::kSize + AllocationMemento::kSize - kHeapObjectTag));
-  Cmpi(scratch_reg, Operand(new_space_start), r0);
-  blt(no_memento_found);
-  mov(ip, Operand(new_space_allocation_top));
-  LoadP(ip, MemOperand(ip));
-  cmp(scratch_reg, ip);
+  const int kMementoMapOffset = JSArray::kSize - kHeapObjectTag;
+  const int kMementoEndOffset = kMementoMapOffset + AllocationMemento::kSize;
+  Register mask = scratch2_reg;
+
+  DCHECK(!AreAliased(receiver_reg, scratch_reg, mask));
+
+  // Bail out if the object is not in new space.
+  JumpIfNotInNewSpace(receiver_reg, scratch_reg, no_memento_found);
+
+  DCHECK((~Page::kPageAlignmentMask & 0xffff) == 0);
+  lis(mask, Operand((~Page::kPageAlignmentMask >> 16)));
+  addi(scratch_reg, receiver_reg, Operand(kMementoEndOffset));
+
+  // If the object is in new space, we need to check whether it is on the same
+  // page as the current top.
+  Xor(r0, scratch_reg, Operand(new_space_allocation_top));
+  and_(r0, r0, mask, SetRC);
+  beq(&top_check, cr0);
+  // The object is on a different page than allocation top. Bail out if the
+  // object sits on the page boundary as no memento can follow and we cannot
+  // touch the memory following it.
+  xor_(r0, scratch_reg, receiver_reg);
+  and_(r0, r0, mask, SetRC);
+  bne(no_memento_found, cr0);
+  // Continue with the actual map check.
+  b(&map_check);
+  // If top is on the same page as the current object, we need to check whether
+  // we are below top.
+  bind(&top_check);
+  Cmpi(scratch_reg, Operand(new_space_allocation_top), r0);
   bgt(no_memento_found);
-  LoadP(scratch_reg, MemOperand(scratch_reg, -AllocationMemento::kSize));
+  // Memento map check.
+  bind(&map_check);
+  LoadP(scratch_reg, MemOperand(receiver_reg, kMementoMapOffset));
   Cmpi(scratch_reg, Operand(isolate()->factory()->allocation_memento_map()),
        r0);
 }
 
-
 Register GetRegisterThatIsNotOneOf(Register reg1, Register reg2, Register reg3,
                                    Register reg4, Register reg5,
                                    Register reg6) {
   RegList regs = 0;
   if (reg1.is_valid()) regs |= reg1.bit();
   if (reg2.is_valid()) regs |= reg2.bit();
   if (reg3.is_valid()) regs |= reg3.bit();
   if (reg4.is_valid()) regs |= reg4.bit();
   if (reg5.is_valid()) regs |= reg5.bit();
   if (reg6.is_valid()) regs |= reg6.bit();
@@ skipping 137 matching lines @@
   }
   if (mag.shift > 0) srawi(result, result, mag.shift);
   ExtractBit(r0, dividend, 31);
   add(result, result, r0);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_PPC