Revert r4715.

src/arm/macro-assembler-arm.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 234 matching lines @@
                                        Register offset,
                                        Register scratch) {
   if (FLAG_debug_code) {
     // Check that the object is not in new space.
     Label not_in_new_space;
     InNewSpace(object, scratch, ne, &not_in_new_space);
     Abort("new-space object passed to RecordWriteHelper");
     bind(&not_in_new_space);
   }
 
-  mov(ip, Operand(Page::kPageAlignmentMask));  // Load mask only once.
+  // This is how much we shift the remembered set bit offset to get the
+  // offset of the word in the remembered set.  We divide by kBitsPerInt (32,
+  // shift right 5) and then multiply by kIntSize (4, shift left 2).
+  const int kRSetWordShift = 3;
 
-  // Calculate region number.
-  add(offset, object, Operand(offset));  // Add offset into the object.
-  and_(offset, offset, Operand(ip));  // Offset into page of the object.
-  mov(offset, Operand(offset, LSR, Page::kRegionSizeLog2));
+  Label fast;
 
-  // Calculate page address.
+  // Compute the bit offset in the remembered set.
+  // object: heap object pointer (with tag)
+  // offset: offset to store location from the object
+  mov(ip, Operand(Page::kPageAlignmentMask));  // load mask only once
+  and_(scratch, object, Operand(ip));  // offset into page of the object
+  add(offset, scratch, Operand(offset));  // add offset into the object
+  mov(offset, Operand(offset, LSR, kObjectAlignmentBits));
+
+  // Compute the page address from the heap object pointer.
+  // object: heap object pointer (with tag)
+  // offset: bit offset of store position in the remembered set
   bic(object, object, Operand(ip));
 
-  // Mark region dirty.
-  ldr(scratch, MemOperand(object, Page::kDirtyFlagOffset));
+  // If the bit offset lies beyond the normal remembered set range, it is in
+  // the extra remembered set area of a large object.
+  // object: page start
+  // offset: bit offset of store position in the remembered set
+  cmp(offset, Operand(Page::kPageSize / kPointerSize));
+  b(lt, &fast);
+
+  // Adjust the bit offset to be relative to the start of the extra
+  // remembered set and the start address to be the address of the extra
+  // remembered set.
+  sub(offset, offset, Operand(Page::kPageSize / kPointerSize));
+  // Load the array length into 'scratch' and multiply by four to get the
+  // size in bytes of the elements.
+  ldr(scratch, MemOperand(object, Page::kObjectStartOffset
+                                  + FixedArray::kLengthOffset));
+  mov(scratch, Operand(scratch, LSL, kObjectAlignmentBits));
+  // Add the page header (including remembered set), array header, and array
+  // body size to the page address.
+  add(object, object, Operand(Page::kObjectStartOffset
+                              + FixedArray::kHeaderSize));
+  add(object, object, Operand(scratch));
+
+  bind(&fast);
+  // Get address of the rset word.
+  // object: start of the remembered set (page start for the fast case)
+  // offset: bit offset of store position in the remembered set
+  bic(scratch, offset, Operand(kBitsPerInt - 1));  // clear the bit offset
+  add(object, object, Operand(scratch, LSR, kRSetWordShift));
+  // Get bit offset in the rset word.
+  // object: address of remembered set word
+  // offset: bit offset of store position
+  and_(offset, offset, Operand(kBitsPerInt - 1));
+
+  ldr(scratch, MemOperand(object));
   mov(ip, Operand(1));
   orr(scratch, scratch, Operand(ip, LSL, offset));
-  str(scratch, MemOperand(object, Page::kDirtyFlagOffset));
+  str(scratch, MemOperand(object));
 }
 
 
 void MacroAssembler::InNewSpace(Register object,
                                 Register scratch,
                                 Condition cc,
                                 Label* branch) {
   ASSERT(cc == eq || cc == ne);
   and_(scratch, object, Operand(ExternalReference::new_space_mask()));
   cmp(scratch, Operand(ExternalReference::new_space_start()));
   b(cc, branch);
 }
 
 
 // Will clobber 4 registers: object, offset, scratch, ip.  The
 // register 'object' contains a heap object pointer.  The heap object
 // tag is shifted away.
 void MacroAssembler::RecordWrite(Register object, Register offset,
                                  Register scratch) {
   // The compiled code assumes that record write doesn't change the
   // context register, so we check that none of the clobbered
   // registers are cp.
   ASSERT(!object.is(cp) && !offset.is(cp) && !scratch.is(cp));
 
   Label done;
 
   // First, test that the object is not in the new space.  We cannot set
-  // region marks for new space pages.
+  // remembered set bits in the new space.
   InNewSpace(object, scratch, eq, &done);
 
   // Record the actual write.
   RecordWriteHelper(object, offset, scratch);
 
   bind(&done);
 
   // Clobber all input registers when running with the debug-code flag
   // turned on to provoke errors.
   if (FLAG_debug_code) {
@@ skipping 262 matching lines @@
   ASSERT(fun.is(r1));
 
   Register expected_reg = r2;
   Register code_reg = r3;
 
   ldr(code_reg, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
   ldr(cp, FieldMemOperand(r1, JSFunction::kContextOffset));
   ldr(expected_reg,
       FieldMemOperand(code_reg,
                       SharedFunctionInfo::kFormalParameterCountOffset));
-  mov(expected_reg, Operand(expected_reg, ASR, kSmiTagSize));
   ldr(code_reg,
       MemOperand(code_reg, SharedFunctionInfo::kCodeOffset - kHeapObjectTag));
   add(code_reg, code_reg, Operand(Code::kHeaderSize - kHeapObjectTag));
 
   ParameterCount expected(expected_reg);
   InvokeCode(code_reg, expected, actual, flag);
 }
 
 
 void MacroAssembler::InvokeFunction(JSFunction* function,
@@ skipping 1090 matching lines @@
 
 void CodePatcher::Emit(Address addr) {
   masm()->emit(reinterpret_cast<Instr>(addr));
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM