Do not mark from native code. Check color and call incremental marker instead.

src/mips/macro-assembler-mips.cc

 
 // Copyright 2012 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 <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/base/bits.h"
@@ skipping 5410 matching lines @@
   jmp(&other_color);
 
   bind(&word_boundary);
   lw(t9, MemOperand(bitmap_scratch, MemoryChunk::kHeaderSize + kPointerSize));
   And(t9, t9, Operand(1));
   Branch(has_color, second_bit == 1 ? ne : eq, t9, Operand(zero_reg));
   bind(&other_color);
 }
 
 
-// Detect some, but not all, common pointer-free objects.  This is used by the
-// incremental write barrier which doesn't care about oddballs (they are always
-// marked black immediately so this code is not hit).
-void MacroAssembler::JumpIfDataObject(Register value,
-                                      Register scratch,
-                                      Label* not_data_object) {
-  DCHECK(!AreAliased(value, scratch, t8, no_reg));
-  Label is_data_object;
-  lw(scratch, FieldMemOperand(value, HeapObject::kMapOffset));
-  LoadRoot(t8, Heap::kHeapNumberMapRootIndex);
-  Branch(&is_data_object, eq, t8, Operand(scratch));
-  DCHECK(kIsIndirectStringTag == 1 && kIsIndirectStringMask == 1);
-  DCHECK(kNotStringTag == 0x80 && kIsNotStringMask == 0x80);
-  // If it's a string and it's not a cons string then it's an object containing
-  // no GC pointers.
-  lbu(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
-  And(t8, scratch, Operand(kIsIndirectStringMask | kIsNotStringMask));
-  Branch(not_data_object, ne, t8, Operand(zero_reg));
-  bind(&is_data_object);
-}
-
-
 void MacroAssembler::GetMarkBits(Register addr_reg,
                                  Register bitmap_reg,
                                  Register mask_reg) {
   DCHECK(!AreAliased(addr_reg, bitmap_reg, mask_reg, no_reg));
   And(bitmap_reg, addr_reg, Operand(~Page::kPageAlignmentMask));
   Ext(mask_reg, addr_reg, kPointerSizeLog2, Bitmap::kBitsPerCellLog2);
   const int kLowBits = kPointerSizeLog2 + Bitmap::kBitsPerCellLog2;
   Ext(t8, addr_reg, kLowBits, kPageSizeBits - kLowBits);
   sll(t8, t8, kPointerSizeLog2);
   Addu(bitmap_reg, bitmap_reg, t8);
   li(t8, Operand(1));
   sllv(mask_reg, t8, mask_reg);
 }
 
 
-void MacroAssembler::EnsureNotWhite(
-    Register value,
-    Register bitmap_scratch,
-    Register mask_scratch,
-    Register load_scratch,
-    Label* value_is_white_and_not_data) {
+void MacroAssembler::JumpIfWhite(Register value, Register bitmap_scratch,
+                                 Register mask_scratch, Register load_scratch,
+                                 Label* value_is_white) {
   DCHECK(!AreAliased(value, bitmap_scratch, mask_scratch, t8));
   GetMarkBits(value, bitmap_scratch, mask_scratch);
 
   // If the value is black or grey we don't need to do anything.
   DCHECK(strcmp(Marking::kWhiteBitPattern, "00") == 0);
   DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0);
   DCHECK(strcmp(Marking::kGreyBitPattern, "11") == 0);
   DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0);
 
-  Label done;
-
   // Since both black and grey have a 1 in the first position and white does
   // not have a 1 there we only need to check one bit.
   lw(load_scratch, MemOperand(bitmap_scratch, MemoryChunk::kHeaderSize));
   And(t8, mask_scratch, load_scratch);
-  Branch(&done, ne, t8, Operand(zero_reg));
-
-  if (emit_debug_code()) {
-    // Check for impossible bit pattern.
-    Label ok;
-    // sll may overflow, making the check conservative.
-    sll(t8, mask_scratch, 1);
-    And(t8, load_scratch, t8);
-    Branch(&ok, eq, t8, Operand(zero_reg));
-    stop("Impossible marking bit pattern");
-    bind(&ok);
-  }
-
-  // Value is white.  We check whether it is data that doesn't need scanning.
-  // Currently only checks for HeapNumber and non-cons strings.
-  Register map = load_scratch;  // Holds map while checking type.
-  Register length = load_scratch;  // Holds length of object after testing type.
-  Label is_data_object;
-
-  // Check for heap-number
-  lw(map, FieldMemOperand(value, HeapObject::kMapOffset));
-  LoadRoot(t8, Heap::kHeapNumberMapRootIndex);
-  {
-    Label skip;
-    Branch(&skip, ne, t8, Operand(map));
-    li(length, HeapNumber::kSize);
-    Branch(&is_data_object);
-    bind(&skip);
-  }
-
-  // Check for strings.
-  DCHECK(kIsIndirectStringTag == 1 && kIsIndirectStringMask == 1);
-  DCHECK(kNotStringTag == 0x80 && kIsNotStringMask == 0x80);
-  // If it's a string and it's not a cons string then it's an object containing
-  // no GC pointers.
-  Register instance_type = load_scratch;
-  lbu(instance_type, FieldMemOperand(map, Map::kInstanceTypeOffset));
-  And(t8, instance_type, Operand(kIsIndirectStringMask | kIsNotStringMask));
-  Branch(value_is_white_and_not_data, ne, t8, Operand(zero_reg));
-  // It's a non-indirect (non-cons and non-slice) string.
-  // If it's external, the length is just ExternalString::kSize.
-  // Otherwise it's String::kHeaderSize + string->length() * (1 or 2).
-  // External strings are the only ones with the kExternalStringTag bit
-  // set.
-  DCHECK_EQ(0, kSeqStringTag & kExternalStringTag);
-  DCHECK_EQ(0, kConsStringTag & kExternalStringTag);
-  And(t8, instance_type, Operand(kExternalStringTag));
-  {
-    Label skip;
-    Branch(&skip, eq, t8, Operand(zero_reg));
-    li(length, ExternalString::kSize);
-    Branch(&is_data_object);
-    bind(&skip);
-  }
-
-  // Sequential string, either Latin1 or UC16.
-  // For Latin1 (char-size of 1) we shift the smi tag away to get the length.
-  // For UC16 (char-size of 2) we just leave the smi tag in place, thereby
-  // getting the length multiplied by 2.
-  DCHECK(kOneByteStringTag == 4 && kStringEncodingMask == 4);
-  DCHECK(kSmiTag == 0 && kSmiTagSize == 1);
-  lw(t9, FieldMemOperand(value, String::kLengthOffset));
-  And(t8, instance_type, Operand(kStringEncodingMask));
-  {
-    Label skip;
-    Branch(&skip, eq, t8, Operand(zero_reg));
-    srl(t9, t9, 1);
-    bind(&skip);
-  }
-  Addu(length, t9, Operand(SeqString::kHeaderSize + kObjectAlignmentMask));
-  And(length, length, Operand(~kObjectAlignmentMask));
-
-  bind(&is_data_object);
-  // Value is a data object, and it is white.  Mark it black.  Since we know
-  // that the object is white we can make it black by flipping one bit.
-  lw(t8, MemOperand(bitmap_scratch, MemoryChunk::kHeaderSize));
-  Or(t8, t8, Operand(mask_scratch));
-  sw(t8, MemOperand(bitmap_scratch, MemoryChunk::kHeaderSize));
-
-  And(bitmap_scratch, bitmap_scratch, Operand(~Page::kPageAlignmentMask));
-  lw(t8, MemOperand(bitmap_scratch, MemoryChunk::kLiveBytesOffset));
-  Addu(t8, t8, Operand(length));
-  sw(t8, MemOperand(bitmap_scratch, MemoryChunk::kLiveBytesOffset));
-
-  bind(&done);
+  Branch(value_is_white, eq, t8, Operand(zero_reg));
 }
 
 
 void MacroAssembler::LoadInstanceDescriptors(Register map,
                                              Register descriptors) {
   lw(descriptors, FieldMemOperand(map, Map::kDescriptorsOffset));
 }
 
 
 void MacroAssembler::NumberOfOwnDescriptors(Register dst, Register map) {
@@ skipping 280 matching lines @@
   if (mag.shift > 0) sra(result, result, mag.shift);
   srl(at, dividend, 31);
   Addu(result, result, Operand(at));
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS