[heap] Black is encoded with 11, grey with 10.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index e302a419ea47513c4474aad05991f411cd89f62f..179ed66b0d81b9763a5778347ce25e57826c0f11 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -5286,16 +5286,13 @@ void MacroAssembler::JumpIfBlack(Register object,
                                  Label* on_black,
                                  Label::Distance on_black_distance) {
   DCHECK(!AreAliased(object, bitmap_scratch, mask_scratch, rcx));
+
   GetMarkBits(object, bitmap_scratch, mask_scratch);
 
-  DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0);
+  DCHECK(strcmp(Marking::kBlackBitPattern, "11") == 0);
   // The mask_scratch register contains a 1 at the position of the first bit
-  // and a 0 at all other positions, including the position of the second bit.
+  // and a 1 at a position of the second bit. All other positions are zero.
   movp(rcx, mask_scratch);
-  // Make rcx into a mask that covers both marking bits using the operation
-  // rcx = mask | (mask << 1).
-  leap(rcx, Operand(mask_scratch, mask_scratch, times_2, 0));
-  // Note that we are using a 4-byte aligned 8-byte load.
   andp(rcx, Operand(bitmap_scratch, MemoryChunk::kHeaderSize));
   cmpp(mask_scratch, rcx);
   j(equal, on_black, on_black_distance);
@@ -5321,7 +5318,7 @@ void MacroAssembler::GetMarkBits(Register addr_reg,
   movp(rcx, addr_reg);
   shrl(rcx, Immediate(kPointerSizeLog2));
   andp(rcx, Immediate((1 << Bitmap::kBitsPerCellLog2) - 1));
-  movl(mask_reg, Immediate(1));
+  movl(mask_reg, Immediate(3));
   shlp_cl(mask_reg);
 }
 
@@ -5334,8 +5331,8 @@ void MacroAssembler::JumpIfWhite(Register value, Register bitmap_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::kBlackBitPattern, "11") == 0);
+  DCHECK(strcmp(Marking::kGreyBitPattern, "10") == 0);
   DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0);
 
   // Since both black and grey have a 1 in the first position and white does