## Sketch of compressed OOPs for amd64.  See also compressed-oops-arm.S.
        .intel_syntax noprefix
        ## Index compressed oop in r8 using heap base pointer in r12
	## to load a compressed oop from memory into r10:
   	## 47 8b 54 c4 10  mov 0x10(%r12,%r8,8),%r10d
	mov r10d, dword ptr [r12 + r8*8 + 16]

        ## Contrast with uncompressed oops:
	## 4d 8b 50 20     mov 0x20(%r8),%r1
        movq r10, [r8 + 32]

        ## What if we instead have 16-bit compressed OOPs and
	## 32-bit-aligned objects?  The above assumes 64-bit-aligned.
        ## This involves slightly larger code but probably only the
        ## same amount of work.
        ## 66 47 8b 54 84 08   mov 0x8(%r12,%r8,4),%r10w
        mov r10w, word ptr [r12 + r8*4 + 8]