Re: [Valgrind-developers] MMX fix

[Julian S. <js...@ac...>]

Um, that don't look right.  [well, actually it might work if the
dest is memory, but not if it's an ireg.]
MOVD can't be done the same way as MOVQ.
Compare the code for 0x6E (  mmxreg := ireg-or-mem   )
against that for     0x6F (  mmxreg := mmxreg-or-mem  ).

0x6E generates MMX2_RegRd or MMX2_MemRd.
0x6F generates MMX2       or MMX2_MemRd.

where  MMX2_RegRd   is for ireg->mmxreg moves
       MMX2_MemRd   is for mem ->mmxreg moves
       MMX2         is for purely internal MMX activity

Now, I notice that in fact my 0x6E is wrong, because the else { } bit
generates MMX2_RegRd when it should generate MMX2_MemRd.

Modulo that correction, I think 0x7F should be done same as 0x6F,
except with the direction of data flow reversed, and generating
MMX2_RegWr or MMX2_MemWr.  MMX2_RegWr is problematic since I 
haven't written any handlers for it, although the code for it should
be a straight rip of all the MMX2_RegRd cases.

J


On Wednesday 02 April 2003 8:39 am, Jeremy Fitzhardinge wrote:
> I tried out Mesa software rendering; it failed because V was missing
> movd reg, r/m.  The fix is simple:
> (http://www.goop.org/~jeremy/valgrind/88-mmxfix.patch)
>
>
> Implement movd mm, r/m
>
>
>  coregrind/vg_to_ucode.c |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff -puN coregrind/vg_to_ucode.c~88-mmxfix coregrind/vg_to_ucode.c
> --- valgrind/coregrind/vg_to_ucode.c~88-mmxfix	Tue Apr  1 18:47:14 2003
> +++ valgrind-jeremy/coregrind/vg_to_ucode.c	Tue Apr  1 19:08:04 2003
> @@ -4867,6 +4867,7 @@ static Addr disInstr ( UCodeBlock* cb, A
>           }
>           break;
>
> +      case 0x7E: /* MOVD (src)mmxreg, (dst)mmxreg-or-mem */
>        case 0x7F: /* MOVQ (src)mmxreg, (dst)mmxreg-or-mem */
>           vg_assert(sz == 4);
>           modrm = getUChar(eip);
> @@ -4882,7 +4883,8 @@ static Addr disInstr ( UCodeBlock* cb, A
>                          (((UShort)(opc)) << 8) | ((UShort)modrm),
>                          TempReg, tmpa);
>              if (dis)
> -               VG_(printf)("movq %s, %s\n",
> +               VG_(printf)("mov%c %s, %s\n",
> +			   opc == 0x7e ? 'd' : 'q',
>                             nameMMXReg(gregOfRM(modrm)),
>                             dis_buf);
>           }
> @@ -5022,9 +5024,9 @@ static Addr disInstr ( UCodeBlock* cb, A
>        unimp2:
>           VG_(printf)("disInstr: unhandled 2-byte opcode: "
>                       "0x%x 0x%x 0x%x\n",
> +                     (Int)getUChar(eip-2),
>                       (Int)getUChar(eip-1),
> -                     (Int)getUChar(eip+0),
> -                     (Int)getUChar(eip+1) );
> +                     (Int)getUChar(eip-0) );
>
>  	 VG_(printf)("This _might_ be the result of executing a "
>                       "SSE, SSE2 or 3DNow!\n" );
>
> _