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Date: Tue, 03 Sep 2013 11:50:40 +0200
From: =?ISO-8859-15?Q?Andreas_F=E4rber?= <afaerber@suse.de>
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Subject: Re: [Qemu-devel] [PATCH 1/4] tcg/optimize: fix know-zero bits
	optimization
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To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org, Richard Henderson <rth@twiddle.net>

FWIW $subject has a typo. While at it...

Am 03.09.2013 08:27, schrieb Aurelien Jarno:
> Known-zero bits optimization is a great idea that helps to generate mor=
e
> optimized code. However the current implementation is basically useless
> as the computed mask is not saved.
>=20
> Fix this to make it really working.
>=20
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
>  tcg/optimize.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>=20
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index b29bf25..41f2906 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -695,7 +695,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s, =
uint16_t *tcg_opc_ptr,
>              break;
>          }
> =20
> -        /* Simplify using known-zero bits */
> +        /* Simplify using known-zero bits. Currently only ops with a s=
ingle
> +           output argument is supported. */

"ops ... are"?

Cheers,
Andreas

>          mask =3D -1;
>          affected =3D -1;
>          switch (op) {
> @@ -1144,6 +1145,11 @@ static TCGArg *tcg_constant_folding(TCGContext *=
s, uint16_t *tcg_opc_ptr,
>              } else {
>                  for (i =3D 0; i < def->nb_oargs; i++) {
>                      reset_temp(args[i]);
> +                    /* Save the corresponding known-zero bits mask for=
 the
> +                       first output argument (only one supported so fa=
r). */
> +                    if (i =3D=3D 0) {
> +                        temps[args[i]].mask =3D mask;
> +                    }
>                  }
>              }
>              for (i =3D 0; i < def->nb_args; i++) {
>=20


--=20
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