Re: [Qemu-devel] [PATCH v4] tcg-i386: Introduce limited deposit support

[Richard Henderson <rth@twiddle.net>]

On 09/29/2011 09:52 AM, Jan Kiszka wrote:
> x86 cannot provide an optimized generic deposit implementation. But at
> least for a few special cases, namely for writing bits 0..7, 8..15, and
> 0..15, versions using only a single instruction are feasible.
> Introducing such limited support improves emulating 16-bit x86 code on
> x86, but also rarer cases where 32-bit or 64-bit code accesses bytes or
> words.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> Changes in v4:
>  - provide correct default TCG_TARGET_deposit_i32_valid
> 
> Changes in v3:
>  - provide default TCG_TARGET_deposit_i32_valid - just in case
> 
> Changes in v2:
>  - introduce restricting predicates TCG_TARGET_deposit_i32/64_valid
>    to decide if deposit support can be used
>  - express register constraints via new 'Q' symbol
> 
>  tcg/i386/tcg-target.c |   24 ++++++++++++++++++++++++
>  tcg/i386/tcg-target.h |    9 +++++++--
>  tcg/tcg-op.h          |    4 ++--
>  tcg/tcg.h             |    7 +++++++
>  4 files changed, 40 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~