Martin Storsjö <[email protected]> writes:

> Originally, prior to 8742a4ff8, the caller code was compiled
> within this condition:
>
> ARCH_X86 && HAVE_7REGS && HAVE_EBX_AVAILABLE && !defined(BROKEN_RELOCATIONS)
>
> Since HAVE_7REGS is defined as
> (ARCH_X86_64 || (HAVE_EBX_AVAILABLE && HAVE_EBP_AVAILABLE))
> the subcondition HAVE_7REGS && HAVE_EBX_AVAILABLE is equal
> to HAVE_7REGS (for 32 bit at least). The correct simplification
> of the original condition thus is HAVE_7REGS, not
> HAVE_EBX_AVAILABLE.
>
> This fixes compilation in some cases where HAVE_EBP_AVAILABLE = 0
> and HAVE_EBX_AVAILABLE = 1.
>
> ---
>
> Reinhard, does this fix compilation in your cases?
>
>  libavcodec/h264_cabac.c    |    2 +-
>  libavcodec/x86/h264_i386.h |    4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/h264_cabac.c b/libavcodec/h264_cabac.c
> index a96f52e..feadf49 100644
> --- a/libavcodec/h264_cabac.c
> +++ b/libavcodec/h264_cabac.c
> @@ -1656,7 +1656,7 @@ decode_cabac_residual_internal(H264Context *h, DCTELEM 
> *block,
>              index[coeff_count++] = last;\
>          }
>          const uint8_t *sig_off = significant_coeff_flag_offset_8x8[MB_FIELD];
> -#if ARCH_X86 && HAVE_EBX_AVAILABLE && !defined(BROKEN_RELOCATIONS)
> +#if ARCH_X86 && HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
>          coeff_count= decode_significance_8x8_x86(CC, 
> significant_coeff_ctx_base, index,
>                                                   last_coeff_ctx_base, 
> sig_off);

7REGS is a bit weird here since the asm only has 6 register operands
(including an ecx clobber).  Presumably the memory operands need a
register as well.  In any case, there is no explicit mention of ebx in
the asm, so that condition is wrong for sure.

Patch OK if it fixes things.

-- 
Måns Rullgård
[email protected]
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