On Sun, Sep 20, 2015 at 4:18 AM, Ganesh Ajjanagadde
<gajjanaga...@gmail.com> wrote:
> This fixes -Wshift-negative-value reported with clang 3.7+, e.g
> http://fate.ffmpeg.org/log.cgi?time=20150919172459&log=compile&slot=x86_64-darwin-clang-polly-notiling-3.7.
> Note that the patch crucially depends on int >= 32 bits,
> an assumption made in many places in the codebase.
>
> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com>
> ---
> libavcodec/apedec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
> index 5536e0f..7b34d26 100644
> --- a/libavcodec/apedec.c
> +++ b/libavcodec/apedec.c
> @@ -1281,7 +1281,7 @@ static void do_apply_filter(APEContext *ctx, int
> version, APEFilter *f,
> /* Update the adaption coefficients */
> absres = FFABS(res);
> if (absres)
> - *f->adaptcoeffs = ((res & (-1<<31)) ^ (-1<<30)) >>
> + *f->adaptcoeffs = ((res & (-(1<<31))) ^ (-(1<<30))) >>
> (25 + (absres <= f->avg*3) + (absres <=
> f->avg*4/3));
> else
> *f->adaptcoeffs = 0;
> --
> 2.5.2
>
After this patch (GCC 5.2, x86)
libavcodec/apedec.c: In function 'do_apply_filter':
libavcodec/apedec.c:1284:44: warning: integer overflow in expression
[-Woverflow]
*f->adaptcoeffs = ((res & (-(1<<31))) ^ (-(1<<30))) >>
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