Re: [PATCH] drm/i915/perf: remove redundant variable 'taken'

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 08/10/2022 12:55, Christophe JAILLET wrote:
> Le 07/10/2022 à 21:53, Colin Ian King a écrit :
> > The assignment to variable taken is redundant and so it can be
> > removed as well as the variable too.
> >
> > Cleans up clang-scan build warnings:
> > warning: Although the value stored to 'taken' is used in the enclosing
> > expression, the value is never actually read from 'taken'
> > [deadcode.DeadStores]
>
> Hi,
>
> #define OA_TAKEN(tail, head)    ((tail - head) & (OA_BUFFER_SIZE - 1))
>
> So if the result is not used, maybe calling OA_TAKEN() can be removed as 
> well?
> It looks like a no-op in such a case.

AFAICS result is used, just the copy/local variable is not.

For the patch:

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>

Thanks for the cleanup, will merge.

Regards,

Tvrtko


> CJ
>
> > Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/i915_perf.c | 6 ++----
> >   1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_perf.c 
> > b/drivers/gpu/drm/i915/i915_perf.c
> > index 0defbb43ceea..15816df916c7 100644
> > --- a/drivers/gpu/drm/i915/i915_perf.c
> > +++ b/drivers/gpu/drm/i915/i915_perf.c
> > @@ -656,7 +656,6 @@ static int gen8_append_oa_reports(struct 
> > i915_perf_stream *stream,
> >       size_t start_offset = *offset;
> >       unsigned long flags;
> >       u32 head, tail;
> > -    u32 taken;
> >       int ret = 0;
> >       if (drm_WARN_ON(&uncore->i915->drm, !stream->enabled))
> > @@ -692,7 +691,7 @@ static int gen8_append_oa_reports(struct 
> > i915_perf_stream *stream,
> >       for (/* none */;
> > -         (taken = OA_TAKEN(tail, head));
> > +         OA_TAKEN(tail, head);
> >            head = (head + report_size) & mask) {
> >           u8 *report = oa_buf_base + head;
> >           u32 *report32 = (void *)report;
> > @@ -950,7 +949,6 @@ static int gen7_append_oa_reports(struct 
> > i915_perf_stream *stream,
> >       size_t start_offset = *offset;
> >       unsigned long flags;
> >       u32 head, tail;
> > -    u32 taken;
> >       int ret = 0;
> >       if (drm_WARN_ON(&uncore->i915->drm, !stream->enabled))
> > @@ -984,7 +982,7 @@ static int gen7_append_oa_reports(struct 
> > i915_perf_stream *stream,
> >       for (/* none */;
> > -         (taken = OA_TAKEN(tail, head));
> > +         OA_TAKEN(tail, head);
> >            head = (head + report_size) & mask) {
> >           u8 *report = oa_buf_base + head;
> >           u32 *report32 = (void *)report;