[Mesa-dev] [PATCH 4/4] mesa/main: drop needless condition check in _mesa_GetPerfCounterInfoINTEL

[Rob Herring]

On Wed, May 31, 2017 at 1:35 AM, Lionel Landwerlin
<lionel.g.landwerlin at intel.com> wrote:
> On 31/05/17 02:04, Ian Romanick wrote:
>
> I've seen this warning a million times, and I always talk myself out of
> fixing it.  If the type of counterIndex ever changes to int (or another
> signed type), this will break.  It may not be obvious at the time of the
> break that it happened, and it will likely be annoying to debug.
>
> I'm not NAKing it, but it makes me nervous.  What do other folks think?
>
>
> Spec says :
>
> "
>
> Performance counter id 0
>     is reserved as an invalid counter.
>
> "
>
> Maybe we should change counterid_to_index() to return a signed integer?
> What are the chances to have more than 1^31 counters?
>
>
> On 05/30/2017 01:47 PM, Rob Herring wrote:
>
> Fixes the following warning:
>
> external/mesa3d/src/mesa/main/performance_query.c:352:21: warning:
> comparison of unsigned expression < 0 is always false
> [-Wtautological-compare]
>    if (counterIndex < 0 || counterIndex >= queryNumCounters) {
>        ~~~~~~~~~~~~ ^ ~
>
> counterIndex will be ~0 if invalid and the 2nd condition is sufficient to
> catch that case.
>
> Signed-off-by: Rob Herring <robh at kernel.org>
> ---
>  src/mesa/main/performance_query.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/mesa/main/performance_query.c
> b/src/mesa/main/performance_query.c
> index 56f6a7da8b9f..b9e7cf9961b5 100644
> --- a/src/mesa/main/performance_query.c
> +++ b/src/mesa/main/performance_query.c
> @@ -349,7 +349,7 @@ _mesa_GetPerfCounterInfoINTEL(GLuint queryId, GLuint
> counterId,
>
>     counterIndex = counterid_to_index(counterId);
>
> -   if (counterIndex < 0 || counterIndex >= queryNumCounters) {
> +   if (counterIndex >= queryNumCounters) {
>        _mesa_error(ctx, GL_INVALID_VALUE,
>                    "glGetPerfCounterInfoINTEL(invalid counterId)");
>        return;
>
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