Re: [dpdk-dev] [PATCH 2/3] mempool/octeontx2: fix build for gcc O1 optimization

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/7/2020 3:05 PM, Ananyev, Konstantin wrote:
> Hi Ferruh, Jerin
> 
>> Can be reproduced with "make EXTRA_CFLAGS='-O1'" command using
>> gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2)
>>
>> Build error:
>> In file included from .../drivers/mempool/octeontx2/otx2_mempool.h:13,
>>                 from .../drivers/mempool/octeontx2/otx2_mempool_ops.c:8:
>> .../drivers/mempool/octeontx2/otx2_mempool_ops.c:
>> In function ‘otx2_npa_alloc’:
>> .../drivers/common/octeontx2/otx2_common.h:94:2:
>>     error: ‘aura_handle’ may be used uninitialized in this function
>>            [-Werror=maybe-uninitialized]
>>    94 |  rte_log(RTE_LOG_DEBUG, otx2_logtype_ ## subsystem,  \
>>       |  ^~~~~~~
>> .../drivers/mempool/octeontx2/otx2_mempool_ops.c:643:11:
>>     note: ‘aura_handle’ was declared here
>>   643 |  uint64_t aura_handle;
>>       |           ^~~~~~~~~~~
>>
>> This looks like false positive, assigning an initial value to
>> 'aura_handle' to fix the build error.
>>
>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
>> ---
>> This is assuming assigning initial value won't have a performance affect
>> if it does, we need to find another fix.
>> And overall not sure why this false positive warning is generated.
>> ---
>>  drivers/mempool/octeontx2/otx2_mempool_ops.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mempool/octeontx2/otx2_mempool_ops.c b/drivers/mempool/octeontx2/otx2_mempool_ops.c
>> index 162b7f01da..078ffac3e2 100644
>> --- a/drivers/mempool/octeontx2/otx2_mempool_ops.c
>> +++ b/drivers/mempool/octeontx2/otx2_mempool_ops.c
>> @@ -640,7 +640,7 @@ otx2_npa_alloc(struct rte_mempool *mp)
>>  struct otx2_npa_lf *lf;
>>  struct npa_aura_s aura;
>>  struct npa_pool_s pool;
>> -uint64_t aura_handle;
>> +uint64_t aura_handle = 0;
>>  size_t padding;
>>  int rc;
>>
>> --
> 
> 
> Confirm that it helps, though I am seeing one more issue with EXTRA_CFLAGS='-O1' (gcc 7.3.0).
> This time with drivers/event/octeontx2/otx2_evdev_stats.h:
> 
> In file included from /local/kananye1/dpdk.2005.rngf1/drivers/event/octeontx2/ot
> x2_evdev.c:15:0:
> /local/kananye1/dpdk.2005.rngf1/drivers/event/octeontx2/otx2_evdev_stats.h: In function ‘otx2_sso_xstats_get’:
> /local/kananye1/dpdk.2005.rngf1/drivers/event/octeontx2/otx2_evdev_stats.h:124:9: error: ‘xstats’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    xstat = &xstats[ids[i] - start_offset];
>    ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /local/kananye1/dpdk.2005.rngf1/drivers/event/octeontx2/otx2_evdev.c: At top level:
> cc1: error: unrecognized command line option ‘-Wno-address-of-packed-member’ [-Werror]
> cc1: all warnings being treated as errors
> 
> As I can see xtstats is not set for RTE_EVENT_DEV_XSTATS_DEVICE case.
> Just to make gcc quiet, I added:
> --- a/drivers/event/octeontx2/otx2_evdev_stats.h
> +++ b/drivers/event/octeontx2/otx2_evdev_stats.h
> @@ -67,6 +67,7 @@ otx2_sso_xstats_get(const struct rte_eventdev *event_dev,
> 
>         switch (mode) {
>         case RTE_EVENT_DEV_XSTATS_DEVICE:
> +               xstats = NULL;
>                 break;
>         case RTE_EVENT_DEV_XSTATS_PORT:
>                 if (queue_port_id >= (signed int)dev->nb_event_ports)
> 
> Konstantin
> 
> 
> 
Thanks Konstantin,

I will make a v2 including above as you suggested.