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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

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