acl: fix build with GCC 11

gcc 11 with '-O2' complains about some variables being used without
being initialized:

In function ‘start_flow_avx512x8’,
    inlined from ‘search_trie_avx512x8.constprop’ at acl_run_avx512_common.h:317:
lib/librte_acl/acl_run_avx512_common.h:210:13: warning:
    ‘pdata’ is used uninitialized [-Wuninitialized]
In function ‘search_trie_avx512x8.constprop’:
lib/librte_acl/acl_run_avx512_common.h:314:32: note: ‘pdata’ declared here
...

Indeed, these variables are not explicitly initialized,
but this is done intentionally.
We rely on constant mask value that we pass to start_flow*() functions
as a parameter to mask out uninitialized values.
Note that '-O3' doesn't produce this warning.
Anyway, to support clean build with gcc-11 this patch adds
explicit initialization for these variables.
I checked the output binary: with '-O3' both clang and gcc 10/11
generate no extra code for it.
Also performance test didn't reveal any regressions.

Bugzilla ID: 673
Fixes: b64c2295f7fc ("acl: add 256-bit AVX512 classify method")
Fixes: 45da22e42ec3 ("acl: add 512-bit AVX512 classify method")
Cc: stable@dpdk.org
Reported-by: Ali Alnubani <alialnu@nvidia.com>
Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/lib/acl/acl_run_avx512_common.h b/lib/acl/acl_run_avx512_common.h
index fafaf59..fbad74d 100644 (file)
--- a/lib/acl/acl_run_avx512_common.h
+++ b/lib/acl/acl_run_avx512_common.h
@@ -303,6 +303,28 @@ _F_(match_check_process)(struct acl_flow_avx512 *flow, uint32_t fm[2],
        }
 }
 
+static inline void
+_F_(reset_flow_vars)(_T_simd di[2], _T_simd idx[2], _T_simd pdata[4],
+       _T_simd tr_lo[2], _T_simd tr_hi[2])
+{
+       di[0] = _M_SI_(setzero)();
+       di[1] = _M_SI_(setzero)();
+
+       idx[0] = _M_SI_(setzero)();
+       idx[1] = _M_SI_(setzero)();
+
+       pdata[0] = _M_SI_(setzero)();
+       pdata[1] = _M_SI_(setzero)();
+       pdata[2] = _M_SI_(setzero)();
+       pdata[3] = _M_SI_(setzero)();
+
+       tr_lo[0] = _M_SI_(setzero)();
+       tr_lo[1] = _M_SI_(setzero)();
+
+       tr_hi[0] = _M_SI_(setzero)();
+       tr_hi[1] = _M_SI_(setzero)();
+}
+
 /*
  * Perform search for up to (2 * _N_) flows in parallel.
  * Use two sets of metadata, each serves _N_ flows max.
@@ -313,6 +335,8 @@ _F_(search_trie)(struct acl_flow_avx512 *flow)
        uint32_t fm[2];
        _T_simd di[2], idx[2], in[2], pdata[4], tr_lo[2], tr_hi[2];
 
+       _F_(reset_flow_vars)(di, idx, pdata, tr_lo, tr_hi);
+
        /* first 1B load */
        _F_(start_flow)(flow, _SIMD_MASK_BIT_, _SIMD_MASK_MAX_,
                        &pdata[0], &idx[0], &di[0]);