lpm: fix build with gcc -O0 option

When rte_lpm.h is used on x86, -O0 option (no optimization at all)
given to gcc causes a compile error like this:

error: the last argument must be an 8-bit immediate
   i24 = _mm_srli_si128(i24, sizeof(uint64_t));

-O0 option is useful for debugging and code coverage measurement, but
this error prevents DPDK programs from building. This patch replaces
"sizeof(uint64_t)" with a constant literal "8" to work around the issue.
The issue occurs on gcc/g++ versions from 4.8 to 5.

Signed-off-by: Sangjin Han <sangjin@eecs.berkeley.edu>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>

diff --git a/lib/librte_lpm/rte_lpm_sse.h b/lib/librte_lpm/rte_lpm_sse.h
index ef33c6a..5f2c4d4 100644 (file)
--- a/lib/librte_lpm/rte_lpm_sse.h
+++ b/lib/librte_lpm/rte_lpm_sse.h
@@ -78,7 +78,8 @@ rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
 
        /* extract values from tbl24[] */
        idx = _mm_cvtsi128_si64(i24);
-       i24 = _mm_srli_si128(i24, sizeof(uint64_t));
+       /* With -O0 option, gcc 4.8 - 5.4 fails to fold sizeof() into a constant */
+       i24 = _mm_srli_si128(i24, /* sizeof(uint64_t) */ 8);
 
        ptbl = (const uint32_t *)&lpm->tbl24[(uint32_t)idx];
        tbl[0] = *ptbl;