From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sangjin Han Subject: [PATCH v2] lpm: fix build error on g++ with -O0 option Date: Fri, 2 Jun 2017 05:07:46 +0000 Message-ID: <1496380066-28535-1-git-send-email-sangjin@eecs.berkeley.edu> Cc: dev@dpdk.org, Sangjin Han To: bruce.richardson@intel.com Return-path: Received: from mail-pf0-f193.google.com (mail-pf0-f193.google.com [209.85.192.193]) by dpdk.org (Postfix) with ESMTP id 049407CCD for ; Fri, 2 Jun 2017 07:08:00 +0200 (CEST) Received: by mail-pf0-f193.google.com with SMTP id n23so11176128pfb.3 for ; Thu, 01 Jun 2017 22:07:59 -0700 (PDT) List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 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 --- v2: * Added a comment * Updated the commit message: both gcc and g++ are affected. --- lib/librte_lpm/rte_lpm_sse.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/librte_lpm/rte_lpm_sse.h b/lib/librte_lpm/rte_lpm_sse.h index ef33c6a..7ab90b7 100644 --- a/lib/librte_lpm/rte_lpm_sse.h +++ b/lib/librte_lpm/rte_lpm_sse.h @@ -78,7 +78,9 @@ 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; -- 2.7.4