Re: [dpdk-dev] Building current 1.8.1-rc1 with clang

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Sep 29, 2014 at 09:50:34PM +0000, Wiles, Roger Keith wrote:
> I just pulled the current repo and stated a build with ‘make install T=x86_64-native-linuxapp-clang’ which produced the following error. I do not think I am allowed to modify this file, correct? If that is the case then someone will have to update the original source. If you want me to submit a patch I can, but I do not think I fully understand what needs to be done. 
> 
> From what I can tell the line:
> 	dma_addr0 = _mm_xor_si128(dma_addr0, dma_addr0);
> needs to be:
> 	dma_addr0 = _mm_setzero_si128();
> 
> == Build lib/librte_pmd_ixgbe
>   CC ixgbe_common.o
>   CC ixgbe_82598.o
>   CC ixgbe_82599.o
>   CC ixgbe_x540.o
>   CC ixgbe_phy.o
>   CC ixgbe_api.o
>   CC ixgbe_vf.o
>   CC ixgbe_dcb.o
>   CC ixgbe_dcb_82599.o
>   CC ixgbe_dcb_82598.o
>   CC ixgbe_mbx.o
>   CC ixgbe_rxtx.o
>   CC ixgbe_ethdev.o
>   CC ixgbe_fdir.o
>   CC ixgbe_pf.o
>   CC ixgbe_rxtx_vec.o
> /home/keithw/projects/dpdk-code/org-dpdk/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c:67:30: error: variable 'dma_addr0' is uninitialized
>       when used here [-Werror,-Wuninitialized]
>                         dma_addr0 = _mm_xor_si128(dma_addr0, dma_addr0);
>                                                   ^~~~~~~~~
> /home/keithw/projects/dpdk-code/org-dpdk/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c:57:2: note: variable 'dma_addr0' is declared here
>         __m128i dma_addr0, dma_addr1;
>         ^
> 1 error generated.
> make[5]: *** [ixgbe_rxtx_vec.o] Error 1
> make[4]: *** [librte_pmd_ixgbe] Error 2
> make[3]: *** [lib] Error 2
> make[2]: *** [all] Error 2
> make[1]: *** [x86_64-native-linuxapp-clang_install] Error 2
> make: *** [install] Error 2
> 
> Thanks
> ++Keith
> 
> Keith Wiles, Principal Technologist with CTO office, Wind River mobile 972-213-5533
> 

I think a simple one-line change like below should fix it. The xor can also 
be written as a setzero call.

diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c 
b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
index 457f267..2236250 100644
--- a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
+++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
@@ -64,7 +64,7 @@ ixgbe_rxq_rearm(struct igb_rx_queue *rxq)
				 RTE_IXGBE_RXQ_REARM_THRESH) < 0) {
		if (rxq->rxrearm_nb + RTE_IXGBE_RXQ_REARM_THRESH >=
		    rxq->nb_rx_desc) {
-                       dma_addr0 = _mm_xor_si128(dma_addr0, dma_addr0);
+                       dma_addr0 = _mm_setzero_si128();
			for (i = 0; i < RTE_IXGBE_DESCS_PER_LOOP; i++) {
				rxep[i].mbuf = &rxq->fake_mbuf;
				_mm_store_si128((__m128i *)&rxdp[i].read,

/Bruce