> Subject: [PATCH 1/3] eal/x86: fix build with clang for old AVX
>
> When configuring RTE_MACHINE to "default", rte_memcpy implementation
> is the default one (old AVX).
> In this code, clang raises a warning thanks to -Wsometimes-uninitialized:
>
> rte_memcpy.h:838:6: error:
> variable 'srcofs' is used uninitialized whenever 'if' condition is false
> if (dstofss > 0) {
> ^~~~~~~~~~~
> rte_memcpy.h:849:6: note: uninitialized use occurs here
> if (srcofs == 0) {
> ^~~~~~
>
> It is fixed by initializing srcofs to 0.
>
> Fixes: 1ae817f9f887 ("eal/x86: tune memcpy for platforms without AVX512")
>
> Signed-off-by: Thomas Monjalon <thomas.monjalon at 6wind.com>
> ---
> lib/librte_eal/common/include/arch/x86/rte_memcpy.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Hi Thomas,
Thanks for pointing this out!
My last hasty modification on this is not correct.
The patch below will fix it. All modifications are tested.
Sorry for all the hassle! :'(
"srcofs" should be calculated based on source address anyway.
--- a/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
+++ b/lib/librte_eal/common/include/arch/x86/rte_memcpy.h
@@ -512,8 +512,9 @@ COPY_BLOCK_64_BACK31:
/**
* Make store aligned when copy size exceeds 512 bytes
*/
- dstofss = 32 - ((uintptr_t)dst & 0x1F);
+ dstofss = (uintptr_t)dst & 0x1F;
if (dstofss > 0) {
+ dstofss = 32 - dstofss;
n -= dstofss;
rte_mov32((uint8_t *)dst, (const uint8_t *)src);
src = (const uint8_t *)src + dstofss;
@@ -834,14 +835,15 @@ COPY_BLOCK_64_BACK15:
* unaligned copy functions require up to 15 bytes
* backwards access.
*/
- dstofss = 16 - ((uintptr_t)dst & 0x0F) + 16;
+ dstofss = (uintptr_t)dst & 0x0F;
if (dstofss > 0) {
+ dstofss = 16 - dstofss + 16;
n -= dstofss;
rte_mov32((uint8_t *)dst, (const uint8_t *)src);
src = (const uint8_t *)src + dstofss;
dst = (uint8_t *)dst + dstofss;
- srcofs = ((uintptr_t)src & 0x0F);
}
+ srcofs = ((uintptr_t)src & 0x0F);
/**
* For aligned copy
