> From: Ferruh Yigit [mailto:ferruh.yi...@xilinx.com] > Sent: Friday, 10 June 2022 12.13 > > On 6/8/2022 11:49 PM, Stephen Hemminger wrote: > > Gcc 12 adds more array bounds checking (good); but it is not smart > > enough to realize that for small fixed sizes, the bigger move options > > are not used. > > > > An example is using rte_memcpy() on a RSS key of 40 bytes may trigger > > rte_memcpy complaints from rte_mov128 reading past end of input. > > > > In order to keep some of the checks add special case for calls > > to rte_memcpy() with fixed size arguments to use the compiler > > builtin instead. Don't want to give all the checking for > > code that uses rte_memcpy() everywhere. > > > > Signed-off-by: Stephen Hemminger <step...@networkplumber.org> > > --- > > lib/eal/x86/include/rte_memcpy.h | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/lib/eal/x86/include/rte_memcpy.h > b/lib/eal/x86/include/rte_memcpy.h > > index 18aa4e43a743..b90cdd8d7326 100644 > > --- a/lib/eal/x86/include/rte_memcpy.h > > +++ b/lib/eal/x86/include/rte_memcpy.h > > @@ -27,6 +27,10 @@ extern "C" { > > #pragma GCC diagnostic ignored "-Wstringop-overflow" > > #endif > > > > +#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 120000) > > +#pragma GCC diagnostic ignored "-Warray-bounds" > > +#endif > > + > > /** > > * Copy bytes from one location to another. The locations must not > overlap. > > * > > @@ -842,19 +846,21 @@ rte_memcpy_aligned(void *dst, const void *src, > size_t n) > > return ret; > > } > > > > +#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 100000) > > +#pragma GCC diagnostic pop > > +#endif > > + > > static __rte_always_inline void * > > rte_memcpy(void *dst, const void *src, size_t n) > > { > > - if (!(((uintptr_t)dst | (uintptr_t)src) & ALIGNMENT_MASK)) > > + if (__builtin_constant_p(n)) > > + return __builtin_memcpy(dst, src, n); > > + else if (!(((uintptr_t)dst | (uintptr_t)src) & ALIGNMENT_MASK)) > > This patch does two things, > > 1. Disable "-Warray-bounds" with above pragma to silence compiler > warnings. > > 2. Use compiler builtin for some cases. > > Second can impact the performance and not really needed for the build > error, what do you think to split the patch in two, since 1. is simple > change but 2. may require more testing before accepting.
Any such testing will be highly compiler dependent. Do you have any specific compilers in mind, where you see a risk for lower performance?
