ping^2 ?
On 21 August 2017 at 15:04, Christophe Lyon <christophe.l...@linaro.org> wrote: > ping ? > https://gcc.gnu.org/ml/gcc-patches/2017-07/msg01063.html > > Christophe > > > On 18 July 2017 at 14:50, Christophe Lyon <christophe.l...@linaro.org> wrote: >> Hello, >> >> I've received a complaint that GCC for AArch64 would generate >> vectorized code relying on unaligned memory accesses even when using >> -mstrict-align. This is a problem for code where such accesses lead to >> memory faults. >> >> A previous patch (r243333) introduced >> aarch64_builtin_support_vector_misalignment, which rejects such >> accesses when the element size is 64 bits, and accept them otherwise, >> which I think it shouldn't. The testcase added at that time only used >> 64 bits elements, and therefore didn't fully test the patch. >> >> The report I received is about vectorized accesses to an array of >> unsigned chars, whose start address is not aligned on a 128 bits >> boundary. >> >> The attached patch fixes the problem by making >> aarch64_builtin_support_vector_misalignment always return false when >> the misalignment is not known at compile time. >> >> I've also added a testcase, which tries to check if the array start >> address alignment is checked (using %16, and-ing with #15), so that >> loop peeling is performed *before* using vectorized accesses. Without >> the patch, vectorized accesses are used at the beginning of the array, >> and byte accesses are used for the remainder at the end, and there is >> not such 'and wX,wX,15'. >> >> BTW, I'm not sure about the same hook for arm... it seems to me it has >> a similar problem. >> >> OK? >> >> Thanks, >> >> Christophe
