On 04/29/2014 05:42 AM, Richard Earnshaw wrote: > On 23/04/14 16:20, Alan Lawrence wrote: >> This patch is a small tidy of a more-complicated expression that just flips >> a >> single bit and can thus be a simple XOR. >> >> No regressions on aarch64-none-elf or aarch64_be-none-elf. (I've verified >> code >> is indeed exercised by dg-torture.exp vshuf-v*.c). >> >> Also ok after applying TBL and testsuite patches in >> http://gcc.gnu.org/ml/gcc-patches/2014-04/msg01309.html and >> http://gcc.gnu.org/ml/gcc-patches/2014-04/msg00579.html. >> >> gcc/ChangeLog: >> 2014-04-23 Alan Lawrence <alan.lawre...@arm.com> >> >> * config/aarch64/aarch64.c (aarch64_expand_vec_perm_1): tidy bit-flip >> expression. >> > > s/tidy/Tidy/ > > It's not obvious from your description (or from the code, for that > matter) that for this to be valid nelt must be a power of 2. > > I suggest that, above the loop, you put > > gcc_assert (nelt == (nelt & -nelt)); > > OK with those changes.
I think it's sort of obvious from context that we're working with a vector. And it also seems obvious that we won't have a vector without a power-of-two number of elements. r~
