https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88234
--- Comment #8 from Jeffrey Walton <noloader at gmail dot com> --- (In reply to Segher Boessenkool from comment #4) > This is documented in the ELFv2 ABI, linked from > https://gcc.gnu.org/readings.html . > > ... > (The vec_vsx_st doesn't have to do with the problem btw. Not that it is > good or anything ;-) ) Yeah, I tried to convert to the C/C++ pointer dereference pattern several times as shown in the literature. I.e., this: byte x[16]; uint8x16_p cc = (uint8x16_p)c; *(uint8x16_p*) &x[0] = cc; Instead of this: byte x[16]; vec_vsx_st((uint8x16_p)c, 0, x); It breaks a lot of our self tests for certain versions of a particular compiler. I narrowed it down to the loads but I could not take it further and develop a reduced case. I don't have the skill to untangle what is happening in ppc asm at -O3. If you want to see something really obscene, then take a look at https://github.com/weidai11/cryptopp/blob/master/ppc_simd.h#L251 . (If you are talking about something else that is wrong or bad, then please point it out.)
