https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82940
--- Comment #8 from Segher Boessenkool <segher at gcc dot gnu.org> --- (In reply to Segher Boessenkool from comment #7) > (In reply to Peter Cordes from comment #6) > > # power64 GCC 9.2.1 (ATI13.0) > > rlwimi 3,4,0,255 # bit-blend according to mask, rotate count=0 > > rldicl 3,3,0,32 # Is this zero-extension to 64-bit redundant? > > It is: the rlwinm does an AND with 0xff already, so that clears the top 32 > bits for sure. Wow I cannot read, it is an rlwimi, so scratch that. The rlwimi here keeps the top 56 bits intact, and they already were 0, so the insn still is redundant.
