https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125746
--- Comment #6 from Dimitar Dimitrov <dimitar at gcc dot gnu.org> --- Created attachment 65194 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65194&action=edit proposed-fix-20260731.patch My proposed-fix-20260615.patch is too naive. Rejecting all modes not compatible with SSE1 also prevents split patterns which help move data between SSE and normal registers. This caused regression fail for case gcc.target/i386/pr31486.c Next I tried to reject only 8-bit and 16-bit modes for SSE1 (see attached proposed-fix-20260731.patch). It passes bootstrap and has no regressions for c and c++. But I noticed a small code quality regression when comparing builds of ffmpeg with and without this patch. I traced it to ix86_modes_tieable_p calling "ix86_hard_regno_mode_ok (FIRST_SSE_REG, mode2)", hence preventing usage of SSE1 registers and causing a slight increase in register spilling.
