https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88476
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Severity|normal |enhancement Last reconfirmed| |2021-09-04 Ever confirmed|0 |1 Component|middle-end |target --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This is a target issue: Trying 22 -> 33: 22: {r108:QI=r100:QI|r111:QI;unspec[0] 159;} REG_DEAD r100:QI 33: {r116:QI=r108:QI&r112:QI;unspec[0] 159;} REG_DEAD r112:QI REG_DEAD r108:QI Can't combine i2 into i3 The reasoning behind the unspec I suspect has gone way since r11-2796 and r11-2795 .