https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119127
--- Comment #7 from chenglulu <chenglulu at loongson dot cn> --- (In reply to Xi Ruoyao from comment #5) > (In reply to chenglulu from comment #4) > > (In reply to Xi Ruoyao from comment #3) > > > It happens at: > > > > > > trying to combine definition of r94 in: > > > 15: r94:DI=r92:DI<<0x2&0xfffffffc > > > REG_DEAD r92:DI > > > into: > > > 17: r96:DI=sign_extend(r87:SI+r94:DI#0) > > > REG_DEAD r94:DI > > > REG_DEAD r87:SI > > > > > > i.e. > > > > > > bstrpick.d t0, a0, 31, 0 > > > slli.d t0, t0, 2 > > > addi.w t0, t0, a1 > > > > > > But we want just > > > > > > alsl.w t0, a0, a1, 2 > > > > > > It seems modifying SImode to DImode as comment 1 will defeat the > > > optimization. I guess we should sign extend mask in > > > loongarch_reassoc_shift_bitwise to mode if it's not already sign-extended. > > My modification will indeed add an extra 'and' operation. I agree with your point of view.
