https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96789
--- Comment #13 from Kewen Lin <linkw at gcc dot gnu.org> --- > 2) on Power, the conversion from unsigned char to unsigned short is nop > conversion, when we counting scalar cost, it's counted, then add costs 32 > totally onto scalar cost. Meanwhile, the conversion from unsigned short to > signed short should be counted but it's not (need to check why further). UH to SH conversion is true when calling vect_nop_conversion_p, so it's not even put into the cost vector. tree_nop_conversion_p's comments saying: /* Return true iff conversion from INNER_TYPE to OUTER_TYPE generates no instruction. */ I may miss something here, but UH to SH conversion does need one explicit extend instruction *extsh*, the precision/mode equality check looks wrong for this conversion.
