[Bug target/81833] [7/8 Regression] PowerPC: VSX: Miscompiles ffmpeg's scalarproduct_int16_vsx at -O1

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81833

--- Comment #2 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
The "altivec_vsumsws" pattern for little endian isn't working as intended. 
This needs to be rewritten.  So does the "altivec_vsum2sws" pattern.  I'll work
on a patch early next week.