If either source of the CMP is modified before an appropriate ADD is
found, the ADD and the CMP will not have the same result.
No shader-db changes on any ELK platform. I suspect the problematic
cases only occur after scheduling has rearranged instructions. This is
likely the reason BRW didn't experience this problem until 09450faf.
Fixes: 020b0055e7 ("i965/fs: Propagate conditional modifiers from compares to adds")
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39967>