[AMDGPU] Fix computed kill mask (#122736)

Replace S_XOR with S_ANDN2 when computing the kill mask in demote/kill
lowering. This has the effect of AND'ing demote/kill condition with exec
which is needed for proper live mask update.

The S_XOR is inadequate because it may return true for lane with exec=0.

This patch fixes an image corruption in game.

I think the issue went unnoticed because demote/kill condition is often
naturally dependent on exec, so AND'ing with exec is usually not
required.

0 files changed, 0 insertions, 0 deletions