[PATCH] D26265: AMDGPU: Remove unnecessary and on conditional branch

[Nicolai Hähnle via llvm-commits]

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I'm pretty sure this can lead to problems with more complicated conditionals, or at least it once could have done so.

The comment was definitely wrong, v_cmp returns a mask that is & EXEC, but the concern I have is when the condition is some boolean combination of conditions instead of coming straight out of v_cmp. For example, we translate a logical negation to simply XOR with ~0 instead of XOR with EXEC (for good reasons, because the condition may have been computed in a different basic block, but still...). In theory negations can always be folded away by a compination of DeMorgan and inverting the v_cmps, but I'm not sure that that always happens.


https://reviews.llvm.org/D26265