[llvm] [AArch64] Normalize (bool CC 1) to (bool NewCC 0) in LowerBR_CC (PR #189380)

[David Green via llvm-commits]

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davemgreen wrote:

When is this worse? It would be good not to have to check canEmitConjunction again.

If this was done as a dag combine for brcond(setcc(x, 1), eq) -> brcond(setcc(x, 0), ne), would it help avoid these special cases? I'm a bit surprised that comparing against 0 is worse than comparing against 1, unless there are some missing folds that might be generally useful.

https://github.com/llvm/llvm-project/pull/189380