[llvm] [AArch64][LV][SLP] Vectorizers use getFRemInstrCost for frem costs (PR #82488)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

Perhaps a better option is for the code generater to emit the function calls as part of legalisation.  If we did that then I'd be more comfortable with modifying `getArithmeticInstrCost`.

https://github.com/llvm/llvm-project/pull/82488