[llvm] [GlobalISel][AArch64] Legalize G_FABS and G_FNEG for SVE (PR #114784)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

My favourite weapon: ` ag fneg llvm/lib/Target/AArch64/*.td`. There are scalar and Neon patterns, but no SVE patterns.

No. This PR has `   .legalFor(HasSVE, {nxv2s64, nxv4s32, nxv8s16})` plus patterns.

https://github.com/llvm/llvm-project/pull/114784