[llvm] [InstCombine] Fold more 'fcmp' 'select' instrs idioms into 'fabs' (PR #83381)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> I'm wondering whether we should be propagating the function-level attributes to instruction flags _somewhere_ so that this is handled generically, rather than in individual folds?

TBH I think fast-math flags should only be function-level attributes :(


https://github.com/llvm/llvm-project/pull/83381