[CodeGen] Teach LLVM how to lower @llvm.{min,max}num to {MIN,MAX}NAN
The behavior of {MIN,MAX}NAN differs from that of {MIN,MAX}NUM when only
one of the inputs is NaN: -NUM will return the non-NaN argument while
-NAN would return NaN.
It is desirable to lower to @llvm.{min,max}num to -NAN if they don't
have a native instruction for -NUM. Notably, ARMv7 NEON's vmin has the
-NAN semantics.
N.B. Of course, it is only safe to do this if the intrinsic call is
marked nnan.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266279 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed