[AArch64] Don't call fma/fmaf for @llvm.fmuladd.f64/f32 in softfp (#205356) @llvm.fmuladd is the IR intrinsic that leaves it up to code generation whether to fuse an FP multiply+add pair or leave them separate. Generally you only fuse them if fused mul+add has good performance. On AArch64, for the float and double instances of this intrinsic, isel was unconditionally fusing the operations. This is sensible with hardware FP, but a bad idea for the rare case of AArch64 without hardware FP, because that leads to a call to the libm `fma()` or `fmaf()` function. That function generally (in multiple libcs) seems to be much slower than separate mul+add operations. So this patch checks for the presence of FP before reporting that fusing the operations is a performance win.
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