[PATCH] D101759: [PowerPC] Scalar IBM MASS library conversion pass

Thu Aug 26 08:26:22 PDT 2021

lebedev.ri added a reviewer: spatel.
lebedev.ri added a comment.

In D101759#2967331 <https://reviews.llvm.org/D101759#2967331>, @masoud.ataei wrote:

> In D101759#2967250 <https://reviews.llvm.org/D101759#2967250>, @lebedev.ri wrote:
>
>> Do we *really* need `-enable-approx-func-fp-math`?
>> I'm pretty sure we are moving away from such global options, onto relying only on the per-instruction fast-math flags.
>
> I am handling LLVM intrinsic math functions in PPCISelLowering.cpp, so I need to check for `TM.Options.ApproxFuncFPMath`. This is the only place that I think I need it.

How is this going to work e.g. in LTO when not all TU's are compiled with fast-math flags?

I'm not familiar with those llc flags, but i'm quite sure that e.g. DAGCombiner
is transitioned away from using them, so i'm wary of adding new ones.

> Currently, I am updating `TM.Options.ApproxFuncFPMath` in `llvm/lib/CodeGen/CommandFlags.cpp` using the global option. Please let me know if there is a better way to update `TM.Options.ApproxFuncFPMath` based on the local fast-math flag.

Repository:
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https://reviews.llvm.org/D101759