bmahjour added a comment. In D101759#2971567 <https://reviews.llvm.org/D101759#2971567>, @efriedma wrote:
> errno handling for math library functions is a mess. Currently, we don't > model it properly; we just mark the calls "readnone" and hope for the best. > If you don't want to fix that, just check for readnone for now. I think using `readnone` would work fine. It seems that clang marks math functions with that attribute when `-fno-math-errno` is in effect. To get the non-finite MASS lowerings at -O3 one would have to compile with both `-fapprox-func` and `-fno-math-errno`, which seems reasonable to me. > I don't think we want to be querying function attributes or options here; afn > plus enabling MASS should be enough. The function attributes are the old > mechanism; we just haven't completely migrated some parts of SelectionDAG yet. I agree. I think the problem is that this patch is trying to decide on a global lowering strategy for `llvm.*` math intrinsics in `llvm/lib/Target/PowerPC/PPCISelLowering.cpp` but such global decision making does not go well with finer granularity of fast-math flags. My understanding is that the reason we need to handle //intrinsic// math functions later is because of strength-reduction transformations like `pow(x,0.5) --> sqrt(x)` that currently operate on intrinsic calls only. If we could apply those operations on things like `__xl_pow_finite` and produce calls to `__xl_sqrt_finite` then we wouldn't have this problem. Another possibility might be to have two versions of `PPCGenScalarMASSEntries` one that handles non-intrinsics and runs earlier, and another one that handles intrinsics after transformations likes `pow(x,0.5) --> sqrt(x)` are done. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D101759/new/ https://reviews.llvm.org/D101759 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
