[PATCH] D21949: [SystemZ] Utilize Test Data Class instructions.
Ulrich Weigand via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 5 05:47:33 PDT 2016
uweigand added a comment.
In http://reviews.llvm.org/D21949#473818, @koriakin wrote:
> In http://reviews.llvm.org/D21949#473812, @uweigand wrote:
> > I haven't looked into the detailed implementation yet. However, one important feature to verify would be that use of the TEST DATA CLASS instruction is not only triggered by those specific IR sequences you test for on the LLVM level, but more importantly, triggered by whatever code clang generates for the isinf/isnan/signbit/fpclassify etc. builtins, since those are what users (hopefully) typically use ... [ This might actually involve changing clang as well, not sure about that. ]
> I've covered signbit and isnormal in the tests, I'll update it to cover isinf and fpclassify as well.
> isnan on its own is not profittable to implement with TEST DATA CLASS (a normal compare is good enough for that).
Agreed, but if we get code like isinf(x) || isnan(x), it might become profitable in combination.
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