[Bug middle-end/79173] add-with-carry and subtract-with-borrow support (x86_64 and others)

pinskia at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Thu Sep 9 09:05:55 GMT 2021


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79173

--- Comment #13 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Vincent Lefèvre from comment #12) 
> One issue is that _addcarry_u64 / x86intrin.h are not documented, so the
> conditions of its use in portable code are not clear. I suppose that it is
> designed to be used in a target-independent compiler builtin.

None of the x86 intrinsics are documented except on the Intel intrinsics guide
page:
e.g:
https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_addcarry_u64


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