https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108787
Segher Boessenkool <segher at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-02-14
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> ---
The maddhd insn does a sign-extend of the addend as well, so simply adding
the high part of it is not enough.
I don't see how to solve this with any machine code using the new madd* insns
that is at least as good code as the mulld;mulhd;addc;adde we would otherwise
generate.
We should still have machine patterns for the insn we have (it can be used
if operands[3] here is only one machine word for example), but we shouldn't
have a define_expand for maddditi4? (For umaddditi4 we can of course, and
that is even useful if it results in better generated code).
