https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71460
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #6)
> (In reply to Uroš Bizjak from comment #5)
> > Following patch fixes the failure:
> >
> > --cut here--
> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > index b807a9a..4526c7d 100644
> > --- a/gcc/config/i386/i386.c
> > +++ b/gcc/config/i386/i386.c
> > @@ -10310,10 +10310,8 @@ ix86_promote_function_mode (const_tree type,
> > machine_mode mode,
> > static bool
> > ix86_member_type_forces_blk (const_tree field, machine_mode mode)
> > {
> > - /* Union with XFmode must be in BLKmode. */
> > - return (mode == XFmode
> > - && (TREE_CODE (DECL_FIELD_CONTEXT (field)) == UNION_TYPE
> > - || TREE_CODE (DECL_FIELD_CONTEXT (field)) ==
> > QUAL_UNION_TYPE));
> > + return (IS_STACK_MODE (mode) && flag_signaling_nans
> > + && RECORD_OR_UNION_TYPE_P (DECL_FIELD_CONTEXT (field)));
> > }
> >
> > rtx
> > --cut here--
> >
> > Patch was tested with various -mfpmath=... compile flags. IMO, we don't need
> > BLKmode when we copy the value using SSE registers (and the test indeed does
> > not fail with -mfpmath=sse), and we still can copy XFmode using x87 regs
> > without -fsignalling-nans.
> >
> > Richi, Joseph - does the new condition look OK to you?
>
> Looks good to me.
Oh - I hope TYPE_MODE does not affect the ABI here ;) You might want to
double-check that (struct-layout tests plus call ABI)
> Btw, the mentioned SRA issue probably still exists for full scalarization
> and re-mat for a call. SRA should probably check member_type_forces_blk
> as well before creating full scalarization accesses. Would be nice to
> have a testcase for the SRA case as well.
