https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91814
--- Comment #3 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Richard Biener from comment #2)
> ISTR discussing this but holding back a fix at the time we weren't sure if
> we'd preserve the non-subreg sets. So sth like
>
> Index: gcc/config/i386/i386-features.c
> ===================================================================
> --- gcc/config/i386/i386-features.c (revision 275698)
> +++ gcc/config/i386/i386-features.c (working copy)
> @@ -668,6 +668,8 @@ scalar_chain::emit_conversion_insns (rtx
> static rtx
> gen_gpr_to_xmm_move_src (enum machine_mode vmode, rtx gpr)
> {
> + if (!x86_64_general_operand (gpr, GET_MODE_INNER (vmode)))
> + gpr = force_reg (GET_MODE_INNER (vmode), gpr);
> switch (GET_MODE_NUNITS (vmode))
> {
> case 1:
>
> fixes it with the question whether the use of x86_64_general_operand
> is correct and whether it's necessary for the NUNITS == 1 case
> (which IIRC isn't exercised anyway).
We should use nonimmediate_operand for NUNITS != 1. Perhaps also add
gcc_unreachable () for NUNITS == 1 case.
