Hi,
On Mon, 2020-04-20 at 14:00 -0500, Aaron Sawdey via Gcc-patches wrote:
> For future architecture with prefix instructions, always use plq
> rather than lq for atomi load of quadword. Then we never have to
atomic :-)
> do the doubleword swap on little endian. Before this fix, -mno-pcrel
> would generate lq with the doubleword swap (which was ok) and -mpcrel
> would generate plq, also with the doubleword swap, which was wrong.
>
> OK for trunk if regstrap passes on ppc64le power9?
>
> Thanks,
> Aaron
>
> 2020-04-20 Aaron Sawdey <acsaw...@linux.ibm.com>
>
> PR target/94622
> * config/rs6000/sync.md (load_quadpti): Make this have attr
> prefixed
> if TARGET_PREFIXED.
I'd rearrange to be
: Add attr "prefixed" if TARGET_PREFIXED.
but thats mostly cosmetic, so no big deal.
> (atomic_load<mode>): Do not swap doublewords if TARGET_PREFIXED
> as
> plq will be used and doesn't need it.
Ok.
> ---
> gcc/config/rs6000/sync.md | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/rs6000/sync.md b/gcc/config/rs6000/sync.md
> index f27edc77b6a..64dfda6ef75 100644
> --- a/gcc/config/rs6000/sync.md
> +++ b/gcc/config/rs6000/sync.md
> @@ -129,7 +129,10 @@ (define_insn "load_quadpti"
> "TARGET_SYNC_TI
> && !reg_mentioned_p (operands[0], operands[1])"
> "lq %0,%1"
> - [(set_attr "type" "load")])
> + [(set_attr "type" "load")
> + (set_attr "prefixed" (if_then_else (match_test "TARGET_PREFIXED")
> + (const_string "yes")
> + (const_string "no")))])
>
> (define_expand "atomic_load<mode>"
> [(set (match_operand:AINT 0 "register_operand") ;;
> output
> @@ -162,7 +165,7 @@ (define_expand "atomic_load<mode>"
>
> emit_insn (gen_load_quadpti (pti_reg, op1));
>
> - if (WORDS_BIG_ENDIAN)
> + if (WORDS_BIG_ENDIAN || TARGET_PREFIXED)
> emit_move_insn (op0, gen_lowpart (TImode, pti_reg));
> else
> {
seems straightforward. lgtm.
Thanks
-Will
