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