Richard Henderson <richard.hender...@linaro.org> writes: > While cmp (extended register) and cmp (immediate) uses <Wn|WSP>, > cmp (shifted register) uses <Wn>. So we can perform cmp xzr, x0. > > For ccmp, we only have <Wn> as an input. > > * config/aarch64/aarch64.md (cmp<GPI>): For operand 0, use > aarch64_reg_or_zero. Shuffle reg/reg to last alternative > and accept Z. > (@ccmpcc<GPI>): For operand 0, use aarch64_reg_or_zero and Z. > (@ccmpcc<GPI>_rev): Likewise.
Looks good, but... > --- > gcc/config/aarch64/aarch64.md | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md > index c7c4d1dd519..b9ae51e48dd 100644 > --- a/gcc/config/aarch64/aarch64.md > +++ b/gcc/config/aarch64/aarch64.md > @@ -502,7 +502,7 @@ > [(match_operand 0 "cc_register" "") > (const_int 0)]) > (compare:CC_ONLY > - (match_operand:GPI 2 "register_operand" "r,r,r") > + (match_operand:GPI 2 "aarch64_reg_or_zero" "rZ,rZ,rZ") > (match_operand:GPI 3 "aarch64_ccmp_operand" "r,Uss,Usn")) > (unspec:CC_ONLY > [(match_operand 5 "immediate_operand")] > @@ -542,7 +542,7 @@ > [(match_operand 5 "immediate_operand")] > UNSPEC_NZCV) > (compare:CC_ONLY > - (match_operand:GPI 2 "register_operand" "r,r,r") > + (match_operand:GPI 2 "aarch64_reg_or_zero" "rZ,rZ,rZ") > (match_operand:GPI 3 "aarch64_ccmp_operand" "r,Uss,Usn"))))] > "" > "@ > @@ -3961,14 +3961,14 @@ > > (define_insn "cmp<mode>" > [(set (reg:CC CC_REGNUM) > - (compare:CC (match_operand:GPI 0 "register_operand" "rk,rk,rk") > - (match_operand:GPI 1 "aarch64_plus_operand" "r,I,J")))] > + (compare:CC (match_operand:GPI 0 "aarch64_reg_or_zero" "rk,rk,rkZ") > + (match_operand:GPI 1 "aarch64_plus_operand" "I,J,rZ")))] > "" > "@ > - cmp\\t%<w>0, %<w>1 > cmp\\t%<w>0, %1 > - cmn\\t%<w>0, #%n1" > - [(set_attr "type" "alus_sreg,alus_imm,alus_imm")] > + cmn\\t%<w>0, #%n1 > + cmp\\t%<w>0, %<w>1" > + [(set_attr "type" "alus_imm,alus_imm,alus_sreg")] > ) > > (define_insn "fcmp<mode>" ...does adding 'Z' to operand 1 enable any new combinations? I guess it allows (compare:CC (const_int 0) (const_int 0)), but it's borderline whether that should be valid rtl. Richard
