On Wed, Jan 19, 2022 at 2:12 AM HAO CHEN GUI <guih...@linux.ibm.com> wrote: > > Hi, > This patch adds a combine pattern for "CA minus one". As CA only has two > values (0 or 1), we could convert following pattern > (sign_extend:DI (plus:SI (reg:SI 98 ca) > (const_int -1 [0xffffffffffffffff])))) > to > (plus:DI (reg:DI 98 ca) > (const_int -1 [0xffffffffffffffff]))) > With this patch, it eliminates one unnecessary sign extend. Also in > rs6000, > regclass of CA register is set to NO_REGS. So CA is not in hard register set > and it can't match register_operand. The patch changes it to any_operand.
Segher changed the class in 2014. https://gcc.gnu.org/pipermail/gcc-patches/2014-September/399192.html We need to ensure that it still is the correct decision in light of these new patterns. Thanks, David > > Bootstrapped and tested on powerpc64-linux BE and LE with no regressions. > Is this okay for trunk? Any recommendations? Thanks a lot. > > ChangeLog > 2022-01-19 Haochen Gui <guih...@linux.ibm.com> > > gcc/ > * config/rs6000/predicates.md (ca_operand): Match any_operand as CA > register is not in hard register set. > * config/rs6000/rs6000.md (extenddi_ca_minus_one): Define. > > gcc/testsuite/ > * gcc.target/powerpc/pr95737.c: New. > > > patch.diff > diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md > index c65dfb91f3d..cd2ae1dc8e0 100644 > --- a/gcc/config/rs6000/predicates.md > +++ b/gcc/config/rs6000/predicates.md > @@ -188,7 +188,7 @@ (define_predicate "vlogical_operand" > > ;; Return 1 if op is the carry register. > (define_predicate "ca_operand" > - (match_operand 0 "register_operand") > + (match_operand 0 "any_operand") > { > if (SUBREG_P (op)) > op = SUBREG_REG (op); > diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md > index 6ecb0bd6142..f1b09aad3b5 100644 > --- a/gcc/config/rs6000/rs6000.md > +++ b/gcc/config/rs6000/rs6000.md > @@ -2358,6 +2358,21 @@ (define_insn "subf<mode>3_carry_in_xx" > "subfe %0,%0,%0" > [(set_attr "type" "add")]) > > +(define_insn_and_split "*extenddi_ca_minus_one" > + [(set (match_operand:DI 0 "gpc_reg_operand") > + (sign_extend:DI (plus:SI (match_operand:SI 1 "ca_operand") > + (const_int -1))))] > + "" > + "#" > + "" > + [(parallel [(set (match_dup 0) > + (plus:DI (match_dup 2) > + (const_int -1))) > + (clobber (match_dup 2))])] > +{ > + operands[2] = copy_rtx (operands[1]); > + PUT_MODE (operands[2], DImode); > +}) > > (define_insn "@neg<mode>2" > [(set (match_operand:GPR 0 "gpc_reg_operand" "=r") > diff --git a/gcc/testsuite/gcc.target/powerpc/pr95737.c > b/gcc/testsuite/gcc.target/powerpc/pr95737.c > new file mode 100644 > index 00000000000..94320f23423 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/powerpc/pr95737.c > @@ -0,0 +1,10 @@ > +/* PR target/95737 */ > +/* { dg-do compile { target lp64 } } */ > +/* { dg-options "-O2 -mdejagnu-cpu=power8" } */ > +/* { dg-final { scan-assembler-not {\mextsw\M} } } */ > + > + > +unsigned long long negativeLessThan (unsigned long long a, unsigned long > long b) > +{ > + return -(a < b); > +}
