Ping [PATCH v3] Modify combine pattern by a pseudo AND with its nonzero bits [PR93453]

[HAO CHEN GUI <guihaoc@linux.ibm.com>]

Hi,
   Gentle ping this:
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598685.html
Thanks.

On 22/7/2022 下午 3:07, HAO CHEN GUI wrote:
> Hi,
>   This patch creates a new function - change_pseudo_and_mask. If recog fails,
> the function converts a single pseudo to the pseudo AND with a mask if the
> outer operator is IOR/XOR/PLUS and inner operator is ASHIFT or AND. The
> conversion helps pattern to match rotate and mask insn on some targets.
> 
>   Bootstrapped and tested on powerpc64-linux BE and LE with no regressions.
> Is this okay for trunk? Any recommendations? Thanks a lot.
> 
> ChangeLog
> 2022-07-22  Haochen Gui  <guihaoc@linux.ibm.com>
> 
> gcc/
> 	PR target/93453
> 	* combine.cc (change_pseudo_and_mask): New.
> 	(recog_for_combine): If recog fails, try again with the pattern
> 	modified by change_pseudo_and_mask.
> 	* config/rs6000/rs6000.md (plus_ior_xor): Remove.
> 	(anonymous split pattern for plus_ior_xor): Remove.
> 
> gcc/testsuite/
> 	PR target/93453
> 	* gcc.target/powerpc/pr93453-2.c: New.
> 	* gcc.target/powerpc/rlwimi-2.c: Both 32/64 bit platforms generate the
> 	same number of rlwimi.  Reset the counter.
> 
> patch.diff
> diff --git a/gcc/combine.cc b/gcc/combine.cc
> index a5fabf397f7..e1c1aa7da1c 100644
> --- a/gcc/combine.cc
> +++ b/gcc/combine.cc
> @@ -11599,6 +11599,48 @@ change_zero_ext (rtx pat)
>    return changed;
>  }
> 
> +/* When the outer code of set_src is IOR/XOR/PLUS and the inner code is
> +   ASHIFT/AND, convert a pseudo to pseudo AND with a mask if its nonzero_bits
> +   is less than its mode mask.  The nonzero_bits in later passes is not a
> +   superset of what is known in combine pass.  So an insn with nonzero_bits
> +   can't be recoged later.  */
> +static bool
> +change_pseudo_and_mask (rtx pat)
> +{
> +  rtx src = SET_SRC (pat);
> +  if ((GET_CODE (src) == IOR
> +       || GET_CODE (src) == XOR
> +       || GET_CODE (src) == PLUS)
> +      && (((GET_CODE (XEXP (src, 0)) == ASHIFT
> +	    || GET_CODE (XEXP (src, 0)) == AND)
> +	   && REG_P (XEXP (src, 1)))))
> +    {
> +      rtx reg = XEXP (src, 1);
> +      machine_mode mode = GET_MODE (reg);
> +      unsigned HOST_WIDE_INT nonzero = nonzero_bits (reg, mode);
> +      if (nonzero < GET_MODE_MASK (mode))
> +	{
> +	  int shift;
> +
> +	  if (GET_CODE (XEXP (src, 0)) == ASHIFT)
> +	    shift = INTVAL (XEXP (XEXP (src, 0), 1));
> +	  else
> +	    shift = ctz_hwi (INTVAL (XEXP (XEXP (src, 0), 1)));
> +
> +	  if (shift > 0
> +	      && (HOST_WIDE_INT_1U << shift) - 1 >= nonzero)
> +	    {
> +	      unsigned HOST_WIDE_INT mask = (HOST_WIDE_INT_1U << shift) - 1;
> +	      rtx x = gen_rtx_AND (mode, reg, GEN_INT (mask));
> +	      SUBST (XEXP (SET_SRC (pat), 1), x);
> +	      maybe_swap_commutative_operands (SET_SRC (pat));
> +	      return true;
> +	    }
> +	}
> +    }
> +  return false;
> +}
> +
>  /* Like recog, but we receive the address of a pointer to a new pattern.
>     We try to match the rtx that the pointer points to.
>     If that fails, we may try to modify or replace the pattern,
> @@ -11646,7 +11688,10 @@ recog_for_combine (rtx *pnewpat, rtx_insn *insn, rtx *pnotes)
>  	    }
>  	}
>        else
> -	changed = change_zero_ext (pat);
> +	{
> +	  changed = change_pseudo_and_mask (pat);
> +	  changed |= change_zero_ext (pat);
> +	}
>      }
>    else if (GET_CODE (pat) == PARALLEL)
>      {
> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index 1367a2cb779..2bd6bd5f908 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -4207,24 +4207,6 @@ (define_insn_and_split "*rotl<mode>3_insert_3_<code>"
>  	(ior:GPR (and:GPR (match_dup 3) (match_dup 4))
>  		 (ashift:GPR (match_dup 1) (match_dup 2))))])
> 
> -(define_code_iterator plus_ior_xor [plus ior xor])
> -
> -(define_split
> -  [(set (match_operand:GPR 0 "gpc_reg_operand")
> -	(plus_ior_xor:GPR (ashift:GPR (match_operand:GPR 1 "gpc_reg_operand")
> -				      (match_operand:SI 2 "const_int_operand"))
> -			  (match_operand:GPR 3 "gpc_reg_operand")))]
> -  "nonzero_bits (operands[3], <MODE>mode)
> -   < HOST_WIDE_INT_1U << INTVAL (operands[2])"
> -  [(set (match_dup 0)
> -	(ior:GPR (and:GPR (match_dup 3)
> -			  (match_dup 4))
> -		 (ashift:GPR (match_dup 1)
> -			     (match_dup 2))))]
> -{
> -  operands[4] = GEN_INT ((HOST_WIDE_INT_1U << INTVAL (operands[2])) - 1);
> -})
> -
>  (define_insn "*rotlsi3_insert_4"
>    [(set (match_operand:SI 0 "gpc_reg_operand" "=r")
>  	(ior:SI (and:SI (match_operand:SI 3 "gpc_reg_operand" "0")
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr93453-2.c b/gcc/testsuite/gcc.target/powerpc/pr93453-2.c
> new file mode 100644
> index 00000000000..a83a6511653
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr93453-2.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +long foo (char a, long b)
> +{
> +  long c = a;
> +  c = c | (b << 12);
> +  return c;
> +}
> +
> +long bar (long b, char a)
> +{
> +  long c = a;
> +  long m = -4096;
> +  c = c | (b & m);
> +  return c;
> +}
> +
> +/* { dg-final { scan-assembler-times {\mrl[wd]imi\M} 2 } } */
> diff --git a/gcc/testsuite/gcc.target/powerpc/rlwimi-2.c b/gcc/testsuite/gcc.target/powerpc/rlwimi-2.c
> index bafa371db73..d4dadacc6cc 100644
> --- a/gcc/testsuite/gcc.target/powerpc/rlwimi-2.c
> +++ b/gcc/testsuite/gcc.target/powerpc/rlwimi-2.c
> @@ -8,8 +8,7 @@
>  /* { dg-final { scan-assembler-times {(?n)^\s+mr} 11 { target lp64 } } } */
>  /* { dg-final { scan-assembler-times {(?n)^\s+rldicl} 7790 { target lp64 } } } */
> 
> -/* { dg-final { scan-assembler-times {(?n)^\s+rlwimi} 1692 { target ilp32 } } } */
> -/* { dg-final { scan-assembler-times {(?n)^\s+rlwimi} 1666 { target lp64 } } } */
> +/* { dg-final { scan-assembler-times {(?n)^\s+rlwimi} 1692 } } */
> 
>  /* { dg-final { scan-assembler-times {(?n)^\s+mulli} 5036 } } */
> 
> 
>