match.pd: Ensure (op CONSTANT_CLASS_P CONSTANT_CLASS_P) is simplified [PR109505]

  Hi!

On the following testcase we hang, because POLY_INT_CST is CONSTANT_CLASS_P,
but BIT_AND_EXPR with it and INTEGER_CST doesn't simplify and the
(x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2)
simplification actually relies on the (CST1 & CST2) simplification,
otherwise it is a deoptimization, trading 2 ops for 3 and furthermore
running into
/* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
   operands are another bit-wise operation with a common input.  If so,
   distribute the bit operations to save an operation and possibly two if
   constants are involved.  For example, convert
     (A | B) & (A | C) into A | (B & C)
   Further simplification will occur if B and C are constants.  */
simplification which simplifies that
(x & CST2) | (CST1 & CST2) back to
CST2 & (x | CST1).
I went through all other places I could find where we have a simplification
with 2 CONSTANT_CLASS_P operands and perform some operation on those two,
while the other spots aren't that severe (just trade 2 operations for
another 2 if the two constants don't simplify, rather than as in the above
case trading 2 ops for 3), I still think all those spots really intend
to optimize only if the 2 constants simplify.

So, the following patch adds to those a ! modifier to ensure that,
even at GENERIC that modifier means !EXPR_P which is exactly what we want
IMHO.

Bootstrapped/regtested on aarch64-linux, powerpc64le-linux, x86_64-linux
and i686-linux, ok for trunk and later 13.2/12.4?

2023-05-20  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/109505
	* match.pd ((x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2),
	Combine successive equal operations with constants,
	(A +- CST1) +- CST2 -> A + CST3, (CST1 - A) +- CST2 -> CST3 - A,
	CST1 - (CST2 - A) -> CST3 + A): Use ! on ops with 2 CONSTANT_CLASS_P
	operands.

	* gcc.target/aarch64/sve/pr109505.c: New test.


	Jakub
  

> Am 20.05.2023 um 22:33 schrieb Jakub Jelinek <jakub@redhat.com>:
> 
> Hi!
> 
> On the following testcase we hang, because POLY_INT_CST is CONSTANT_CLASS_P,
> but BIT_AND_EXPR with it and INTEGER_CST doesn't simplify and the
> (x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2)
> simplification actually relies on the (CST1 & CST2) simplification,
> otherwise it is a deoptimization, trading 2 ops for 3 and furthermore
> running into
> /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
>   operands are another bit-wise operation with a common input.  If so,
>   distribute the bit operations to save an operation and possibly two if
>   constants are involved.  For example, convert
>     (A | B) & (A | C) into A | (B & C)
>   Further simplification will occur if B and C are constants.  */
> simplification which simplifies that
> (x & CST2) | (CST1 & CST2) back to
> CST2 & (x | CST1).
> I went through all other places I could find where we have a simplification
> with 2 CONSTANT_CLASS_P operands and perform some operation on those two,
> while the other spots aren't that severe (just trade 2 operations for
> another 2 if the two constants don't simplify, rather than as in the above
> case trading 2 ops for 3), I still think all those spots really intend
> to optimize only if the 2 constants simplify.
> 
> So, the following patch adds to those a ! modifier to ensure that,
> even at GENERIC that modifier means !EXPR_P which is exactly what we want
> IMHO.
> 
> Bootstrapped/regtested on aarch64-linux, powerpc64le-linux, x86_64-linux
> and i686-linux, ok for trunk and later 13.2/12.4?

Ok.

Thanks,
Richard 

> 2023-05-20  Jakub Jelinek  <jakub@redhat.com>
> 
>    PR tree-optimization/109505
>    * match.pd ((x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2),
>    Combine successive equal operations with constants,
>    (A +- CST1) +- CST2 -> A + CST3, (CST1 - A) +- CST2 -> CST3 - A,
>    CST1 - (CST2 - A) -> CST3 + A): Use ! on ops with 2 CONSTANT_CLASS_P
>    operands.
> 
>    * gcc.target/aarch64/sve/pr109505.c: New test.
> 
> --- gcc/match.pd.jj    2023-05-17 20:57:59.000000000 +0200
> +++ gcc/match.pd    2023-05-20 09:51:27.094277249 +0200
> @@ -1916,7 +1916,7 @@ (define_operator_list SYNC_FETCH_AND_AND
> /* (x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2) */
> (simplify
>   (bit_and (bit_ior @0 CONSTANT_CLASS_P@1) CONSTANT_CLASS_P@2)
> -  (bit_ior (bit_and @0 @2) (bit_and @1 @2)))
> +  (bit_ior (bit_and @0 @2) (bit_and! @1 @2)))
> 
> /* Combine successive equal operations with constants.  */
> (for bitop (bit_and bit_ior bit_xor)
> @@ -1925,7 +1925,7 @@ (define_operator_list SYNC_FETCH_AND_AND
>   (if (!CONSTANT_CLASS_P (@0))
>    /* This is the canonical form regardless of whether (bitop @1 @2) can be
>       folded to a constant.  */
> -   (bitop @0 (bitop @1 @2))
> +   (bitop @0 (bitop! @1 @2))
>    /* In this case we have three constants and (bitop @0 @1) doesn't fold
>       to a constant.  This can happen if @0 or @1 is a POLY_INT_CST and if
>       the values involved are such that the operation can't be decided at
> @@ -2998,13 +2998,13 @@ (define_operator_list SYNC_FETCH_AND_AND
>     forever if something doesn't simplify into a constant.  */
>       (if (!CONSTANT_CLASS_P (@0))
>        (if (outer_op == PLUS_EXPR)
> -    (plus (view_convert @0) (inner_op @2 (view_convert @1)))
> -    (minus (view_convert @0) (neg_inner_op @2 (view_convert @1)))))
> +    (plus (view_convert @0) (inner_op! @2 (view_convert @1)))
> +    (minus (view_convert @0) (neg_inner_op! @2 (view_convert @1)))))
>       (if (!ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
>       || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
>        (if (outer_op == PLUS_EXPR)
> -    (view_convert (plus @0 (inner_op (view_convert @2) @1)))
> -    (view_convert (minus @0 (neg_inner_op (view_convert @2) @1))))
> +    (view_convert (plus @0 (inner_op! (view_convert @2) @1)))
> +    (view_convert (minus @0 (neg_inner_op! (view_convert @2) @1))))
>        /* If the constant operation overflows we cannot do the transform
>      directly as we would introduce undefined overflow, for example
>      with (a - 1) + INT_MIN.  */
> @@ -3035,10 +3035,10 @@ (define_operator_list SYNC_FETCH_AND_AND
>      /* If all 3 captures are CONSTANT_CLASS_P, punt, as we might recurse
>    forever if something doesn't simplify into a constant.  */
>      (if (!CONSTANT_CLASS_P (@0))
> -      (minus (outer_op (view_convert @1) @2) (view_convert @0)))
> +      (minus (outer_op! (view_convert @1) @2) (view_convert @0)))
>      (if (!ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
>      || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
> -      (view_convert (minus (outer_op @1 (view_convert @2)) @0))
> +      (view_convert (minus (outer_op! @1 (view_convert @2)) @0))
>       (if (types_match (type, @0) && !TYPE_OVERFLOW_SANITIZED (type))
>        (with { tree cst = const_binop (outer_op, type, @1, @2); }
>    (if (cst && !TREE_OVERFLOW (cst))
> @@ -3054,10 +3054,10 @@ (define_operator_list SYNC_FETCH_AND_AND
>     /* If all 3 captures are CONSTANT_CLASS_P, punt, as we might recurse
>       forever if something doesn't simplify into a constant.  */
>     (if (!CONSTANT_CLASS_P (@0))
> -     (plus (view_convert @0) (minus @1 (view_convert @2))))
> +     (plus (view_convert @0) (minus! @1 (view_convert @2))))
>     (if (!ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
>     || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
> -     (view_convert (plus @0 (minus (view_convert @1) @2)))
> +     (view_convert (plus @0 (minus! (view_convert @1) @2)))
>      (if (types_match (type, @0) && !TYPE_OVERFLOW_SANITIZED (type))
>       (with { tree cst = const_binop (MINUS_EXPR, type, @1, @2); }
>        (if (cst && !TREE_OVERFLOW (cst))
> --- gcc/testsuite/gcc.target/aarch64/sve/pr109505.c.jj    2023-05-20 09:58:15.646446786 +0200
> +++ gcc/testsuite/gcc.target/aarch64/sve/pr109505.c    2023-05-20 09:58:06.295580225 +0200
> @@ -0,0 +1,12 @@
> +/* PR tree-optimization/109505 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -march=armv8.2-a+sve" } */
> +
> +#pragma GCC aarch64 "arm_sve.h"
> +
> +unsigned long
> +foo (unsigned long x)
> +{
> +  unsigned long y = svcntb ();
> +  return (x | 15) & y;
> +}
> 
>    Jakub
>