On Mon, 15 Jan 2024, Robin Dapp wrote:
> I gave it another shot now by introducing a separate function as
> Richard suggested. It's probably not at the location he intended.
>
> The way I read the discussion there hasn't been any consensus
> on how (or rather where) to properly tackle the problem. Any
> other ideas still?
I'm happy enough with the patch, esp. at this stage. OK if
Richard S. doesn't disagree.
Thanks,
Richard.
> Regards
> Robin
>
>
> Found in PR112971 this patch adds folding support for bitwise operations
> of const duplicate zero/one vectors with stepped vectors.
> On riscv we have the situation that a folding would perpetually continue
> without simplifying because e.g. {0, 0, 0, ...} & {7, 6, 5, ...} would
> not be folded to {0, 0, 0, ...}.
>
> gcc/ChangeLog:
>
> PR middle-end/112971
>
> * fold-const.cc (simplify_const_binop): New function for binop
> simplification of two constant vectors when element-wise
> handling is not necessary.
> (const_binop): Call new function.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/pr112971.c: New test.
> ---
> gcc/fold-const.cc | 31 +++++++++++++++++++
> .../gcc.target/riscv/rvv/autovec/pr112971.c | 18 +++++++++++
> 2 files changed, 49 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr112971.c
>
> diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> index 385e4a69ab3..2ef425aec0f 100644
> --- a/gcc/fold-const.cc
> +++ b/gcc/fold-const.cc
> @@ -1343,6 +1343,29 @@ distributes_over_addition_p (tree_code op, int opno)
> }
> }
>
> +/* OP is the INDEXth operand to CODE (counting from zero) and OTHER_OP
> + is the other operand. Try to use the value of OP to simplify the
> + operation in one step, without having to process individual elements. */
> +static tree
> +simplify_const_binop (tree_code code, tree op, tree other_op,
> + int index ATTRIBUTE_UNUSED)
> +{
> + /* AND, IOR as well as XOR with a zerop can be simplified directly. */
> + if (TREE_CODE (op) == VECTOR_CST && TREE_CODE (other_op) == VECTOR_CST)
> + {
> + if (integer_zerop (other_op))
> + {
> + if (code == BIT_IOR_EXPR || code == BIT_XOR_EXPR)
> + return op;
> + else if (code == BIT_AND_EXPR)
> + return other_op;
> + }
> + }
> +
> + return NULL_TREE;
> +}
> +
> +
> /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
> constant. We assume ARG1 and ARG2 have the same data type, or at least
> are the same kind of constant and the same machine mode. Return zero if
> @@ -1646,6 +1669,14 @@ const_binop (enum tree_code code, tree arg1, tree arg2)
> return build_complex (type, real, imag);
> }
>
> + tree simplified;
> + if ((simplified = simplify_const_binop (code, arg1, arg2, 0)))
> + return simplified;
> +
> + if (commutative_tree_code (code)
> + && (simplified = simplify_const_binop (code, arg2, arg1, 1)))
> + return simplified;
> +
> if (TREE_CODE (arg1) == VECTOR_CST
> && TREE_CODE (arg2) == VECTOR_CST
> && known_eq (TYPE_VECTOR_SUBPARTS (TREE_TYPE (arg1)),
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr112971.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr112971.c
> new file mode 100644
> index 00000000000..816ebd3c493
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr112971.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv_zvl256b -mabi=lp64d -O3
> -fno-vect-cost-model" } */
> +
> +int a;
> +short b[9];
> +char c, d;
> +void e() {
> + d = 0;
> + for (;; d++) {
> + if (b[d])
> + break;
> + a = 8;
> + for (; a >= 0; a--) {
> + char *f = &c;
> + *f &= d == (a & d);
> + }
> + }
> +}
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
