On Mon, 13 May 2024, Jakub Jelinek wrote:
> Hi!
>
> We pattern recognize already many different patterns, and closest to the
> requested one also
> yc = (type) y;
> zc = (type) z;
> x = yc + zc;
> w = (typeof_y) x;
> if (x > max)
> where y/z has the same unsigned type and type is a wider unsigned type
> and max is maximum value of the narrower unsigned type.
> But apparently people are creative in writing this in diffent ways,
> this requests
> yc = (type) y;
> zc = (type) z;
> x = yc + zc;
> w = (typeof_y) x;
> if (x >> narrower_type_bits)
>
> The following patch implements that.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK. Seeing the large matching code I wonder if using a match
in match.pd might be more easy to maintain (eh, and I'd still
like to somehow see "inline" match patterns in source files, not
sure how, but requiring some gen* program extracting them).
Thanks,
Richard.
> 2024-05-13 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/113982
> * tree-ssa-math-opts.cc (arith_overflow_check_p): Also return 1
> for RSHIFT_EXPR by precision of maxval if shift result is only
> used in a cast or comparison against zero.
> (match_arith_overflow): Handle the RSHIFT_EXPR use case.
>
> * gcc.dg/pr113982.c: New test.
>
> --- gcc/tree-ssa-math-opts.cc.jj 2024-04-11 09:26:36.318369218 +0200
> +++ gcc/tree-ssa-math-opts.cc 2024-05-10 18:17:08.795744811 +0200
> @@ -3947,6 +3947,66 @@ arith_overflow_check_p (gimple *stmt, gi
> else
> return 0;
>
> + if (maxval
> + && ccode == RSHIFT_EXPR
> + && crhs1 == lhs
> + && TREE_CODE (crhs2) == INTEGER_CST
> + && wi::to_widest (crhs2) == TYPE_PRECISION (TREE_TYPE (maxval)))
> + {
> + tree shiftlhs = gimple_assign_lhs (use_stmt);
> + if (!shiftlhs)
> + return 0;
> + use_operand_p use;
> + if (!single_imm_use (shiftlhs, &use, &cur_use_stmt))
> + return 0;
> + if (gimple_code (cur_use_stmt) == GIMPLE_COND)
> + {
> + ccode = gimple_cond_code (cur_use_stmt);
> + crhs1 = gimple_cond_lhs (cur_use_stmt);
> + crhs2 = gimple_cond_rhs (cur_use_stmt);
> + }
> + else if (is_gimple_assign (cur_use_stmt))
> + {
> + if (gimple_assign_rhs_class (cur_use_stmt) == GIMPLE_BINARY_RHS)
> + {
> + ccode = gimple_assign_rhs_code (cur_use_stmt);
> + crhs1 = gimple_assign_rhs1 (cur_use_stmt);
> + crhs2 = gimple_assign_rhs2 (cur_use_stmt);
> + }
> + else if (gimple_assign_rhs_code (cur_use_stmt) == COND_EXPR)
> + {
> + tree cond = gimple_assign_rhs1 (cur_use_stmt);
> + if (COMPARISON_CLASS_P (cond))
> + {
> + ccode = TREE_CODE (cond);
> + crhs1 = TREE_OPERAND (cond, 0);
> + crhs2 = TREE_OPERAND (cond, 1);
> + }
> + else
> + return 0;
> + }
> + else
> + {
> + enum tree_code sc = gimple_assign_rhs_code (cur_use_stmt);
> + tree castlhs = gimple_assign_lhs (cur_use_stmt);
> + if (!CONVERT_EXPR_CODE_P (sc)
> + || !castlhs
> + || !INTEGRAL_TYPE_P (TREE_TYPE (castlhs))
> + || (TYPE_PRECISION (TREE_TYPE (castlhs))
> + > TYPE_PRECISION (TREE_TYPE (maxval))))
> + return 0;
> + return 1;
> + }
> + }
> + else
> + return 0;
> + if ((ccode != EQ_EXPR && ccode != NE_EXPR)
> + || crhs1 != shiftlhs
> + || !integer_zerop (crhs2))
> + return 0;
> + return 1;
> + }
> +
> if (TREE_CODE_CLASS (ccode) != tcc_comparison)
> return 0;
>
> @@ -4049,6 +4109,7 @@ arith_overflow_check_p (gimple *stmt, gi
> _8 = IMAGPART_EXPR <_7>;
> if (_8)
> and replace (utype) x with _9.
> + Or with x >> popcount (max) instead of x > max.
>
> Also recognize:
> x = ~z;
> @@ -4481,10 +4542,62 @@ match_arith_overflow (gimple_stmt_iterat
> gcc_checking_assert (is_gimple_assign (use_stmt));
> if (gimple_assign_rhs_class (use_stmt) == GIMPLE_BINARY_RHS)
> {
> - gimple_assign_set_rhs1 (use_stmt, ovf);
> - gimple_assign_set_rhs2 (use_stmt, build_int_cst (type, 0));
> - gimple_assign_set_rhs_code (use_stmt,
> - ovf_use == 1 ? NE_EXPR : EQ_EXPR);
> + if (gimple_assign_rhs_code (use_stmt) == RSHIFT_EXPR)
> + {
> + g2 = gimple_build_assign (make_ssa_name (boolean_type_node),
> + ovf_use == 1 ? NE_EXPR : EQ_EXPR,
> + ovf, build_int_cst (type, 0));
> + gimple_stmt_iterator gsiu = gsi_for_stmt (use_stmt);
> + gsi_insert_before (&gsiu, g2, GSI_SAME_STMT);
> + gimple_assign_set_rhs_with_ops (&gsiu, NOP_EXPR,
> + gimple_assign_lhs (g2));
> + update_stmt (use_stmt);
> + use_operand_p use;
> + single_imm_use (gimple_assign_lhs (use_stmt), &use,
> + &use_stmt);
> + if (gimple_code (use_stmt) == GIMPLE_COND)
> + {
> + gcond *cond_stmt = as_a <gcond *> (use_stmt);
> + gimple_cond_set_lhs (cond_stmt, ovf);
> + gimple_cond_set_rhs (cond_stmt, build_int_cst (type, 0));
> + }
> + else
> + {
> + gcc_checking_assert (is_gimple_assign (use_stmt));
> + if (gimple_assign_rhs_class (use_stmt)
> + == GIMPLE_BINARY_RHS)
> + {
> + gimple_assign_set_rhs1 (use_stmt, ovf);
> + gimple_assign_set_rhs2 (use_stmt,
> + build_int_cst (type, 0));
> + }
> + else if (gimple_assign_cast_p (use_stmt))
> + gimple_assign_set_rhs1 (use_stmt, ovf);
> + else
> + {
> + tree_code sc = gimple_assign_rhs_code (use_stmt);
> + gcc_checking_assert (sc == COND_EXPR);
> + tree cond = gimple_assign_rhs1 (use_stmt);
> + cond = build2 (TREE_CODE (cond),
> + boolean_type_node, ovf,
> + build_int_cst (type, 0));
> + gimple_assign_set_rhs1 (use_stmt, cond);
> + }
> + }
> + update_stmt (use_stmt);
> + gsi_remove (&gsiu, true);
> + gsiu = gsi_for_stmt (g2);
> + gsi_remove (&gsiu, true);
> + continue;
> + }
> + else
> + {
> + gimple_assign_set_rhs1 (use_stmt, ovf);
> + gimple_assign_set_rhs2 (use_stmt, build_int_cst (type, 0));
> + gimple_assign_set_rhs_code (use_stmt,
> + ovf_use == 1
> + ? NE_EXPR : EQ_EXPR);
> + }
> }
> else
> {
> --- gcc/testsuite/gcc.dg/pr113982.c.jj 2024-05-10 15:00:28.536651833
> +0200
> +++ gcc/testsuite/gcc.dg/pr113982.c 2024-05-10 15:01:49.721570343 +0200
> @@ -0,0 +1,60 @@
> +/* PR middle-end/113982 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-widening_mul" } */
> +
> +#if __SIZEOF_INT128__
> +typedef __uint128_t W;
> +typedef unsigned long long T;
> +#else
> +typedef unsigned long long W;
> +typedef unsigned int T;
> +#endif
> +#define B __CHAR_BIT__ * sizeof (T)
> +
> +struct S { int p; T r; };
> +
> +struct S
> +foo (T x, T y)
> +{
> + W z = (W) x + y;
> + return (struct S) { z >> B, (T) z };
> +}
> +
> +struct S
> +bar (T x)
> +{
> + W z = (W) x + 132;
> + return (struct S) { z >> B, (T) z };
> +}
> +
> +struct S
> +baz (T x, unsigned short y)
> +{
> + W z = (W) x + y;
> + return (struct S) { z >> B, (T) z };
> +}
> +
> +struct S
> +qux (unsigned short x, T y)
> +{
> + W z = (W) x + y;
> + return (struct S) { z >> B, (T) z };
> +}
> +
> +struct S
> +corge (T x, T y)
> +{
> + T w = x + y;
> + W z = (W) x + y;
> + return (struct S) { z >> B, w };
> +}
> +
> +struct S
> +garple (T x, T y)
> +{
> + W z = (W) x + y;
> + T w = x + y;
> + return (struct S) { z >> B, w };
> +}
> +
> +/* { dg-final { scan-tree-dump-times "ADD_OVERFLOW" 6 "widening_mul" {
> target { i?86-*-* x86_64-*-* } } } } */
>
> Jakub
>
>
--
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)
