On Tue, 24 Sep 2019, Jakub Jelinek wrote:
> Hi!
>
> As mentioned in the PR, the following patch decreases number of +/-
> operation when one is inside sign extension, done with undefined overflow,
> and the outer is using wrapping arithmetics.
>
> The :s as well as the outer + are there in order to make sure it is actually
> beneficial, that we decrease the number of +/-, either from two to one or
> from two to zero, depending on whether they cancel each other.
> The price for the reduction is that we loose information about the undefined
> behavior for certain @0 values.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2019-09-24 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/91866
> * match.pd (((T)(A)) + CST -> (T)(A + CST)): Formatting fix.
> (((T)(A + CST1)) + CST2 -> (T)(A) + (T)CST1 + CST2): New optimization.
>
> * gcc.dg/tree-ssa/pr91866.c: New test.
>
> --- gcc/match.pd.jj 2019-09-21 23:53:52.108385196 +0200
> +++ gcc/match.pd 2019-09-24 10:18:58.804114496 +0200
> @@ -2265,8 +2265,9 @@ (define_operator_list COND_TERNARY
> max_ovf = wi::OVF_OVERFLOW;
> tree inner_type = TREE_TYPE (@0);
>
> - wide_int w1 = wide_int::from (wi::to_wide (@1), TYPE_PRECISION
> (inner_type),
> - TYPE_SIGN (inner_type));
> + wide_int w1
> + = wide_int::from (wi::to_wide (@1), TYPE_PRECISION (inner_type),
> + TYPE_SIGN (inner_type));
>
> wide_int wmin0, wmax0;
> if (get_range_info (@0, &wmin0, &wmax0) == VR_RANGE)
> @@ -2280,6 +2281,20 @@ (define_operator_list COND_TERNARY
> )))
> #endif
>
> +/* ((T)(A + CST1)) + CST2 -> (T)(A) + (T)CST1 + CST2 */
> +#if GIMPLE
> + (for op (plus minus)
> + (simplify
> + (plus (convert:s (op:s @0 INTEGER_CST@1)) INTEGER_CST@2)
> + (if (TREE_CODE (TREE_TYPE (@0)) == INTEGER_TYPE
> + && TREE_CODE (type) == INTEGER_TYPE
> + && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0))
> + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))
> + && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0))
> + && TYPE_OVERFLOW_WRAPS (type))
> + (plus (convert @0) (op @2 (convert @1))))))
> +#endif
> +
> /* ~A + A -> -1 */
> (simplify
> (plus:c (bit_not @0) @0)
> --- gcc/testsuite/gcc.dg/tree-ssa/pr91866.c.jj 2019-09-24
> 10:35:34.035784152 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr91866.c 2019-09-24 10:36:59.858463024
> +0200
> @@ -0,0 +1,12 @@
> +/* PR middle-end/91866 */
> +/* { dg-do compile { target { ilp32 || lp64 } } } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } * /
> +/* { dg-final { scan-tree-dump-times " \\+ 11;" 3 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times " \[+-] \[0-9-]\[0-9]*;" 3 "optimized"
> } } */
> +/* { dg-final { scan-tree-dump-times "\\(long long unsigned int\\) x_" 5
> "optimized" } } */
> +
> +unsigned long long f1 (int x) { return (x + 1) - 1ULL; }
> +unsigned long long f2 (int x) { return (x - 5) + 5ULL; }
> +unsigned long long f3 (int x) { return (x - 15) + 26ULL; }
> +unsigned long long f4 (int x) { return (x + 6) + 5ULL; }
> +unsigned long long f5 (int x) { return (x - (-1 - __INT_MAX__)) + 10ULL -
> __INT_MAX__; }
>
> Jakub
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 247165 (AG München)
