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Re: [Patch][PR91504] Inlining misses some logical operation folding
- From: Richard Biener <rguenther at suse dot de>
- To: kamlesh kumar <kamleshbhalui at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 26 Aug 2019 14:04:25 +0200 (CEST)
- Subject: Re: [Patch][PR91504] Inlining misses some logical operation folding
- References: <CABKRkgjqsRUyH+c_yWgaQfzo4a-aBxqQdG+Hb07eeJVNgMok-w@mail.gmail.com>
On Mon, 26 Aug 2019, kamlesh kumar wrote:
> 2019-08-26 Kamlesh Kumar <kamleshbhalui@gmail.com>
>
> * gcc/match.pd: Added simplification
> pattern.
> * gcc.dg/tree-ssa/pr91504.c: New test.
> ====================
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 93dcef9..b3734f8 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -831,6 +831,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (bit_xor:c (bit_and:cs @0 (bit_not @1)) (bit_not @0))
> (bit_not (bit_and @0 @1)))
>
> +/* (~a & b) ^ a --> (a | b) */
> +(simplify
> + (bit_xor:c (bit_and:cs (bit_not @0) @1) @0)
> + (bit_ior @0 @1))
> +
Are you sure?
(~1804289383 & 846930886) ^ 1804289383 != 1804289383 | 846930886
#include <stdio.h>
#include <stdlib.h>
int main ()
{
while (1)
{
int a = random();
int b = random();
if ((~a & b) ^ a != a | b)
{
fprintf (stderr, "%d, %d\n", a, b);
abort ();
}
}
}
> /* (a | b) & ~(a ^ b) --> a & b */
> (simplify
> (bit_and:c (bit_ior @0 @1) (bit_not (bit_xor:c @0 @1)))
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
> new file mode 100644
> index 0000000..a52dea4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fdump-tree-optimized-raw" } */
> +
> +static inline unsigned deposit32(unsigned value, int start, int length,
> + unsigned fieldval)
> +{
> + unsigned mask = (~0U >> (32 - length)) << start;
> + return (value & ~mask) | ((fieldval << start) & mask);
> +}
> +
> +unsigned foo(unsigned value)
> +{
> + return deposit32(value, 10, 1, 1);
> +}
> +
> +/* { dg-final { scan-tree-dump-not "bit_and_expr" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "bit_xor_expr" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "bit_not_expr" "optimized" } } */
>
--
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 247165 (AG München)