Hi Jakub,
On 31/03/2021 21:30, Jakub Jelinek via Gcc-patches wrote:
> Hi!
>
> In GCC8/9 we used to optimize this into a bswap, but we no longer do.
> Handling byteswapping of pointers is easy, all we need is to allow them,
> for the __builtin_bswap* we already use TYPE_PRECISION to determine
> the precision and we cast the operand and result to the correct type
> if they aren't uselessly convertible to what the builtin expects.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2021-03-31 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/96573
> * gimple-ssa-store-merging.c (init_symbolic_number): Handle
> also pointer types.
>
> * gcc.dg/pr96573.c: New test.
FYI, I'm seeing the new test failing on aarch64:
PASS: gcc.dg/pr96573.c (test for excess errors)
FAIL: gcc.dg/pr96573.c scan-tree-dump optimized "__builtin_bswap"
Thanks,
Alex
>
> --- gcc/gimple-ssa-store-merging.c.jj 2021-02-22 17:54:05.701798074 +0100
> +++ gcc/gimple-ssa-store-merging.c 2021-03-31 11:30:55.519845647 +0200
> @@ -333,7 +333,7 @@ init_symbolic_number (struct symbolic_nu
> {
> int size;
>
> - if (! INTEGRAL_TYPE_P (TREE_TYPE (src)))
> + if (!INTEGRAL_TYPE_P (TREE_TYPE (src)) && !POINTER_TYPE_P (TREE_TYPE
> (src)))
> return false;
>
> n->base_addr = n->offset = n->alias_set = n->vuse = NULL_TREE;
> --- gcc/testsuite/gcc.dg/pr96573.c.jj 2021-03-31 11:39:19.382122478 +0200
> +++ gcc/testsuite/gcc.dg/pr96573.c 2021-03-31 11:39:54.186727148 +0200
> @@ -0,0 +1,20 @@
> +/* PR tree-optimization/96573 */
> +/* { dg-do compile { target { lp64 || ilp32 } } } */
> +/* { dg-require-effective-target bswap } */
> +/* { dg-options "-O3 -fdump-tree-optimized" } */
> +/* { dg-final { scan-tree-dump "__builtin_bswap" "optimized" } } */
> +
> +typedef __SIZE_TYPE__ size_t;
> +
> +void *
> +foo (void * const p)
> +{
> + const size_t m = sizeof (p) - 1;
> + const unsigned char * const o = (unsigned char*) &p;
> + void *n;
> + unsigned char * const q = (unsigned char *) &n;
> + unsigned char i;
> + for (i = 0; i <= m; ++i)
> + q[m - i] = o[i];
> + return n;
> +}
>
> Jakub
>
