On Mon, 2 Jan 2012, Richard Guenther wrote:
>
> I am testing the following patch to fix PR51730.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
> Richard.
>
> 2012-01-02 Richard Guenther <rguent...@suse.de>
>
> PR middle-end/51730
> * fold-const.c (fold_comparison): Properly canonicalize
> tree offset and HOST_WIDE_INT bit position.
>
> * gcc.dg/fold-compare-6.c: New testcase.
>
> Index: gcc/fold-const.c
> ===================================================================
> --- gcc/fold-const.c (revision 182784)
> +++ gcc/fold-const.c (working copy)
> @@ -8886,6 +8886,14 @@ fold_comparison (location_t loc, enum tr
> indirect_base0 = true;
> }
> offset0 = TREE_OPERAND (arg0, 1);
> + if (host_integerp (offset0, 0)
> + && ((HOST_WIDE_INT) (TREE_INT_CST_LOW (offset0) * BITS_PER_UNIT)
> + / BITS_PER_UNIT
> + == (HOST_WIDE_INT) TREE_INT_CST_LOW (offset0)))
> + {
> + bitpos0 = TREE_INT_CST_LOW (offset0) * BITS_PER_UNIT;
> + offset0 = NULL_TREE;
> + }
> }
>
> base1 = arg1;
> @@ -8909,6 +8917,14 @@ fold_comparison (location_t loc, enum tr
> indirect_base1 = true;
> }
> offset1 = TREE_OPERAND (arg1, 1);
> + if (host_integerp (offset1, 0)
> + && ((HOST_WIDE_INT) (TREE_INT_CST_LOW (offset1) * BITS_PER_UNIT)
> + / BITS_PER_UNIT
> + == (HOST_WIDE_INT) TREE_INT_CST_LOW (offset1)))
> + {
> + bitpos1 = TREE_INT_CST_LOW (offset1) * BITS_PER_UNIT;
> + offset1 = NULL_TREE;
> + }
> }
>
> /* A local variable can never be pointed to by
> Index: gcc/testsuite/gcc.dg/fold-compare-6.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/fold-compare-6.c (revision 0)
> +++ gcc/testsuite/gcc.dg/fold-compare-6.c (revision 0)
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fdump-tree-original" } */
> +
> +char digs[] = "0123456789";
> +int foo (void)
> +{
> + int xlcbug = 1 / (&(digs + 5)[-2 + (_Bool) 1] == &digs[4] ? 1 : -1);
> + return xlcbug;
> +}
> +
> +/* { dg-final { scan-tree-dump "xlcbug = 1;" "original" } } */
> +/* { dg-final { cleanup-tree-dump "original" } } */
>
--
Richard Guenther <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer
