On Wed, 4 Mar 2020, Jakub Jelinek wrote:
> Hi!
>
> On Wed, Mar 04, 2020 at 11:33:06AM +0100, Richard Biener wrote:
> > > where POINTER_PLUS_EXPR last operand has sizetype type, thus unsigned,
> > > and in the testcase gimple_assign_rhs2 (def) is thus 0xf000000000000001ULL
> > > which multiplied by 8 doesn't fit into signed HWI. If it would be treated
> > > as signed offset instead, it would fit (-0xfffffffffffffffLL, multiplied
> > > by 8 is -0x7ffffffffffffff8LL). Unfortunately with the poly_int
> > > obfuscation
> > > I'm not sure how to convert it from unsigned to signed poly_int.
> >
> > mem_ref_offset provides a boiler-plate for this:
> >
> > poly_offset_int::from (wi::to_poly_wide (TREE_OPERAND (t, 1)), SIGNED);
>
> Thanks, that seems to work.
> So, is the following ok for trunk if it passes bootstrap/regtest?
> The test now works on both big-endian and little-endian.
Yes.
Thanks,
Richard.
> 2020-03-04 Richard Biener <rguent...@suse.de>
> Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/93582
> * tree-ssa-sccvn.c (vn_reference_lookup_3): Treat POINTER_PLUS_EXPR
> last operand as signed when looking for memset offset. Formatting
> fix.
>
> * gcc.dg/tree-ssa/pr93582-11.c: New test.
>
> --- gcc/tree-ssa-sccvn.c.jj 2020-03-04 12:46:09.809610729 +0100
> +++ gcc/tree-ssa-sccvn.c 2020-03-04 13:07:07.982902846 +0100
> @@ -2656,7 +2656,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> {
> poly_int64 soff;
> if (TREE_CODE (base) != MEM_REF
> - || !(mem_ref_offset (base) << LOG2_BITS_PER_UNIT).to_shwi (&soff))
> + || !(mem_ref_offset (base)
> + << LOG2_BITS_PER_UNIT).to_shwi (&soff))
> return (void *)-1;
> offset += soff;
> offset2 = 0;
> @@ -2666,10 +2667,13 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> if (is_gimple_assign (def)
> && gimple_assign_rhs_code (def) == POINTER_PLUS_EXPR
> && gimple_assign_rhs1 (def) == TREE_OPERAND (base, 0)
> - && poly_int_tree_p (gimple_assign_rhs2 (def))
> - && (wi::to_poly_offset (gimple_assign_rhs2 (def))
> - << LOG2_BITS_PER_UNIT).to_shwi (&offset2))
> + && poly_int_tree_p (gimple_assign_rhs2 (def)))
> {
> + tree rhs2 = gimple_assign_rhs2 (def);
> + if (!(poly_offset_int::from (wi::to_poly_wide (rhs2),
> + SIGNED)
> + << LOG2_BITS_PER_UNIT).to_shwi (&offset2))
> + return (void *)-1;
> ref2 = gimple_assign_rhs1 (def);
> if (TREE_CODE (ref2) == SSA_NAME)
> ref2 = SSA_VAL (ref2);
> --- gcc/testsuite/gcc.dg/tree-ssa/pr93582-11.c.jj 2020-03-04
> 13:12:22.819222647 +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr93582-11.c 2020-03-04
> 13:13:47.234968590 +0100
> @@ -0,0 +1,16 @@
> +/* PR tree-optimization/93582 */
> +/* { dg-do compile { target lp64 } } */
> +/* { dg-options "-O2 -fdump-tree-fre1" } */
> +/* { dg-final { scan-tree-dump "return 9223372036854775806;" "fre1" } } */
> +
> +union U { struct A { unsigned long long a : 1, b : 62, c : 1; } a; unsigned
> long long i; };
> +
> +unsigned long long
> +foo (char *p)
> +{
> + __builtin_memset (p - 0xfffffffffffffffULL, 0, 0xffffffffffffffeULL);
> + __builtin_memset (p + 1, 0, 0xffffffffffffffeULL);
> + union U *q = (union U *) (void *) (p - 4);
> + q->a.b = -1;
> + return q->i;
> +}
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
