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.
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
