On Thu, 27 Feb 2020, Jakub Jelinek wrote:
> Hi!
>
> The following is the last spot in vn_reference_lookup_3 that didn't allow
> non-byte aligned offsets or sizes. To be precise, it did allow size that
> wasn't multiple of byte size and that caused a wrong-code issue on
> big-endian, as the pr93945.c testcase shows, so for GCC 9 we should add
> && multiple_p (ref->size, BITS_PER_UNIT) check instead.
> For the memset with SSA_NAME middle-argument, it still requires byte-aligned
> offset, as we'd otherwise need to rotate the value at runtime.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2020-02-27 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/93582
> PR tree-optimization/93945
> * tree-ssa-sccvn.c (vn_reference_lookup_3): Handle memset with
> non-zero INTEGER_CST second argument and ref->offset or ref->size
> not a multiple of BITS_PER_UNIT.
>
> * gcc.dg/tree-ssa/pr93582-9.c: New test.
> * gcc.c-torture/execute/pr93945.c: New test.
>
> --- gcc/tree-ssa-sccvn.c.jj 2020-02-24 12:55:32.619143689 +0100
> +++ gcc/tree-ssa-sccvn.c 2020-02-26 13:38:01.899937521 +0100
> @@ -2386,7 +2386,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> vn_reference_t vr = data->vr;
> gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
> tree base = ao_ref_base (ref);
> - HOST_WIDE_INT offseti, maxsizei;
> + HOST_WIDE_INT offseti = 0, maxsizei, sizei = 0;
> static vec<vn_reference_op_s> lhs_ops;
> ao_ref lhs_ref;
> bool lhs_ref_ok = false;
> @@ -2541,9 +2541,13 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> && (integer_zerop (gimple_call_arg (def_stmt, 1))
> || ((TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST
> || (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
> - && CHAR_BIT == 8 && BITS_PER_UNIT == 8
> + && CHAR_BIT == 8
> + && BITS_PER_UNIT == 8
> + && BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN
> && offset.is_constant (&offseti)
> - && offseti % BITS_PER_UNIT == 0))
> + && ref->size.is_constant (&sizei)
> + && (offseti % BITS_PER_UNIT == 0
> + || TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST)))
> && poly_int_tree_p (gimple_call_arg (def_stmt, 2))
> && (TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR
> || TREE_CODE (gimple_call_arg (def_stmt, 0)) == SSA_NAME))
> @@ -2604,7 +2608,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> else
> return (void *)-1;
> tree len = gimple_call_arg (def_stmt, 2);
> - HOST_WIDE_INT leni, offset2i, offseti;
> + HOST_WIDE_INT leni, offset2i;
> /* Sometimes the above trickery is smarter than alias analysis. Take
> advantage of that. */
> if (!ranges_maybe_overlap_p (offset, maxsize, offset2,
> @@ -2618,7 +2622,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> tree val;
> if (integer_zerop (gimple_call_arg (def_stmt, 1)))
> val = build_zero_cst (vr->type);
> - else if (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8))
> + else if (INTEGRAL_TYPE_P (vr->type)
> + && known_eq (ref->size, 8)
> + && offseti % BITS_PER_UNIT == 0)
> {
> gimple_match_op res_op (gimple_match_cond::UNCOND, NOP_EXPR,
> vr->type, gimple_call_arg (def_stmt, 1));
> @@ -2630,10 +2636,34 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> }
> else
> {
> - unsigned buflen = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (vr->type));
> + unsigned buflen = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (vr->type)) +
> 1;
> + if (INTEGRAL_TYPE_P (vr->type))
> + buflen = GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (vr->type)) + 1;
> unsigned char *buf = XALLOCAVEC (unsigned char, buflen);
> memset (buf, TREE_INT_CST_LOW (gimple_call_arg (def_stmt, 1)),
> buflen);
> + if (BYTES_BIG_ENDIAN)
> + {
> + unsigned int amnt
> + = (((unsigned HOST_WIDE_INT) offseti + sizei)
> + % BITS_PER_UNIT);
> + if (amnt)
> + {
> + shift_bytes_in_array_right (buf, buflen,
> + BITS_PER_UNIT - amnt);
> + buf++;
> + buflen--;
> + }
> + }
> + else if (offseti % BITS_PER_UNIT != 0)
> + {
> + unsigned int amnt
> + = BITS_PER_UNIT - ((unsigned HOST_WIDE_INT) offseti
> + % BITS_PER_UNIT);
> + shift_bytes_in_array_left (buf, buflen, amnt);
> + buf++;
> + buflen--;
> + }
> val = native_interpret_expr (vr->type, buf, buflen);
> if (!val)
> return (void *)-1;
> --- gcc/testsuite/gcc.dg/tree-ssa/pr93582-9.c.jj 2020-02-26
> 13:47:42.246393489 +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr93582-9.c 2020-02-26 13:48:42.786502204
> +0100
> @@ -0,0 +1,23 @@
> +/* PR tree-optimization/93582 */
> +/* { dg-do compile { target int32 } } */
> +/* { dg-options "-O2 -fdump-tree-fre1" } */
> +/* { dg-final { scan-tree-dump "return 5364;" "fre1" { target le } } } */
> +/* { dg-final { scan-tree-dump "return 7838;" "fre1" { target be } } } */
> +/* { dg-final { scan-tree-dump "return 1959;" "fre1" { target le } } } */
> +/* { dg-final { scan-tree-dump "return 1268;" "fre1" { target be } } } */
> +
> +union U { char a[8]; struct S { unsigned int b : 8, c : 13, d : 11; } e; } u;
> +
> +__attribute__((noipa)) int
> +foo (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.c;
> +}
> +
> +__attribute__((noipa)) int
> +baz (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.d;
> +}
> --- gcc/testsuite/gcc.c-torture/execute/pr93945.c.jj 2020-02-26
> 13:49:47.165554390 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr93945.c 2020-02-26
> 12:56:13.659868782 +0100
> @@ -0,0 +1,45 @@
> +/* PR tree-optimization/93945 */
> +
> +union U { char a[8]; struct S { unsigned int b : 8, c : 13, d : 11; } e; } u;
> +
> +__attribute__((noipa)) int
> +foo (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.c;
> +}
> +
> +__attribute__((noipa)) int
> +bar (void)
> +{
> + asm volatile ("" : : "g" (&u) : "memory");
> + return u.e.c;
> +}
> +
> +__attribute__((noipa)) int
> +baz (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.d;
> +}
> +
> +__attribute__((noipa)) int
> +qux (void)
> +{
> + asm volatile ("" : : "g" (&u) : "memory");
> + return u.e.d;
> +}
> +
> +int
> +main ()
> +{
> + int a = foo ();
> + int b = bar ();
> + if (a != b)
> + __builtin_abort ();
> + a = baz ();
> + b = qux ();
> + if (a != b)
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
