On Tue, 20 Mar 2018, Jakub Jelinek wrote:
> Hi!
>
> Boolean !x is often expanded as ^ 1, but store merging it actually merges
> as ^ 255 (for 8-bit bool), which is incorrect.
>
> The following patch fixes it to do that ^ 1 instead.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux and checked on the
> testcase with -> powerpc64-linux cross, ok for trunk?
>
> 2018-03-20 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/84982
> * gimple-ssa-store-merging.c (invert_op): Handle boolean inversion
> by flipping the least significant bit rather than all bits from
> bitpos to bitpos + bitsize - 1.
>
> * c-c++-common/pr84982.c: New test.
>
> --- gcc/gimple-ssa-store-merging.c.jj 2018-03-20 13:53:31.701938584 +0100
> +++ gcc/gimple-ssa-store-merging.c 2018-03-20 14:39:50.925657339 +0100
> @@ -3248,16 +3248,22 @@ invert_op (split_store *split_store, int
> unsigned int i;
> store_immediate_info *info;
> unsigned int cnt = 0;
> + bool any_bools = false;
> FOR_EACH_VEC_ELT (split_store->orig_stores, i, info)
> {
> bool bit_not_p = idx < 2 ? info->ops[idx].bit_not_p : info->bit_not_p;
> if (bit_not_p)
> - ++cnt;
> + {
> + ++cnt;
> + tree lhs = gimple_assign_lhs (info->stmt);
> + if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE && info->bitsize > 1)
So I'm slightly uncomfortable with keying this just on BOOLEAN_TYPE.
Do you think anything would go wrong with simply using
if (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
&& TYPE_PRECISION (TREE_TYPE (lhs)) < info->bitsize)
?
It would then be any_padding rather than any_bool.
> + any_bools = true;
> + }
> }
> mask = NULL_TREE;
> if (cnt == 0)
> return NOP_EXPR;
> - if (cnt == split_store->orig_stores.length ())
> + if (cnt == split_store->orig_stores.length () && !any_bools)
> return BIT_NOT_EXPR;
>
> unsigned HOST_WIDE_INT try_bitpos = split_store->bytepos * BITS_PER_UNIT;
> @@ -3275,13 +3281,34 @@ invert_op (split_store *split_store, int
> set in the mask. */
> unsigned HOST_WIDE_INT bitsize = info->bitsize;
> unsigned int pos_in_buffer = 0;
> + bool is_bool = false;
> + if (any_bools && bitsize > 1)
> + {
> + tree lhs = gimple_assign_lhs (info->stmt);
> + if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE)
> + is_bool = true;
> + }
> if (info->bitpos < try_bitpos)
> {
> gcc_assert (info->bitpos + bitsize > try_bitpos);
> bitsize -= (try_bitpos - info->bitpos);
> + if (is_bool && !BYTES_BIG_ENDIAN)
> + continue;
> }
> else
> pos_in_buffer = info->bitpos - try_bitpos;
> + if (is_bool && bitsize)
> + {
> + /* If this is a bool inversion, invert just the LSB
> + rather than all bits of it. */
> + if (BYTES_BIG_ENDIAN)
> + {
> + pos_in_buffer += bitsize - 1;
> + if (pos_in_buffer >= split_store->size)
> + continue;
> + }
> + bitsize = 1;
> + }
> if (pos_in_buffer + bitsize > split_store->size)
> bitsize = split_store->size - pos_in_buffer;
> unsigned char *p = buf + (pos_in_buffer / BITS_PER_UNIT);
> --- gcc/testsuite/c-c++-common/pr84982.c.jj 2018-03-20 14:49:00.259744750
> +0100
> +++ gcc/testsuite/c-c++-common/pr84982.c 2018-03-20 12:27:34.111363552
> +0100
> @@ -0,0 +1,38 @@
> +/* PR tree-optimization/84982 */
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +#ifndef __cplusplus
> +#define bool _Bool
> +#define true 1
> +#define false 0
> +#endif
> +
> +struct S { bool a, b, c, d; };
> +
> +__attribute__((noipa)) void
> +bar (bool *x)
> +{
> + if (x[0] || !x[1] || !x[2] || x[3])
> + __builtin_abort ();
> +}
> +
> +__attribute__((noipa)) void
> +foo (struct S *x)
> +{
> + bool a[4];
> + a[0] = !x->a;
> + a[1] = !x->b;
> + a[2] = x->c;
> + a[3] = !x->d;
> + bar (a);
> +}
> +
> +int
> +main ()
> +{
> + struct S s;
> + s.a = true; s.b = false; s.c = true; s.d = true;
> + foo (&s);
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
