> Am 01.12.2024 um 02:59 schrieb Andrew Pinski <quic_apin...@quicinc.com>:
>
> Like r15-5063-g6e84a41622f56c, but this is for the `a != 0` case.
> After adding vn_valueize to the handle the `a ==/!= 0` case
> of insert_predicates_for_cond, it would go into an infinite loop
> as the Value number for a could be the same as what it
> is for the whole expression. This avoids that recursion so there is
> no infinite loop here.
>
> Note lim was introducing `bool_var2 = bool_var1 != 0` originally but
> with the gimple testcase in -2, there is no dependency on what passes
> before hand will do.
>
> Bootstrapped and tested on x86_64-linux-gnu.
Ok
Richard
> PR tree-optimization/117859
>
> gcc/ChangeLog:
>
> * tree-ssa-sccvn.cc (insert_predicates_for_cond): If the
> valueization for the new lhs for `lhs != 0`
> is the same as the old ones, don't recurse.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/torture/pr117859-1.c: New test.
> * gcc.dg/torture/pr117859-2.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/testsuite/gcc.dg/torture/pr117859-1.c | 23 ++++++++++
> gcc/testsuite/gcc.dg/torture/pr117859-2.c | 51 +++++++++++++++++++++++
> gcc/tree-ssa-sccvn.cc | 3 +-
> 3 files changed, 76 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/pr117859-1.c
> create mode 100644 gcc/testsuite/gcc.dg/torture/pr117859-2.c
>
> diff --git a/gcc/testsuite/gcc.dg/torture/pr117859-1.c
> b/gcc/testsuite/gcc.dg/torture/pr117859-1.c
> new file mode 100644
> index 00000000000..21e0a26e5ca
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr117859-1.c
> @@ -0,0 +1,23 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-ssa-phiopt -fno-expensive-optimizations" } */
> +
> +/* PR tree-optimization/117859 */
> +
> +unsigned char a;
> +int b, c, d, e, g, h, j, k;
> +struct {
> + int f : 1;
> +} i;
> +char l(int m) { return a > 255 >> m ? 0 : m; }
> +int main() {
> + if (i.f)
> + d = b;
> + k = e = 1;
> + for (; e; e--)
> + g = 0;
> + h = g ? 1 << g : 1;
> + c = h || i.f;
> + while (b)
> + j = l(k && i.f);
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/torture/pr117859-2.c
> b/gcc/testsuite/gcc.dg/torture/pr117859-2.c
> new file mode 100644
> index 00000000000..83549a80d3e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr117859-2.c
> @@ -0,0 +1,51 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fgimple" } */
> +
> +/* PR tree-optimization/117859 */
> +
> +void __GIMPLE (ssa,startwith("pre"))
> +m (int p, int b)
> +{
> + int _6;
> + _Bool _48;
> + _Bool _50;
> + int _57;
> + _Bool _59;
> +
> + __BB(2):
> + _6 = 0; // This needs to be prop'ed to make _48 unconditional
> + if (_6 != 0)
> + goto __BB5;
> + else
> + goto __BB14;
> +
> + __BB(14):
> + _48 = p_2(D) != 0;
> + goto __BB7;
> +
> + __BB(5):
> + goto __BB7;
> +
> + __BB(7):
> + _59 = __PHI (__BB5: _Literal (_Bool) 1, __BB14: _48);
> + if (b_36(D) != 0)
> + goto __BB8;
> + else
> + goto __BB13;
> +
> + __BB(8):
> + _50 = _59 != _Literal (_Bool) 0; // Important being != 0
> + _57 = _50 ? 1 : 0; // can be unused but need around for _50 being used
> + goto __BB9;
> +
> + __BB(9,loop_header(2)):
> + if (_59 != _Literal (_Bool) 0)
> + goto __BB13;
> + else
> + goto __BB9;
> +
> + __BB(13):
> + return;
> +
> +
> +}
> diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
> index 7ef0bd01d3c..8d74731a891 100644
> --- a/gcc/tree-ssa-sccvn.cc
> +++ b/gcc/tree-ssa-sccvn.cc
> @@ -7964,7 +7964,8 @@ insert_predicates_for_cond (tree_code code, tree lhs,
> tree rhs,
> edge nf = false_e;
> if (code == EQ_EXPR)
> std::swap (nt, nf);
> - insert_predicates_for_cond (nc, nlhs, nrhs, nt, nf);
> + if (lhs != nlhs)
> + insert_predicates_for_cond (nc, nlhs, nrhs, nt, nf);
> }
> /* (a | b) == 0 ->
> on true edge assert: a == 0 & b == 0. */
> --
> 2.43.0
>
