> Am 09.11.2024 um 02:36 schrieb Andrew Pinski <quic_apin...@quicinc.com>:
>
> After adding vn_valueize to the handle the `a | b ==/!= 0` case
> of insert_predicates_for_cond, it would go into an infinite loop
> as the Value number for either a or b could be the same as what it
> is for the whole expression. This avoids that recursion so there is
> no infinite loop here.
>
> Bootstrapped and tested on x86_64-linux.
Ok
Richard
> PR tree-optimization/117496
>
> gcc/ChangeLog:
>
> * tree-ssa-sccvn.cc (insert_predicates_for_cond): If the
> valueization for the new lhs is the same as the old one,
> don't recurse.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/torture/pr117496-1.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/testsuite/gcc.dg/torture/pr117496-1.c | 25 +++++++++++++++++++++++
> gcc/tree-ssa-sccvn.cc | 11 ++++++++--
> 2 files changed, 34 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/pr117496-1.c
>
> diff --git a/gcc/testsuite/gcc.dg/torture/pr117496-1.c
> b/gcc/testsuite/gcc.dg/torture/pr117496-1.c
> new file mode 100644
> index 00000000000..f35d13dfa85
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr117496-1.c
> @@ -0,0 +1,25 @@
> +/* { dg-do compile } */
> +
> +
> +/* PR tree-optimization/117496 */
> +/* This would go into an infinite loop into VN while recording
> + the predicates for the `tracks == 0 && wm == 0` GIMPLE_COND.
> + As wm_N and tracks_N would valueize back to `tracks | wm`. */
> +
> +int main_argc, gargs_preemp, gargs_nopreemp;
> +static void gargs();
> +void main_argv() {
> + int tracks = 0;
> + gargs(main_argc, main_argv, &tracks);
> +}
> +void gargs(int, char *, int *tracksp) {
> + int tracks = *tracksp, wm;
> + for (;;) {
> + if (tracks == 0)
> + wm |= 4;
> + if (gargs_nopreemp)
> + gargs_preemp = 0;
> + if (tracks == 0 && wm == 0)
> + tracks++;
> + }
> +}
> diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
> index 16299662b95..e93acb44200 100644
> --- a/gcc/tree-ssa-sccvn.cc
> +++ b/gcc/tree-ssa-sccvn.cc
> @@ -7900,6 +7900,7 @@ insert_related_predicates_on_edge (enum tree_code code,
> tree *ops, edge pred_e)
>
> /* Insert on the TRUE_E true and FALSE_E false predicates
> derived from LHS CODE RHS. */
> +
> static void
> insert_predicates_for_cond (tree_code code, tree lhs, tree rhs,
> edge true_e, edge false_e)
> @@ -7977,10 +7978,16 @@ insert_predicates_for_cond (tree_code code, tree lhs,
> tree rhs,
> tree nlhs;
>
> nlhs = vn_valueize (gimple_assign_rhs1 (def_stmt));
> - insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
> + /* A valueization of the `a` might return the old lhs
> + which is already handled above. */
> + if (nlhs != lhs)
> + insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
>
> + /* A valueization of the `b` might return the old lhs
> + which is already handled above. */
> nlhs = vn_valueize (gimple_assign_rhs2 (def_stmt));
> - insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
> + if (nlhs != lhs)
> + insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
> }
> }
> }
> --
> 2.43.0
>
