https://gcc.gnu.org/g:b9e703f0b42b2a86c9e18cd12497a0c19d2eb96c
commit r15-10357-gb9e703f0b42b2a86c9e18cd12497a0c19d2eb96c
Author: Richard Biener <rguent...@suse.de>
Date: Mon Sep 22 10:14:31 2025 +0200
tree-optimization/122016 - PRE insertion breaks abnormal coalescing
When PRE asks VN to simplify a NARY but not insert, that bypasses
the abnormal guard in maybe_push_res_to_seq and we blindly accept
new uses of abnormals. The following fixes this.
PR tree-optimization/122016
* tree-ssa-sccvn.cc (vn_nary_simplify): Do not use the
simplified expression when it references abnormals.
* gcc.dg/torture/pr122016.c: New testcase.
(cherry picked from commit 52b53cfb5392257536fce8dd22ea60412ceaee7d)
Diff:
---
gcc/testsuite/gcc.dg/torture/pr122016.c | 27 +++++++++++++++++++++++++++
gcc/tree-ssa-sccvn.cc | 6 ++++++
2 files changed, 33 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/torture/pr122016.c
b/gcc/testsuite/gcc.dg/torture/pr122016.c
new file mode 100644
index 000000000000..027a63d42562
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr122016.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-ftree-pre" } */
+
+int merge_parse_args_argc;
+char merge_parse_args_argv_0;
+int strncmp(char *, char *, long);
+void _setjmp();
+typedef enum { FALSE, TRUE } boool;
+void directory_exists();
+void merge_parse_args() {
+ int i;
+ boool help_found = FALSE;
+ while (i < merge_parse_args_argc && !help_found) {
+ if (strncmp("", &merge_parse_args_argv_0, 2))
+ help_found = TRUE;
+ else {
+ for (;;) {
+ _setjmp();
+ break;
+ }
+ i++;
+ directory_exists();
+ }
+ i++;
+ }
+ _setjmp();
+}
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 9bf25c67dc95..a217bab88762 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -2622,6 +2622,12 @@ vn_nary_simplify (vn_nary_op_t nary)
nary->type, nary->length);
memcpy (op.ops, nary->op, sizeof (tree) * nary->length);
tree res = vn_nary_build_or_lookup_1 (&op, false, true);
+ /* Do not update *NARY with a simplified result that contains abnormals.
+ This matches what maybe_push_res_to_seq does when requesting insertion.
*/
+ for (unsigned i = 0; i < op.num_ops; ++i)
+ if (TREE_CODE (op.ops[i]) == SSA_NAME
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op.ops[i]))
+ return res;
if (op.code.is_tree_code ()
&& op.num_ops <= nary->length
&& (tree_code) op.code != CONSTRUCTOR)
