The following makes sure to guard the modref query in VN on a
pointer typed argument.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

2022-03-08  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/104825
        * tree-ssa-sccvn.c (visit_reference_op_call): Properly
        guard modref get_ao_ref on a pointer typed argument.

        * gcc.dg/torture/pr104825.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr104825.c | 14 ++++++++++++++
 gcc/tree-ssa-sccvn.cc                   |  5 +++--
 2 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr104825.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr104825.c 
b/gcc/testsuite/gcc.dg/torture/pr104825.c
new file mode 100644
index 00000000000..7affacc2094
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr104825.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-Wno-stringop-overread" } */
+
+int foo (fmt)
+char* fmt;
+{
+  return (__builtin_strchr (fmt, '*') != 0
+          || __builtin_strchr (fmt, 'n') != 0);
+}
+void bar ()
+{
+  if (foo (1))
+    __builtin_abort ();
+}
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index d4d0aba880c..66b4fc21f5b 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -5140,11 +5140,12 @@ visit_reference_op_call (tree lhs, gcall *stmt)
                {
                  accesses.quick_grow (accesses.length () + 1);
                  ao_ref *r = &accesses.last ();
-                 if (!access_node.get_ao_ref (stmt, r))
+                 tree arg = access_node.get_call_arg (stmt);
+                 if (!POINTER_TYPE_P (TREE_TYPE (arg))
+                     || !access_node.get_ao_ref (stmt, r))
                    {
                      /* Initialize a ref based on the argument and
                         unknown offset if possible.  */
-                     tree arg = access_node.get_call_arg (stmt);
                      if (arg && TREE_CODE (arg) == SSA_NAME)
                        arg = SSA_VAL (arg);
                      if (arg
-- 
2.34.1

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