[gcc r14-11495] ipa: Do not modify cgraph edges from thunk clones during inlining (PR116572)

[Martin Jambor via Gcc-cvs]

https://gcc.gnu.org/g:5312a8f62a6bcae36f6aa40f88c8b58dfae7db21

commit r14-11495-g5312a8f62a6bcae36f6aa40f88c8b58dfae7db21
Author: Martin Jambor <mjam...@suse.cz>
Date:   Fri Mar 14 16:07:01 2025 +0100

    ipa: Do not modify cgraph edges from thunk clones during inlining (PR116572)
    
    In PR 116572 we hit an assert that a thunk which does not have a body
    looks like it has one.  It does not, but the call_stmt of its outgoing
    edge points to a statement, which should not.  In fact it has several
    outgoing call graph edges, which cannot be.  The problem is that the
    code updating the edges to reflect inlining into the master clone (an
    ex-thunk, unlike the clone, which is still an unexpanded thunk) is
    being updated during inling into the master clone.  This patch simply
    makes the code to skip unexpanded thunk clones.
    
    gcc/ChangeLog:
    
    2025-03-13  Martin Jambor  <mjam...@suse.cz>
    
            PR ipa/116572
            * cgraph.cc (cgraph_update_edges_for_call_stmt): Do not update
            edges of clones that are unexpanded thunk.  Assert that the node
            passed as the parameter is not an unexpanded thunk.
    
    gcc/testsuite/ChangeLog:
    
    2025-03-13  Martin Jambor  <mjam...@suse.cz>
    
            PR ipa/116572
            * g++.dg/ipa/pr116572.C: New test.
    
    (cherry picked from commit 075ec330307c5b1fe5ed166a633c718c06b01437)

Diff:
---
 gcc/cgraph.cc                       |  7 +++++--
 gcc/testsuite/g++.dg/ipa/pr116572.C | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/gcc/cgraph.cc b/gcc/cgraph.cc
index 8226c7d96e05..dc18a16f8917 100644
--- a/gcc/cgraph.cc
+++ b/gcc/cgraph.cc
@@ -1710,12 +1710,15 @@ cgraph_update_edges_for_call_stmt (gimple *old_stmt, 
tree old_decl,
   cgraph_node *node;
 
   gcc_checking_assert (orig);
+  gcc_assert (!orig->thunk);
   cgraph_update_edges_for_call_stmt_node (orig, old_stmt, old_decl, new_stmt);
   if (orig->clones)
     for (node = orig->clones; node != orig;)
       {
-       cgraph_update_edges_for_call_stmt_node (node, old_stmt, old_decl,
-                                               new_stmt);
+       /* Do not attempt to adjust bodies of yet unexpanded thunks.  */
+       if (!node->thunk)
+         cgraph_update_edges_for_call_stmt_node (node, old_stmt, old_decl,
+                                                 new_stmt);
        if (node->clones)
          node = node->clones;
        else if (node->next_sibling_clone)
diff --git a/gcc/testsuite/g++.dg/ipa/pr116572.C 
b/gcc/testsuite/g++.dg/ipa/pr116572.C
new file mode 100644
index 000000000000..909568e1c72c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/pr116572.C
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c++20 -O3 -fsanitize=undefined" } */
+
+long v;
+template <class> struct A;
+template <typename C, typename = A<C>, typename = C>
+class B;
+template <>
+struct A<char>
+{
+  static int foo(char *s, const char *t, long n) { return __builtin_memcmp(s, 
t, n); }
+};
+template <typename C, typename, typename>
+struct B {
+  long b;
+  B(const C *);
+  C *bar() const;
+  constexpr unsigned long baz(const C *, unsigned long, unsigned long) const 
noexcept;
+  void baz() { C c; baz(&c, 0, v); }
+};
+template <typename C, typename D, typename E>
+constexpr unsigned long
+B<C, D, E>::baz(const C *s, unsigned long, unsigned long n) const noexcept
+{
+  C *x = bar(); if (!x) return b; D::foo(x, s, n); return 0;
+}
+namespace {
+struct F { virtual ~F() {} };
+struct F2 { virtual void foo(B<char>) const; };
+struct F3 : F, F2 { void foo(B<char> s) const { s.baz(); } } f;
+}
+int
+main()
+{
+  F *p;
+  dynamic_cast<F2 *>(p)->foo("");
+}