[gcc r14-12321] ipa-cp: Fix assert triggering with -fno-toplevel-reorder (PR 106260)

[Martin Jambor]

https://gcc.gnu.org/g:8aa5af5736f6fe284d2b2454d786f90a16076c2d

commit r14-12321-g8aa5af5736f6fe284d2b2454d786f90a16076c2d
Author: Martin Jambor <mjambor@suse.cz>
Date:   Wed Feb 18 13:53:34 2026 +0100

    ipa-cp: Fix assert triggering with -fno-toplevel-reorder (PR 106260)
    
    with -fno-toplevel-reorder (and -fwhole-program), there apparently can
    be local functions without any callers.  This is something that IPA-CP
    does not like because its propagation verifier checks that local
    functions do not end up with TOP in their lattices.  Therefore there
    is an assert checking that all call-less unreachable functions have
    been removed, which tigers in PR 106260 with these two options.
    
    This patch detects the situation and marks the lattices as variable,
    thus avoiding both the assert trigger and the verification failure.
    
    gcc/ChangeLog:
    
    2022-07-13  Martin Jambor  <mjambor@suse.cz>
    
            PR ipa/106260
            * ipa-cp.cc (initialize_node_lattices): Replace assert that there are
            callers with handling that situation when -fno-toplevel_reorder.
    
    gcc/testsuite/ChangeLog:
    
    2022-07-13  Martin Jambor  <mjambor@suse.cz>
    
            PR ipa/106260
            * g++.dg/ipa/pr106260.C: New test.

Diff:
---
 gcc/ipa-cp.cc                       |  6 +++-
 gcc/testsuite/g++.dg/ipa/pr106260.C | 64 +++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc
index 222ba01c576f..141752adca05 100644
--- a/gcc/ipa-cp.cc
+++ b/gcc/ipa-cp.cc
@@ -1323,10 +1323,14 @@ initialize_node_lattices (struct cgraph_node *node)
       int caller_count = 0;
       node->call_for_symbol_thunks_and_aliases (count_callers, &caller_count,
 						true);
-      gcc_checking_assert (caller_count > 0);
       if (caller_count == 1)
 	node->call_for_symbol_thunks_and_aliases (set_single_call_flag,
 						  NULL, true);
+      else if (caller_count == 0)
+	{
+	  gcc_checking_assert (!opt_for_fn (node->decl, flag_toplevel_reorder));
+	  variable = true;
+	}
     }
   else
     {
diff --git a/gcc/testsuite/g++.dg/ipa/pr106260.C b/gcc/testsuite/g++.dg/ipa/pr106260.C
new file mode 100644
index 000000000000..bd3b6e0af790
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/pr106260.C
@@ -0,0 +1,64 @@
+// { dg-do compile }
+// { dg-options "-O2 -std=gnu++14 -fwhole-program -fno-unit-at-a-time" }
+
+struct A;
+template <class T>
+struct Q { Q (T); };
+template<typename T, class D>
+struct U {
+  ~U () { m1 (nullptr); }
+  D m2 ();
+  T *u;
+  void m1 (T *) { m2 () (u); }
+};
+struct F { F (int *); };
+template <class, class T = F>
+using W = Q<T>;
+int a, b;
+void fn1 (void *);
+template <class T>
+void
+fn2 (T *x)
+{
+  if (x)
+    x->~T();
+  fn1 (x);
+}
+template <typename T>
+struct C {
+  void operator() (T *x) { fn2 (x); }
+};
+struct D;
+template <typename T, typename D = C<T> >
+using V = U<T, D>;
+struct A {
+  A (int *);
+};
+struct S;
+struct G {
+  V<S> m3 ();
+};
+struct S {
+  int e;
+  virtual ~S () {}
+};
+template<typename T>
+struct H {
+  H (int, T x, int) : h(x) {}
+  G g;
+  void m4 () { g.m3 (); }
+  T h;
+};
+struct I {
+  I(A, W<D>);
+};
+void
+test ()
+{
+  A c (&b);
+  W<D> d (&b);
+  I e (c, d);
+  H<I> f (0, e, a);
+  f.m4 ();
+}
+