[gcc r16-7136] tree-optimization/123596 - fix partial virtual SSA update in eh_cleanup

[Richard Biener]

https://gcc.gnu.org/g:4c49f8e53698cce2fc93fb31cbd190c7ff3d04c4

commit r16-7136-g4c49f8e53698cce2fc93fb31cbd190c7ff3d04c4
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jan 29 10:41:16 2026 +0100

    tree-optimization/123596 - fix partial virtual SSA update in eh_cleanup
    
    The following replaces the not quite correct use of
    mark_virtual_operand_for_renaming by an appropriate way of dealing
    with a possibly partially up-to-date virtual SSA form.  Namely
    when we just move stmts and not remove a VDEF we should arrange
    for missing virtual PHIs to be created and just queue its arguments
    for possible renaming.  For the testcase at hand there's no renaming
    necessary in the end when done this way.
    
            PR tree-optimization/123596
            * tree-eh.cc (sink_clobbers): Create a virtual PHI when
            one is required but not present, queuing arguments
            for renaming.
    
            * g++.dg/torture/pr123596.C: New testcase.

Diff:
---
 gcc/testsuite/g++.dg/torture/pr123596.C | 18 ++++++++++++++++++
 gcc/tree-eh.cc                          | 20 ++++++++++++--------
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/gcc/testsuite/g++.dg/torture/pr123596.C b/gcc/testsuite/g++.dg/torture/pr123596.C
new file mode 100644
index 000000000000..f146e41d5552
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr123596.C
@@ -0,0 +1,18 @@
+// { dg-do compile }
+
+struct b {
+  ~b() {}
+};
+struct c {
+  c(long, const int &, b = b());
+};
+int _setjmp();
+long d;
+void e(int *);
+int a;
+int main()
+{
+  auto f = [](int *data) { e(data); };
+  f(&a);
+  c(d, _setjmp());
+}
diff --git a/gcc/tree-eh.cc b/gcc/tree-eh.cc
index ea093544b510..512dca807a71 100644
--- a/gcc/tree-eh.cc
+++ b/gcc/tree-eh.cc
@@ -3861,6 +3861,18 @@ sink_clobbers (basic_block bb,
     }
   if (first_sunk)
     {
+      /* If there isn't a single predecessor but no virtual PHI node
+	 create one and arrange for virtual operands to be renamed as
+	 we cannot be sure all incoming edges will updated from sinking
+	 something.  */
+      if (!vphi && !single_pred_p (succbb))
+	{
+	  vphi = create_phi_node (gimple_vop (cfun), succbb);
+	  FOR_EACH_EDGE (e, ei, succbb->preds)
+	    add_phi_arg (vphi, gimple_vop (cfun), e, UNKNOWN_LOCATION);
+	  mark_virtual_operands_for_renaming (cfun);
+	  todo |= TODO_update_ssa_only_virtuals;
+	}
       /* Adjust virtual operands if we sunk across a virtual PHI.  */
       if (vphi)
 	{
@@ -3880,14 +3892,6 @@ sink_clobbers (basic_block bb,
 		   gimple_vuse (last_sunk));
 	  SET_USE (gimple_vuse_op (last_sunk), phi_def);
 	}
-      /* If there isn't a single predecessor but no virtual PHI node
-         arrange for virtual operands to be renamed.  */
-      else if (!single_pred_p (succbb)
-	       && TREE_CODE (gimple_vuse (last_sunk)) == SSA_NAME)
-	{
-	  mark_virtual_operand_for_renaming (gimple_vuse (last_sunk));
-	  todo |= TODO_update_ssa_only_virtuals;
-	}
     }
 
   return todo;