[PATCH] Fix cgraph edge redirection with non-POD lhs (PR middle-end/71387)

[Jakub Jelinek]

Hi!

Apparently my r236430 change (trunk) and r236431 (6.x) broke the following
testcase.  In the later similar change to gimple-fold.c in r236506
I've added code to tweak gimple_call_fntype if we have newly one of the
void something (void) __attribute__((noreturn)) functions like
__builtin_unreachable or __cxa_pure_virtual, and drop the lhs even if it
has been before non-POD, but the new fntype has void return type,
but apparently we need to do the same in cgraph.c as well.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/6.2?

2016-06-02  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/71387
        * cgraph.c (cgraph_edge::redirect_call_stmt_to_callee): If redirecting
        to noreturn e->callee->decl that has void return type and void
        arguments, adjust gimple_call_fntype and remove lhs even if it had
        previously addressable type.

        * g++.dg/opt/pr71387.C: New test.

--- gcc/cgraph.c.jj     2016-05-26 10:37:54.000000000 +0200
+++ gcc/cgraph.c        2016-06-02 17:17:58.963052785 +0200
@@ -1512,8 +1512,20 @@ cgraph_edge::redirect_call_stmt_to_calle
       update_stmt_fn (DECL_STRUCT_FUNCTION (e->caller->decl), new_stmt);
     }
 
+  /* If changing the call to __cxa_pure_virtual or similar noreturn function,
+     adjust gimple_call_fntype too.  */
+  if (gimple_call_noreturn_p (new_stmt)
+      && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (e->callee->decl)))
+      && TYPE_ARG_TYPES (TREE_TYPE (e->callee->decl))
+      && (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (e->callee->decl)))
+         == void_type_node))
+    gimple_call_set_fntype (new_stmt, TREE_TYPE (e->callee->decl));
+
   /* If the call becomes noreturn, remove the LHS if possible.  */
-  if (gimple_call_noreturn_p (new_stmt) && should_remove_lhs_p (lhs))
+  if (lhs
+      && gimple_call_noreturn_p (new_stmt)
+      && (VOID_TYPE_P (TREE_TYPE (gimple_call_fntype (new_stmt)))
+         || should_remove_lhs_p (lhs)))
     {
       if (TREE_CODE (lhs) == SSA_NAME)
        {
--- gcc/testsuite/g++.dg/opt/pr71387.C.jj       2016-06-02 17:37:59.868769557 
+0200
+++ gcc/testsuite/g++.dg/opt/pr71387.C  2016-06-02 17:23:51.000000000 +0200
@@ -0,0 +1,52 @@
+// PR middle-end/71387
+// { dg-do compile }
+// { dg-options "-Og" }
+
+struct A
+{
+  A ();
+  inline A (const A &);
+};
+
+struct B
+{
+  explicit B (unsigned long) : b(0), c(1) {}
+  A a;
+  unsigned long b;
+  int c;
+};
+
+struct C {};
+
+struct D
+{
+  explicit D (const C *) {}
+};
+
+struct E : public D
+{
+  E (const C *x) : D(x) {}
+  virtual A foo () const = 0;
+  virtual A bar () const = 0;
+};
+
+struct F : public B
+{
+  inline void baz ();
+  F (const E *);
+  const E *f;
+};
+
+inline void
+F::baz ()
+{
+  if (b == 0)
+    a = f->bar ();
+  else
+    a = f->foo ();
+}
+
+F::F (const E *) : B(4)
+{
+  baz ();
+}

        Jakub