Fix PR rtl-optimization/113140

[Eric Botcazou]

This is a small regression present on the mainline and 13 branch, although the 
underlying problem has probably been there for ages, in the form of a segfault 
during the delay slot scheduling pass, for a function that falls through to 
exit without any RTL instruction generated for the end of function.

Tested on SPARC64/Linux, applied on the mainline and 13 branch.


2024-01-09  Eric Botcazou  <ebotca...@adacore.com>

        PR rtl-optimization/113140
        * reorg.cc (fill_slots_from_thread): If we are to branch after the
        last instruction of the function, create an end label.


2024-01-09  Eric Botcazou  <ebotca...@adacore.com>

        * g++.dg/opt/delay-slot-2.C: New test.

-- 
Eric Botcazou
diff --git a/gcc/reorg.cc b/gcc/reorg.cc
index e85af7134f4..99228a22c69 100644
--- a/gcc/reorg.cc
+++ b/gcc/reorg.cc
@@ -2641,7 +2641,8 @@ fill_slots_from_thread (rtx_jump_insn *insn, rtx condition,
      arithmetic insn after the jump insn and put the arithmetic insn in the
      delay slot.  If we can't do this, return.  */
   if (delay_list->is_empty () && likely
-      && new_thread && !ANY_RETURN_P (new_thread)
+      && new_thread
+      && !ANY_RETURN_P (new_thread)
       && NONJUMP_INSN_P (new_thread)
       && !RTX_FRAME_RELATED_P (new_thread)
       && GET_CODE (PATTERN (new_thread)) != ASM_INPUT
@@ -2729,14 +2730,16 @@ fill_slots_from_thread (rtx_jump_insn *insn, rtx condition,
 
       gcc_assert (thread_if_true);
 
-      if (new_thread && simplejump_or_return_p (new_thread)
+      if (new_thread
+	  && simplejump_or_return_p (new_thread)
 	  && redirect_with_delay_list_safe_p (insn,
 					      JUMP_LABEL (new_thread),
 					      *delay_list))
-	new_thread = follow_jumps (JUMP_LABEL (new_thread), insn,
-				   &crossing);
+	new_thread = follow_jumps (JUMP_LABEL (new_thread), insn, &crossing);
 
-      if (ANY_RETURN_P (new_thread))
+      if (!new_thread)
+	label = find_end_label (simple_return_rtx);
+      else if (ANY_RETURN_P (new_thread))
 	label = find_end_label (new_thread);
       else if (LABEL_P (new_thread))
 	label = new_thread;

// PR rtl-optimization/113140
// Reduced testcase by Rainer Orth <r...@gcc.gnu.org>

// { dg-options "-O -w" }

int *m();
struct StaticValue {
  long _val;
  void setM(int *) { _val = 0; }
};
struct Value : StaticValue {
  template <typename T> T *as();
};
Value *alloc();
struct Scoped {
  Scoped() {
    Value v;
    ptr = alloc();
    Value *__trans_tmp_1 = v.as<Value>();
    ptr->setM(__trans_tmp_1 ? m() : 0);
  }
  Value *ptr;
};
struct QObjectMethod {
  unsigned long long callInternal() const;
};
unsigned long long QObjectMethod::callInternal() const {
  [] {
    if (Scoped(); 0)
      ;
  }();
}