[PATCH 3/5] Fix NOTE_INSN_PROLOGUE_END after unconditional jump.

[Marcin Kościelnicki]

With the new s390 split-stack support, when optimization is enabled,
the cold path of calling __morestack is likely to be moved to the
end of the function.  This will result in the function ending in
split_stack_call_esa, which is an unconditional jump instruction and
part of the function prologue.  reposition_prologue_and_epilogue_notes
will insert NOTE_INSN_PROLOGUE_END right after it (and before the
following barrier), causing a verification error.  Insert it after
the barrier instead (and outside of basic block).

gcc/ChangeLog:

        * function.c (reposition_prologue_and_epilogue_notes): Avoid
        verification error if the last insn of prologue is an unconditional
        jump.
---
 gcc/ChangeLog  | 6 ++++++
 gcc/function.c | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6aef3f9..56e31f6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2016-01-02  Marcin Kościelnicki  <koria...@0x04.net>
 
+       * function.c (reposition_prologue_and_epilogue_notes): Avoid
+       verification error if the last insn of prologue is an unconditional
+       jump.
+
+2016-01-02  Marcin Kościelnicki  <koria...@0x04.net>
+
        * config/s390/s390.c (s390_asm_declare_function_size): Add code
        to actually emit the .size directive.
 
diff --git a/gcc/function.c b/gcc/function.c
index 035a49e..921945f 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -6348,6 +6348,12 @@ reposition_prologue_and_epilogue_notes (void)
          /* Avoid placing note between CODE_LABEL and BASIC_BLOCK note.  */
          if (LABEL_P (last))
            last = NEXT_INSN (last);
+         if (BARRIER_P (last) && BLOCK_FOR_INSN (note))
+           {
+             if (BB_END (BLOCK_FOR_INSN (note)) == note)
+               BB_END (BLOCK_FOR_INSN (note)) = PREV_INSN (note);
+             BLOCK_FOR_INSN (note) = 0;
+           }
          reorder_insns (note, note, last);
        }
     }
-- 
2.6.4