[Bug debug/63581] New: undefined references in debug_info

[Bug debug/63581] New: undefined references in debug_info

[xur at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63581

            Bug ID: 63581
           Summary: undefined references in debug_info
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xur at google dot com

Created attachment 33752
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33752&action=edit
reproducer

I got the following error when compiling a file with FDO.

/tmp/cc6azLyK.o:(.debug_info+0x228): undefined reference to `.L29'

The error is triggered by function splitting. Adding
-fno-reorder-blocks-and-partition will make the build pass.

Here is the diagnosis: 
We generate a label die and assume the label instruction will be generated in
final pass. This label is marked as deleted, but because it's a user
defined label, we should output it in the final pass. 

This label instruction is removed from insn stream in
record_effective_endpoints() and put the header of one bb and later
merged to the footer of another. The bb footer got overwritten in
emit_barrier_after_bb() (from add_labels_and_missing_jumps()). Since it's
overwritten, it never gets to put back to inst stream in cfg_layout_finalize.

I think the overwritten in emit_barrier_after_bb() is wrong. We should append
to the bb footer if the footer contains non-barrier instruction.

Once I do the appending, the label is emitted.

Reproducer attached. Build instructions are in the head of the file.

[Bug debug/63581] undefined references in debug_info

[xur at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63581

--- Comment #1 from xur at google dot com ---
Patches is here:
https://gcc.gnu.org/ml/gcc-patches/2014-10/msg01795.html

[Bug debug/63581] undefined references in debug_info

[xur at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63581

--- Comment #2 from xur at gcc dot gnu.org ---
Author: xur
Date: Fri Nov 14 00:30:31 2014
New Revision: 217530

URL: https://gcc.gnu.org/viewcvs?rev=217530&root=gcc&view=rev
Log:
2014-11-13  Rong Xu  <xur@google.com>

gcc:
    PR debug/63581
    * cfgrtl.c (emit_barrier_after_bb): Append the barrier to the
     footer, instead of unconditionally overwritten

gcc/testsuite:
    PR debug/63581
    * g++.dg/tree-prof/pr63581.C: New test.


Added:
    trunk/gcc/testsuite/g++.dg/tree-prof/pr63581.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgrtl.c
    trunk/gcc/testsuite/ChangeLog

[Bug debug/63581] undefined references in debug_info

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63581

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |arnetheduck at gmail dot com

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 64593 has been marked as a duplicate of this bug. ***