[Bug target/18749] GCC fails to mark stack-popping instruction in unwind-info

["davidm at hpl dot hp dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From davidm at hpl dot hp dot com  2004-12-20 22:13 -------
(In reply to comment #1)
> Without a test case, nobody can give this bug a proper look.  Can you  
> provide an example of how this fails for you?

Sorry, that was sloppy of me.  I'll attach a minimal test-case (bug.c).  With
that file:

$ gcc -v 2>&1|grep version
gcc version 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
$ gcc -c -O2 bug.c
$ objdump -d bug.o |tail -2
  76:   48 81 c4 28 10 00 00    add    $0x1028,%rsp
  7d:   c3                      retq   
$ readelf -wf bug.o 
The section .eh_frame contains:

00000000 00000014 00000000 CIE
  Version:               1
  Augmentation:          ""
  Code alignment factor: 1
  Data alignment factor: -8
  Return address column: 16

  DW_CFA_def_cfa: r7 ofs 8
  DW_CFA_offset: r16 at cfa-8
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop

00000018 00000024 0000001c FDE cie=00000000 pc=00000000..0000007e
  DW_CFA_advance_loc: 5 to 00000005
  DW_CFA_offset: r6 at cfa-32
  DW_CFA_advance_loc: 24 to 0000001d
  DW_CFA_def_cfa_offset: 4144
  DW_CFA_offset: r13 at cfa-16
  DW_CFA_offset: r3 at cfa-40
  DW_CFA_offset: r12 at cfa-24

While the code came out slightly differently, the same problem exists: the
DWARF2 frame info fails to describe the effect of popping the stack in the
second-last instruction.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18749