[Bug debug/41558] New: gfortran -O code excessive DW_OP_deref's

[Bug debug/41558] New: gfortran -O code excessive DW_OP_deref's

[jan dot kratochvil at redhat dot com]

GNU Fortran (GCC) 4.5.0 20091003 (experimental)

  subroutine f(s)
  character*3 s
  s = s
  end
  call f ('foo')
  end

gdb -nx -ex 'b 3' -ex r -ex 'p s' ./file
->
Cannot access memory at address 0x6f6f66

 <2><4a>: Abbrev Number: 3 (DW_TAG_formal_parameter)
    <4b>   DW_AT_name        : s        
    <4f>   DW_AT_type        : <0x64>   
    <53>   DW_AT_location    : 4 byte block: 75 0 6 6   (DW_OP_breg5: 0;
DW_OP_deref; DW_OP_deref)

If I patch those two DW_OP_deref -> DW_OP_nop then GDB prints:
$1 = 'foo'

gfortran -o 1 1.f90 -Wall -g -O1 

currently:
.LC0:
        .ascii  "foo"
...
        movl    $.LC0, %edi
...
        .byte   0x4     # DW_AT_location
        .byte   0x75    # DW_OP_breg5
        .sleb128 0
        .byte   0x6     # DW_OP_deref
        .byte   0x6     # DW_OP_deref


-- 
           Summary: gfortran -O code excessive DW_OP_deref's
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jan dot kratochvil at redhat dot com
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41558

[Bug debug/41558] gfortran -O code excessive DW_OP_deref's

[jakub at gcc dot gnu dot org]

------- Comment #1 from jakub at gcc dot gnu dot org  2009-10-05 09:52 -------
Created an attachment (id=18706)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18706&action=view)
gcc45-pr41558.patch

Patch I'm going to bootstrap/regtest.

BTW, gdb 7.0.50.20091005-cvs doesn't work with the guality.exp testcases well,
something broke in it recently.  6.8.91.20090917-1.fc12 works fine.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41558

[Bug debug/41558] gfortran -O code excessive DW_OP_deref's

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2009-10-05 19:51 -------
Subject: Bug 41558

Author: jakub
Date: Mon Oct  5 19:50:57 2009
New Revision: 152467

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152467
Log:
        PR debug/41558
        * dwarf2out.c (loc_by_reference): Removed.
        (dw_loc_list_1): New function.
        (dw_loc_list): Remove toplev argument, add want_address argument.
        Don't look at decl_by_reference_p at all.  Use dw_loc_list_1.
        (loc_list_from_tree) <case VAR_DECL>: Pass want_address rather than
        want_address == 2 to dw_loc_list.  For successful dw_loc_list
        set have_address to 1 only if want_address is not 0.

        * gcc.dg/guality/guality.exp: Move gdb-test proc into...
        * lib/gcc-gdb-test.exp: ... here.  New file.
        * gfortran.dg/guality/guality.exp: New file.
        * gfortran.dg/guality/pr41558.f90: New test.
        * gfortran.dg/guality/arg1.f90: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/guality/
    trunk/gcc/testsuite/gfortran.dg/guality/arg1.f90
    trunk/gcc/testsuite/gfortran.dg/guality/guality.exp
    trunk/gcc/testsuite/gfortran.dg/guality/pr41558.f90
    trunk/gcc/testsuite/lib/gcc-gdb-test.exp
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/guality/guality.exp


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41558

[Bug debug/41558] gfortran -O code excessive DW_OP_deref's

[jan dot kratochvil at redhat dot com]

------- Comment #3 from jan dot kratochvil at redhat dot com  2009-10-06 15:28 -------
(In reply to comment #1)
> BTW, gdb 7.0.50.20091005-cvs doesn't work with the guality.exp testcases well,
> something broke in it recently.  6.8.91.20090917-1.fc12 works fine.

There is an array with variable size: integer :: a(n), n
VLA support is still missing in FSF GDB, it is present in Archer (+Fedora)
branch archer-jankratochvil-vla:
http://sourceware.org/gdb/wiki/ArcherBranchManagement


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41558

[Bug debug/41558] gfortran -O code excessive DW_OP_deref's

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2009-10-12 19:09 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41558