[Bug lto/55021] New: [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[Bug lto/55021] New: [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

             Bug #: 55021
           Summary: [4.8 Regression] The tests
                    gfortran.dg/integer_exponentiation_5.F90 and
                    masklr_1.F90 are miscompiled with -flto after revision
                    192529
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dominiq@lps.ens.fr
                CC: rguenth@gcc.gnu.org


The tests gfortran.dg/integer_exponentiation_5.F90 (with -O1) and masklr_1.F90
are miscompiled with -flto after revision 192529 (r192528 is OK):

[macbook] f90/bug% /opt/gcc/gcc4.8p-192559/bin/gfortran
/opt/gcc/work/gcc/testsuite/gfortran.dg/integer_exponentiation_5.F90
-fno-range-check -O1 -flto
[macbook] f90/bug% a.out                                                        
Backtrace for this error:
#0  0x1000041ae
#1  0x100004536
#2  0x1000d6108
#3  0x100000c19
#4  0x100000cd5
Abort

[macbook] f90/bug% /opt/gcc/gcc4.8p-192559/bin/gfortran
/opt/gcc/work/gcc/testsuite/gfortran.dg/masklr_1.F90 -ffree-line-length-none
-flto
[macbook] f90/bug% a.out 

Backtrace for this error:
#0  0x1000051ae
#1  0x100005536
#2  0x1000d7108
#3  0x100001b33
#4  0x100001cff
Abort

Reduced test case

module mod_check
  implicit none

contains

  subroutine check_i8 (a, b)
    integer(kind=8), intent(in) :: a, b
    if (a /= b) call abort()
  end subroutine check_i8

end module mod_check

program test
  use mod_check
  implicit none

  integer(kind=8) :: i8

  i8 = 3_8
  call check_i8(i8**43_8,3_8**43_8)

end program test

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2012-10-22
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-22 13:42:33 UTC ---
I get

> ./gfortran -B. -B ../x86_64-unknown-linux-gnu/libgfortran/.libs t.f90 -ffree-line-length-none
t.f90:20.28:

  call check_i8(i8**43_8,3_8**43_8)
                            1
Error: Arithmetic overflow at (1)

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2012-10-22 13:48:27 UTC ---
> I get
>
> > ./gfortran -B. -B ../x86_64-unknown-linux-gnu/libgfortran/.libs t.f90 -ffree-line-length-none
> t.f90:20.28:
>
>   call check_i8(i8**43_8,3_8**43_8)
>                            1
> Error: Arithmetic overflow at (1)

If t.f90 is the reduced test in comment #0 (reduced from
integer_exponentiation_5.F90), you need -fno-range-check (no need for
-ffree-line-length-none).

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-22 14:05:36 UTC ---
Confirmed.  Note that due to a Frontend issue (wrong decls for check_i8?)
without LTO no inlining takes place.  As soon as we inline we have

  _gfortran_set_options (7, &options.0[0]);
  _10 = 0xffffffff00000000565d7b7b;
  _7 = _10;
  _8 = -3784425932234851461;
  if (_7 != _8)
    goto <bb 3>;

from

  D.1880 = -3784425932234851461;
  check_i8 (&D.1880, &C.1881);

With the simplified

subroutine check_i8 (a, b)
  integer(kind=8), intent(in) :: a, b
  if (a /= b) call abort()
end subroutine check_i8

program test
  implicit none

  integer(kind=8) :: i8

  i8 = 3_8
  call check_i8(i8**43_8,3_8**43_8)

end program test

I can get non-LTO to inline check_i8 with -fwhole-prgram.

I think your bisection is wrong and

2012-10-18  Richard Guenther  <rguenther@suse.de>

        * lto-streamer.h (enum LTO_tags): Add LTO_integer_cst.
        * lto-streamer-in.c (lto_input_tree): Use it.
        * lto-streamer-out.c (lto_output_tree): Likewise, for
        !TREE_OVERFLOW integer constants only.
        * tree-streamer-in.c (unpack_ts_int_cst_value_fields): New function.
        (unpack_value_fields): Call it.
        (streamer_read_integer_cst): Simplify.
        * tree-streamer-out.c (pack_ts_int_cst_value_fields): New function.
        (streamer_pack_tree_bitfields): Call it.
        (streamer_write_integer_cst): Adjust.

must be the issue.  Very likely we have an INTEGER_CST with TREE_OVERFLOW
flag set.

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.8.0

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-22 14:07:37 UTC ---
I have an obvious patch.

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-22 14:10:31 UTC ---
Author: rguenth
Date: Mon Oct 22 14:10:06 2012
New Revision: 192691

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=192691
Log:
2012-10-22  Richard Biener  <rguenther@suse.de>

    PR lto/55021
    * tree-streamer-in.c (unpack_ts_int_cst_value_fields): Remove
    bogus truncations.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-streamer-in.c

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-22 14:10:49 UTC ---
Fixed.

[Bug lto/55021] [4.8 Regression] The tests gfortran.dg/integer_exponentiation_5.F90 and masklr_1.F90 are miscompiled with -flto after revision 192529

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55021

--- Comment #7 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2012-10-22 14:14:19 UTC ---
> I think your bisection is wrong ...

Indeed I meant r192559 (see /opt/gcc/gcc4.8p-192559/bin/gfortran in comment#0).
Thanks for the quick fix.