[Bug middle-end/32533] New: [4.2] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[Bug middle-end/32533] New: [4.2] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[jv244 at cam dot ac dot uk]

derived from CP2K and discussed in PR 29975, the following is miscompiled with
the current 4.2 branch :

vondele@pcihopt3:/scratch/vondele/clean/cp2k/src> cat test.f90
      SUBROUTINE T(nsubcell,sab_max,subcells)
       INTEGER, PARAMETER :: dp=KIND(0.0D0)
       REAL(dp) :: sab_max(3), subcells,nsubcell(3)

        nsubcell(:) = MIN(MAX(1,NINT(0.5_dp*subcells/sab_max(:))),20)
        write(6,*) nsubcell
      END SUBROUTINE

       INTEGER, PARAMETER :: dp=KIND(0.0D0)
       REAL(dp) :: sab_max(3), subcells,nsubcell(3)
       subcells=2.00000000000000
       sab_max=0.590060749244805_dp
       write(6,*) NINT(0.5_dp*subcells/sab_max(1))
       CALL T(nsubcell,sab_max,subcells)
     END


vondele@pcihopt3:/scratch/vondele/clean/cp2k/src> gfortran -v -O3 -ffast-math
-ftree-vectorize -march=native test.f90
Driving: gfortran -v -O3 -ffast-math -ftree-vectorize -march=native test.f90
-lgfortranbegin -lgfortran -lm -shared-libgcc
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /data03/vondele/gcc_4_2_branch/gcc/configure
--prefix=/data03/vondele/gcc_4_2_branch/build --with-gmp=/data03/vondele/
--with-mpfr=/data03/vondele/ --enable-languages=c,fortran
Thread model: posix
gcc version 4.2.1 20070627 (prerelease)

/data03/vondele/gcc_4_2_branch/build/libexec/gcc/x86_64-unknown-linux-gnu/4.2.1/f951
test.f90 -march=k8 -mtune=k8 -quiet -dumpbase test.f90 -auxbase test -O3
-version -ffast-math -ftree-vectorize -I
/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/finclude
-o /tmp/ccTYHMGd.s
GNU F95 version 4.2.1 20070627 (prerelease) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.2.1 20070627 (prerelease).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
 as -V -Qy -o /tmp/ccs8OyYj.o /tmp/ccTYHMGd.s
GNU assembler version 2.16.91.0.5 (x86_64-suse-linux) using BFD version
2.16.91.0.5 20051219 (SUSE Linux)

/data03/vondele/gcc_4_2_branch/build/libexec/gcc/x86_64-unknown-linux-gnu/4.2.1/collect2
--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/../lib64/crt1.o /usr/lib/../lib64/crti.o
/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/crtbegin.o
-L/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1
-L/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/../../../../lib64
-L/lib/../lib64 -L/usr/lib/../lib64
-L/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/../../..
/tmp/ccs8OyYj.o -lgfortranbegin -lgfortran -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/crtfastmath.o
/data03/vondele/gcc_4_2_branch/build/lib/gcc/x86_64-unknown-linux-gnu/4.2.1/crtend.o
/usr/lib/../lib64/crtn.o
vondele@pcihopt3:/scratch/vondele/clean/cp2k/src> ./a.out
           2
   20.0000000000000        20.0000000000000        20.0000000000000
vondele@pcihopt3:/scratch/vondele/clean/cp2k/src> gfortran -O0 test.f90
vondele@pcihopt3:/scratch/vondele/clean/cp2k/src> ./a.out
           2
   2.00000000000000        2.00000000000000        2.00000000000000

the result is incorrectly 20.0 instead of 2.0 with optimization


-- 
           Summary: [4.2] miscompilation at -O3 -ffast-math -ftree-vectorize
                    -march=native
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jv244 at cam dot ac dot uk


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #1 from ubizjak at gmail dot com  2007-06-28 08:13 -------
Looks like problems in tree ifcvt pass. Before ifcvt, we have:

  M.2_16 = (int4) D.1257_15;
  if (M.2_16 > 1) goto <L7>; else goto <L9>;

<L7>:;
  if (M.2_16 > 20) goto <L10>; else goto <L9>;

  # M.2_64 = PHI <M.2_16(6), 1(5)>;
<L9>:;
  pretmp.118_78 = (real8) M.2_64;

  # prephitmp.119_79 = PHI <2.0e+1(6), pretmp.118_78(7)>;
  # M.2_4 = PHI <20(6), M.2_64(7)>;
<L10>:;

But ifcvt creates:

  D.1446_84 = M.2_16 > 1;
  D.1447_85 = M.2_16 > 20;
  _ifc_.127_86 = D.1446_84 && D.1447_85;
  D.1449_87 = M.2_16 > 1;
  D.1450_88 = M.2_16 <= 20;
  _ifc_.128_89 = D.1449_87 && D.1450_88;
  M.2_64 = M.2_16 > 1 ? M.2_16 : 1;
  pretmp.118_78 = (real8) M.2_64;
  prephitmp.119_79 = M.2_16 > 1 ? 2.0e+1 : pretmp.118_78;
  M.2_4 = M.2_16 > 1 ? 20 : M.2_64;

Note the last two lines, where we compare "M.2_16 > 1" instead of "M.2_16 >
20".

This bug could be hidden in 4.3.0 as we use MIN_EXPR and MAX_EXPR here.


-- 

ubizjak at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|middle-end                  |tree-optimization
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-06-28 08:13:14
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #2 from ubizjak at gmail dot com  2007-06-28 08:14 -------
(In reply to comment #1)

> This bug could be hidden in 4.3.0 as we use MIN_EXPR and MAX_EXPR here.

To clear the typo - we use MIN_EXPR and MAX_EXPR in 4.3.0.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
      Known to fail|4.0.2                       |4.2.0
   Target Milestone|---                         |4.2.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[jv244 at cam dot ac dot uk]

------- Comment #3 from jv244 at cam dot ac dot uk  2007-06-29 07:13 -------
I'm wondering if it is still required to turn fortran testcases in the
equivalent C testcase in order to mark this kind of bugs as P1. This does seem
a bit of a waste of time... and just think about the engineers using Fortran to
design nuclear power plants... ;-)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[jv244 at cam dot ac dot uk]

------- Comment #4 from jv244 at cam dot ac dot uk  2007-06-29 07:50 -------
also fails with 4.1.3

gfortran  -march=k8 -mtune=k8 -ftree-vectorize -ffast-math -O3 test.f90
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /data03/vondele/gcc_4_1_branch/gcc/configure
--prefix=/data03/vondele/gcc_4_1_branch/build --with-gmp=/data03/vondele/
--with-mpfr=/data03/vondele/ --enable-languages=c,fortran
Thread model: posix
gcc version 4.1.3 20070629 (prerelease)


-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|4.2.0                       |4.2.0 4.1.3
            Summary|[4.2 regression]            |[4.1/4.2 regression]
                   |miscompilation at -O3 -     |miscompilation at -O3 -
                   |ffast-math -ftree-vectorize |ffast-math -ftree-vectorize
                   |-march=native               |-march=native


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[jv244 at cam dot ac dot uk]

------- Comment #5 from jv244 at cam dot ac dot uk  2007-06-29 08:06 -------
works correctly with 4.0.4, so it is a regression:
gfortran -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /data03/vondele/gcc_4_0_branch/gcc/configure
--prefix=/data03/vondele/gcc_4_0_branch/build --with-gmp=/data03/vondele/
--with-mpfr=/data03/vondele/ --enable-languages=c,fortran
Thread model: posix
gcc version 4.0.4


-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.3.0                       |4.3.0 4.0.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #6 from ubizjak at gmail dot com  2007-06-30 15:39 -------
Hm, in the dump (gcc-4.1.3), preceeding ifcvt, we have:

<L4>:;
  D.985_28 = iftmp.5_4 + D.964_27;
  M.2_29 = (int4) D.985_28;
  if (M.2_29 > 1) goto <L7>; else goto <L9>;

<L7>:;
  if (M.2_29 > 20) goto <L10>; else goto <L9>;

  # M.2_61 = PHI <M.2_29(4), 1(3)>;                  <<<<<<---- here
<L9>:;
  pretmp.98_1 = (real8) M.2_61;

  # prephitmp.99_39 = PHI <2.0e+1(4), pretmp.98_1(5)>;
  # M.2_3 = PHI <20(4), M.2_61(5)>;
<L10>:;

Isn't marked statement unreachable?

Comparing _.ssa dumps between 4.1 (wrong result) and 4.3 (correct result), we
have:

(4.1)
--cut here--

<L5>:;
  M.1_36 = D.966_29;
  goto <bb 8> (<L7>);

<L6>:;
  M.1_35 = 1;

  # M.1_2 = PHI <M.1_36(6), M.1_35(7)>;              <<<< here (4.1)
<L7>:;
  if (M.1_2 > 20) goto <L8>; else goto <L9>;

<L8>:;
  M.2_34 = 20;
  goto <bb 11> (<L10>);
--cut here--

versus

(4.3)
--cut here--
<bb 8>:
  M.1_17 = D.1365_16;
  goto <bb 10>;

<bb 9>:
  M.1_18 = 1;

<bb 10>:
  # M.1_1 = PHI <M.1_17(8), M.1_18(9)>               <<<< here (4.3)
  if (20 < M.1_1)
    goto <bb 11>;
  else
    goto <bb 12>;

<bb 11>:
  M.2_19 = 20;
  goto <bb 13>;
---cut here---


-- 

ubizjak at gmail dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[dorit at gcc dot gnu dot org]

------- Comment #7 from dorit at gcc dot gnu dot org  2007-07-01 08:51 -------
PR31966 is also wrong code which seems to be a result of the tree-level
if-conversion (nothing gets vectorized these, and if tree-if-conversion is
disabled everything works ok).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #8 from ubizjak at gmail dot com  2007-07-01 09:40 -------
(In reply to comment #6)
> Hm, in the dump (gcc-4.1.3), preceeding ifcvt, we have:

> Isn't marked statement unreachable?

The problem is in ifcvt pass, as confirmed by a c testcase in PR31966. This
problem is also present in 4.3 branch, but (as explained in Comment #1), not
triggered by the fortran testcase in this PR.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #9 from ubizjak at gmail dot com  2007-07-02 09:40 -------
Created an attachment (id=13822)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13822&action=view)
The patch to fix tree-if-conv.c

Joost, could you please test this 4.2 patch with CP2K? It fixes the testcase
you provided (and PR31966, FWIW).

BTW: Could you create the testcase that would be suitable for gfortran
testsuite?


-- 

ubizjak at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |ubizjak at gmail dot com
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[jv244 at cam dot ac dot uk]

------- Comment #10 from jv244 at cam dot ac dot uk  2007-07-02 10:21 -------

> Joost, could you please test this 4.2 patch with CP2K? It fixes the testcase
> you provided (and PR31966, FWIW).
> 

the testcase passes, the CP2K tests that were previously failing now seem to
pass as well .... many thanks for fixing this issue

> BTW: Could you create the testcase that would be suitable for gfortran
> testsuite?

this aborts before and passes after the patch:

      SUBROUTINE T(nsubcell,sab_max,subcells)
       INTEGER, PARAMETER :: dp=KIND(0.0D0)
       REAL(dp) :: sab_max(3), subcells,nsubcell(3)
       nsubcell(:) = MIN(MAX(1,NINT(0.5_dp*subcells/sab_max(:))),20)
      END SUBROUTINE

      INTEGER, PARAMETER :: dp=KIND(0.0D0)
      REAL(dp) :: sab_max(3), subcells,nsubcell(3)
      subcells=2.0_dp
      sab_max=0.590060749244805_dp
      CALL T(nsubcell,sab_max,subcells)
      IF (ANY(nsubcell.NE.2.0_dp)) CALL ABORT()
     END


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[uros at gcc dot gnu dot org]

------- Comment #11 from uros at gcc dot gnu dot org  2007-07-02 14:26 -------
Subject: Bug 32533

Author: uros
Date: Mon Jul  2 14:26:11 2007
New Revision: 126206

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=126206
Log:
        PR tree-optimization/31966
        PR tree-optimization/32533
        * tree-if-conv.c (add_to_dst_predicate_list): Use "edge", not
        "basic_block" description as its third argument.  Update function
        calls to get destination bb from "edge" argument.  Save "cond" into
        aux field of the edge.  Update prototype for changed arguments.
        (find_phi_replacement_condition): Operate on incoming edges, not
        on predecessor blocks.  If there is a condition saved in the
        incoming edge aux field, AND it with incoming bb predicate.
        Return source bb of the first edge.
        (clean_predicate_lists): Clean aux field of outgoing node edges.
        (tree_if_conversion): Do not initialize cond variable. Move
        variable declaration into the loop.
        (replace_phi_with_cond_gimple_modify_stmt): Remove unneded
        initializations of new_stmt, arg0 and arg1 variables.

testsuite/ChangeLog:

        PR tree-optimization/31966
        PR tree-optimization/32533
        * gcc.dg/tree-ssa/pr31966.c: New runtime test.
        * gfortran.dg/pr32533.f90: Ditto.


Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr31966.c
    trunk/gcc/testsuite/gfortran.dg/pr32533.f90
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-if-conv.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[mmitchel at gcc dot gnu dot org]

------- Comment #12 from mmitchel at gcc dot gnu dot org  2007-07-04 03:31 -------
Uros, is it feasible to backport this to 4.2?


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[uros at gcc dot gnu dot org]

------- Comment #13 from uros at gcc dot gnu dot org  2007-07-04 05:41 -------
Subject: Bug 32533

Author: uros
Date: Wed Jul  4 05:40:58 2007
New Revision: 126301

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=126301
Log:
        PR tree-optimization/31966
        PR tree-optimization/32533
        * tree-if-conv.c (add_to_dst_predicate_list): Use "edge", not
        "basic_block" description as its third argument.  Update function
        calls to get destination bb from "edge" argument.  Save "cond" into
        aux field of the edge.  Update prototype for changed arguments.
        (if_convertible_loop_p): Clear aux field of incoming edges if bb
        contains phi node.
        (find_phi_replacement_condition): Operate on incoming edges, not
        on predecessor blocks.  If there is a condition saved in the
        incoming edge aux field, AND it with incoming bb predicate.
        Return source bb of the first edge.
        (clean_predicate_lists): Clean aux field of outgoing node edges.
        (tree_if_conversion): Do not initialize cond variable. Move
        variable declaration into the loop.
        (replace_phi_with_cond_gimple_modify_stmt): Remove unneded
        initializations of new_stmt, arg0 and arg1 variables.

testsuite/ChangeLog:

        PR tree-optimization/31966
        PR tree-optimization/32533
        * gcc.dg/tree-ssa/pr31966.c: New runtime test.
        * gfortran.dg/pr32533.f90: Ditto.


Added:
    branches/gcc-4_2-branch/gcc/testsuite/gcc.dg/tree-ssa/pr31966.c
    branches/gcc-4_2-branch/gcc/testsuite/gfortran.dg/pr32533.f90
Modified:
    branches/gcc-4_2-branch/gcc/ChangeLog
    branches/gcc-4_2-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_2-branch/gcc/tree-if-conv.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[uros at gcc dot gnu dot org]

------- Comment #14 from uros at gcc dot gnu dot org  2007-07-04 05:49 -------
Subject: Bug 32533

Author: uros
Date: Wed Jul  4 05:49:31 2007
New Revision: 126302

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=126302
Log:
        PR tree-optimization/31966
        PR tree-optimization/32533
        * tree-if-conv.c (add_to_dst_predicate_list): Use "edge", not
        "basic_block" description as its third argument.  Update function
        calls to get destination bb from "edge" argument.  Save "cond" into
        aux field of the edge.  Update prototype for changed arguments.
        (if_convertible_loop_p): Clear aux field of incoming edges if bb
        contains phi node.
        (find_phi_replacement_condition): Operate on incoming edges, not
        on predecessor blocks.  If there is a condition saved in the
        incoming edge aux field, AND it with incoming bb predicate.
        Return source bb of the first edge.
        (clean_predicate_lists): Clean aux field of outgoing node edges.
        (tree_if_conversion): Do not initialize cond variable. Move
        variable declaration into the loop.
        (replace_phi_with_cond_gimple_modify_stmt): Remove unneded
        initializations of new_stmt, arg0 and arg1 variables.

testsuite/ChangeLog:

        PR tree-optimization/31966
        PR tree-optimization/32533
        * gcc.dg/tree-ssa/pr31966.c: New runtime test.
        * gfortran.dg/pr32533.f90: Ditto.


Added:
    branches/gcc-4_1-branch/gcc/testsuite/gcc.dg/tree-ssa/pr31966.c
    branches/gcc-4_1-branch/gcc/testsuite/gfortran.dg/pr32533.f90
Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_1-branch/gcc/tree-if-conv.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533

[Bug tree-optimization/32533] [4.1/4.2 regression] miscompilation at -O3 -ffast-math -ftree-vectorize -march=native

[ubizjak at gmail dot com]

------- Comment #15 from ubizjak at gmail dot com  2007-07-04 05:56 -------
(In reply to comment #12)
> Uros, is it feasible to backport this to 4.2?

Sure, the patch was just waiting a couple of days on mainline for possible
problems.  This bug is now fixed on mainline and branches.


-- 

ubizjak at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|ubizjak at gmail dot com    |
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32533