[Bug fortran/40386] New: wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[Bug fortran/40386] New: wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

I'm observing a wrong code generation bug with the 189.lucas benchmark in SPEC
CPU2000.

When the Fortran benchmark is being compiled with -O1
-fno-ira-share-spill-slots, the benchmark outputs the following:

iteration=         2  000000000000000E
iteration=         3  00000000000000C2
iteration=         4  0000000000009302
iteration=         5  00000000546B4C02
iteration=         6  1BD696D9F03D3002
M75460003 Roundoff warning on iteration       7 maxerr =  0.499999970088
 FATAL ERROR...Halting execution.

When compiled with -O1, this is (part of) the output (which is correct, as
specified by the CPU2000 framework):

iteration=         2  000000000000000E
iteration=         3  00000000000000C2
iteration=         4  0000000000009302
iteration=         5  00000000546B4C02
iteration=         6  1BD696D9F03D3002
iteration=         7  8CC88407A9F4C002
iteration=         8  55599F9D37D30002
<snip>
iteration=       122  E9639F5835FD3C2C
  exponent     residue
  75460003  DDD9C8B13BCB64AE


I'm sorry I'm unable to provide a self-contained testcase for this, but I know
little about Fortran. I hope someone else can jump in and provide a testcase
for me.


-- 
           Summary: wrong code generation for SPEC CPU2000's 189.lucas with
                    -O1 -fno-ira-share-spill-slots
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kenneth dot hoste at elis dot ugent dot be
 GCC build triplet: linux, x86-64
  GCC host triplet: linux, x86-64
GCC target triplet: linux, x86-64


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2009-06-09 12:24 -------
Richard, can you try to reproduce this? I don't have SPEC and anyhow it sounds
like a middle-end problem.


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
          Component|fortran                     |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

------- Comment #2 from kenneth dot hoste at elis dot ugent dot be  2009-06-09 13:35 -------
I did some more experiments, and have some more details to share.

It seems the problem with lucas only occurs with the SVN head of the 4.4 branch
I'm working on (r148268), and not with the 4.4.0 release.

However, a similar problem is occuring with the 172.mgrid benchmark, and this
_is_ occuring both with the 4.4.0 release and with revision 148268 of the 4.4
branch.

Again, -O1 -fno-ira-share-spill-slots leads to a binary not producing correct
output (but there's not noticeable crash of the benchmark this time). Using -O1
yields no problems though.

The SPEC framework reports the below as a diff between the expected and
observed output for mgrid, and considers the difference to be serious enough to
report the run to be invalid.

0019:      0.103090E-02
          -0.907513E-03
                      ^
0020:      0.103090E-02
          -0.907513E-03
                      ^
0021:      0.184495E-02
           0.261074E-02
                      ^
0022:      0.184495E-02
           0.261074E-02
                      ^
0023:      0.366257E-03
          -0.677032E-04
                      ^
0024:      0.366257E-03
          -0.677032E-04
                      ^
0025:      0.436098E-03
           0.179609E-03
                      ^
0026:      0.436098E-03
           0.179609E-03
                      ^
0027:      0.442029E-03
           0.212079E-03
                      ^
0028:      0.442029E-03
           0.212079E-03
                      ^
0029:      0.442962E-03
           0.217171E-03
                      ^


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

------- Comment #3 from kenneth dot hoste at elis dot ugent dot be  2009-06-09 14:12 -------
Same problem with 187.facerec, 173.applu and 301.apsi: runs correctly at -O1,
wrong code at -O1 -fno-ira-share-spill-slots.

All these benchmarks are written Fortran (both F77 and F90), so it seems this
might be Fortran related.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-06-09 14:22 -------
Are you running in 32bit mode?  Vlad, what does this IRA option do?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

------- Comment #5 from kenneth dot hoste at elis dot ugent dot be  2009-06-09 14:30 -------
(In reply to comment #4)
> Are you running in 32bit mode? 

No, I'm not. Using either -m32 or -m64 makes no difference for lucas, and if
I'm either m32 or m64, then I still obtain a 64-bit binary (when not using
-fno-ira-share-spill-slots), so definitely 64-bit mode.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

------- Comment #6 from kenneth dot hoste at elis dot ugent dot be  2009-06-09 14:51 -------
Some more related details which might help shed light on the cause behind this.

The 178.galgel benchmark (again, Fortran), is also being miscompiled, but now
using

-ffixed-form -fno-ira-share-spill-slots -fno-tree-loop-im 

in combination with -O3 or -Os. Note that -O1 and -O2 are working fine with
these options specified. 
(-ffixed-form is always needed to compile galgel, so this one is probably of
minor importance here)

On top of this, additionally specifying
 -fno-tree-dominator-opts 
resolves the issue at -O3 (corrext code is being emitted), but this is not the
case at -Os, where the miscompile still occurs.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[zsojka at seznam dot cz]

------- Comment #7 from zsojka at seznam dot cz  2010-04-12 13:47 -------
Running check on gcc/g++ shows further miscompilations with
-fno-ira-share-spill-slots (as of r158131, x86_64-linux):

gcc.c-torture/execute/20021120-1.c FAILs with:
-O2 -fno-ira-share-spill-slots
or
-O1 -foptimize-register-move -fno-ira-share-spill-slots

gcc.c-torture/execute/pr28982a.c FAILs with:
-O1 -fno-ira-share-spill-slots

gcc.dg/graphite/interchange-8.c FAILs with:
-O2 -fpeel-loops -fno-ira-share-spill-slots

gcc.c-torture/execute/regstack-1.c FAILs with:
-Os -fschedule-insns -fno-ira-share-spill-slots
-fno-sched-critical-path-heuristic

There are further FAILs with more complicated compiler flags needed to
reproduce, and it's also possible I haven't checked all
-fno-ira-share-spill-slots miscompilations


-- 

zsojka at seznam dot cz changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zsojka at seznam dot cz


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[zsojka at seznam dot cz]

------- Comment #8 from zsojka at seznam dot cz  2010-04-12 18:55 -------
Created an attachment (id=20370)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20370&action=view)
execution tests that FAIL with -fno-ira-share-spill-slots

r158225, x86_64-linux, languages=c,c++,lto,fortran

$ make check RUNTESTFLAGS="--target_board=unix/-fno-ira-share-spill-slots"
$ cat gcc/testsuite/*/*.log | grep '^FAIL:' | grep 'exec' &> pr40386.txt

Without duplicates, this is the list of files that at least once fail the
execution test:
c-c++-common/torture/complex-sign-mixed-div.c
gcc.c-torture/execute/builtins/pr22237.c
gcc.c-torture/execute/pr23135.c
gcc.c-torture/execute/pr28982a.c
gcc.c-torture/execute/pr28982b.c
gcc.c-torture/execute/20020508-2.c
gcc.c-torture/execute/20020508-3.c
gcc.c-torture/execute/20021120-1.c
gcc.dg/guality/inline-params.c
gcc.dg/vect/vect-strided-u8-i8-gap4.c
gcc.target/x86_64/abi/test_passing_floats.c
gfortran.dg/alloc_comp_assign_2.f90
gfortran.dg/alloc_comp_assign_3.f90
gfortran.dg/eoshift_large_1.f90
gfortran.dg/func_derived_1.f90
gfortran.dg/reshape_rank7.f90
gfortran.fortran-torture/execute/intrinsic_cshift.f90
g++.old-deja/g++.eh/ia64-1.C

There were no ICEs caused by this flag.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[vmakarov at redhat dot com]

------- Comment #9 from vmakarov at redhat dot com  2010-09-08 17:44 -------
The problem is in that pseudos (r121 in our case) spilled by IRA are
not added to live_throughout of reload chain.  As the result,
pseudo_forbidden_regs are not set up for such pseudos and they can get
a hard registers (42 in our case) even if they live through insns
(insn 153 in our case) using reload (0th in our case) with this
register when another pseudo is spilled and reload ask IRA to assign
the correspodning hard register to other pseudo.

Here are some parts of IRA dump:

Spilling for insn 153.
Using reg 2 for reload 1
Using reg 42 for reload 0
...
Spilling for insn 238.
Using reg 2 for reload 0
      Spill 117(a35), cost=5000
      Spilled regs 117
        Try assign 121(a6), cost=5000: reassign to 42


The fix is pretty simple.  I'll send it soon.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[vmakarov at gcc dot gnu dot org]

------- Comment #10 from vmakarov at gcc dot gnu dot org  2010-09-09 13:43 -------
Subject: Bug 40386

Author: vmakarov
Date: Thu Sep  9 13:42:51 2010
New Revision: 164095

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164095
Log:
2010-09-08  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * ira.c (pseudo_for_reload_consideration_p): Don't use
        flag_ira_share_spill_slots.

2010-09-08  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * gcc.c-torture/execute/{pr40386.c,pr40386.x}: New testcase.


Added:
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr40386.c
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr40386.x
Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/ira.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[vmakarov at gcc dot gnu dot org]

------- Comment #11 from vmakarov at gcc dot gnu dot org  2010-09-09 13:47 -------
Subject: Bug 40386

Author: vmakarov
Date: Thu Sep  9 13:47:14 2010
New Revision: 164097

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164097
Log:
2010-09-08  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * ira.c (pseudo_for_reload_consideration_p): Don't use
        flag_ira_share_spill_slots.

2010-09-08  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * gcc.c-torture/execute/{pr40386.c,pr40386.x}: New testcase.


Added:
    branches/gcc-4_5-branch/gcc/testsuite/gcc.c-torture/execute/pr40386.c
    branches/gcc-4_5-branch/gcc/testsuite/gcc.c-torture/execute/pr40386.x
Modified:
    branches/gcc-4_5-branch/gcc/ChangeLog
    branches/gcc-4_5-branch/gcc/ira.c
    branches/gcc-4_5-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[vmakarov at gcc dot gnu dot org]

------- Comment #12 from vmakarov at gcc dot gnu dot org  2010-09-09 13:51 -------
Subject: Bug 40386

Author: vmakarov
Date: Thu Sep  9 13:51:25 2010
New Revision: 164100

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164100
Log:
2010-09-09  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * ira.c (pseudo_for_reload_consideration_p): Don't use
        flag_ira_share_spill_slots.

2010-09-09  Vladimir Makarov  <vmakarov@redhat.com>

        PR middle-end/40386
        * gcc.c-torture/execute/{pr40386.c,pr40386.x}: New testcase.



Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr40386.c
    trunk/gcc/testsuite/gcc.c-torture/execute/pr40386.x
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ira.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386

[Bug middle-end/40386] wrong code generation for several SPEC CPU2000 benchmarks (lucas, mgrid, face, applu, apsi) with -O1 -fno-ira-share-spill-slots

[zsojka at seznam dot cz]

------- Comment #13 from zsojka at seznam dot cz  2010-09-15 00:05 -------
It seems all the testsuite failures caused by -fno-ira-share-spill-slots and
gone now, good!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386