[Bug target/50906] New: e500 exception unwinding under "-Os" causes SIGSEGV

[Bug target/50906] New: e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

             Bug #: 50906
           Summary: e500 exception unwinding under "-Os" causes SIGSEGV
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Kyle.D.Moffett@boeing.com


Created attachment 25649
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25649
Test case, part 1

The libffi test-suite is failing on an e500v2 build of GCC 4.6.1 with a
segmentation fault in libgcc (called from "throw()" in the "unwindtest.cc"
file).

The target GCC configure options:
  --build/--host/--target=powerpc-linux-gnuspe
  --with-cpu=8548
  --enable-e500_double
  --with-long-double-128

I have extracted it to the attached minimal test-case, compiled as follows:

  $ g++ -Wall -Wextra -Werror -ggdb3 -Os -c unwindtest.cc -o unwindtest.o
  $ g++ -Wall -Wextra -Werror -ggdb3 -Os -c unwindtestfunc.cc -o
unwindtestfunc.o
  $ g++ -ggdb3 -Os -o unwindtest unwindtest.o unwindtestfunc.o

The test fails if "unwindtestfunc.cc" is built with "-Os", but not if it is
built with "-O2".  The compile options for unwindtest.cc have no effect on the
success or failure of the test.

Cheers,
Kyle Moffett

--
Curious about my work on the Debian powerpcspe port?
I'm keeping a blog here: http://pureperl.blogspot.com/

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #1 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-10-28 20:29:53 UTC ---
Created attachment 25650
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25650
Test case, part 2

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #3 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-10-28 20:32:18 UTC ---
Created attachment 25652
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25652
Assembled unwindtestfunc.cc (with -Os)

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #2 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-10-28 20:31:54 UTC ---
Created attachment 25651
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25651
Assembled unwindtestfunc.cc (with -O2)

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-11-01
                 CC|                            |amodra at gmail dot com
     Ever Confirmed|0                           |1

--- Comment #4 from Alan Modra <amodra at gmail dot com> 2011-11-01 23:44:04 UTC ---
_Z16closure_test_fn1P7ffi_cifPvPS1_S1_:
.LFB0:
    .file 1 "unwindtestfunc.cc"
    .loc 1 17 0
    .cfi_startproc
.LVL0:
    stwu 1,-128(1)
.LCFI0:
    .cfi_def_cfa_offset 128
    mflr 0
    mr 3,6
.LVL1:
    stw 0,132(1)
    addi 11,1,-16
.LCFI1:
    .cfi_def_cfa 11, 160

That last .cfi directive is wrong.  To match the instructions it should be
    .cfi_def_cfa 11, 144

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #5 from Alan Modra <amodra at gmail dot com> 2011-11-02 00:05:42 UTC ---
    bl _save64gpr_24
    .loc 1 17 0
    mr 31,4
    .cfi_offset 31, -100
    .cfi_offset 1231, -104
    .cfi_offset 30, -108
    .cfi_offset 1230, -112
    .cfi_offset 29, -116
    .cfi_offset 1229, -120
    .cfi_offset 28, -124
    .cfi_offset 1228, -128
    .cfi_offset 27, -132
    .cfi_offset 1227, -136
    .cfi_offset 26, -140
    .cfi_offset 1226, -144
    .cfi_offset 25, -148
    .cfi_offset 1225, -152
    .cfi_offset 24, -156
    .cfi_offset 1224, -160

These are all wrong too, I think.

    .loc 1 26 0
    lwz 9,0(5)
    .loc 1 17 0
    mr 11,5

Yikes!!  Using r11 for something else, but no cfi directive to say the frame is
no longer in r11.

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #6 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-02 18:24:02 UTC ---
Created attachment 25692
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25692
Archive of RTL dumps of failing testcase built with "-Os"

I spent some time looking through the RTL dump.  It looks like the stack
references first show up in 194r.split2, but I couldn't understand enough of
what I was looking at to match it up with the assembly output or figure out
where the CFI information went wrong.

I've attached a tar.gz of the RTL dumps in case that helps isolate the issue.

Cheers,
Kyle Moffett

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

Alan Modra <amodra at gmail dot com> changed:

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

--- Comment #7 from Alan Modra <amodra at gmail dot com> 2011-11-03 04:17:09 UTC ---
There are multiple problems in TARGET_SPE_ABI parts of rs6000_emit_prologue. 
Hacking on it.

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #8 from Alan Modra <amodra at gmail dot com> 2011-11-03 12:54:32 UTC ---
Created attachment 25702
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25702
Proposed mainline fix

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #9 from Alan Modra <amodra at gmail dot com> 2011-11-03 12:55:29 UTC ---
Created attachment 25703
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25703
gcc-4.6 fix

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #10 from Alan Modra <amodra at gmail dot com> 2011-11-03 12:59:10 UTC ---
Please test out these patches.  bootstrap and regression tests with -Os in
BOOT_CFLAGS on spe would be ideal.  I'll be running a powerpc-linux regression
test, but can't do that for spe.

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #11 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-03 16:48:43 UTC ---
Ok, I'm running a "bootstrap-lean" + "make check" by way of a full Debian GCC
package build with this patch added.  The first build will just do
C/C++/ObjC/ObjC++/Fortran; if that works out OK I will also do a Java build in
a little while.

I applied a 1-line patch to make the package build set "BOOT_CFLAGS := -g -O2"
as you requested, so hopefully any fallout will be obvious during the GCC build
itself.

There are 2 other patches I have applied on top of the Debian GCC 4.6.2-3
package to fix the SPE build:
  * http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=647288
  * http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=647324

The libffi one applies on top of these patches already in the Debian package:
  * http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=644338

Based on the speed of this board and the fact that I am using it for other
testing as well, I expect to have the test results in roughly 6-8 hours.

Cheers,
Kyle Moffett

--
Curious about my work on the Debian powerpcspe port?
I'm keeping a blog here: http://pureperl.blogspot.com/

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #25702|0                           |1
        is obsolete|                            |

--- Comment #12 from Alan Modra <amodra at gmail dot com> 2011-11-04 10:00:43 UTC ---
Created attachment 25711
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25711
mainline fix

Revised patch.  I'd forgotten that you can't compare hard reg rtx's, ever since

2002-06-16  Jeff Law <law@redhat.com>

    * emit-rtl.c (gen_rtx_REG): Temporarily turn off automatic
    sharing of hard registers.

Some "temporarily" that turned out to be. :)

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #25703|0                           |1
        is obsolete|                            |

--- Comment #13 from Alan Modra <amodra at gmail dot com> 2011-11-04 10:01:34 UTC ---
Created attachment 25712
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25712
gcc-4.6 fix

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #14 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-04 21:20:18 UTC ---
I'm now rebuilding the Debian GCC 4.6.2-4 (which now includes the other 2
patches I mentioned previously) with the updated 4.6 patch, I'll let you know
what the results are (including testsuite deltas between unpatched-O2,
patched-O2, and patched-Os).

I probably won't have any results for you before Monday.

Cheers,
Kyle Moffett

--
Curious about my work on the Debian powerpcspe port?
I'm keeping a blog here: http://pureperl.blogspot.com/

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #15 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-08 19:12:04 UTC ---
Sorry for the delay.  I've suddenly started experiencing odd kernel panics on
my test boards in the middle of the test-suite runs and I'm in the process of
tracking them down.  Based on where the kernel is crashing I don't think it's
caused by the GCC changes, just bad luck that I didn't notice this bug before.

>From the test suites that have completed so far, I'm not seeing any new FAILs
relative to the old GCC, but I have to wait for them all to finish in order to
be able to diff properly.

I'll let you know when I have something to report.

Cheers,
Kyle Moffett

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[dvdkhlng at gmx dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

David Kühling <dvdkhlng at gmx dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dvdkhlng at gmx dot de

--- Comment #16 from David Kühling <dvdkhlng at gmx dot de> 2011-11-11 09:51:05 UTC ---
@Kyle: wrt random kernel panics, I had them too on my P2020RDB and attributed
them to RAM errors.  Before they happen, the kernel already complains about
corrupt data in the logs and GCC randomly crashes when running a sufficiently
large parallel build.  After power-cycling the GCC crashes usually vanish, so
maybe there's a small chance that DDR RAM is slightly miscalibrated by u-boot? 
Reducing the DDR clock might help.

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #17 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-22 18:50:20 UTC ---
Ok, a new kernel based on 3.2-rc1 resolved my crashing issues entirely.  I
wasn't too worried about my DDR clocks since I have ECC memory and EDAC never
reported any errors.

Using the gcc-4.6 fix on top of 4.6.2, I get the following diffs in the
testsuite summary between 4.6.2-unpatched and 4.6.2-patched.  I'm in the
process of running a second build with BOOT_CFLAGS="-Os", but I'll be out of
the office for Thanksgiving until next Monday and probably won't be able to
check on it during that time.

These appear to be EH bugs fixed by your changes:
-FAIL: g++.dg/torture/stackalign/eh-vararg-1.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-2.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-1.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-2.C -Os execution test

These are tests that shouldn't be run on e500/SPE as they build with
"-mcpu=power5".  These tests fail with SIGILL while executing an "lfd" opcode;
I'm not sure why they passed before:
+FAIL: gcc.target/powerpc/ppc-fma-5.c execution test
+FAIL: gfortran.dg/pr47614.f  -O0 execution test
+FAIL: gfortran.dg/pr47614.f  -O1 execution test
+FAIL: gfortran.dg/pr47614.f  -O2 execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer -funroll-loops
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer -funroll-all-loops
-finline-functions execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -g execution test
+FAIL: gfortran.dg/pr47614.f  -Os execution test

There's no other delta in the testsuite summary, so I feel pretty confident
that there were no regressions introduced by this patch for e500 at least.

Thanks again for your help!

Cheers,
Kyle Moffett

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[Kyle.D.Moffett at boeing dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #18 from Kyle Moffett <Kyle.D.Moffett at boeing dot com> 2011-11-28 19:30:07 UTC ---
I am happy to report that your updated 4.6.2 patch seems to be 100% functional
on e500/SPE.

I get identical "test-summary" reports for patched-4.6.2 with and without
BOOT_CFLAGS="-g -Os", apart from the different build directory paths (EG:
/srv/build/gcc-4.6-normal versus /srv/build/gcc-4.6-Os), 

As before, the following testsuite failures are fixed relative to unpatched
4.6.2:
-FAIL: g++.dg/torture/stackalign/eh-vararg-1.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-2.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-1.C -Os execution test
-FAIL: g++.dg/torture/stackalign/eh-vararg-2.C -Os execution test

And again, as before, the following 64-bit-only tests are erroneously run on
32-bit e500 CPUs, although they were inexplicably successful during a previous
build.
+FAIL: gcc.target/powerpc/ppc-fma-5.c execution test
+FAIL: gfortran.dg/pr47614.f  -O0 execution test
+FAIL: gfortran.dg/pr47614.f  -O1 execution test
+FAIL: gfortran.dg/pr47614.f  -O2 execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer -funroll-loops
+FAIL: gfortran.dg/pr47614.f  -O3 -fomit-frame-pointer -funroll-all-loops
-finline-functions execution test
+FAIL: gfortran.dg/pr47614.f  -O3 -g execution test
+FAIL: gfortran.dg/pr47614.f  -Os execution test

Thanks again for your help!

Cheers,
Kyle Moffett

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #19 from Alan Modra <amodra at gcc dot gnu.org> 2011-12-06 03:41:49 UTC ---
Author: amodra
Date: Tue Dec  6 03:41:44 2011
New Revision: 182039

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182039
Log:
    PR target/50906
    * config/rs6000/rs6000.c (rs6000_emit_prologue <TARGET_SPE_ABI>):
    Do not mark r11 setup as frame-related.  Pass correct offset to
    rs6000_emit_savres_rtx.  Correct out-of-line rs6000_frame_related
    arguments.  Correct sp_offset.  Remove "offset" fudge from
    in-line rs6000_frame_related call.  Rename misleading variable.
    Fix comments and whitespace.  Tidy some expressions.
    (rs6000_emit_epilogue <TARGET_SPE_ABI>): Always set frame_reg_rtx
    to r11 in out-of-line case.  Correct sp_offset.  Pass correct
    offset to rs6000_emit_savres_rtx.  Rename misleading variable.
    Fix comments and whitespace.  Tidy some expressions.
    (rs6000_emit_epilogue <non-TARGET_SPE_ABI>): Add sp_offset
    adjustment when !saving_GPRs_inline.  Correct register mode
    used in address calcs.
    (rs6000_emit_epilogue <non-TARGET_SPE_ABI>): Similarly when
    !restoring_GPRs_inline.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/rs6000/rs6000.c

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

--- Comment #20 from Alan Modra <amodra at gcc dot gnu.org> 2011-12-06 03:47:40 UTC ---
Author: amodra
Date: Tue Dec  6 03:47:37 2011
New Revision: 182040

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182040
Log:
    PR target/50906
    * config/rs6000/rs6000.c (rs6000_emit_prologue <TARGET_SPE_ABI>):
    Do not mark r11 setup as frame-related.  Pass correct offset to
    rs6000_emit_savres_rtx.  Correct out-of-line rs6000_frame_related
    arguments.  Correct sp_offset.  Remove "offset" fudge from
    in-line rs6000_frame_related call.  Rename misleading variable.
    Fix comments and whitespace.  Tidy some expressions.
    (rs6000_emit_epilogue <TARGET_SPE_ABI>): Always set frame_reg_rtx
    to r11 in out-of-line case.  Correct sp_offset.  Pass correct
    offset to rs6000_emit_savres_rtx.  Rename misleading variable.
    Fix comments and whitespace.  Tidy some expressions.
    (rs6000_emit_epilogue <non-TARGET_SPE_ABI>): Add sp_offset
    adjustment when !saving_GPRs_inline.  Correct register mode
    used in address calcs.
    (rs6000_emit_epilogue <non-TARGET_SPE_ABI>): Similarly when
    !restoring_GPRs_inline.


Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/config/rs6000/rs6000.c

[Bug target/50906] e500 exception unwinding under "-Os" causes SIGSEGV

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50906

Alan Modra <amodra at gmail dot com> changed:

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

--- Comment #21 from Alan Modra <amodra at gmail dot com> 2011-12-06 03:48:32 UTC ---
patch applied 4.7 and 4.6