[Bug target/56484] New: ICE in assign_by_spills, at lra-assigns.c:1268

[Bug target/56484] New: ICE in assign_by_spills, at lra-assigns.c:1268

[mgretton at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

             Bug #: 56484
           Summary: ICE in assign_by_spills, at lra-assigns.c:1268
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mgretton@gcc.gnu.org


Created attachment 29552
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29552
Test case

The attached test case ICEs on trunk (svn revision: 196329) as follows:

$ x86_64-unknown-linux-gnu-gcc -O2 besttry.c
besttry.c: In function ‘output_spdif’:
besttry.c:26:1: internal compiler error: in assign_by_spills, at
lra-assigns.c:1268
 }
 ^
0x7f1cf8 assign_by_spills
    /work/sources/gcc-fsf/master/gcc/lra-assigns.c:1268
0x7f29b3 lra_assign()
    /work/sources/gcc-fsf/master/gcc/lra-assigns.c:1425
0x7eebe1 lra(_IO_FILE*)
    /work/sources/gcc-fsf/master/gcc/lra.c:2307
0x7b6e18 do_reload
    /work/sources/gcc-fsf/master/gcc/ira.c:4619
0x7b6e18 rest_of_handle_reload
    /work/sources/gcc-fsf/master/gcc/ira.c:4731
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

Believe this is a target issue as the original test case does not trigger the
failure for arm-none-linux-gnueabihf

[Bug target/56484] ICE in assign_by_spills, at lra-assigns.c:1268

[doko at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

Matthias Klose <doko at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |doko at gcc dot gnu.org

--- Comment #1 from Matthias Klose <doko at gcc dot gnu.org> 2013-02-28 15:22:58 UTC ---
I can't reproduce this with r196236

[Bug target/56484] ICE in assign_by_spills, at lra-assigns.c:1268

[mgretton at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

mgretton at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-none-linux-gnu
               Host|                            |x86_64-none-linux-gnu

--- Comment #2 from mgretton at gcc dot gnu.org 2013-02-28 16:18:30 UTC ---
Forgot to add gcc -v output:
Using built-in specs.
COLLECT_GCC=/work/builds/gcc-fsf-master/tools/bin/x86_64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/work/builds/gcc-fsf-master/tools/libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /work/sources/gcc-fsf/master/configure
--target=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu
--build=x86_64-unknown-linux-gnu --prefix=/work/builds/gcc-fsf-master/tools
--enable-languages=c,c++,fortran
--with-ppl-include=/usr/include/x86_64-linux-gnu
Thread model: posix
gcc version 4.8.0 20130228 (experimental) (GCC)

[Bug target/56484] ICE in assign_by_spills, at lra-assigns.c:1268

[venkataramanan.kumar at amd dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

Venkataramanan <venkataramanan.kumar at amd dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |venkataramanan.kumar at amd
                   |                            |dot com

--- Comment #3 from Venkataramanan <venkataramanan.kumar at amd dot com> 2013-03-01 07:04:28 UTC ---
(In reply to comment #1)
> I can't reproduce this with r196236

I tried with some old revisions I had on a SLES 11 SP1 machine.

I am getting this issue with r193549 at lra-assigns.c.
reload.c spill failure when I use 190150 (does not have LRA). This seems to be
a long known issue in trunk. 

I am triaging further

[Bug target/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-03-01
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |uros at gcc dot gnu.org
   Target Milestone|---                         |4.8.0
            Summary|ICE in assign_by_spills, at |[4.8 Regression] ICE in
                   |lra-assigns.c:1268          |assign_by_spills, at
                   |                            |lra-assigns.c:1268
     Ever Confirmed|0                           |1

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-01 08:30:31 UTC ---
Started with http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188526
but it was merely latent before that, so it isn't LRA bug, because it fails
with reload equally.
I think the problem is in combine, where we have:
ax = call ...
flags = r59 != 0
r60 = flags >= 0 ? ax : r59
r65 = buf
r68 = 768
rep stosd [r65 .. r65 + r68 - 4] = 0
r59 = r60

and the combiner combines the r60 = flags >= 0 ? ax : r59 instruction with
r59 = r60 into r59 = flags >= 0 ? ax : r59 instruction in the last spot, thus
extending the lifetime of the ax and flags hard registers across various other
instructions.

[Bug target/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[venkataramanan.kumar at amd dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

--- Comment #5 from Venkataramanan <venkataramanan.kumar at amd dot com> 2013-03-01 08:42:42 UTC ---
-fno-tree-coalesce-vars for workarround

[Bug target/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

--- Comment #6 from Uros Bizjak <ubizjak at gmail dot com> 2013-03-01 18:06:28 UTC ---
(In reply to comment #4)

> and the combiner combines the r60 = flags >= 0 ? ax : r59 instruction with
> r59 = r60 into r59 = flags >= 0 ? ax : r59 instruction in the last spot, thus
> extending the lifetime of the ax and flags hard registers across various other
> instructions.

But AX is member of likely spilled class, so combine should take some more care
with this insn. Should we just prevent propagations of all insns that mention
likely spilled hard regs?

[Bug target/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 11:06:26 UTC ---
Actually, looking more at this, I'd say combiner is innocent here, the problem
is earlier , during ce1 pass, which transforms:
   16: ax:SI=call [`output_play'] argc:0
      REG_DEAD di:DI
      REG_DEAD si:SI
   17: r60:SI=ax:SI
      REG_DEAD ax:SI
   18: flags:CCGOC=cmp(r59:SI,0)
   19: pc={(flags:CCGOC>=0)?L21:pc}
      REG_DEAD flags:CCGOC
      REG_BR_PROB 0x1c84
   20: NOTE_INSN_BASIC_BLOCK 4
    6: r60:SI=r59:SI
      REG_DEAD r59:SI
   21: L21:
   22: NOTE_INSN_BASIC_BLOCK 5
into:
   16: ax:SI=call [`output_play'] argc:0
      REG_DEAD di:DI
      REG_DEAD si:SI
   17: r60:SI=ax:SI
      REG_DEAD ax:SI
   18: flags:CCGOC=cmp(r59:SI,0)
   53: flags:CCGOC=cmp(r59:SI,0)
   54: r60:SI={(flags:CCGOC>=0)?ax:SI:r59:SI}
   22: NOTE_INSN_BASIC_BLOCK 4

i.e. does what combiner tries to avoid with hard registers.  I don't understand
why it can't use r60:SI instead of ax:SI.

[Bug rtl-optimization/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 11:48:49 UTC ---
Created attachment 29583
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29583
gcc48-pr56484.patch

Untested fix.

[Bug rtl-optimization/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 22:25:50 UTC ---
Author: jakub
Date: Tue Mar  5 22:25:43 2013
New Revision: 196478

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196478
Log:
    PR rtl-optimization/56484
    * ifcvt.c (noce_process_if_block): If else_bb is NULL, avoid extending
    lifetimes of hard registers on small register class machines.

Added:
    trunk/gcc/testsuite/gcc.c-torture/compile/pr56484.c
Modified:
    trunk/gcc/ifcvt.c

[Bug rtl-optimization/56484] [4.8 Regression] ICE in assign_by_spills, at lra-assigns.c:1268

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 22:34:19 UTC ---
Fixed.