[Bug target/52575] New: avr*: error: unable to find a register to spill in class 'POINTER_REGS

[Bug target/52575] New: avr*: error: unable to find a register to spill in class 'POINTER_REGS

[ralf_corsepius at rtems dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52575

             Bug #: 52575
           Summary: avr*: error: unable to find a register to spill in
                    class 'POINTER_REGS
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ralf_corsepius@rtems.org
                CC: eric.weddington@atmel.com, gjl@gcc.gnu.org,
                    joel.sherrill@oarcorp.com
            Target: avr-*


Created attachment 26883
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26883
*.i of the file triggering the error

Bootstrapping gcc-4.7.0-RC-20120203 ICEs for avr-rtems*:

/builddir/build/BUILD/rtems-4.11-avr-rtems4.11-gcc-4.7.0/build/./gcc/xgcc
-B/builddir/build/BUILD/rtems-4.11-avr-rtems4.11-gcc-4.7.0/build/./gcc/
-nostdinc
-B/builddir/build/BUILD/rtems-4.11-avr--4.7.0/build/avr-rtems4.11/avr25/newlib/
-isystem
/builddir/build/BUILD/rtems-4.11-avr-rtems4.11-gcc-4.7.0/build/avr-rtems4.11/avr25/newlib/targ-include
-isystem
/builddir/build/BUILD/rtems-4.11-avr-rtems4.11-gcc-4.7.0/gcc-4.7.0-RC-20120302/newlib/libc/include
-B/opt/rtems-4.11/avr-rtems4.11/bin/ -B/opt/rtems-4.11/avr-rtems4.11/lib/
-isystem /opt/rtems-4.11/avr-rtems4.11/include -isystem
/opt/rtems-4.11/avr-rtems4.11/sys-include  -mmcu=avr25
-DPACKAGE_NAME=\"newlib\" -DPACKAGE_TARNAME=\"newlib\"
-DPACKAGE_VERSION=\"1.20.0\" -DPACKAGE_STRING=\"newlib\ 1.20.0\"
-DPACKAGE_BUGREPORT=\"\" -DPACKAGE_URL=\"\" -I.
-I../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search -Os
-DPREFER_SIZE_OVER_SPEED -mcall-prologues -D_COMPILING_NEWLIB -DMALLOC_PROVIDED
-DEXIT_PROVIDED -DSIGNAL_PROVIDED -DREENTRANT_SYSCALLS_PROVIDED
-DHAVE_NANOSLEEP -DHAVE_BLKSIZE -DHAVE_FCNTL -DHAVE_ASSERT_FUNC -D_NO_GETLOGIN
-D_NO_GETPWENT -D_NO_GETUT -D_NO_GETPASS -D_NO_SIGSET -D_NO_WORDEXP -D_NO_POPEN
-fno-builtin      -g -O2 -c -o lib_a-hash.o `test -f 'hash.c' || echo
'../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/'`hash.c
-save-temps
../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/hash.c: In function
'__expand_table':
../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/hash.c:898:1: error:
unable to find a register to spill in class 'POINTER_REGS'
../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/hash.c:898:1: error:
this is the insn:
(insn 172 96 173 10 (set (reg:QI 18 r18)
        (mem/c:QI (plus:HI (reg/f:HI 28 r28)
                (const_int 5 [0x5])) [16 S1 A8]))
../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/hash.c:886 18
{movqi_insn}
     (nil))
../../../../../../gcc-4.7.0-RC-20120302/newlib/libc/search/hash.c:898: confused
by earlier errors, bailing out

Configuration:
CC='gcc -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector --param=ssp-buffer-size=4  -m64 -mtune=generic'
../gcc-4.7.0-RC-20120302/configure --prefix=/opt/rtems-4.11
--bindir=/opt/rtems-4.11/bin --exec_prefix=/opt/rtems-4.11
--includedir=/opt/rtems-4.11/include --libdir=/opt/rtems-4.11/lib
--libexecdir=/opt/rtems-4.11/libexec --mandir=/opt/rtems-4.11/share/man
--infodir=/opt/rtems-4.11/share/info --datadir=/opt/rtems-4.11/share
--build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu
--target=avr-rtems4.11  --disable-libstdcxx-pch --with-gnu-as --with-gnu-ld
--verbose --with-newlib --with-system-zlib --disable-nls
--without-included-gettext --disable-win32-registry
--enable-version-specific-runtime-libs --enable-threads --disable-lto
--disable-plugin --enable-newlib-io-c99-formats --enable-newlib-iconv
--enable-languages=c

[Bug target/52575] avr*: error: unable to find a register to spill in class 'POINTER_REGS

[ralf_corsepius at rtems dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52575

--- Comment #1 from Ralf Corsepius <ralf_corsepius at rtems dot org> 2012-03-13 08:11:56 UTC ---
FWIW: As things currently appear, this breakdown is not restricted to the
-mmcu=avr25 multilib-variant, but affects all RTEMS multilibs.

[Bug target/52575] avr*: error: unable to find a register to spill in class 'POINTER_REGS

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52575

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE

--- Comment #2 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-03-13 09:44:04 UTC ---
There are already spill fails reported for AVR, it's a known problem.

At this point it cannot be said if this PR is really the same as PR50925, but
it's not unlikely.

Thus, marking as duplicate resp. yet another testcase for a potential fix of
PR50925.

*** This bug has been marked as a duplicate of bug 50925 ***

[Bug target/52575] avr*: error: unable to find a register to spill in class 'POINTER_REGS

[ralf_corsepius at rtems dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52575

--- Comment #3 from Ralf Corsepius <ralf_corsepius at rtems dot org> 2012-03-13 14:08:21 UTC ---
(In reply to comment #2)
> There are already spill fails reported for AVR, it's a known problem.
> 
> At this point it cannot be said if this PR is really the same as PR50925, but
> it's not unlikely.

I am confused: 

PR50925 says "fails to build 4.6.2", however avr-rtems-gcc4.6.2 and 4.6.3 are
known to build, c.f. 
(4.6.2-based rpms) ftp://ftp.rtems.org/pub/rtems/linux/obsolete/4.11/fedora/16/
and
(4.6.3-based rpms) ftp://ftp.rtems.org/pub/rtems/linux/4.11/fedora/16

... but 4.7.0 does not BUILD at all!
=> Regression

[Bug target/52575] avr*: error: unable to find a register to spill in class 'POINTER_REGS

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52575

--- Comment #4 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-03-15 12:14:56 UTC ---
(In reply to comment #3)
> (In reply to comment #2)
> > There are already spill fails reported for AVR, it's a known problem.
> > 
> > At this point it cannot be said if this PR is really the same as PR50925,
> > but it's not unlikely.
> 
> I am confused: 
> 
> PR50925 says "fails to build 4.6.2", however avr-rtems-gcc4.6.2 and 4.6.3 are
> known to build,

These spill fails might come or go with slight variations in surrounding code,
compiler source (i.e. version) or change of compiler options. The absence of a
spill fail does not mean that it is not present in the compiler, it just means
it does not show with that specific test case and set of options.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50925#c19
test case breaks 4.5, 4.6, 4.7 and 4.8 for example.

PR42204 indicates that the problem occurs with framepointer needed/framepointer
not needed transitions and changing back and forth. Such transitions depend on
the surrounding code and compiler optimizations, of course.

PR52148 is a bit different: The root cause is the same. But a code cleanup made
the test case pass. Therefore it's not marked as a duplicate, even though it's
very likely that its root cause is also the same as in PR50925. However, the
code cleanup along with PR52148 does not fix the root cause; it's just a
cleanup that's nice in itself.