gcc-4.9 miscompiles linux kernel zlib for armv3

[Arnd Bergmann]

I did some more kernel build tests with random configurations, using the latest gcc-4.9 snapshot (20140413)

$ arm-linux-gnueabihf-gcc-4.9.0 --version
arm-linux-gnueabihf-gcc-4.9.0 (GCC) 4.9.0 20140413 (prerelease)

$ arm-linux-gnueabihf-gcc-4.9.0 -O -march=armv3 /tmp/inffast.i
/tmp/inffast.i: In function 'inflate_fast':
/tmp/inffast.i:385:1: internal compiler error: Segmentation fault
 }
 ^
0x997a5f crash_signal
        ../../gcc/toplev.c:337
0xc46dbb arm_reload_in_hi(rtx_def**)
        ../../gcc/config/arm/arm.c:14944
0xcb5b24 gen_reload_inhi(rtx_def*, rtx_def*, rtx_def*)
        ../../gcc/config/arm/arm.md:7049
0x8924c3 insn_gen_fn::operator()(rtx_def*, rtx_def*, rtx_def*) const
        ../../gcc/recog.h:285
0x8924c3 check_and_process_move
        ../../gcc/lra-constraints.c:1061
0x8924c3 curr_insn_transform
        ../../gcc/lra-constraints.c:3283
0x893134 lra_constraints(bool)
        ../../gcc/lra-constraints.c:4216
0x883c2c lra(_IO_FILE*)
        ../../gcc/lra.c:2353
0x845276 do_reload
        ../../gcc/ira.c:5457
0x845276 rest_of_handle_reload
        ../../gcc/ira.c:5598
0x845276 execute
        ../../gcc/ira.c:5627

The source code comes from the Linux kernel, but is fact a copy of the popular zlib library. I have taken all unrelated code out of the preprocessed source file, but have not attempted to reduce the inflate_fast funcion any further. The same problem happens with today's gcc-4.10.0 snapshot (20140413).

[Arnd Bergmann (arnd-arndb)]

Should this get mirrored into the main gcc bug tracker?

[Kugan Vivekanandarajah (kugan-vivekanandarajah)]

It fails only for armv3 and below and works for armv4 and above. Looks likes another LRA issue and works when -mno-lra is used. I will create a bug report upstream.

[Kugan Vivekanandarajah (kugan-vivekanandarajah)]

reload_inhi pattern has

witn -mno-lra operands[0], operands[1] and operands[2] are
(reg:HI 1 r1)
(mem/c:HI (reg/f:SI 13 sp) [0 %sfp+-8 S2 A64])
(reg:DI 0 r0)

with lra, operands[0], operands[1] and operands[2] are
(reg:SI 144)
(reg/v:HI 117 [ g ])
(reg:DI 145)

operand[1] for reload_inhi is arm_reload_memory_operand and looks like LRA is doing something wrong.

Stack trace:

0x95de1f crash_signal
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/toplev.c:337
0xc0d096 arm_reload_in_hi(rtx_def**)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/config/arm/arm.c:14945
0xc7be24 gen_reload_inhi(rtx_def*, rtx_def*, rtx_def*)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/config/arm/arm.md:7049
0x8588e3 insn_gen_fn::operator()(rtx_def*, rtx_def*, rtx_def*) const
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/recog.h:285
0x8588e3 check_and_process_move
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:1061
0x8588e3 curr_insn_transform
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:3268
0x859554 lra_constraints(bool)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:4201
0x84a02c lra(_IO_FILE*)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra.c:2353
0x80b676 do_reload
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/ira.c:5457
0x80b676 rest_of_handle_reload
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/ira.c:5598
0x80b676 execute
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/ira.c:5627
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.

[Kugan (kugan)]

Created attachment 33392
testcase

rm-none-linux-gnueabi-gcc -O -march=armv3 inffast.i
inffast.i: In function ‘inflate_fast’:
inffast.i:385:1: internal compiler error: Segmentation fault
 }
 ^
0x9b878f crash_signal
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/toplev.c:337
0xc90cf6 arm_reload_in_hi(rtx_def**)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/config/arm/arm.c:15279
0xd025cc gen_reload_inhi(rtx_def*, rtx_def*, rtx_def*)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/config/arm/arm.md:6346
0x89ca2b insn_gen_fn::operator()(rtx_def*, rtx_def*, rtx_def*) const
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/recog.h:309
0x89ca2b check_and_process_move
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:1163
0x89ca2b curr_insn_transform
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:3270
0x89d5ac lra_constraints(bool)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra-constraints.c:4200
0x88a59f lra(_IO_FILE*)
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/lra.c:2189
0x848da6 do_reload
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/ira.c:5306
0x848da6 execute
 /home/kugan/work/sources/gcc-fsf/trunk/gcc/ira.c:5465
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.

arm-none-linux-gnueabi-gcc -v
Using built-in specs.
COLLECT_GCC=/home/kugan/work/builds/gcc-fsf-trunk/tools/bin/arm-none-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/home/kugan/work/builds/gcc-fsf-trunk/tools/libexec/gcc/arm-none-linux-gnueabi/5.0.0/lto-wrapper
Target: arm-none-linux-gnueabi
Configured with: /home/kugan/work/sources/gcc-fsf/trunk/configure --target=arm-none-linux-gnueabi --prefix=/home/kugan/work/builds/gcc-fsf-trunk/tools --with-sysroot=/home/kugan/work/builds/gcc-fsf-trunk/sysroot-arm-none-linux-gnueabi --disable-libssp --disable-libgomp --disable-libmudflap --disable-libatomic --disable-libquadmath --without-libquadmath --enable-languages=c --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=softfp --with-thumb
Thread model: posix
gcc version 5.0.0 20140820 (experimental) (GCC)

[Kugan (kugan)]

Imported from LP https://bugs.launchpad.net/gcc-linaro/+bug/1307197

[Kugan Vivekanandarajah (kugan-vivekanandarajah)]

Created a bug report at https://bugs.linaro.org/show_bug.cgi?id=410

[Rguenth (rguenth)]

Not exactly "miscompile"