[Bug target/44129] Building linux kernel with gcc-4.5.0 and CONFIG_CC_OPTIMIZE_FOR_SIZE segfaults

["bdubbs at linuxfromscratch dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #9 from bdubbs at linuxfromscratch dot org  2010-05-16 06:38 -------
I have traced the problem file for this bug to the kernel file

arch/x86/kernel/tsc.c

I have two source trees for the 2.6.33.4 kernel, one compiled with gcc-4.4.1
which works and gcc version 4.5.1 20100514 (prerelease) which fails.  I have
attached the config file that generates the error.

I traced the problem to the above file, but don't know enough about the kernel
and gcc internals to either parse it down much further or fix the problem. 
When I copy arch/x86/kernel/tsc.o from the 4.4.1 build to the 4.5.1 kernel tree
and rebuild, the system (relatively generic Dell x86_64) boots properly.

The file build command is:

gcc -Wp,-MD,arch/x86/kernel/.tsc.o.d  -nostdinc -isystem
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.5.1/include
-I/sources/linux-2.6.33.4-gcc45/arch/x86/include -Iinclude  -include
include/generated/autoconf.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes
-Wno-trigraphs -fno-strict-aliasing -fno-common
-Werror-implicit-function-declaration -Wno-format-security
-fno-delete-null-pointer-checks -Os -m64 -march=core2 -mno-red-zone
-mcmodel=kernel -funit-at-a-time -maccumulate-outgoing-args -DCONFIG_AS_CFI=1
-DCONFIG_AS_CFI_SIGNAL_FRAME=1 -pipe -Wno-sign-compare
-fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
-Wframe-larger-than=2048 -fno-stack-protector -fno-omit-frame-pointer
-fno-optimize-sibling-calls -Wdeclaration-after-statement -Wno-pointer-sign
-fno-strict-overflow -fno-dwarf2-cfi-asm -fconserve-stack -fno-stack-protector 
 -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(tsc)" 
-D"KBUILD_MODNAME=KBUILD_STR(tsc)"  -c -o arch/x86/kernel/tsc.o
arch/x86/kernel/tsc.c

When I tried removing the -Os option, it did not fix the problem.

I'm guessing the problem is around lines 724-761 because of the ifdef
CONFIG_X86_64 and the use of rdtsc_barrier() in the panic info above.

I'm really at the limits of what I know how to do here.  I think I
rebuilt/rebooted a hundred times to narrow things down so far.  Let me know if
I can do anything else.

Many Bothans died to bring us this information.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44129