Created attachment 2873 [details]
bugpoint program output

After making two changes to the kernel to get it to build with clang,

1. In kernel's Makefile, scripts/Makefile.lib and scripts/Makefile.host, perform the following substitution:

     s/-Wp,-MD,/-MD -MF /

2. In include/linux/kernel.h, force macro _THIS_IP_ to return zero, rather than using __label__.  (Older kernels may not require this step)

clang successfully begins the build process, making it to one of the first actual kernel files, init/main.c, where it crashes (shown below).

I ran bugpoint, and have attached the output.


  clang -MD -MF init/.main.o.d  -nostdinc -isystem include -Iinclude  -I/spare/repo/linux-2.6/arch/x86/include -include include/linux/autoconf.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -O2 -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 -pg -Wdeclaration-after-statement -Wno-pointer-sign -fwrapv -fno-dwarf2-cfi-asm   -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(main)"  -D"KBUILD_MODNAME=KBUILD_STR(main)"  -c -o init/main.o init/main.c
clang: warning: the clang compiler does not yet support '-pg'
warning: unknown warning option: -Wframe-larger-than=2048
init/main.c:570:9: warning: format string is not a string literal (potentially insecure) [-Wformat-nonliteral]
        printk(linux_banner);
               ^~~~~~~~~~~~
init/main.c:628:9: warning: format string is not a string literal (potentially insecure) [-Wformat-nonliteral]
                panic(panic_later, panic_param);
                      ^~~~~~~~~~~
clang-cc: /garz/repo/llvm/include/llvm/Target/TargetRegisterInfo.h:301: static bool llvm::TargetRegisterInfo::isPhysicalRegister(unsigned int): Assertion `Reg && "this is not a register!"' failed.
0   clang-cc        0x000000000103677f
1   clang-cc        0x0000000001036b69
2   libpthread.so.0 0x00000034c020f0f0
3   libc.so.6       0x00000034bf632f05 gsignal + 53
4   libc.so.6       0x00000034bf634a73 abort + 387
5   libc.so.6       0x00000034bf62bef9 __assert_fail + 233
6   clang-cc        0x0000000000a45532
7   clang-cc        0x0000000000a4721e
8   clang-cc        0x0000000000d1a410
9   clang-cc        0x0000000000a4619b
10  clang-cc        0x0000000000a46b0e
11  clang-cc        0x0000000000fd2b49
12  clang-cc        0x0000000000fd352e
13  clang-cc        0x0000000000fd373b
14  clang-cc        0x00000000004386e5
15  clang-cc        0x0000000000438b17
16  clang-cc        0x00000000005a431d
17  clang-cc        0x0000000000474c56
18  clang-cc        0x000000000047c0e1 main + 1953
19  libc.so.6       0x00000034bf61e576 __libc_start_main + 230
20  clang-cc        0x00000000004287e9
Stack dump:
0.	Program arguments: /usr/local/bin/../libexec/clang-cc -triple x86_64-unknown-linux-gnu -S -disable-free -main-file-name main.c --relocation-model static --disable-fp-elim --unwind-tables=1 --disable-red-zone --mattr -mmx,-sse,-sse2,-3dnow --fmath-errno=1 -nostdinc -dependency-file init/.main.o.d -MT init/main.o -sys-header-deps -isystem include -include include/linux/autoconf.h -D__KERNEL__ -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DKBUILD_STR(s)=#s -DKBUILD_BASENAME=KBUILD_STR(main) -DKBUILD_MODNAME=KBUILD_STR(main) -Iinclude -I/spare/repo/linux-2.6/arch/x86/include -O2 -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -Werror-implicit-function-declaration -Wno-sign-compare -Wframe-larger-than=2048 -Wdeclaration-after-statement -Wno-pointer-sign -fno-common -fdiagnostics-show-option -o /tmp/cc-ZU4Nhi.s -x c init/main.c 
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'X86 AT&T-Style Assembly Printer' on function '@start_kernel'
make[1]: *** [init/main.o] Error 250
make: *** [init] Error 2