glibc depends on order of top-level asm blocks and functions #2515
Description
| Bugzilla Link | 2143 |
| Resolution | INVALID |
| Resolved on | Apr 27, 2008 18:16 |
| Version | unspecified |
| OS | Linux |
| Attachments | initfini.c, Makefile used to build initfini.s, crtn.S, ..., generated from initfini.s built using gcc, generated from initfini.s built using gcc, initfini.s generated by gcc, crtn.S generated from initfini.s built by llvm, crti.S generated from initfini.s built by llvm, initfini.s generated by llvm |
| CC | @asl |
Extended Description
Generating crti.S, crtn.S, initfini.s is done via a call to compiler -S, and postprocessed using sed.
Unfortunately llvm's output is not what glibc's build system expects, and the result is wrong crti.S, crtn.S with a linker error about duplicate symbols.
As a comment in csu/Makefile says:
"In ELF we also install crti.o and crtn.o, special "initializer" and "finalizer" files used in the link to make the .init and .fini sections work right; both these files are built (in an arcane manner) from initfini.c"
This is the linker error:
/home/edwin/llvm/install/bin/llvm-gcc -nostdlib -nostartfiles -o /home/edwin/glibc-2.7/build-tree/i386-libc/iconv/iconvconfig -Wl,-dynamic-linker=/lib/ld-linux.so.2 -Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crt1.o /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.o /home/edwin/llvm/install/bin/llvm-gcc --print-file-name=crtbegin.o /home/edwin/glibc-2.7/build-tree/i386-libc/iconv/iconvconfig.o /home/edwin/glibc-2.7/build-tree/i386-libc/iconv/strtab.o /home/edwin/glibc-2.7/build-tree/i386-libc/iconv/xmalloc.o /home/edwin/glibc-2.7/build-tree/i386-libc/iconv/hash-string.o -Wl,-rpath-link=/home/edwin/glibc-2.7/build-tree/i386-libc:/home/edwin/glibc-2.7/build-tree/i386-libc/math:/home/edwin/glibc-2.7/build-tree/i386-libc/elf:/home/edwin/glibc-2.7/build-tree/i386-libc/dlfcn:/home/edwin/glibc-2.7/build-tree/i386-libc/nss:/home/edwin/glibc-2.7/build-tree/i386-libc/nis:/home/edwin/glibc-2.7/build-tree/i386-libc/rt:/home/edwin/glibc-2.7/build-tree/i386-libc/resolv:/home/edwin/glibc-2.7/build-tree/i386-libc/crypt:/home/edwin/glibc-2.7/build-tree/i386-libc/nptl /home/edwin/glibc-2.7/build-tree/i386-libc/libc.so.6 /home/edwin/glibc-2.7/build-tree/i386-libc/libc_nonshared.a -lgcc -Wl,--as-needed -lgcc_s -Wl,--no-as-needed /home/edwin/llvm/install/bin/llvm-gcc --print-file-name=crtend.o /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o: In function dummy': /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.S:15: multiple definition of dummy'
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.o:/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.S:36: first defined here
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o: In function _init': /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.S:41: multiple definition of _init'
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.o:/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.S:88: first defined here
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o: In function _fini': /home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.S:100: multiple definition of _fini'
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.o:/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.S:152: first defined here
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crti.o: In function _fini': (.fini+0x14): undefined reference to i_am_not_a_leaf'
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o: In function _fini': (.fini+0x27): undefined reference to i_am_not_a_leaf'
/home/edwin/glibc-2.7/build-tree/i386-libc/csu/crtn.o: In function _fini': (.fini+0x2c): undefined reference to i_am_not_a_leaf'
collect2: ld returned 1 exit status
I will attach initfini.c, and the initfini.s, crti.S, crtn.S generated by gcc and llvm.
At a first glance it looks like inline assembly comments are emitted at the wrong place (too early):
csu/initfini.s is the gcc one, ../i386-libc/csu/initfini.s is llvm's.
--- csu/initfini.s 2008-03-12 17:36:26.837217313 +0200
+++ ../i386-libc/csu/initfini.s 2008-03-12 17:12:39.480693562 +0200
@@ -1,36 +1,57 @@
- .file "initfini.c"
-#APP
+# Start of file scope inline assembly
#include "defs.h"
/@HEADER_ENDS/
/@TESTS_BEGIN/
-#NO_APP
+
+/@TESTS_END/
+
+/@_init_PROLOG_BEGINS/
+.section .init
+END_INIT
+
+/@_init_EPILOG_ENDS/
+
+/@_fini_PROLOG_BEGINS/
+.section .fini
+END_FINI
+
+/@_fini_EPILOG_ENDS/
+
+/@TRAILER_BEGINS/
+# End of file scope inline assembly
+
+
.text
- .p2align 2,,3
- .align 16
.globl dummy
.type dummy, @function
dummy:
pushl %ebp
movl %esp, %ebp
- subl $8, %esp
- pushl %ebx
- subl $4, %esp
- call .Lllvm$1.$piclabel
+.Lllvm$1.$piclabel: - popl %ebx
- addl $GLOBAL_OFFSET_TABLE + [.-.Lllvm$1.$piclabel], %ebx
movl 8(%ebp), %eax
testl %eax, %eax
- je .L4
- je .LBB1_2 # UnifiedReturnBlock
+.LBB1_1: # bb
call *%eax
-.L4:
- leave
+.LBB1_2: # UnifiedReturnBlock
- addl $4, %esp
- popl %ebx
- popl %ebp
ret
-#APP - .size dummy, .-dummy
-/@TESTS_END/
-/@_init_PROLOG_BEGINS/
.section .init
-#NO_APP
- .section .init,"ax",@progbits
- .p2align 2,,3
- .align 16
.globl _init
.type _init, @function
_init:
@@ -38,38 +59,41 @@
movl %esp, %ebp
pushl %ebx
subl $4, %esp
- call .L10
-.L10:
- call .Lllvm$2.$piclabel
+.Lllvm$2.$piclabel:
popl %ebx
- addl $GLOBAL_OFFSET_TABLE+[.-.L10], %ebx
- movl gmon_start@got(%ebx), %edx
- testl %edx, %edx
- je .L7
- addl $GLOBAL_OFFSET_TABLE + [.-.Lllvm$2.$piclabel], %ebx
- cmpl $0, gmon_start@got(%ebx)
- je .LBB2_2 # bb4
+.LBB2_1: # bb
call gmon_start@plt
-.L7:
+.LBB2_2: # bb4
#APP
ALIGN - #NO_APP
- #APP
END_INIT - #NO_APP
- #APP
/@_init_PROLOG_ENDS/
- #NO_APP
- #APP
/@_init_EPILOG_BEGINS/
- #NO_APP
- #APP
.section .init
#NO_APP
- popl %eax
- addl $4, %esp
popl %ebx
- leave
- popl %ebp
ret
-#APP
- END_INIT
- .size _init, .-_init
-/@_init_EPILOG_ENDS/
-/@_fini_PROLOG_BEGINS/
.section .fini
-#NO_APP
- .section .fini,"ax",@progbits
- .p2align 2,,3
- .align 16
.globl _fini
.type _fini, @function
_fini:
@@ -77,13 +101,17 @@
movl %esp, %ebp
pushl %ebx
subl $4, %esp
- call .L13
-.L13:
- call .Lllvm$3.$piclabel
+.Lllvm$3.$piclabel:
popl %ebx
- addl $GLOBAL_OFFSET_TABLE+[.-.L13], %ebx
- addl $GLOBAL_OFFSET_TABLE + [.-.Lllvm$3.$piclabel], %ebx
#APP
ALIGN - #NO_APP
- #APP
END_FINI - #NO_APP
- #APP
/@_fini_PROLOG_ENDS/
#NO_APP
@@ -91,18 +119,15 @@
#APP
/@_fini_EPILOG_BEGINS/
- #NO_APP
- #APP
.section .fini
#NO_APP
- popl %ecx
- addl $4, %esp
popl %ebx
- leave
- popl %ebp
ret
-#APP
- END_FINI
-/@_fini_EPILOG_ENDS/
-/@TRAILER_BEGINS/
- .size _fini, .-_fini
.weak gmon_start
- .ident "GCC: (GNU) 4.2.3 (Debian 4.2.3-2)"
- .section .note.GNU-stack,"",@progbits
- .ident "GCC: (GNU) 4.2.1 (Based on Apple Inc. build 5546) (LLVM build)"