gcc -flto=auto : function ‘uftrace___cyg_profile_func_exit’ redeclared as variable
vitlav opened this issue · 9 comments
vitlav commented
With -flto=auto optflag I got
LINK libmcount/libmcount.so
/tmp/.private/lav/RPM/BUILD/uftrace-0.10/libmcount/plthook.c:93:1: error: function ‘uftrace___cyg_profile_func_exit’ redeclared as variable
93 | ALIAS_DECL(__cyg_profile_func_exit);
| ^
/tmp/.private/lav/RPM/BUILD/uftrace-0.10/libmcount/mcount.c:1994:1: note: previously declared here
1994 | UFTRACE_ALIAS(__cyg_profile_func_exit);
| ^
/tmp/.private/lav/RPM/BUILD/uftrace-0.10/libmcount/plthook.c:92:1: error: function ‘uftrace___cyg_profile_func_enter’ redeclared as variable
92 | ALIAS_DECL(__cyg_profile_func_enter);
| ^
/tmp/.private/lav/RPM/BUILD/uftrace-0.10/libmcount/mcount.c:1988:1: note: previously declared here
1988 | UFTRACE_ALIAS(__cyg_profile_func_enter);
pltook.c:
/* use weak reference for non-defined (arch-dependent) symbols */
#define ALIAS_DECL(_sym) extern __weak void (*uftrace_##_sym)(void);
mcount.c:
#define UFTRACE_ALIAS(_func) void uftrace_##_func(void*, void*) __alias(_func)
namhyung commented
Thanks for the report, I'll take a look.
honggyukim commented
Hmm.. The error is also shown only with -flto and it looks tricky anyway.
Is there any special reason to use -flto=auto or -flto option when building uftrace?
vitlav commented
Hmm.. The error is also shown only with
-fltoand it looks tricky anyway.Is there any special reason to use
-flto=autoor-fltooption when building uftrace?
That redeclation looks like a hidden bug for me.
There is no special reason to use LTO exclude the reason all vendors enable it by default:
https://fedoraproject.org/wiki/LTOByDefault
https://wiki.ubuntu.com/ToolChain/LTO
https://en.opensuse.org/openSUSE:LTO
honggyukim commented
Hmm.. we will think more about it. Thanks for reporting the issue.
FantasqueX commented
Same issue here when trying to package uftrace for ArchLinux. Temporarily disable LTO to solve the problem.
amadio commented
Related bug in Gentoo Linux: https://bugs.gentoo.org/858503
namhyung commented
I'm not sure but does the below help?
diff --git a/libmcount/plthook.c b/libmcount/plthook.c
index 5b5620bd6a..aa54bbc364 100644
--- a/libmcount/plthook.c
+++ b/libmcount/plthook.c
@@ -81,13 +81,14 @@ static void resolve_pltgot(struct plthook_data *pd, int idx)
/* use weak reference for non-defined (arch-dependent) symbols */
#define ALIAS_DECL(_sym) extern __weak void (*uftrace_##_sym)(void);
+#define ALIAS_DECL2(_sym) extern __weak void (*uftrace_##_sym)(void *, void *);
ALIAS_DECL(mcount);
ALIAS_DECL(_mcount);
ALIAS_DECL(__fentry__);
ALIAS_DECL(__gnu_mcount_nc);
-ALIAS_DECL(__cyg_profile_func_enter);
-ALIAS_DECL(__cyg_profile_func_exit);
+ALIAS_DECL2(__cyg_profile_func_enter);
+ALIAS_DECL2(__cyg_profile_func_exit);
#define SKIP_SYM(func) \
{ \amadio commented
Unfortunately, no. I still get a compile error:
/tmp/portage/dev-util/uftrace-0.12/work/uftrace-0.12/libmcount/plthook.c:93:1: error: function ‘uftrace___cyg_profile_func_exit’ redeclared as variable
93 | ALIAS_DECL2(__cyg_profile_func_exit);
| ^
/tmp/portage/dev-util/uftrace-0.12/work/uftrace-0.12/libmcount/mcount.c:2004:1: note: previously declared here
2004 | UFTRACE_ALIAS(__cyg_profile_func_exit);
| ^
/tmp/portage/dev-util/uftrace-0.12/work/uftrace-0.12/libmcount/plthook.c:92:1: error: function ‘uftrace___cyg_profile_func_enter’ redeclared as variable
92 | ALIAS_DECL2(__cyg_profile_func_enter);
| ^
/tmp/portage/dev-util/uftrace-0.12/work/uftrace-0.12/libmcount/mcount.c:1998:1: note: previously declared here
1998 | UFTRACE_ALIAS(__cyg_profile_func_enter);
| ^
lto1: fatal error: errors during merging of translation units
compilation terminated.
lto-wrapper: fatal error: x86_64-pc-linux-gnu-gcc returned 1 exit status
compilation terminated.
If you want to reproduce this locally, try using
CFLAGS="-O2 -flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing"
when building.
namhyung commented
Thanks, I was able to reproduce it locally with your help. :)
This patch fixes the redeclaration error.
diff --git a/libmcount/plthook.c b/libmcount/plthook.c
index 5b5620bd6a..d9f1e8dd6a 100644
--- a/libmcount/plthook.c
+++ b/libmcount/plthook.c
@@ -80,14 +80,15 @@ static void resolve_pltgot(struct plthook_data *pd, int idx)
}
/* use weak reference for non-defined (arch-dependent) symbols */
-#define ALIAS_DECL(_sym) extern __weak void (*uftrace_##_sym)(void);
+#define ALIAS_DECL(_sym) extern __weak void uftrace_##_sym(void);
+#define ALIAS_DECL2(_sym) extern __weak void uftrace_##_sym(void *, void *);
ALIAS_DECL(mcount);
ALIAS_DECL(_mcount);
ALIAS_DECL(__fentry__);
ALIAS_DECL(__gnu_mcount_nc);
-ALIAS_DECL(__cyg_profile_func_enter);
-ALIAS_DECL(__cyg_profile_func_exit);
+ALIAS_DECL2(__cyg_profile_func_enter);
+ALIAS_DECL2(__cyg_profile_func_exit);
#define SKIP_SYM(func) \
{ \But it reveals another problem like below. :-(
$ make
LINK libmcount/libmcount.so
lto-wrapper: warning: using serial compilation of 3 LTRANS jobs
lto-wrapper: note: see the ‘-flto’ option documentation for more information
/usr/bin/ld: /tmp/ccKRh5HD.ltrans0.ltrans.o: in function `mcount_rstack_restore':
/home/namhyung/project/uftrace/libmcount/misc.c:128: undefined reference to `plthook_return'
/usr/bin/ld: /tmp/ccKRh5HD.ltrans0.ltrans.o: in function `mcount_rstack_reset':
/home/namhyung/project/uftrace/libmcount/misc.c:207: undefined reference to `plthook_return'
/usr/bin/ld: /tmp/ccKRh5HD.ltrans0.ltrans.o: in function `mcount_startup.part.0':
/home/namhyung/project/uftrace/libmcount/mcount.c:1843: undefined reference to `mcount_return'
/usr/bin/ld: /tmp/ccKRh5HD.ltrans2.ltrans.o: in function `mcount_setup_trampoline':
/home/namhyung/project/uftrace/arch/x86_64/mcount-dynamic.c:79: undefined reference to `__dentry__'
/usr/bin/ld: /home/namhyung/project/uftrace/arch/x86_64/mcount-dynamic.c:59: undefined reference to `__xray_entry'
/usr/bin/ld: /home/namhyung/project/uftrace/arch/x86_64/mcount-dynamic.c:64: undefined reference to `__xray_exit'
collect2: error: ld returned 1 exit status
make: *** [Makefile:261: /home/namhyung/project/uftrace/libmcount/libmcount.so] Error 1