hi, there!
On Fri, 15 Sep 2000, John Polstra wrote:
> > there were some problems with pthreads initialization (but David will not
> > like the way I did it -- some files in contrib/gcc should be changed).
> > this happened because we initialize pthreads from static object
> > constructor (which is not the right thing anyway).
>
> It seemed like a good idea at the time. :-) What is the problem --
> is it that libc_r is initialized at the wrong time? What would you
> suggest as a better method for initializing the library? I'd hate to
> introduce a bunch of "if (!initted) { ... }" checks, since those add
> runtime overhead on every call.
`__register_frame_info' should be called from `do_ctors' in
src/lib/csu/common/crtbegin.c to load frame information from .eh_frame
sections before any constructors are executed because try/catch can be
used in constructors of static objects (`__register_frame_info'
is defined in src/contrib/gcc/frame.c, this file is linked into
libgcc[_r].a). however `__register_frame_info' uses locks and other
threading stuff (using pthreads on FreeBSD) so we must have pthreads
initialized before locks are used.
another issue with our pthreads initialization is that pthreads can be
used in static object constructors so the first `pthread_xxx' call can
happen before `_thread_init' is called from constructor of our
_thread_init_invoker (it depends on order in which constructors are placed
in .ctors section).
I see two solutions (both seem to be hacks for me):
1) we can insert if (!initted) ... in `pthread_once' (this seem to be the
first pthreads function called from __register_frame_info)
2) we can insert
#if __GTHREADS
_thread_init();
#endif
at the very beginning of `__register_frame_info'
The second approach seems to be cleaner but require changes in
src/contrib/gcc/
/fjoe
PS I have attached patches and Makefile.inc which should be placed
into src/lib/csu. Makefile.inc can be slightly out of date (I made it
somewhere around May/Jun 2000)
--- contrib/gcc/config/freebsd.h.orig Wed Jul 19 07:30:53 2000
+++ contrib/gcc/config/freebsd.h Sun Jul 23 17:59:33 2000
@@ -137,12 +137,6 @@
#undef HANDLE_SYSV_PRAGMA
#define HANDLE_SYSV_PRAGMA
-/* FreeBSD ELF using our home-grown crtbegin.o/crtend.o does not support the
- DWARF2 unwinding mechanisms. Once `make world' bootstraping problems with
- the EGCS crtstuff.c is overcome, we will switch to the non-sjlj-exceptions
- type exception machanism. */
-#define DWARF2_UNWIND_INFO 0
-
/* Do not use ``thunks'' to implement C++ vtables. This method still has
fatal bugs. Also, GCC 3.0 will have a new C++ ABI that may not even
support `thunks'. */
--- contrib/gcc/frame.c.orig Mon Jul 24 00:29:25 2000
+++ contrib/gcc/frame.c Mon Jul 24 00:33:28 2000
@@ -725,6 +725,10 @@
void
__register_frame_info (void *begin, struct object *ob)
{
+#if __GTHREADS
+ _thread_init();
+#endif
+
ob->fde_begin = begin;
ob->pc_begin = ob->pc_end = 0;
--- lib/csu/common/crtbegin.c.orig Mon Jul 10 16:15:25 2000
+++ lib/csu/common/crtbegin.c Mon Jul 24 00:36:25 2000
@@ -26,6 +26,9 @@
*/
#include <sys/param.h>
+#include "tm.h"
+#include "defaults.h"
+#include <frame.h>
#define ABI_VENDOR "FreeBSD"
#define ABI_SECTION ".note.ABI-tag"
@@ -33,13 +36,23 @@
typedef void (*fptr)(void);
+extern void __register_frame_info(void *, struct object *)
+ __attribute__((weak));
+extern void *__deregister_frame_info(void *)
+ __attribute__((weak));
+
static fptr ctor_list[1] __attribute__((section(".ctors"))) = { (fptr) -1 };
static fptr dtor_list[1] __attribute__((section(".dtors"))) = { (fptr) -1 };
+static char eh_frame_begin[] __attribute__((section(".eh_frame"))) = { };
static void
do_ctors(void)
{
fptr *fpp;
+ static struct object object;
+
+ if (__register_frame_info)
+ __register_frame_info(eh_frame_begin, &object);
for(fpp = ctor_list + 1; *fpp != 0; ++fpp)
;
@@ -54,6 +67,9 @@
for(fpp = dtor_list + 1; *fpp != 0; ++fpp)
(**fpp)();
+
+ if (__deregister_frame_info)
+ __deregister_frame_info(eh_frame_begin);
}
/*
--- lib/csu/common/crtend.c.orig Mon Jul 10 16:15:28 2000
+++ lib/csu/common/crtend.c Sun Jul 23 17:59:33 2000
@@ -26,8 +26,11 @@
*/
#include <sys/cdefs.h>
+#include <sys/types.h>
typedef void (*fptr)(void);
static fptr ctor_end[1] __attribute__((section(".ctors"))) __unused = { 0 };
static fptr dtor_end[1] __attribute__((section(".dtors"))) __unused = { 0 };
+static u_int32_t eh_frame_end[1] __attribute__((section(".eh_frame")))
+ __unused = { 0 };
TARGET_ARCH?= ${MACHINE_ARCH}
.if ${TARGET_ARCH} == "mipsel" || ${TARGET_ARCH} == "mipseb"
GCC_ARCH= mips
.else
GCC_ARCH= ${TARGET_ARCH}
.endif
GCCDIR= ${.CURDIR}/../../../contrib/gcc
GENSRCS= tm.h
SRCS+= ${GENSRCS}
CLEANFILES+= ${GENSRCS}
CFLAGS+= -I. -I${GCCDIR} -I${GCCDIR}/config\
-I${.CURDIR}/../../../gnu/usr.bin/cc/cc_tools
# KEEP THIS IN SYNC with src/gcc/lib/libgcc/Makefile !!
tm.h:
echo '#include "${GCC_ARCH}/${GCC_ARCH}.h"' > ${.TARGET}
.if ${GCC_ARCH} == "i386"
echo '#include "${GCC_ARCH}/att.h"' >> ${.TARGET}
.endif
echo '#include <freebsd.h>' >> ${.TARGET}
echo '#include "${GCC_ARCH}/freebsd.h"' >> ${.TARGET}
.if ${GCC_ARCH} == "i386"
echo '#include "${GCC_ARCH}/perform.h"' >> ${.TARGET}
.endif
echo '#include <freebsd-native.h>' >> ${.TARGET}
