On Tue, Oct 2, 2012 at 12:58 AM, Ian Lance Taylor <i...@google.com> wrote:
>> Without -fasynchronous-unwind-tables, FDE is not generated for
>> backtrace_full and backtrace_simple wrappers. Without FDE, unwinding
>> terminates at these functions.
>
> I'm not opposed to -fasynchronous-unwind-tables, but now that you
> bring it up I'm fairly certain that it would suffice to use
> -funwind-tables. I've been testing mainly on x86_64, and I forgot
> that on x86_64 -funwind-tables is the default. Sorry about that. And
> -fasynchronous-unwind-tables is the default also, so I could be wrong
> that -funwind-tables is all that is needed.
Yes, you are correct. -funwind-tables works as well.
>> Attached patch fixes this problem by adding
>> -fasynchronous-unwind-tables, and this way forcing FDEs for all
>> functions. With this change, btest passes OK, failing log and
>> runtime/pprof from libgo testsuite also pass OK.
>
> This is basically fine but libbacktrace may be compiled by the host
> compiler and that may not be GCC, so please add a configure test to
> see if the compiler accepts the -fasynchronous-unwind-tables option.
I have simplified the check for -funwind-tables to just look if the
library is compiled with gcc. This option is supported by gcc-2.96
(and probably earlier versions too).
2012-10-02 Uros Bizjak <ubiz...@gmail.com>
PR other/54761
* configure.ac (CFLAGS): Add -funwind-tables when compiling with GCC.
* configure: Regenerate.
The patch is re-tested on x86_64-linux-gnu and alphaev68-linux-gnu.
OK for mainline?
Uros.
Index: configure
===================================================================
--- configure (revision 191953)
+++ configure (working copy)
@@ -4872,8 +4872,12 @@
+if test "x$GCC" = "xyes"; then
+ CFLAGS="$CFLAGS -funwind-tables"
+fi
+
if test -n "$ac_tool_prefix"; then
# Extract the first word of "${ac_tool_prefix}ranlib", so it can be a
program name with args.
set dummy ${ac_tool_prefix}ranlib; ac_word=$2
@@ -11080,7 +11084,7 @@
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11083 "configure"
+#line 11087 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -11186,7 +11190,7 @@
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11189 "configure"
+#line 11193 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
Index: configure.ac
===================================================================
--- configure.ac (revision 191953)
+++ configure.ac (working copy)
@@ -66,6 +66,10 @@
AC_PROG_CC
m4_rename_force([backtrace_PRECIOUS],[_AC_ARG_VAR_PRECIOUS])
+if test "x$GCC" = "xyes"; then
+ CFLAGS="$CFLAGS -funwind-tables"
+fi
+
AC_SUBST(CFLAGS)
AC_PROG_RANLIB
