http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56747
Bug #: 56747
Summary: throw segfaults on 64bit Cygwin if -O2
(-freorder-blocks) is used with g++ 4.8.0
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: fra...@computer.org
The test program below segfaults during __cxa_throw if -O2 is used. The problem
is possibly related to generation of unwinding-information in conjunction with
-freorder-blocks optimization.
Testcase:
$ uname -srvmo
CYGWIN_NT-6.1 1.7.18(0.263/5/3) 2013-03-26 14:56 x86_64 Cygwin
$ g++ --version
g++ (GCC) 4.8.0
$ cat throw.cc
#include <string>
static int main_worker(int argc)
{
std::string s[32];
if (argc < 2)
throw 42;
return argc;
}
int main(int argc, char **argv)
{
try {
return main_worker(argc);
}
catch (int i) {
return i;
}
}
$ g++ -O1 -o throw throw.cc
$ ./throw; echo $?
42
$ g++ -O2 -o throw throw.cc
$ ./throw; echo $?
Segmentation fault
139
$ g++ -O2 -fno-reorder-blocks -o throw throw.cc
$ ./throw; echo $?
42
$ g++ -O1 -freorder-blocks -g -o throw throw.cc
$ ./throw; echo $?
Segmentation fault
139
$ gdb throw
...
(gdb) r
Starting program: /tmp/throw/throw
[New Thread 4164.0xe58]
[New Thread 4164.0x7e8]
gdb: unknown target exception 0x20474343 at 0x7fefd7c9e5d
Program received signal ?, Unknown signal.
0x000007fefd7c9e5d in RaiseException () from
/cygdrive/c/Windows/system32/KERNELBASE.dll
