[Bug c++/33874] New: (cygwin/mingw) sjlj exception handling corrupts stack

[darkxun at paran dot com]

# On g++-sjlj.exe (GCC) 4.2.1-sjlj (mingw32 sjlj-unwind)
# g++ -v
Using built-in specs.
Target: mingw32
Configured with: ../gcc-4.2.1/configure --with-gcc --enable-libgomp
--host=mingw32 --build=mingw32 --target=mingw32 --program-suffix=-sjlj
--with-arch=i486 --with-tune=generic --disable-werror --prefix=/mingw
--with-local-prefix=/mingw --enable-threads --disable-nls
--enable-languages=c,c++,fortran,objc,obj-c++,ada --disable-win32-registry
--enable-sjlj-exceptions --enable-libstdcxx-debug
--enable-cxx-flags=-fno-function-sections -fno-data-sections
--enable-version-specific-runtime-libs --disable-bootstrap
Thread model: win32
gcc version 4.2.1-sjlj (mingw32 sjlj-unwind)
# And
# On g++ (GCC) 3.4.4 (cygming special, gdc 0.12, using dmd 0.125) // sjlj-EH
# g++ -v
Configured with: /usr/build/package/orig/test.respin/gcc-3.4.4-3/configure
--verbose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--enable-languages=c,ada,c++,d,f77,pascal,java,objc --enable-nls
--without-included-gettext --enable-version-specific-runtime-libs --without-x
--enable-libgcj --disable-java-awt --with-system-zlib --enable-interpreter
--disable-libgcj-debug --enable-threads=posix --enable-java-gc=boehm
--disable-win32-registry --enable-sjlj-exceptions --enable-hash-synchronization
--enable-libstdcxx-debug
Thread model: posix
gcc version 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
-------------------------------------------------------------

The test case below shows
that Gcc sjlj exception handling corrupts stack and can make the process crash
when the stack frame 
  contains VLA(variable length array) or alloca()'ed variables 
  and has no catch handler for the exception being handled.


And this is my solution for this bug
        ==> http://home.paran.com/darkxun/libcyn/GccBugFix.html
I'm not offending you guys. Just wanted to make a prof that it is my own work
(not plagiarized).
Sorry.


<problem.cc>-------------------------------------------------
#include <stdio.h>
static int __seq = 0;
struct Temp {
    int    _i;
    Temp() : _i(__seq++) { fprintf(stderr,"%d\n", _i);  }
    virtual ~Temp()      { fprintf(stderr,"%d\n", _i);  }
};

void problem( void(*func)() )
{
    int N=5;
    Temp temp[N];

    func();
}

<main.cc>----------------------------------------------------
void problem( void(*func)() );
void bugger() {
    throw "anything";
}

int main()
{
    try {
        problem( bugger );
    }
    catch(...) {}
}

<compilation>------------------------------------------------
#using static problem.o
    g++ -o problem.o problem.cc -c
    g++ main.cc problem.o
#or shared problem.dll
    g++ -o problem.dll problem.cc -shared
    g++ main.cc problem.dll


-- 
           Summary: (cygwin/mingw) sjlj exception handling corrupts stack
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: darkxun at paran dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33874