cygwin gcc -O2 problem

[markus_heiden]

Hi,

when I compile with the current cygwin g++ (v.3.4.4) I get 'strange' errors in the link step when I use the -O2 option for compiling. This happens since I use the stl.

Example:
g++ -mno-cygwin -w -O2 -march=i686 -I<some include dir...> -c -o xxx.o xxx.cpp
g++ -mno-cygwin -fPIC -shared -o my.dll xxx.o yyy.o....

The linker then shows multiple errors like this:
...undefined reference to `std::basic_filebuf<char, std::char_traits<char> >::_close()'


This does not happen, when I do not use the -O2 option. Then everything works fine. What am I doing wrong?

Markus

[Whistler]

I'm using MinGW and it's no problem. Have you tried using the "dllwrap" command?

[markus_heiden]

Hi Whistler,

Originally Posted by Whistler

I'm using MinGW and it's no problem. Have you tried using the "dllwrap" command?

I have never tried the dllwrap command. Whatfor is it good? I only use the dlltool.

Someone got any clues where the problem with the -O2 option is?

Markus

[Pierre-Marie Baty]

It suggests a faulty STL implementation in GCC... Try downgrading the optimization level ?

[markus_heiden]

Yes, I tried already leaving -O2 away, that fixes the problem. But I want to optimize the binary, so that is no real solution. Maybe waiting for a new gcc version is the only option...

Markus

[Whistler]

PHP Code:

k25@xg25 /cygdrive/c
$ g++ -O2 -c -o 1.o 1.cpp

k25@xg25 /cygdrive/c
$ g++ -fPIC -shared -o 1.dll 1.o 


well I just can't resemble your problem here... the above thing runs well and no error. Here's my 1.cpp:

PHP Code:

#include <iostream>
using namespace std;

__declspec(dllexport) int test1()
{
  cout << "test1" << endl;
} 


[markus_heiden]

The problem seems to come from the stl (I think). Since you use no stl in your example, there is no problem.

Strange is, that most of the stl code compiles fine with -O2, just some parts show this error.

Markus

[sfx1999]

Try using -O1 on the files that have the error.

[jeefo]

Since you use no stl in your example

And what about cout << "test1" << endl;

[@$3.1415rin]

that's std c++ library, stl would be rather std::list, vector whatever