[Mingw-users] stack alignment and SSE

[Julien P. <jul...@in...>]

Hi,

I know this issue has already been discussed, but I would like to know if there
is now a better solution than the one that I am using:
current mingw does not enforce stack alignment on 16 bit boundaries (the
functions just keep it aligned if it was aligned on entry). As my code relies
very heavily on SSE, this leads to crashes if I do not realign the stack
pointer on 16 bits boundaries. Right now I'm using this trick, which works with
gcc 3.4 as long as the optimization level is not too high :

  void aligned_foo() {
     __m128 bar;
     assert(&bar & 0xf); // die if not correctly aligned
  }

  void unaligned_foo() __attribute__((noinline)) {
    (void)__builtin_return_address(1); // to force call frame
    asm volatile ("andl $-16, %%esp" ::: "%esp");
    aligned_foo();
  }

This has to be done in each entry point of my code (which is a DLL), in each
thread proc, each event handler etc. Since gcc uses spontaneously "movaps"
instructions in some surprising places, I really have to protect every function
which may be called from a non "16-bit aligned" place.

So I would really like to find a better solution, is there a patch or something
? Will gcc 4 provide a switch for enforcing the stack alignment ?

Thanks in advance,
Julien