[Bug libffi/52221] [libffi] r183675,r184021 needs to be fixed.

["jojelino at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52221

gee <jojelino at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #26653|0                           |1
        is obsolete|                            |

--- Comment #9 from gee <jojelino at gmail dot com> 2012-02-16 20:19:22 UTC ---
Created attachment 26686
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26686
script used for generating trampoline code.

trampoline code in attachment 26685 based on following source code.

extern int* esp asm ("%esp");
volatile int
sideeffect();
static volatile int ctx;
int __cdecl
main()
{
  int ret;
  extern int ecx asm("%ecx");
  /*
   * CFLAGS -O4
   */
#define NUM_CLOBBERED_REG 1
  /* expected layout
   /* ret   esp[4]
   * ?      esp[3]
   * clobbered
   */
  asm volatile("blk1:");
#define swap(x,y,tmp,...) {\
    asm ("movl %0,%2 # movl x,tmp\n\
    movl %1,%0 # movl y,x\n\
    movl %2,%1 # movl tmp,y":"+g"(x),"+g"(y),"+g"(tmp)::__VA_ARGS__);\
}
  swap(esp[NUM_CLOBBERED_REG+1], ecx, esp[NUM_CLOBBERED_REG], "ecx");
  /* expected layout
   * ecx    esp[4]
   * ret    esp[3]
   * clobbered
   */
  asm ("movl %0,%%eax"::"i"(&ctx):"eax");
  esp -= NUM_CLOBBERED_REG + 1;
  asm volatile ("call _sideeffect":"+a"(ret)::"memory","ecx","edx");
  ecx = esp[NUM_CLOBBERED_REG + 1];
  esp[NUM_CLOBBERED_REG + 1] = esp[NUM_CLOBBERED_REG];

  /* expected layout
   * ret    esp[4]
   * ret    esp[3]
   * clobbered
   */
  esp += NUM_CLOBBERED_REG + 1;
  asm volatile("ret");
  asm volatile("blk2:");
  return ret;
}
volatile int
sideeffect()
{
  return (volatile int) 0;
}