[RFA] Pb stepping inside DLL function

[Joel Brobecker <brobecker@gnat.com>]

Hello,

We have the following little C program (a.c):

        #include <stdio.h>
        
        extern _stdcall int sub ();
        
        main ()
        {
          int a = 0;
          
          a = sub ();
          printf ("%d\n", a);
        }

``sub()'' is a function provided by a DLL. It has all the necessary
debug information. The following transcript shows that GDB is currently
unable to step into sub():

        (gdb) start
        Breakpoint 1 at 0x4012d2: file a.c, line 7.
        Starting program: /[...]/a.exe 
        main () at a.c:7
        7         int a = 0;
        (gdb) step
        9         a = sub ();
        (gdb) p a
        $1 = 0
        (gdb) step
        10        printf ("%d\n", a);
        (gdb) print a
        $2 = 5

During the step, GDB lands inside sub@0, which is the trampoline
for sub(), but doesn't realize it. The fix is to teach GDB how to
recognize them, and hand to find where they will eventually take us.
For that, I found a function that was actually dead but did exactly
what I needed, so I reused it.

2004-06-23  Joel Brobecker  <brobecker@gnat.com>

        * i386-cygwin-tdep.c (i386-cygwin-tdep.c): New function.
        (i386_cygwin_in_solib_call_trampoline): New function.
        (i386_cygwin_init_abi): Initialize the in_solib_call_trampoline
        and skip_trampoline_code gdbarch methods.

Tested on x86-windows (XP), no regression.
OK to apply?

Thanks,
-- 
Joel