Help needed with SEH exception handler (not really Win32 specific)

Mon Mar 17 11:22:00 GMT 2003

> > printf( "Normal Execution!\n");
> > 
> > /* Without this redundant check, GCC considers the following code
> > * unreachable and eliminates it! 
> > */
> > if (er.hlr_addr != 0)
> > goto rm_hlr;
> > 
> > ex_hlr:
>> There's a potential problem here. gcc doesn't know that the printf()
> above has not happened. For example, it is possible that gcc will
> generate this:
>> move #printf, r1
> move #string1, r0
> call r1
> cmp er.hlr_addr, #0
> bne rm_hlr
>> ex_hlr:
> move #string2, r0
> call r1
>> Bad -- the address of printf isn't in r1. The compiler needs to know
> that there is an abnormal edge to ex_hlr in the control flow graph.
>> I don't know the right way to tell gcc that this might happen. There
> may be a way that uses __builtin_setjmp.

As in something like the following?
----------------------------- 8< -----------------------------
 /* Set up exception handler... */
 ...
 if (__builtin_setjmp (jmpbuf) == 0)
 {
 retVal = inner_foo( x);
 printf( "Normal Execution!\n");
 }
 else
 {
ex_hlr:
 printf( "*** Abnormal Execution! ***\n");
 retVal = x*10;
 }
 ...
 /* Tear down exception handler... */
----------------------------- 8< -----------------------------
However, I'm a bit uneasy about using this function because of this
comment in gcc/builtins.c (expand_builtin_setjmp):
----------------------------- 8< -----------------------------
 NOTE: This is intended for use by GNAT and the exception handling
 scheme in the compiler and will only work in the method used by
 them. */
----------------------------- 8< -----------------------------
It's not immediately clear to me what the "proper" way is supposed
to be.
Also worth noting is the fact that this obviously will not work if 
"-fomit-frame-pointer" is specified while compiling the program.
Ranjit.