1.1 --- a/acinclude.m4	Thu Dec 11 23:28:50 2008 +0000
     1.2 +++ b/acinclude.m4	Tue Jan 06 01:58:08 2009 +0000
     1.3 @@ -18,3 +18,37 @@
     1.4     $2 ])
     1.5  ])
     1.6  
     1.7 +# AC_CHECK_FRAME_ADDRESS([if-ok],[if-notok])
     1.8 +# Test if the compiler will let us modify the return address on the stack
     1.9 +# via __builtin_frame_address()
    1.10 +# -----------------------
    1.11 +AC_DEFUN([AC_CHECK_FRAME_ADDRESS], [
    1.12 +AC_MSG_CHECKING([if we have a working __builtin_frame_address()]);
    1.13 +AC_RUN_IFELSE([
    1.14 +  AC_LANG_SOURCE([[
    1.15 +void * __attribute__((noinline)) first_arg( void *x, void *y ) { return x; }
    1.16 +int __attribute__((noinline)) foo( int arg, void *exc )
    1.17 +{
    1.18 +    if( arg < 2 ) {
    1.19 +        *(((void **)__builtin_frame_address(0))+1) = exc;
    1.20 +    }
    1.21 +    return 0;
    1.22 +}
    1.23 +
    1.24 +int main(int argc, char *argv[])
    1.25 +{
    1.26 +   goto *first_arg(&&start, &&except);
    1.27 +   
    1.28 +start:
    1.29 +   return foo( argc, &&except ) + 1;
    1.30 +
    1.31 +except:
    1.32 +   return 0;
    1.33 +}]])], [ 
    1.34 +   AC_MSG_RESULT([yes])
    1.35 +   $1 ], [ 
    1.36 +   AC_MSG_RESULT([no])
    1.37 +   $2 ])
    1.38 +])
    1.39 +
    1.40 +