A patch to constify gcc.c (Really, summarizing remaining warnings)

[Kaveh R. Ghazi]

 > From: Zack Weinberg <zack@rabi.columbia.edu>
 > 
 > On Thu, 11 Mar 1999 11:08:45 -0500 (EST), "Kaveh R. Ghazi" wrote:
 > >	I attempted to figure this out myself and I poked around one
 > >of the places where the warning occurs.  One triggering site is in
 > >cse.c:simplify_relational_operation, where it calls setjmp().  The
 > >particular code in question does this:
 > >
 > > >   else if (GET_CODE (op0) == CONST_DOUBLE && GET_CODE (op1) == CONST_DOUBLE
 > > >            && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT)
 > > >     {
 > > >       REAL_VALUE_TYPE d0, d1;
 > > >       jmp_buf handler;
 > > >  
 > > >       if (setjmp (handler))
 > > >         return 0;
 > > >  
 > > >       set_float_handler (handler);
 > > >       REAL_VALUE_FROM_CONST_DOUBLE (d0, op0);
 > > >       REAL_VALUE_FROM_CONST_DOUBLE (d1, op1);
 > > >       equal = REAL_VALUES_EQUAL (d0, d1);
 > > >       op0lt = op0ltu = REAL_VALUES_LESS (d0, d1);
 > > >       op1lt = op1ltu = REAL_VALUES_LESS (d1, d0);
 > > >       set_float_handler (NULL_PTR);
 > > >     }
 > 
 > I bet something like this will have the same effect as rth's suggestion:
 > 
 >     {
 >       jmp_buf handler;
 >  
 >       if (setjmp (handler))
 >         return 0;
 >  
 >       set_float_handler (handler);
 >       {
 >         REAL_VALUE_TYPE d0, d1;
 > 
 >         REAL_VALUE_FROM_CONST_DOUBLE (d0, op0);
 >         REAL_VALUE_FROM_CONST_DOUBLE (d1, op1);
 >         equal = REAL_VALUES_EQUAL (d0, d1);
 >         op0lt = op0ltu = REAL_VALUES_LESS (d0, d1);
 >         op1lt = op1ltu = REAL_VALUES_LESS (d1, d0);
 >       }
 >       set_float_handler (NULL_PTR);
 >     }
 > 
 > d0 and d1 are out of scope of the longjmp target, so it should be
 > clear to gcc that we don't care about the values if we jump.
 > zw


	That doesn't fix the warnings.  In this case, gcc is warning about
arguments of the enclosing function, not the local variables `d0' and `d1'.
See below:

 > cse.c: In function `simplify_relational_operation':
 > cse.c:4607: warning: argument `code' might be clobbered by `longjmp' or `vfork'
 > cse.c:4609: warning: argument `op0' might be clobbered by `longjmp' or `vfork'
 > cse.c:4609: warning: argument `op1' might be clobbered by `longjmp' or `vfork'

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Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions