Re: Help with new builtin

["Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>]

 > From: Brad Lucier <lucier@math.purdue.edu> 
 > 
 > I would like to patch my copy of gcc to add a builtin that can be
 > exploited by CPar, a parallel version of C developed by Marc Feeley
 > and his students at the University of Montreal.  CPar can be compiled
 > without this builtin, but supporting it leads to much smaller
 > task-switching times.
 > 
 > The builtin was originally patched into gcc-2.7.2.3; after looking at
 > the source and the info files, I realize that although it looks easy
 > to provide a new patch for the current development compiler, I have no
 > clue how to do it.  Rather than try to mimic other code that I don't
 > know the purpose of, I'm asking if some kind soul can show me the few
 > lines of code that will meet how things are done in the current
 > compiler.
 > 
 > Brad Lucier


I've spent some time working on builtins recently.  The code has moved
around a lot since 2.7.x, but its actually pretty close in form.  I
think you can easily port it over with a couple of pointers to where
the new code lives.  If you have more questions after these hints,
feel free to ask specifics.

 > The old patches follow:
 > 
 > diff -c gcc-2.7.2.3.before/c-decl.c gcc-2.7.2.3.after/c-decl.c
 > *** gcc-2.7.2.3.before/c-decl.c Fri Oct 27 05:44:43 1995
 > --- gcc-2.7.2.3.after/c-decl.c  Sat Feb 19 17:06:11 2000
 > ***************
 > *** 3097,3102 ****
 > --- 3097,3111 ----
 >                                                     sizetype,
 >                                                     endlink)),
 >                     BUILT_IN_ALLOCA, "alloca");
 > + 
 > +   builtin_function ("_cparMoveSP",
 > +                     build_function_type (ptr_type_node,
 > +                                          tree_cons (NULL_TREE,
 > +                                                     sizetype,
 > +                                                     endlink)),
 > +                     BUILT_IN_CPAR_MOVESP, NULL_PTR);

This stuff has moved to c-common.c:c_common_nodes_and_builtins().
There's one extra parameter to builtin_function, just pass it
BUILT_IN_NORMAL and insert it as the second to last arg, and it should
work.





 > diff -c gcc-2.7.2.3.before/expr.c gcc-2.7.2.3.after/expr.c
 > *** gcc-2.7.2.3.before/expr.c   Sat Jun 29 12:26:15 1996
 > --- gcc-2.7.2.3.after/expr.c    Sat Feb 19 17:06:32 2000
 > ***************
 > *** 7656,7661 ****
 > --- 7656,7667 ----
 >           return tem;
 >         }
 >   
 > +     case BUILT_IN_CPAR_MOVESP:
 > +     
 > +       op0 = expand_expr (TREE_VALUE (arglist), NULL_RTX, VOIDmode,
 > 1);
 > +       adjust_stack(op0);
 > +       return target;

This stuff has moved to builtins.c:expand_builtin().  And the guts are
usually made into a static function.  Though in this case it doesn't
seem necessary.  I don't know if op0 is still in scope here.



 > diff -c gcc-2.7.2.3.before/tree.h gcc-2.7.2.3.after/tree.h
 > *** gcc-2.7.2.3.before/tree.h   Mon Sep 25 17:49:40 1995
 > --- gcc-2.7.2.3.after/tree.h    Sat Feb 19 17:06:06 2000
 > ***************
 > *** 105,110 ****
 > --- 105,111 ----
 >     BUILT_IN_VEC_DELETE,
 >   
 >     /* Upper bound on non-language-specific builtins. */
 > +   BUILT_IN_CPAR_MOVESP,
 >     END_BUILTINS

This has moved to builtins.def.

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