PATCH (volatile support)

[mrs at wrs dot com (Mike Stump)]

Here's one that adds volatile use support to the compiler.  This is
necessary because ANSI C says that one must mark variables that expect
to have the right values across setjmp/longjmp must be marked as
volatile, as I recall.

tree.h almost seemed like the exact wrong place for this code, but
nothing struct me as the right place for it.  Maybe someone with a
better sense of the big picture can recommend a better place for it.

There are only two other places I know of that have this same exact
problem.  In the C lexer and in the C++ lexer.  I wanted to think
about the performace impact on those two before changing them.


1998-05-01  Mike Stump  <mrs@kankakee.wrs.com>

	* tree.h: Add support for using volatile in the compiler.
	* tree.c (build_real_from_int_cst): Use volatile to protect
	values across setmp/longjmp.
	* fold-const.c (const_binop): Likewise.
	(fold_convert): Likewise.

Doing diffs in tree.h.~1~:
*** tree.h.~1~	Fri Apr 17 16:15:43 1998
--- tree.h	Fri May  1 17:58:52 1998
*************** extern void dwarf2out_begin_prologue	PRO
*** 2221,2223 ****
--- 2221,2227 ----
     code for a function definition.  */
  
  extern void dwarf2out_end_epilogue	PROTO((void));
+ 
+ #ifndef __STDC__
+ #define volatile
+ #endif
--------------
Doing diffs in fold-const.c.~1~:
*** fold-const.c.~1~	Mon Apr 27 13:17:46 1998
--- fold-const.c	Fri May  1 17:40:23 1998
*************** int_const_binop (code, arg1, arg2, notru
*** 1255,1261 ****
  static tree
  const_binop (code, arg1, arg2, notrunc)
       enum tree_code code;
!      register tree arg1, arg2;
       int notrunc;
  {
    STRIP_NOPS (arg1); STRIP_NOPS (arg2);
--- 1255,1261 ----
  static tree
  const_binop (code, arg1, arg2, notrunc)
       enum tree_code code;
!      volatile tree arg1, arg2;
       int notrunc;
  {
    STRIP_NOPS (arg1); STRIP_NOPS (arg2);
*************** const_binop (code, arg1, arg2, notrunc)
*** 1268,1274 ****
      {
        REAL_VALUE_TYPE d1;
        REAL_VALUE_TYPE d2;
!       int overflow = 0;
        REAL_VALUE_TYPE value;
        tree t;
  
--- 1268,1274 ----
      {
        REAL_VALUE_TYPE d1;
        REAL_VALUE_TYPE d2;
!       volatile int overflow = 0;
        REAL_VALUE_TYPE value;
        tree t;
  
*************** fold_convert (t, arg1)
*** 1497,1503 ****
       register tree arg1;
  {
    register tree type = TREE_TYPE (t);
!   int overflow = 0;
  
    if (POINTER_TYPE_P (type) || INTEGRAL_TYPE_P (type))
      {
--- 1497,1503 ----
       register tree arg1;
  {
    register tree type = TREE_TYPE (t);
!   volatile int overflow = 0;
  
    if (POINTER_TYPE_P (type) || INTEGRAL_TYPE_P (type))
      {
--------------
Doing diffs in tree.c.~1~:
*** tree.c.~1~	Thu Apr 16 12:00:10 1998
--- tree.c	Fri May  1 17:29:35 1998
*************** build_real_from_int_cst (type, i)
*** 1458,1464 ****
       tree i;
  {
    tree v;
!   int overflow = TREE_OVERFLOW (i);
    REAL_VALUE_TYPE d;
    jmp_buf float_error;
  
--- 1458,1464 ----
       tree i;
  {
    tree v;
!   volatile int overflow = TREE_OVERFLOW (i);
    REAL_VALUE_TYPE d;
    jmp_buf float_error;
  
--------------