BSD 4_1c_2 release

[unix-history] / usr / src / usr.bin / struct / 3.then.c

#ifndef lint
static char sccsid[] = "@(#)3.then.c    4.1     (Berkeley)      2/11/83";
#endif not lint

#include <stdio.h>
#include "def.h"
#include "3.def.h"

#define BRANCHTYPE(t)   (t == STOPVX || t == RETVX || t == BRKVX || t == NXTVX || t == GOVX)
#define MAXCHUNK        20
               /* if else clause smaller than MAXCHUNK and smaller than then clause,
                       and there is no reason not to negate the if, negate the if */

getthen(v)              /* turn IFVX into THEN when appropriate, create else ifs where possible  */
VERT v;
       {
       VERT tch, fch;
       int tn,fn;
       int recvar;

       if (NTYPE(v) == IFVX)
               {
               tch = LCHILD(v,THEN);
               fch = LCHILD(v,ELSE);
               if (!DEFINED(fch))
                       mkthen(v);
               else if (!DEFINED(tch))
                       {
                       negate(v);
                       mkthen(v);
                       }
               else if (BRANCHTYPE(NTYPE(tch)))
                       mkthen(v);
               else if (BRANCHTYPE(NTYPE(fch)))
                       {
                       negate(v);
                       mkthen(v);
                       }
               else if (NTYPE(fch) != IFVX || DEFINED(RSIB(fch)))      /* not an else if */
                       if ( NTYPE(tch) == IFVX && !DEFINED(RSIB(tch)))
                                       /* invert into else if */
                               negate(v);
                       else
                               {
                               /* asoc(v,n) returns number of statements associated with v
                                       if <= n, -1 otherwise */
                               tn = asoc(tch,MAXCHUNK);
                               fn = asoc(fch,MAXCHUNK);
                               if (fn >= 0 && (tn < 0 || fn < tn))
                                       /* else clause smaller */
                                       negate(v);
                               }
               }
       RECURSE(getthen,v,recvar);
       }

mkthen(v)
VERT v;
       {
       VERT w,tc;
       w = LCHILD(v,ELSE);
       tc = LCHILD(v,THEN);
       ASSERT(!DEFINED(w) || (DEFINED(tc) && BRANCHTYPE(NTYPE(tc)) ),mkthen);
       if (DEFINED(w))
               {
               insib(v,w);
               LCHILD(v,ELSE) = UNDEFINED;
               }
       ASSERT(IFTHEN(v),mkthen);
       }


negate(v)
VERT v;
       {
       ASSERT(NTYPE(v) == IFVX,negate);
       exchange(&LCHILD(v,THEN), &LCHILD(v,ELSE));
       NEG(v) = !NEG(v);
       }