4.3BSD - /usr/src/usr.bin/struct/3.loop.c

   1: #ifndef lint
   2: static char sccsid[] = "@(#)3.loop.c	4.1	(Berkeley)	2/11/83";
   3: #endif not lint
   4: 
   5: #include <stdio.h>
   6: #include "def.h"
   7: #include "3.def.h"
   8: 
   9: #define ARCCOUNT(v) REACH(v)
  10: 
  11: 
  12: fixhd(v,hd,head)
  13: VERT v,hd,*head;
  14:     {
  15:     VERT w,newhd;
  16:     int i;
  17:     head[v] = hd;
  18:     newhd = (NTYPE(v) == ITERVX) ? v : hd;
  19:     for (i = 0; i < CHILDNUM(v); ++i)
  20:         for (w = LCHILD(v,i); DEFINED(w); w = RSIB(w))
  21:             fixhd(w,newhd,head);
  22:     }
  23: 
  24: getloop()
  25:     {
  26:     cntarcs();
  27:     fixloop(START);
  28:     }
  29: 
  30: 
  31: cntarcs()   /* count arcs entering each node */
  32:     {
  33:     VERT w,v;
  34:     int i;
  35:     for (v = 0; v < nodenum; ++v)
  36:         ARCCOUNT(v) = 0;
  37:     for (v = 0; v < nodenum; ++v)
  38:         for (i = 0; i < ARCNUM(v); ++i)
  39:             {
  40:             w = ARC(v,i);
  41:             if (!DEFINED(w)) continue;
  42:             ++ARCCOUNT(w);
  43:             }
  44:     }
  45: 
  46: 
  47: fixloop(v)      /* find WHILE loops  */
  48: VERT v;
  49:     {
  50:     int recvar;
  51:     if (NTYPE(v) == LOOPVX)
  52:         {
  53:         ASSERT(DEFINED(ARC(v,0)),fixloop);
  54:         NXT(ARC(v,0)) = ARC(v,0);
  55:         if (!getwh(v))
  56:             getun(v);
  57:         }
  58:     else if (NTYPE(v) == IFVX && arbcase)
  59:         getswitch(v);
  60:     else if (NTYPE(v)==DOVX)
  61:         {
  62:         ASSERT(DEFINED(ARC(v,0)),fixloop);
  63:         NXT(ARC(v,0))=ARC(v,0);
  64:         }
  65:     RECURSE(fixloop,v,recvar);
  66:     }
  67: 
  68: 
  69: getwh(v)
  70: VERT v;
  71:     {
  72:     VERT vchild, vgrand,vgreat;
  73:     ASSERT(NTYPE(v) == LOOPVX,getwh);
  74:     vchild = LCHILD(v,0);
  75:     ASSERT(DEFINED(vchild),getwh);
  76:     ASSERT(NTYPE(vchild) == ITERVX,getwh);
  77:     vgrand = LCHILD(vchild,0);
  78:     if (!DEFINED(vgrand) || !IFTHEN(vgrand) )
  79:         return(FALSE);
  80:     vgreat = LCHILD(vgrand,THEN);
  81:     if (DEFINED(vgreat) && NTYPE(vgreat) == GOVX && ARC(vgreat,0) == BRK(vchild))
  82:         {
  83:         /* turn into WHILE */
  84:         NTYPE(v) = WHIVX;
  85:         NEG(vgrand) = !NEG(vgrand);
  86:         LPRED(vchild) = vgrand;
  87:         LCHILD(vchild,0) = RSIB(vgrand);
  88:         RSIB(vgrand) = UNDEFINED;
  89:         return(TRUE);
  90:         }
  91:     return(FALSE);
  92:     }
  93: 
  94: 
  95: 
  96: getun(v)        /* change loop to REPEAT UNTIL if possible */
  97: VERT v;
  98:     {
  99:     VERT vchild, vgrand,  vgreat, before, ch;
 100:     ASSERT(NTYPE(v) == LOOPVX,getun);
 101:     vchild = LCHILD(v,0);
 102:     ASSERT(DEFINED(vchild), getun);
 103:     if (ARCCOUNT(vchild) > 2)
 104:         return(FALSE);      /* loop can be iterated without passing through predicate of UNTIL */
 105:     vgrand = ARC(vchild,0);
 106:     if (!DEFINED(vgrand))
 107:         return(FALSE);
 108:     for (ch = vgrand,before = UNDEFINED; DEFINED(RSIB(ch)); ch = RSIB(ch))
 109:         before = ch;
 110:     if (!IFTHEN(ch))
 111:         return(FALSE);
 112:     vgreat = LCHILD(ch,THEN);
 113:     if (DEFINED(vgreat) && NTYPE(vgreat) == GOVX && ARC(vgreat,0) == BRK(vchild))
 114:         {
 115:         /* create  UNTIL node */
 116:         NTYPE(v) = UNTVX;
 117:         NXT(vchild) = ch;
 118:         LPRED(vchild)=ch;
 119:         RSIB(before) = UNDEFINED;
 120:         return(TRUE);
 121:         }
 122:     return(FALSE);
 123:     }
 124: 
 125: 
 126: #define FORMCASE(w) (DEFINED(w) && !DEFINED(RSIB(w)) && NTYPE(w) == IFVX && ARCCOUNT(w) == 1)
 127: 
 128: getswitch(v)
 129: VERT v;
 130:     {
 131:     VERT ch, grand, temp;
 132:     /* must be of form if ... else if ... else if ... */
 133:     if (NTYPE(v) != IFVX) return(FALSE);
 134:     ch = LCHILD(v,ELSE);
 135:     if (!FORMCASE(ch)) return(FALSE);
 136:     grand = LCHILD(ch,ELSE);
 137:     if (!FORMCASE(grand)) return(FALSE);
 138: 
 139:     temp = create(SWCHVX,0);
 140:     exchange(&graph[temp],&graph[v]);   /* want arcs to enter switch, not first case*/
 141:     BEGCOM(v) = UNDEFINED;
 142:     RSIB(v) = RSIB(temp);       /* statements which followed IFVX should follow switch */
 143:     EXP(v) = UNDEFINED;
 144:     LCHILD(v,0) = temp;
 145:     NTYPE(temp) = ACASVX;
 146:     for (ch = LCHILD(temp,ELSE); FORMCASE(ch); )
 147:         {
 148:         LCHILD(temp,ELSE) = UNDEFINED;
 149:         RSIB(temp) = ch;
 150:         NTYPE(ch) = ACASVX;
 151:         temp = ch;
 152:         ch = LCHILD(temp,ELSE);
 153:         }
 154:     ASSERT(!DEFINED(RSIB(temp)),getswitch);
 155:     return(TRUE);
 156:     }

Defined functions

Defined variables

Defined macros