code review 6922048: cmd/{5,6,8}g: reduce size of Prog and Addr

src/cmd/6g/gsubr.c

 // Derived from Inferno utils/6c/txt.c
 // http://code.google.com/p/inferno-os/source/browse/utils/6c/txt.c
 //
 //      Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //      Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
 //      Portions Copyright © 1997-1999 Vita Nuova Limited
 //      Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
 //      Portions Copyright © 2004,2006 Bruce Ellis
 //      Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
 //      Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
@@ skipping 99 matching lines @@
  */
 Prog*
 gbranch(int as, Type *t, int likely)
 {
         Prog *p;
 ········
         USED(t);
 
         p = prog(as);
         p->to.type = D_BRANCH;
-        p->to.branch = P;
+        p->to.u.branch = P;
         if(as != AJMP && likely != 0) {
                 p->from.type = D_CONST;
                 p->from.offset = likely > 0;
         }
         return p;
 }
 
 /*
  * patch previous branch to jump to to.
  */
 void
 patch(Prog *p, Prog *to)
 {
         if(p->to.type != D_BRANCH)
                 fatal("patch: not a branch");
-        p->to.branch = to;
+        p->to.u.branch = to;
         p->to.offset = to->loc;
 }
 
 Prog*
 unpatch(Prog *p)
 {
         Prog *q;
 
         if(p->to.type != D_BRANCH)
                 fatal("unpatch: not a branch");
-        q = p->to.branch;
-        p->to.branch = P;
+        q = p->to.u.branch;
+        p->to.u.branch = P;
         p->to.offset = 0;
         return q;
 }
 
 /*
  * start a new Prog list.
  */
 Plist*
 newplist(void)
 {
@@ skipping 1036 matching lines @@
                 }
                 break;
 
         case OLITERAL:
                 switch(n->val.ctype) {
                 default:
                         fatal("naddr: const %lT", n->type);
                         break;
                 case CTFLT:
                         a->type = D_FCONST;
-                        a->dval = mpgetflt(n->val.u.fval);
+                        a->u.dval = mpgetflt(n->val.u.fval);
                         break;
                 case CTINT:
                 case CTRUNE:
                         a->sym = S;
                         a->type = D_CONST;
                         a->offset = mpgetfix(n->val.u.xval);
                         break;
                 case CTSTR:
                         datagostring(n->val.u.sval, a);
                         break;
@@ skipping 1033 matching lines @@
         naddr(&n2, a, 1);
         goto yes;
 
 yes:
         return 1;
 
 no:
         sudoclean();
         return 0;
 }