make variables that are assigned to alive, at least for a short while

diff --git a/util/ego/lv/lv.c b/util/ego/lv/lv.c
index 86210b0..8b06bc7 100644 (file)
--- a/util/ego/lv/lv.c
+++ b/util/ego/lv/lv.c
@@ -326,15 +326,17 @@ STATIC block_entry(b,prev)
 
        for (v = 1; v <= nrlocals; v++) {
                loc = locals[v];
-               vn = LOC_TO_VARNR(v);
-               if (prev == (bblock_p) 0) {
-                       was_live = loc->lc_off >= 0;
-               } else {
-                       was_live = Cis_elem(vn,L_OUT(prev));
-               }
-               is_live = Cis_elem(vn,L_IN(b));
-               if (was_live != is_live) {
-                       app_block(make_mesg((is_live?ms_liv:ms_ded),loc),b);
+               if (IS_REGVAR(loc)) {
+                       vn = LOC_TO_VARNR(v);
+                       if (prev == (bblock_p) 0) {
+                               was_live = loc->lc_off >= 0;
+                       } else {
+                               was_live = Cis_elem(vn,L_OUT(prev));
+                       }
+                       is_live = Cis_elem(vn,L_IN(b));
+                       if (was_live != is_live) {
+                               app_block(make_mesg((is_live?ms_liv:ms_ded),loc),b);
+                       }
                }
        }
 }
@@ -386,12 +388,27 @@ STATIC definition(l,useless_out,v_out,mesgflag)
                *v_out = v;
                loc = locals[TO_LOCAL(v)];
                if (IS_REGVAR(loc)) {
+                       /*      Tricky stuff here. Make sure that a variable
+                               that is assigned to is alive, at least for
+                               a very very short time. Otherwize, the
+                               register allocation pass might think that it
+                               is never alive, and (incorrectly) use the
+                               same register for this variable as for 
+                               another variable, that is alive at this point.
+                               If this variable is dead after the assignment,
+                               the two messages (ms_liv, ms_ded) are right
+                               after each other. Luckily, this IS an interval.
+                       */
+                       if (!mesgflag) {
+                               appnd_line(make_mesg(ms_liv,loc), l);
+                               l = l->l_next;
+                       }
                        if (IS_LIVE(loc)) {
-                               if (!mesgflag) {
-                                       appnd_line(make_mesg(ms_liv,loc), l);
-                               }
                                DEAD(loc);
                        } else {
+                               if (!mesgflag) {
+                                       appnd_line(make_mesg(ms_ded, loc), l);
+                               }
                                *useless_out = TRUE;
                        }
                }
@@ -519,6 +536,8 @@ OUTVERBOSE("useless assignment ,proc %d,local %d", curproc->p_id,
   (int) locals[TO_LOCAL(v)]->lc_off);
                                        Slv++;
                                }
+                               else {
+                               }
                        } else {
                                if (is_dir_use(l))  {
                                        use(l,mesgflag);