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

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This commit is contained in:
ceriel 1987-10-02 10:41:13 +00:00
parent 7f400e5073
commit c0dd8055c2
1 changed files with 31 additions and 12 deletions
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43
util/ego/lv/lv.c
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@ -326,15 +326,17 @@ STATIC block_entry(b,prev)
for (v = 1; v <= nrlocals; v++) { for (v = 1; v <= nrlocals; v++) {
loc = locals[v]; loc = locals[v];
vn = LOC_TO_VARNR(v); if (IS_REGVAR(loc)) {
if (prev == (bblock_p) 0) { vn = LOC_TO_VARNR(v);
was_live = loc->lc_off >= 0; if (prev == (bblock_p) 0) {
} else { was_live = loc->lc_off >= 0;
was_live = Cis_elem(vn,L_OUT(prev)); } else {
} was_live = Cis_elem(vn,L_OUT(prev));
is_live = Cis_elem(vn,L_IN(b)); }
if (was_live != is_live) { is_live = Cis_elem(vn,L_IN(b));
app_block(make_mesg((is_live?ms_liv:ms_ded),loc),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; *v_out = v;
loc = locals[TO_LOCAL(v)]; loc = locals[TO_LOCAL(v)];
if (IS_REGVAR(loc)) { 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 (IS_LIVE(loc)) {
if (!mesgflag) {
appnd_line(make_mesg(ms_liv,loc), l);
}
DEAD(loc); DEAD(loc);
} else { } else {
if (!mesgflag) {
appnd_line(make_mesg(ms_ded, loc), l);
}
*useless_out = TRUE; *useless_out = TRUE;
} }
} }
@ -519,6 +536,8 @@ OUTVERBOSE("useless assignment ,proc %d,local %d", curproc->p_id,
(int) locals[TO_LOCAL(v)]->lc_off); (int) locals[TO_LOCAL(v)]->lc_off);
Slv++; Slv++;
} }
else {
}
} else { } else {
if (is_dir_use(l)) { if (is_dir_use(l)) {
use(l,mesgflag); use(l,mesgflag);