do not rewrite overwritten slots in memopt

1 files changed, 2 insertions, 0 deletions

diff --git a/mem.c b/mem.c
index b94f0a7..c59d7fe 100644
--- a/mem.c
+++ b/mem.c
@@ -43,6 +43,8 @@ memopt(Fn *fn)
 		/* specific to NAlign == 3 */
 		assert(rtype(i->to) == RTmp);
 		t = &fn->tmp[i->to.val];
+		if (t->ndef != 1)
+			goto Skip;
 		k = -1;
 		s = -1;
 		for (u=t->use; u != &t->use[t->nuse]; u++) {