qbe

commit ae80e4f7caa6be31f83ae6a94a26ab3b60a5b064
parent 2b64b75c845d0491c7a701e44485d2856eeb686d
Author: Quentin Carbonneaux <quentin@c9x.me>
Date:   Thu, 17 Aug 2017 04:47:10 -0400

fix bug in jumps simplification

In presence of jump loops, the algorithm would
create cycles in the disjoint-set data structure.
This caused infinite recursion and stack overflows.

Diffstat:
M
cfg.c
 | 
7
+++++--

1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/cfg.c b/cfg.c
@@ -304,8 +304,11 @@ simpljmp(Fn *fn)
 	for (b=fn->start; b; b=b->link) {
 		assert(!b->phi);
 		if (b->nins == 0)
-		if (b->jmp.type == Jjmp)
-			uf[b->id] = b->s1;
+		if (b->jmp.type == Jjmp) {
+			uffind(&b->s1, uf);
+			if (b->s1 != b)
+				uf[b->id] = b->s1;
+		}
 	}
 	for (b=fn->start; b; b=b->link) {
 		if (b->s1)