From e7704c8d005a07bfc90f0f6d280a0399f3d36495 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <eduard@urbach.dev>
Date: Fri, 29 Aug 2025 14:16:15 +0200
Subject: [PATCH] Fixed infinite loop during liveness analysis

---
 src/codegen/markAlive.go       | 10 ++++++++--
 tests/loop-infinite-lifetime.q |  9 +++++++++
 tests/tests_test.go            |  1 +
 3 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 tests/loop-infinite-lifetime.q

diff --git a/src/codegen/markAlive.go b/src/codegen/markAlive.go
index 625afa4..8f10adb 100644
--- a/src/codegen/markAlive.go
+++ b/src/codegen/markAlive.go
@@ -46,8 +46,14 @@ func (f *Function) markAlive(live *Step, block *ssa.Block, use *Step) {
 	}
 
 	for _, pre := range block.Predecessors {
-		if pre.CanReachPredecessor(live.Block) {
-			f.markAlive(live, pre, use)
+		if pre == block {
+			continue
+		}
+
+		if !pre.CanReachPredecessor(live.Block) {
+			continue
 		}
+
+		f.markAlive(live, pre, use)
 	}
 }
\ No newline at end of file
diff --git a/tests/loop-infinite-lifetime.q b/tests/loop-infinite-lifetime.q
new file mode 100644
index 0000000..fb68bcc
--- /dev/null
+++ b/tests/loop-infinite-lifetime.q
@@ -0,0 +1,9 @@
+main() {
+	x := 0
+
+	loop {
+		f(x)
+	}
+}
+
+f(_ int) {}
\ No newline at end of file
diff --git a/tests/tests_test.go b/tests/tests_test.go
index 349619d..53ee956 100644
--- a/tests/tests_test.go
+++ b/tests/tests_test.go
@@ -61,6 +61,7 @@ var tests = []run{
 	{"loop-copy-from", "", "", 0},
 	{"loop-copy-until", "", "", 0},
 	{"loop-modify-struct", "", "12345", 0},
+	{"loop-infinite-lifetime", "", "", -1},
 	{"factorial", "", "", 0},
 	{"fibonacci", "", "", 0},
 	{"memory", "", "Hello\n", 0},
-- 
2.51.2