From 016938932f3ea02cc2709b07144799bc0604d91a Mon Sep 17 00:00:00 2001
From: Eduard Urbach <eduard@urbach.dev>
Date: Sun, 9 Mar 2025 17:51:24 +0100
Subject: [PATCH] Fixed incorrect register lifetime in for loops

---
 src/asmc/compileX86.go     |  3 ++-
 src/core/CompileFor.go     |  4 +++-
 tests/programs/fibonacci.q | 26 ++++++++++++++++++++++++++
 tests/programs_test.go     |  1 +
 4 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 tests/programs/fibonacci.q

diff --git a/src/asmc/compileX86.go b/src/asmc/compileX86.go
index b4279de..13ee381 100644
--- a/src/asmc/compileX86.go
+++ b/src/asmc/compileX86.go
@@ -90,7 +90,8 @@ func (c *compiler) compileX86(x asm.Instruction) {
 		c.jump(x)
 
 	case asm.LABEL:
-		c.codeLabels[x.Data.(*asm.Label).Name] = Address(len(c.code))
+		label := x.Data.(*asm.Label)
+		c.codeLabels[label.Name] = Address(len(c.code))
 
 	case asm.LOAD:
 		c.load(x)
diff --git a/src/core/CompileFor.go b/src/core/CompileFor.go
index 973c6f6..0d1530f 100644
--- a/src/core/CompileFor.go
+++ b/src/core/CompileFor.go
@@ -81,11 +81,13 @@ func (f *Function) CompileFor(loop *ast.For) error {
 	case *eval.Register:
 		if value.IsAlive() {
 			tmp := f.NewRegister()
-			f.RegisterRegister(asm.MOVE, tmp, value.Register)
 			defer f.FreeRegister(tmp)
+			f.RegisterRegister(asm.MOVE, tmp, value.Register)
 			f.AddLabel(label)
 			f.RegisterRegister(asm.COMPARE, counter, tmp)
 		} else {
+			f.UseRegister(value.Register)
+			defer f.FreeRegister(value.Register)
 			f.AddLabel(label)
 			f.RegisterRegister(asm.COMPARE, counter, value.Register)
 		}
diff --git a/tests/programs/fibonacci.q b/tests/programs/fibonacci.q
new file mode 100644
index 0000000..a930713
--- /dev/null
+++ b/tests/programs/fibonacci.q
@@ -0,0 +1,26 @@
+main() {
+	for i := 0..10 {
+		assert fib1(i) == fib2(i)
+	}
+}
+
+fib1(n int) -> int {
+	b := 0
+	c := 1
+
+	for 0..n {
+		a := b
+		b = c
+		c = a + b
+	}
+
+	return b
+}
+
+fib2(n int) -> int {
+	if n <= 1 {
+		return n
+	}
+
+	return fib2(n - 1) + fib2(n - 2)
+}
\ No newline at end of file
diff --git a/tests/programs_test.go b/tests/programs_test.go
index a1e76ce..cfb6d2a 100644
--- a/tests/programs_test.go
+++ b/tests/programs_test.go
@@ -62,6 +62,7 @@ var programs = []struct {
 	{"loop-lifetime", 0},
 	{"loop-in-loop", 0},
 	{"for", 0},
+	{"fibonacci", 0},
 	{"memory-free", 0},
 	{"out-of-memory", 0},
 	{"index-static", 0},