start at some basic passes

pass/cfg_test.go

@@ -0,0 +1,77 @@
+package pass
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/mmcloughlin/avo"
+)
+
+func TestLabelTarget(t *testing.T) {
+	expect := map[avo.Label]*avo.Instruction{
+		"lblA": &avo.Instruction{Opcode: "A"},
+		"lblB": &avo.Instruction{Opcode: "B"},
+	}
+
+	f := avo.NewFunction("happypath")
+	for lbl, i := range expect {
+		f.AddLabel(lbl)
+		f.AddInstruction(i)
+		f.AddInstruction(&avo.Instruction{Opcode: "IDK"})
+	}
+
+	if err := LabelTarget(f); err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(expect, f.LabelTarget) {
+		t.Fatalf("incorrect LabelTarget value\ngot=%#v\nexpext=%#v\n", f.LabelTarget, expect)
+	}
+}
+
+func TestLabelTargetDuplicate(t *testing.T) {
+	f := avo.NewFunction("dupelabel")
+	f.AddLabel(avo.Label("lblA"))
+	f.AddInstruction(&avo.Instruction{Opcode: "A"})
+	f.AddLabel(avo.Label("lblA"))
+	f.AddInstruction(&avo.Instruction{Opcode: "A"})
+
+	err := LabelTarget(f)
+
+	if err == nil || err.Error() != "duplicate label \"lblA\"" {
+		t.Fatalf("expected error on duplcate label; got %v", err)
+	}
+}
+
+func TestLabelTargetEndsWithLabel(t *testing.T) {
+	f := avo.NewFunction("endswithlabel")
+	f.AddInstruction(&avo.Instruction{Opcode: "A"})
+	f.AddLabel(avo.Label("theend"))
+
+	err := LabelTarget(f)
+
+	if err == nil || err.Error() != "function ends with label" {
+		t.Fatalf("expected error when function ends with label; got %v", err)
+	}
+}
+
+func TestLabelTargetInstructionFollowLabel(t *testing.T) {
+	f := avo.NewFunction("expectinstafterlabel")
+	f.AddLabel(avo.Label("lblA"))
+	f.AddLabel(avo.Label("lblB"))
+	f.AddInstruction(&avo.Instruction{Opcode: "A"})
+
+	err := LabelTarget(f)
+
+	if err == nil || err.Error() != "instruction should follow a label" {
+		t.Fatalf("expected error when label is not followed by instruction; got %v", err)
+	}
+}
+
+func TestCFG(t *testing.T) {
+	// TODO(mbm): jump backward
+	// TODO(mbm): jump forward
+	// TODO(mbm): multiple returns
+	// TODO(mbm): infinite loop
+	// TODO(mbm): very short infinite loop
+}