From a1440c51a4cd7f09e7e31d6fef8e977c58b41786 Mon Sep 17 00:00:00 2001
From: Michael McLoughlin <mmcloughlin@gmail.com>
Date: Fri, 28 Dec 2018 15:48:37 -0800
Subject: [PATCH] pass: some basic allocator test cases

---
 pass/alloc.go      |  6 +++++-
 pass/alloc_test.go | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 pass/alloc_test.go

diff --git a/pass/alloc.go b/pass/alloc.go
index ce07890..dd616f3 100644
--- a/pass/alloc.go
+++ b/pass/alloc.go
@@ -64,11 +64,15 @@ func (a *Allocator) Add(r reg.Register) {
 }
 
 func (a *Allocator) Allocate() (reg.Allocation, error) {
-	for a.remaining() > 0 {
+	for {
 		if err := a.update(); err != nil {
 			return nil, err
 		}
 
+		if a.remaining() == 0 {
+			break
+		}
+
 		v := a.mostrestricted()
 		if err := a.alloc(v); err != nil {
 			return nil, err
diff --git a/pass/alloc_test.go b/pass/alloc_test.go
new file mode 100644
index 0000000..e9b246e
--- /dev/null
+++ b/pass/alloc_test.go
@@ -0,0 +1,46 @@
+package pass
+
+import (
+	"testing"
+
+	"github.com/mmcloughlin/avo/reg"
+)
+
+func TestAllocatorSimple(t *testing.T) {
+	c := reg.NewCollection()
+	x, y := c.Xv(), c.Yv()
+
+	a, err := NewAllocatorForKind(reg.SSEAVX)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a.Add(x)
+	a.Add(y)
+	a.AddInterference(x, y)
+
+	alloc, err := a.Allocate()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Log(alloc)
+
+	if alloc[x] != reg.X0 || alloc[y] != reg.Y1 {
+		t.Fatalf("unexpected allocation")
+	}
+}
+
+func TestAllocatorImpossible(t *testing.T) {
+	a, err := NewAllocatorForKind(reg.SSEAVX)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a.AddInterference(reg.X7, reg.Z7)
+
+	_, err = a.Allocate()
+	if err == nil {
+		t.Fatal("expected allocation error")
+	}
+}