interp: add testing for scanning for side effects

interp/scan_test.go

@@ -0,0 +1,87 @@
+package interp
+
+import (
+	"os"
+	"sort"
+	"testing"
+
+	"tinygo.org/x/go-llvm"
+)
+
+var scanTestTable = []struct {
+	name            string
+	severity        sideEffectSeverity
+	mentionsGlobals []string
+}{
+	{"returnsConst", sideEffectNone, nil},
+	{"returnsArg", sideEffectNone, nil},
+	{"externalCallOnly", sideEffectNone, nil},
+	{"externalCallAndReturn", sideEffectLimited, nil},
+	{"externalCallBranch", sideEffectLimited, nil},
+	{"readCleanGlobal", sideEffectNone, []string{"cleanGlobalInt"}},
+	{"readDirtyGlobal", sideEffectLimited, []string{"dirtyGlobalInt"}},
+	{"callFunctionPointer", sideEffectAll, []string{"functionPointer"}},
+}
+
+func TestScan(t *testing.T) {
+	t.Parallel()
+
+	// Read the input IR.
+	path := "testdata/scan.ll"
+	ctx := llvm.NewContext()
+	buf, err := llvm.NewMemoryBufferFromFile(path)
+	os.Stat(path) // make sure this file is tracked by `go test` caching
+	if err != nil {
+		t.Fatalf("could not read file %s: %v", path, err)
+	}
+	mod, err := ctx.ParseIR(buf)
+	if err != nil {
+		t.Fatalf("could not load module:\n%v", err)
+	}
+
+	// Check all to-be-tested functions.
+	for _, tc := range scanTestTable {
+		// Create an eval object, for testing.
+		e := &Eval{
+			Mod:          mod,
+			TargetData:   llvm.NewTargetData(mod.DataLayout()),
+			dirtyGlobals: map[llvm.Value]struct{}{},
+		}
+
+		// Mark some globals dirty, for testing.
+		e.markDirty(mod.NamedGlobal("dirtyGlobalInt"))
+
+		// Scan for side effects.
+		fn := mod.NamedFunction(tc.name)
+		if fn.IsNil() {
+			t.Errorf("scan test: could not find tested function %s in the IR", tc.name)
+			continue
+		}
+		result := e.hasSideEffects(fn)
+
+		// Check whether the result is what we expect.
+		if result.severity != tc.severity {
+			t.Errorf("scan test: function %s should have severity %s but it has %s", tc.name, tc.severity, result.severity)
+		}
+
+		// Check whether the mentioned globals match with what we'd expect.
+		mentionsGlobalNames := make([]string, 0, len(result.mentionsGlobals))
+		for global := range result.mentionsGlobals {
+			mentionsGlobalNames = append(mentionsGlobalNames, global.Name())
+		}
+		sort.Strings(mentionsGlobalNames)
+		globalsMismatch := false
+		if len(result.mentionsGlobals) != len(tc.mentionsGlobals) {
+			globalsMismatch = true
+		} else {
+			for i, globalName := range mentionsGlobalNames {
+				if tc.mentionsGlobals[i] != globalName {
+					globalsMismatch = true
+				}
+			}
+		}
+		if globalsMismatch {
+			t.Errorf("scan test: expected %s to mention globals %v, but it mentions globals %v", tc.name, tc.mentionsGlobals, mentionsGlobalNames)
+		}
+	}
+}