interp: limit max instructions per function

interp/interp.go

@@ -32,10 +32,11 @@ type runner struct {
 	start         time.Time
 	timeout       time.Duration
 	maxDepth      int
+	maxInstr      int
 	callsExecuted uint64
 }
 
-func newRunner(mod llvm.Module, timeout time.Duration, maxDepth int, debug bool) *runner {
+func newRunner(mod llvm.Module, timeout time.Duration, maxDepth int, maxInstr int, debug bool) *runner {
 	r := runner{
 		mod:           mod,
 		targetData:    llvm.NewTargetData(mod.DataLayout()),
@@ -46,6 +47,7 @@ func newRunner(mod llvm.Module, timeout time.Duration, maxDepth int, debug bool)
 		start:         time.Now(),
 		timeout:       timeout,
 		maxDepth:      maxDepth,
+		maxInstr:      maxInstr,
 	}
 	r.pointerSize = uint32(r.targetData.PointerSize())
 	r.i8ptrType = llvm.PointerType(mod.Context().Int8Type(), 0)
@@ -62,8 +64,8 @@ func (r *runner) dispose() {
 
 // Run evaluates runtime.initAll function as much as possible at compile time.
 // Set debug to true if it should print output while running.
-func Run(mod llvm.Module, timeout time.Duration, maxDepth int, debug bool) error {
-	r := newRunner(mod, timeout, maxDepth, debug)
+func Run(mod llvm.Module, timeout time.Duration, maxDepth int, maxInstr int, debug bool) error {
+	r := newRunner(mod, timeout, maxDepth, maxInstr, debug)
 	defer r.dispose()
 
 	initAll := mod.NamedFunction("runtime.initAll")
@@ -203,10 +205,10 @@ func Run(mod llvm.Module, timeout time.Duration, maxDepth int, debug bool) error
 
 // RunFunc evaluates a single package initializer at compile time.
 // Set debug to true if it should print output while running.
-func RunFunc(fn llvm.Value, timeout time.Duration, maxDepth int, debug bool) error {
+func RunFunc(fn llvm.Value, timeout time.Duration, maxDepth int, maxInstr int, debug bool) error {
 	// Create and initialize *runner object.
 	mod := fn.GlobalParent()
-	r := newRunner(mod, timeout, maxDepth, debug)
+	r := newRunner(mod, timeout, maxDepth, maxInstr, debug)
 	defer r.dispose()
 	initName := fn.Name()
 	if !strings.HasSuffix(initName, ".init") {

interp/interp_test.go

@@ -53,7 +53,7 @@ func runTest(t *testing.T, pathPrefix string) {
 	defer mod.Dispose()
 
 	// Perform the transform.
-	err = Run(mod, 10*time.Minute, 10, false)
+	err = Run(mod, 10*time.Minute, 10, 0, false)
 	if err != nil {
 		if err, match := err.(*Error); match {
 			println(err.Error())

interp/interpreter.go

@@ -33,7 +33,14 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, depth
 	lastBB := -1 // last basic block is undefined, only defined after a branch
 	var operands []value
 	startRTInsts := len(mem.instructions)
+	instCount := 0
 	for instIndex := 0; instIndex < len(bb.instructions); instIndex++ {
+		instCount++
+		if r.maxInstr > 0 && instCount > r.maxInstr {
+			fmt.Printf("interp: excess instructions evaluated in %v\n", fn.name)
+			return nil, mem, r.errorAt(fn.blocks[0].instructions[0], errDepthExceeded)
+		}
+
 		if instIndex == 0 {
 			if r.maxDepth > 0 && depth >= r.maxDepth {
 				fmt.Printf("interp: depth exceeded in %v\n", fn.name)