Example #1
0
// genInstr generates constraints for instruction instr in context cgn.
func (a *analysis) genInstr(cgn *cgnode, instr ssa.Instruction) {
	if a.log != nil {
		var prefix string
		if val, ok := instr.(ssa.Value); ok {
			prefix = val.Name() + " = "
		}
		fmt.Fprintf(a.log, "; %s%s\n", prefix, instr)
	}

	switch instr := instr.(type) {
	case *ssa.DebugRef:
		// no-op.

	case *ssa.UnOp:
		switch instr.Op {
		case token.ARROW: // <-x
			// We can ignore instr.CommaOk because the node we're
			// altering is always at zero offset relative to instr
			tElem := instr.X.Type().Underlying().(*types.Chan).Elem()
			a.genLoad(cgn, a.valueNode(instr), instr.X, 0, a.sizeof(tElem))

		case token.MUL: // *x
			a.genLoad(cgn, a.valueNode(instr), instr.X, 0, a.sizeof(instr.Type()))

		default:
			// NOT, SUB, XOR: no-op.
		}

	case *ssa.BinOp:
		// All no-ops.

	case ssa.CallInstruction: // *ssa.Call, *ssa.Go, *ssa.Defer
		a.genCall(cgn, instr)

	case *ssa.ChangeType:
		a.copy(a.valueNode(instr), a.valueNode(instr.X), 1)

	case *ssa.Convert:
		a.genConv(instr, cgn)

	case *ssa.Extract:
		a.copy(a.valueNode(instr),
			a.valueOffsetNode(instr.Tuple, instr.Index),
			a.sizeof(instr.Type()))

	case *ssa.FieldAddr:
		a.genOffsetAddr(cgn, instr, a.valueNode(instr.X),
			a.offsetOf(mustDeref(instr.X.Type()), instr.Field))

	case *ssa.IndexAddr:
		a.genOffsetAddr(cgn, instr, a.valueNode(instr.X), 1)

	case *ssa.Field:
		a.copy(a.valueNode(instr),
			a.valueOffsetNode(instr.X, instr.Field),
			a.sizeof(instr.Type()))

	case *ssa.Index:
		a.copy(a.valueNode(instr), 1+a.valueNode(instr.X), a.sizeof(instr.Type()))

	case *ssa.Select:
		recv := a.valueOffsetNode(instr, 2) // instr : (index, recvOk, recv0, ... recv_n-1)
		for _, st := range instr.States {
			elemSize := a.sizeof(st.Chan.Type().Underlying().(*types.Chan).Elem())
			switch st.Dir {
			case types.RecvOnly:
				a.genLoad(cgn, recv, st.Chan, 0, elemSize)
				recv += nodeid(elemSize)

			case types.SendOnly:
				a.genStore(cgn, st.Chan, a.valueNode(st.Send), 0, elemSize)
			}
		}

	case *ssa.Return:
		results := a.funcResults(cgn.obj)
		for _, r := range instr.Results {
			sz := a.sizeof(r.Type())
			a.copy(results, a.valueNode(r), sz)
			results += nodeid(sz)
		}

	case *ssa.Send:
		a.genStore(cgn, instr.Chan, a.valueNode(instr.X), 0, a.sizeof(instr.X.Type()))

	case *ssa.Store:
		a.genStore(cgn, instr.Addr, a.valueNode(instr.Val), 0, a.sizeof(instr.Val.Type()))

	case *ssa.Alloc, *ssa.MakeSlice, *ssa.MakeChan, *ssa.MakeMap, *ssa.MakeInterface:
		v := instr.(ssa.Value)
		a.addressOf(v.Type(), a.valueNode(v), a.objectNode(cgn, v))

	case *ssa.ChangeInterface:
		a.copy(a.valueNode(instr), a.valueNode(instr.X), 1)

	case *ssa.TypeAssert:
		a.typeAssert(instr.AssertedType, a.valueNode(instr), a.valueNode(instr.X), true)

	case *ssa.Slice:
		a.copy(a.valueNode(instr), a.valueNode(instr.X), 1)

	case *ssa.If, *ssa.Jump:
		// no-op.

	case *ssa.Phi:
		sz := a.sizeof(instr.Type())
		for _, e := range instr.Edges {
			a.copy(a.valueNode(instr), a.valueNode(e), sz)
		}

	case *ssa.MakeClosure:
		fn := instr.Fn.(*ssa.Function)
		a.copy(a.valueNode(instr), a.valueNode(fn), 1)
		// Free variables are treated like global variables.
		for i, b := range instr.Bindings {
			a.copy(a.valueNode(fn.FreeVars[i]), a.valueNode(b), a.sizeof(b.Type()))
		}

	case *ssa.RunDefers:
		// The analysis is flow insensitive, so we just "call"
		// defers as we encounter them.

	case *ssa.Range:
		// Do nothing.  Next{Iter: *ssa.Range} handles this case.

	case *ssa.Next:
		if !instr.IsString { // map
			// Assumes that Next is always directly applied to a Range result.
			theMap := instr.Iter.(*ssa.Range).X
			tMap := theMap.Type().Underlying().(*types.Map)

			ksize := a.sizeof(tMap.Key())
			vsize := a.sizeof(tMap.Elem())

			// The k/v components of the Next tuple may each be invalid.
			tTuple := instr.Type().(*types.Tuple)

			// Load from the map's (k,v) into the tuple's (ok, k, v).
			osrc := uint32(0) // offset within map object
			odst := uint32(1) // offset within tuple (initially just after 'ok bool')
			sz := uint32(0)   // amount to copy

			// Is key valid?
			if tTuple.At(1).Type() != tInvalid {
				sz += ksize
			} else {
				odst += ksize
				osrc += ksize
			}

			// Is value valid?
			if tTuple.At(2).Type() != tInvalid {
				sz += vsize
			}

			a.genLoad(cgn, a.valueNode(instr)+nodeid(odst), theMap, osrc, sz)
		}

	case *ssa.Lookup:
		if tMap, ok := instr.X.Type().Underlying().(*types.Map); ok {
			// CommaOk can be ignored: field 0 is a no-op.
			ksize := a.sizeof(tMap.Key())
			vsize := a.sizeof(tMap.Elem())
			a.genLoad(cgn, a.valueNode(instr), instr.X, ksize, vsize)
		}

	case *ssa.MapUpdate:
		tmap := instr.Map.Type().Underlying().(*types.Map)
		ksize := a.sizeof(tmap.Key())
		vsize := a.sizeof(tmap.Elem())
		a.genStore(cgn, instr.Map, a.valueNode(instr.Key), 0, ksize)
		a.genStore(cgn, instr.Map, a.valueNode(instr.Value), ksize, vsize)

	case *ssa.Panic:
		a.copy(a.panicNode, a.valueNode(instr.X), 1)

	default:
		panic(fmt.Sprintf("unimplemented: %T", instr))
	}
}
Example #2
0
// visitInstr interprets a single ssa.Instruction within the activation
// record frame.  It returns a continuation value indicating where to
// read the next instruction from.
func visitInstr(fr *frame, instr ssa.Instruction) continuation {
	switch instr := instr.(type) {
	case *ssa.DebugRef:
		// no-op

	case *ssa.UnOp:
		fr.env[instr] = unop(instr, fr.get(instr.X))

	case *ssa.BinOp:
		fr.env[instr] = binop(instr.Op, instr.X.Type(), fr.get(instr.X), fr.get(instr.Y))

	case *ssa.Call:
		fn, args := prepareCall(fr, &instr.Call)
		fr.env[instr] = call(fr.i, fr, instr.Pos(), fn, args)

	case *ssa.ChangeInterface:
		fr.env[instr] = fr.get(instr.X)

	case *ssa.ChangeType:
		fr.env[instr] = fr.get(instr.X) // (can't fail)

	case *ssa.Convert:
		fr.env[instr] = conv(instr.Type(), instr.X.Type(), fr.get(instr.X))

	case *ssa.MakeInterface:
		fr.env[instr] = iface{t: instr.X.Type(), v: fr.get(instr.X)}

	case *ssa.Extract:
		fr.env[instr] = fr.get(instr.Tuple).(tuple)[instr.Index]

	case *ssa.Slice:
		fr.env[instr] = slice(fr.get(instr.X), fr.get(instr.Low), fr.get(instr.High), fr.get(instr.Max))

	case *ssa.Return:
		switch len(instr.Results) {
		case 0:
		case 1:
			fr.result = fr.get(instr.Results[0])
		default:
			var res []value
			for _, r := range instr.Results {
				res = append(res, fr.get(r))
			}
			fr.result = tuple(res)
		}
		fr.block = nil
		return kReturn

	case *ssa.RunDefers:
		fr.runDefers()

	case *ssa.Panic:
		panic(targetPanic{fr.get(instr.X)})

	case *ssa.Send:
		fr.get(instr.Chan).(chan value) <- fr.get(instr.X)

	case *ssa.Store:
		store(deref(instr.Addr.Type()), fr.get(instr.Addr).(*value), fr.get(instr.Val))

	case *ssa.If:
		succ := 1
		if fr.get(instr.Cond).(bool) {
			succ = 0
		}
		fr.prevBlock, fr.block = fr.block, fr.block.Succs[succ]
		return kJump

	case *ssa.Jump:
		fr.prevBlock, fr.block = fr.block, fr.block.Succs[0]
		return kJump

	case *ssa.Defer:
		fn, args := prepareCall(fr, &instr.Call)
		fr.defers = &deferred{
			fn:    fn,
			args:  args,
			instr: instr,
			tail:  fr.defers,
		}

	case *ssa.Go:
		fn, args := prepareCall(fr, &instr.Call)
		go call(fr.i, nil, instr.Pos(), fn, args)

	case *ssa.MakeChan:
		fr.env[instr] = make(chan value, asInt(fr.get(instr.Size)))

	case *ssa.Alloc:
		var addr *value
		if instr.Heap {
			// new
			addr = new(value)
			fr.env[instr] = addr
		} else {
			// local
			addr = fr.env[instr].(*value)
		}
		*addr = zero(deref(instr.Type()))

	case *ssa.MakeSlice:
		slice := make([]value, asInt(fr.get(instr.Cap)))
		tElt := instr.Type().Underlying().(*types.Slice).Elem()
		for i := range slice {
			slice[i] = zero(tElt)
		}
		fr.env[instr] = slice[:asInt(fr.get(instr.Len))]

	case *ssa.MakeMap:
		reserve := 0
		if instr.Reserve != nil {
			reserve = asInt(fr.get(instr.Reserve))
		}
		fr.env[instr] = makeMap(instr.Type().Underlying().(*types.Map).Key(), reserve)

	case *ssa.Range:
		fr.env[instr] = rangeIter(fr.get(instr.X), instr.X.Type())

	case *ssa.Next:
		fr.env[instr] = fr.get(instr.Iter).(iter).next()

	case *ssa.FieldAddr:
		x := fr.get(instr.X)
		// FIXME wrong!  &global.f must not change if we do *global = zero!
		fr.env[instr] = &(*x.(*value)).(structure)[instr.Field]

	case *ssa.Field:
		fr.env[instr] = fr.get(instr.X).(structure)[instr.Field]

	case *ssa.IndexAddr:
		x := fr.get(instr.X)
		idx := fr.get(instr.Index)
		switch x := x.(type) {
		case []value:
			fr.env[instr] = &x[asInt(idx)]
		case *value: // *array
			fr.env[instr] = &(*x).(array)[asInt(idx)]
		default:
			panic(fmt.Sprintf("unexpected x type in IndexAddr: %T", x))
		}

	case *ssa.Index:
		fr.env[instr] = fr.get(instr.X).(array)[asInt(fr.get(instr.Index))]

	case *ssa.Lookup:
		fr.env[instr] = lookup(instr, fr.get(instr.X), fr.get(instr.Index))

	case *ssa.MapUpdate:
		m := fr.get(instr.Map)
		key := fr.get(instr.Key)
		v := fr.get(instr.Value)
		switch m := m.(type) {
		case map[value]value:
			m[key] = v
		case *hashmap:
			m.insert(key.(hashable), v)
		default:
			panic(fmt.Sprintf("illegal map type: %T", m))
		}

	case *ssa.TypeAssert:
		fr.env[instr] = typeAssert(fr.i, instr, fr.get(instr.X).(iface))

	case *ssa.MakeClosure:
		var bindings []value
		for _, binding := range instr.Bindings {
			bindings = append(bindings, fr.get(binding))
		}
		fr.env[instr] = &closure{instr.Fn.(*ssa.Function), bindings}

	case *ssa.Phi:
		for i, pred := range instr.Block().Preds {
			if fr.prevBlock == pred {
				fr.env[instr] = fr.get(instr.Edges[i])
				break
			}
		}

	case *ssa.Select:
		var cases []reflect.SelectCase
		if !instr.Blocking {
			cases = append(cases, reflect.SelectCase{
				Dir: reflect.SelectDefault,
			})
		}
		for _, state := range instr.States {
			var dir reflect.SelectDir
			if state.Dir == types.RecvOnly {
				dir = reflect.SelectRecv
			} else {
				dir = reflect.SelectSend
			}
			var send reflect.Value
			if state.Send != nil {
				send = reflect.ValueOf(fr.get(state.Send))
			}
			cases = append(cases, reflect.SelectCase{
				Dir:  dir,
				Chan: reflect.ValueOf(fr.get(state.Chan)),
				Send: send,
			})
		}
		chosen, recv, recvOk := reflect.Select(cases)
		if !instr.Blocking {
			chosen-- // default case should have index -1.
		}
		r := tuple{chosen, recvOk}
		for i, st := range instr.States {
			if st.Dir == types.RecvOnly {
				var v value
				if i == chosen && recvOk {
					// No need to copy since send makes an unaliased copy.
					v = recv.Interface().(value)
				} else {
					v = zero(st.Chan.Type().Underlying().(*types.Chan).Elem())
				}
				r = append(r, v)
			}
		}
		fr.env[instr] = r

	default:
		panic(fmt.Sprintf("unexpected instruction: %T", instr))
	}

	// if val, ok := instr.(ssa.Value); ok {
	// 	fmt.Println(toString(fr.env[val])) // debugging
	// }

	return kNext
}