9 files changed, 166 insertions, 5 deletions
diff --git a/go/ssa/interp/testdata/src/fmt/fmt.go b/go/ssa/interp/testdata/src/fmt/fmt.go
index 2185eb708..af304029c 100644
--- a/go/ssa/interp/testdata/src/fmt/fmt.go
+++ b/go/ssa/interp/testdata/src/fmt/fmt.go
@@ -1,14 +1,28 @@
 package fmt
 
+import (
+	"errors"
+	"strings"
+)
+
 func Sprint(args ...interface{}) string
 
-func Print(args ...interface{}) {
+func Sprintln(args ...interface{}) string {
+	return Sprint(args...) + "\n"
+}
+
+func Print(args ...interface{}) (int, error) {
+	var n int
 	for i, arg := range args {
 		if i > 0 {
 			print(" ")
+			n++
 		}
-		print(Sprint(arg))
+		msg := Sprint(arg)
+		n += len(msg)
+		print(msg)
 	}
+	return n, nil
 }
 
 func Println(args ...interface{}) {
@@ -17,10 +31,30 @@ func Println(args ...interface{}) {
 }
 
 // formatting is too complex to fake
+// handle the bare minimum needed for tests
 
-func Printf(args ...interface{}) string {
-	panic("Printf is not supported")
+func Printf(format string, args ...interface{}) (int, error) {
+	msg := Sprintf(format, args...)
+	print(msg)
+	return len(msg), nil
 }
+
 func Sprintf(format string, args ...interface{}) string {
-	panic("Sprintf is not supported")
+	// handle extremely simple cases that appear in tests.
+	if len(format) == 0 {
+		return ""
+	}
+	switch {
+	case strings.HasPrefix("%v", format) || strings.HasPrefix("%s", format):
+		return Sprint(args[0]) + Sprintf(format[2:], args[1:]...)
+	case !strings.HasPrefix("%", format):
+		return format[:1] + Sprintf(format[1:], args...)
+	default:
+		panic("unsupported format string for testing Sprintf")
+	}
+}
+
+func Errorf(format string, args ...interface{}) error {
+	msg := Sprintf(format, args...)
+	return errors.New(msg)
 }
diff --git a/go/ssa/interp/testdata/src/io/io.go b/go/ssa/interp/testdata/src/io/io.go
new file mode 100644
index 000000000..8cde43061
--- /dev/null
+++ b/go/ssa/interp/testdata/src/io/io.go
@@ -0,0 +1,5 @@
+package io
+
+import "errors"
+
+var EOF = errors.New("EOF")
diff --git a/go/ssa/interp/testdata/src/log/log.go b/go/ssa/interp/testdata/src/log/log.go
new file mode 100644
index 000000000..8897c1d21
--- /dev/null
+++ b/go/ssa/interp/testdata/src/log/log.go
@@ -0,0 +1,15 @@
+package log
+
+import (
+	"fmt"
+	"os"
+)
+
+func Println(v ...interface{}) {
+	fmt.Println(v...)
+}
+
+func Fatalln(v ...interface{}) {
+	Println(v...)
+	os.Exit(1)
+}
diff --git a/go/ssa/interp/testdata/src/math/math.go b/go/ssa/interp/testdata/src/math/math.go
index f51e5f572..64fe60c99 100644
--- a/go/ssa/interp/testdata/src/math/math.go
+++ b/go/ssa/interp/testdata/src/math/math.go
@@ -11,3 +11,5 @@ func Float64bits(float64) uint64
 func Signbit(x float64) bool {
 	return Float64bits(x)&(1<<63) != 0
 }
+
+func Sqrt(x float64) float64
diff --git a/go/ssa/interp/testdata/src/reflect/reflect.go b/go/ssa/interp/testdata/src/reflect/reflect.go
index f6c4e2794..8a23d272f 100644
--- a/go/ssa/interp/testdata/src/reflect/reflect.go
+++ b/go/ssa/interp/testdata/src/reflect/reflect.go
@@ -2,6 +2,8 @@ package reflect
 
 type Type interface {
 	String() string
+	Kind() Kind
+	Elem() Type
 }
 
 type Value struct {
@@ -9,8 +11,47 @@ type Value struct {
 
 func (Value) String() string
 
+func (Value) Elem() string
+func (Value) Kind() Kind
+func (Value) Int() int64
+
 func SliceOf(Type) Type
 
 func TypeOf(interface{}) Type
 
 func ValueOf(interface{}) Value
+
+type Kind uint
+
+// Constants need to be kept in sync with the actual definitions for comparisons in tests.
+const (
+	Invalid Kind = iota
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	Array
+	Chan
+	Func
+	Interface
+	Map
+	Pointer
+	Slice
+	String
+	Struct
+	UnsafePointer
+)
+
+const Ptr = Pointer
diff --git a/go/ssa/interp/testdata/src/sort/sort.go b/go/ssa/interp/testdata/src/sort/sort.go
new file mode 100644
index 000000000..d94d6dabe
--- /dev/null
+++ b/go/ssa/interp/testdata/src/sort/sort.go
@@ -0,0 +1,5 @@
+package sort
+
+func Strings(x []string)
+func Ints(x []int)
+func Float64s(x []float64)
diff --git a/go/ssa/interp/testdata/src/strconv/strconv.go b/go/ssa/interp/testdata/src/strconv/strconv.go
new file mode 100644
index 000000000..3f6f8772b
--- /dev/null
+++ b/go/ssa/interp/testdata/src/strconv/strconv.go
@@ -0,0 +1,6 @@
+package strconv
+
+func Itoa(i int) string
+func Atoi(s string) (int, error)
+
+func FormatFloat(float64, byte, int, int) string
diff --git a/go/ssa/interp/testdata/src/strings/strings.go b/go/ssa/interp/testdata/src/strings/strings.go
index dd86dcf4f..4c74f1b82 100644
--- a/go/ssa/interp/testdata/src/strings/strings.go
+++ b/go/ssa/interp/testdata/src/strings/strings.go
@@ -7,3 +7,20 @@ func Index(haystack, needle string) int
 func Contains(haystack, needle string) bool {
 	return Index(haystack, needle) >= 0
 }
+
+func HasPrefix(s, prefix string) bool {
+	return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
+}
+
+func EqualFold(s, t string) bool
+func ToLower(s string) string
+
+type Builder struct {
+	s string
+}
+
+func (b *Builder) WriteString(s string) (int, error) {
+	b.s += s
+	return len(s), nil
+}
+func (b *Builder) String() string { return b.s }
diff --git a/go/ssa/interp/testdata/src/sync/sync.go b/go/ssa/interp/testdata/src/sync/sync.go
new file mode 100644
index 000000000..457a670d6
--- /dev/null
+++ b/go/ssa/interp/testdata/src/sync/sync.go
@@ -0,0 +1,36 @@
+package sync
+
+// Rudimentary implementation of a mutex for interp tests.
+type Mutex struct {
+	c chan int // Mutex is held when held c!=nil and is empty. Access is guarded by g.
+}
+
+func (m *Mutex) Lock() {
+	c := ch(m)
+	<-c
+}
+
+func (m *Mutex) Unlock() {
+	c := ch(m)
+	c <- 1
+}
+
+// sequentializes Mutex.c access.
+var g = make(chan int, 1)
+
+func init() {
+	g <- 1
+}
+
+// ch initializes the m.c field if needed and returns it.
+func ch(m *Mutex) chan int {
+	<-g
+	defer func() {
+		g <- 1
+	}()
+	if m.c == nil {
+		m.c = make(chan int, 1)
+		m.c <- 1
+	}
+	return m.c
+}