reflect: add tests for reflect.Value.Call for the new ABI

This change adds tests for reflect.Value.Call for calling functions
using the new register-based ABI.

For #40724.

Change-Id: Ia9afd43e26dd80c7e36dd135a5b71acce8074801
Reviewed-on: https://go-review.googlesource.com/c/go/+/299269
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

2 files changed, 461 insertions, 1 deletions

diff --git a/src/reflect/abi_test.go b/src/reflect/abi_test.go
new file mode 100644
index 0000000000..418896ee87
--- /dev/null
+++ b/src/reflect/abi_test.go
@@ -0,0 +1,447 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build goexperiment.regabi
+//go:build goexperiment.regabi
+
+package reflect_test
+
+import (
+	"internal/abi"
+	"math/rand"
+	"reflect"
+	"runtime"
+	"testing"
+	"testing/quick"
+)
+
+func TestReflectValueCallABI(t *testing.T) {
+	// Enable register-based reflect.Call and ensure we don't
+	// use potentially incorrect cached versions by clearing
+	// the cache before we start and after we're done.
+	var oldRegs struct {
+		ints, floats int
+		floatSize    uintptr
+	}
+	oldRegs.ints = *reflect.IntArgRegs
+	oldRegs.floats = *reflect.FloatArgRegs
+	oldRegs.floatSize = *reflect.FloatRegSize
+	*reflect.IntArgRegs = abi.IntArgRegs
+	*reflect.FloatArgRegs = abi.FloatArgRegs
+	*reflect.FloatRegSize = uintptr(abi.EffectiveFloatRegSize)
+	reflect.ClearLayoutCache()
+	defer func() {
+		*reflect.IntArgRegs = oldRegs.ints
+		*reflect.FloatArgRegs = oldRegs.floats
+		*reflect.FloatRegSize = oldRegs.floatSize
+		reflect.ClearLayoutCache()
+	}()
+
+	// Execute the functions defined below which all have the
+	// same form and perform the same function: pass all arguments
+	// to return values. The purpose is to test the call boundary
+	// and make sure it works.
+	r := rand.New(rand.NewSource(genValueRandSeed))
+	for _, fn := range []interface{}{
+		passNone,
+		passInt,
+		passInt8,
+		passInt16,
+		passInt32,
+		passInt64,
+		passUint,
+		passUint8,
+		passUint16,
+		passUint32,
+		passUint64,
+		passFloat32,
+		passFloat64,
+		passComplex64,
+		passComplex128,
+		passManyInt,
+		passManyFloat64,
+		passArray1,
+		passArray,
+		passArray1Mix,
+		passString,
+		// TODO(mknyszek): Test passing interface values.
+		passSlice,
+		passPointer,
+		passStruct1,
+		passStruct2,
+		passStruct3,
+		passStruct4,
+		passStruct5,
+		passStruct6,
+		passStruct7,
+		passStruct8,
+		passStruct9,
+		passStruct10,
+		// TODO(mknyszek): Test passing unsafe.Pointer values.
+		// TODO(mknyszek): Test passing chan values.
+		passStruct11,
+		passStruct12,
+		passStruct13,
+		pass2Struct1,
+		passEmptyStruct,
+	} {
+		fn := reflect.ValueOf(fn)
+		t.Run(runtime.FuncForPC(fn.Pointer()).Name(), func(t *testing.T) {
+			typ := fn.Type()
+			if typ.Kind() != reflect.Func {
+				t.Fatalf("test case is not a function, has type: %s", typ.String())
+			}
+			if typ.NumIn() != typ.NumOut() {
+				t.Fatalf("test case has different number of inputs and outputs: %d in, %d out", typ.NumIn(), typ.NumOut())
+			}
+			var args []reflect.Value
+			for i := 0; i < typ.NumIn(); i++ {
+				args = append(args, genValue(t, typ.In(i), r))
+			}
+			results := fn.Call(args)
+			for i := range results {
+				x, y := args[i].Interface(), results[i].Interface()
+				if reflect.DeepEqual(x, y) {
+					continue
+				}
+				t.Errorf("arg and result %d differ: got %+v, want %+v", i, x, y)
+			}
+		})
+	}
+}
+
+// Functions for testing reflect.Value.Call.
+
+//go:registerparams
+//go:noinline
+func passNone() {}
+
+//go:registerparams
+//go:noinline
+func passInt(a int) int {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passInt8(a int8) int8 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passInt16(a int16) int16 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passInt32(a int32) int32 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passInt64(a int64) int64 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passUint(a uint) uint {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passUint8(a uint8) uint8 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passUint16(a uint16) uint16 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passUint32(a uint32) uint32 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passUint64(a uint64) uint64 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passFloat32(a float32) float32 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passFloat64(a float64) float64 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passComplex64(a complex64) complex64 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passComplex128(a complex128) complex128 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passArray1(a [1]uint32) [1]uint32 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passArray(a [2]uintptr) [2]uintptr {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passArray1Mix(a int, b [1]uint32, c float64) (int, [1]uint32, float64) {
+	return a, b, c
+}
+
+//go:registerparams
+//go:noinline
+func passString(a string) string {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passSlice(a []byte) []byte {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passPointer(a *byte) *byte {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passManyInt(a, b, c, d, e, f, g, h, i, j int) (int, int, int, int, int, int, int, int, int, int) {
+	return a, b, c, d, e, f, g, h, i, j
+}
+
+//go:registerparams
+//go:noinline
+func passManyFloat64(a, b, c, d, e, f, g, h, i, j, l, m, n, o, p, q, r, s, t float64) (float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64, float64) {
+	return a, b, c, d, e, f, g, h, i, j, l, m, n, o, p, q, r, s, t
+}
+
+//go:registerparams
+//go:noinline
+func passStruct1(a Struct1) Struct1 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct2(a Struct2) Struct2 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct3(a Struct3) Struct3 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct4(a Struct4) Struct4 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct5(a Struct5) Struct5 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct6(a Struct6) Struct6 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct7(a Struct7) Struct7 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct8(a Struct8) Struct8 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct9(a Struct9) Struct9 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct10(a Struct10) Struct10 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct11(a Struct11) Struct11 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct12(a Struct12) Struct12 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func passStruct13(a Struct13) Struct13 {
+	return a
+}
+
+//go:registerparams
+//go:noinline
+func pass2Struct1(a, b Struct1) (x, y Struct1) {
+	return a, b
+}
+
+//go:registerparams
+//go:noinline
+func passEmptyStruct(a int, b struct{}, c float64) (int, struct{}, float64) {
+	return a, b, c
+}
+
+// Struct1 is a simple integer-only aggregate struct.
+type Struct1 struct {
+	A, B, C uint
+}
+
+// Struct2 is Struct1 but with an array-typed field that will
+// force it to get passed on the stack.
+type Struct2 struct {
+	A, B, C uint
+	D       [2]uint32
+}
+
+// Struct3 is Struct2 but with an anonymous array-typed field.
+// This should act identically to Struct2.
+type Struct3 struct {
+	A, B, C uint
+	D       [2]uint32
+}
+
+// Struct4 has byte-length fields that should
+// each use up a whole registers.
+type Struct4 struct {
+	A, B int8
+	C, D uint8
+	E    bool
+}
+
+// Struct5 is a relatively large struct
+// with both integer and floating point values.
+type Struct5 struct {
+	A             uint16
+	B             int16
+	C, D          uint32
+	E             int32
+	F, G, H, I, J float32
+}
+
+// Struct6 has a nested struct.
+type Struct6 struct {
+	Struct1
+}
+
+// Struct7 is a struct with a nested array-typed field
+// that cannot be passed in registers as a result.
+type Struct7 struct {
+	Struct1
+	Struct2
+}
+
+// Struct8 is large aggregate struct type that may be
+// passed in registers.
+type Struct8 struct {
+	Struct5
+	Struct1
+}
+
+// Struct9 is a type that has an array type nested
+// 2 layers deep, and as a result needs to be passed
+// on the stack.
+type Struct9 struct {
+	Struct1
+	Struct7
+}
+
+// Struct10 is a struct type that is too large to be
+// passed in registers.
+type Struct10 struct {
+	Struct5
+	Struct8
+}
+
+// Struct11 is a struct type that has several reference
+// types in it.
+type Struct11 struct {
+	X map[string]int
+}
+
+// Struct12 has Struct11 embedded into it to test more
+// paths.
+type Struct12 struct {
+	A int
+	Struct11
+}
+
+// Struct13 tests an empty field.
+type Struct13 struct {
+	A int
+	X struct{}
+	B int
+}
+
+const genValueRandSeed = 0
+
+// genValue generates a pseudorandom reflect.Value with type t.
+// The reflect.Value produced by this function is always the same
+// for the same type.
+func genValue(t *testing.T, typ reflect.Type, r *rand.Rand) reflect.Value {
+	// Re-seed and reset the PRNG because we want each value with the
+	// same type to be the same random value.
+	r.Seed(genValueRandSeed)
+	v, ok := quick.Value(typ, r)
+	if !ok {
+		t.Fatal("failed to generate value")
+	}
+	return v
+}
diff --git a/src/reflect/export_test.go b/src/reflect/export_test.go
index ddcfca9dee..3a5ed5af3c 100644
--- a/src/reflect/export_test.go
+++ b/src/reflect/export_test.go
@@ -4,7 +4,10 @@
 
 package reflect
 
-import "unsafe"
+import (
+	"sync"
+	"unsafe"
+)
 
 // MakeRO returns a copy of v with the read-only flag set.
 func MakeRO(v Value) Value {
@@ -17,6 +20,12 @@ func IsRO(v Value) bool {
 	return v.flag&flagStickyRO != 0
 }
 
+var (
+	IntArgRegs   = &intArgRegs
+	FloatArgRegs = &floatArgRegs
+	FloatRegSize = &floatRegSize
+)
+
 var CallGC = &callGC
 
 const PtrSize = ptrSize
@@ -122,3 +131,7 @@ func ResolveReflectName(s string) {
 type Buffer struct {
 	buf []byte
 }
+
+func ClearLayoutCache() {
+	layoutCache = sync.Map{}
+}