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path: root/src/pkg/reflect/value.go
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Diffstat (limited to 'src/pkg/reflect/value.go')
-rw-r--r--src/pkg/reflect/value.go968
1 files changed, 562 insertions, 406 deletions
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go
index df549f5e1..576cbc398 100644
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -62,14 +62,15 @@ type Value struct {
// typ holds the type of the value represented by a Value.
typ *rtype
- // val holds the 1-word representation of the value.
- // If flag's flagIndir bit is set, then val is a pointer to the data.
- // Otherwise val is a word holding the actual data.
- // When the data is smaller than a word, it begins at
- // the first byte (in the memory address sense) of val.
- // We use unsafe.Pointer so that the garbage collector
- // knows that val could be a pointer.
- val unsafe.Pointer
+ // Pointer-valued data or, if flagIndir is set, pointer to data.
+ // Valid when either flagIndir is set or typ.pointers() is true.
+ ptr unsafe.Pointer
+
+ // Non-pointer-valued data. When the data is smaller
+ // than a word, it begins at the first byte (in the memory
+ // address sense) of this field.
+ // Valid when flagIndir is not set and typ.pointers() is false.
+ scalar uintptr
// flag holds metadata about the value.
// The lowest bits are flag bits:
@@ -108,6 +109,78 @@ func (f flag) kind() Kind {
return Kind((f >> flagKindShift) & flagKindMask)
}
+// pointer returns the underlying pointer represented by v.
+// v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
+func (v Value) pointer() unsafe.Pointer {
+ if v.typ.size != ptrSize || !v.typ.pointers() {
+ panic("can't call pointer on a non-pointer Value")
+ }
+ if v.flag&flagIndir != 0 {
+ return *(*unsafe.Pointer)(v.ptr)
+ }
+ return v.ptr
+}
+
+// packEface converts v to the empty interface.
+func packEface(v Value) interface{} {
+ t := v.typ
+ var i interface{}
+ e := (*emptyInterface)(unsafe.Pointer(&i))
+ // First, fill in the data portion of the interface.
+ switch {
+ case t.size > ptrSize:
+ // Value is indirect, and so is the interface we're making.
+ ptr := v.ptr
+ if v.flag&flagAddr != 0 {
+ // TODO: pass safe boolean from valueInterface so
+ // we don't need to copy if safe==true?
+ c := unsafe_New(t)
+ memmove(c, ptr, t.size)
+ ptr = c
+ }
+ e.word = iword(ptr)
+ case v.flag&flagIndir != 0:
+ // Value is indirect, but interface is direct. We need
+ // to load the data at v.ptr into the interface data word.
+ if t.pointers() {
+ e.word = iword(*(*unsafe.Pointer)(v.ptr))
+ } else {
+ e.word = iword(loadScalar(v.ptr, t.size))
+ }
+ default:
+ // Value is direct, and so is the interface.
+ if t.pointers() {
+ e.word = iword(v.ptr)
+ } else {
+ e.word = iword(v.scalar)
+ }
+ }
+ // Now, fill in the type portion. We're very careful here not
+ // to have any operation between the e.word and e.typ assignments
+ // that would let the garbage collector observe the partially-built
+ // interface value.
+ e.typ = t
+ return i
+}
+
+// unpackEface converts the empty interface i to a Value.
+func unpackEface(i interface{}) Value {
+ e := (*emptyInterface)(unsafe.Pointer(&i))
+ // NOTE: don't read e.word until we know whether it is really a pointer or not.
+ t := e.typ
+ if t == nil {
+ return Value{}
+ }
+ f := flag(t.Kind()) << flagKindShift
+ if t.size > ptrSize {
+ return Value{t, unsafe.Pointer(e.word), 0, f | flagIndir}
+ }
+ if t.pointers() {
+ return Value{t, unsafe.Pointer(e.word), 0, f}
+ }
+ return Value{t, nil, uintptr(e.word), f}
+}
+
// A ValueError occurs when a Value method is invoked on
// a Value that does not support it. Such cases are documented
// in the description of each method.
@@ -139,28 +212,21 @@ func methodName() string {
// bigger than a pointer, its word is a pointer to v's data.
// Otherwise, its word holds the data stored
// in its leading bytes (so is not a pointer).
-// Because the value sometimes holds a pointer, we use
-// unsafe.Pointer to represent it, so that if iword appears
-// in a struct, the garbage collector knows that might be
-// a pointer.
+// This type is very dangerous for the garbage collector because
+// it must be treated conservatively. We try to never expose it
+// to the GC here so that GC remains precise.
type iword unsafe.Pointer
-func (v Value) iword() iword {
- if v.flag&flagIndir != 0 && v.typ.size <= ptrSize {
- // Have indirect but want direct word.
- return loadIword(v.val, v.typ.size)
- }
- return iword(v.val)
-}
-
-// loadIword loads n bytes at p from memory into an iword.
-func loadIword(p unsafe.Pointer, n uintptr) iword {
+// loadScalar loads n bytes at p from memory into a uintptr
+// that forms the second word of an interface. The data
+// must be non-pointer in nature.
+func loadScalar(p unsafe.Pointer, n uintptr) uintptr {
// Run the copy ourselves instead of calling memmove
// to avoid moving w to the heap.
- var w iword
+ var w uintptr
switch n {
default:
- panic("reflect: internal error: loadIword of " + strconv.Itoa(int(n)) + "-byte value")
+ panic("reflect: internal error: loadScalar of " + strconv.Itoa(int(n)) + "-byte value")
case 0:
case 1:
*(*uint8)(unsafe.Pointer(&w)) = *(*uint8)(p)
@@ -182,13 +248,13 @@ func loadIword(p unsafe.Pointer, n uintptr) iword {
return w
}
-// storeIword stores n bytes from w into p.
-func storeIword(p unsafe.Pointer, w iword, n uintptr) {
+// storeScalar stores n bytes from w into p.
+func storeScalar(p unsafe.Pointer, w uintptr, n uintptr) {
// Run the copy ourselves instead of calling memmove
// to avoid moving w to the heap.
switch n {
default:
- panic("reflect: internal error: storeIword of " + strconv.Itoa(int(n)) + "-byte value")
+ panic("reflect: internal error: storeScalar of " + strconv.Itoa(int(n)) + "-byte value")
case 0:
case 1:
*(*uint8)(p) = *(*uint8)(unsafe.Pointer(&w))
@@ -278,7 +344,7 @@ func (v Value) Addr() Value {
if v.flag&flagAddr == 0 {
panic("reflect.Value.Addr of unaddressable value")
}
- return Value{v.typ.ptrTo(), v.val, (v.flag & flagRO) | flag(Ptr)<<flagKindShift}
+ return Value{v.typ.ptrTo(), v.ptr, 0, (v.flag & flagRO) | flag(Ptr)<<flagKindShift}
}
// Bool returns v's underlying value.
@@ -286,9 +352,9 @@ func (v Value) Addr() Value {
func (v Value) Bool() bool {
v.mustBe(Bool)
if v.flag&flagIndir != 0 {
- return *(*bool)(v.val)
+ return *(*bool)(v.ptr)
}
- return *(*bool)(unsafe.Pointer(&v.val))
+ return *(*bool)(unsafe.Pointer(&v.scalar))
}
// Bytes returns v's underlying value.
@@ -299,7 +365,7 @@ func (v Value) Bytes() []byte {
panic("reflect.Value.Bytes of non-byte slice")
}
// Slice is always bigger than a word; assume flagIndir.
- return *(*[]byte)(v.val)
+ return *(*[]byte)(v.ptr)
}
// runes returns v's underlying value.
@@ -310,7 +376,7 @@ func (v Value) runes() []rune {
panic("reflect.Value.Bytes of non-rune slice")
}
// Slice is always bigger than a word; assume flagIndir.
- return *(*[]rune)(v.val)
+ return *(*[]rune)(v.ptr)
}
// CanAddr returns true if the value's address can be obtained with Addr.
@@ -358,19 +424,28 @@ func (v Value) CallSlice(in []Value) []Value {
return v.call("CallSlice", in)
}
+var callGC bool // for testing; see TestCallMethodJump
+
+var makeFuncStubFn = makeFuncStub
+var makeFuncStubCode = **(**uintptr)(unsafe.Pointer(&makeFuncStubFn))
+var methodValueCallFn = methodValueCall
+var methodValueCallCode = **(**uintptr)(unsafe.Pointer(&methodValueCallFn))
+
func (v Value) call(op string, in []Value) []Value {
// Get function pointer, type.
t := v.typ
var (
- fn unsafe.Pointer
- rcvr iword
+ fn unsafe.Pointer
+ rcvr Value
+ rcvrtype *rtype
)
if v.flag&flagMethod != 0 {
- t, fn, rcvr = methodReceiver(op, v, int(v.flag)>>flagMethodShift)
+ rcvr = v
+ rcvrtype, t, fn = methodReceiver(op, v, int(v.flag)>>flagMethodShift)
} else if v.flag&flagIndir != 0 {
- fn = *(*unsafe.Pointer)(v.val)
+ fn = *(*unsafe.Pointer)(v.ptr)
} else {
- fn = v.val
+ fn = v.ptr
}
if fn == nil {
@@ -434,23 +509,36 @@ func (v Value) call(op string, in []Value) []Value {
}
nout := t.NumOut()
- // Compute arg size & allocate.
- // This computation is 5g/6g/8g-dependent
- // and probably wrong for gccgo, but so
- // is most of this function.
- size, _, _, _ := frameSize(t, v.flag&flagMethod != 0)
-
- // Copy into args.
- //
- // TODO(rsc): This will need to be updated for any new garbage collector.
- // For now make everything look like a pointer by allocating
- // a []unsafe.Pointer.
- args := make([]unsafe.Pointer, size/ptrSize)
- ptr := unsafe.Pointer(&args[0])
+ // If target is makeFuncStub, short circuit the unpack onto stack /
+ // pack back into []Value for the args and return values. Just do the
+ // call directly.
+ // We need to do this here because otherwise we have a situation where
+ // reflect.callXX calls makeFuncStub, neither of which knows the
+ // layout of the args. That's bad for precise gc & stack copying.
+ x := (*makeFuncImpl)(fn)
+ if x.code == makeFuncStubCode {
+ return x.fn(in)
+ }
+
+ // If the target is methodValueCall, do its work here: add the receiver
+ // argument and call the real target directly.
+ // We need to do this here because otherwise we have a situation where
+ // reflect.callXX calls methodValueCall, neither of which knows the
+ // layout of the args. That's bad for precise gc & stack copying.
+ y := (*methodValue)(fn)
+ if y.fn == methodValueCallCode {
+ rcvr = y.rcvr
+ rcvrtype, t, fn = methodReceiver("call", rcvr, y.method)
+ }
+
+ // Compute frame type, allocate a chunk of memory for frame
+ frametype, _, retOffset := funcLayout(t, rcvrtype)
+ args := unsafe_New(frametype)
off := uintptr(0)
- if v.flag&flagMethod != 0 {
- // Hard-wired first argument.
- *(*iword)(ptr) = rcvr
+
+ // Copy inputs into args.
+ if rcvrtype != nil {
+ storeRcvr(rcvr, args)
off = ptrSize
}
for i, v := range in {
@@ -459,30 +547,35 @@ func (v Value) call(op string, in []Value) []Value {
a := uintptr(targ.align)
off = (off + a - 1) &^ (a - 1)
n := targ.size
- addr := unsafe.Pointer(uintptr(ptr) + off)
+ addr := unsafe.Pointer(uintptr(args) + off)
v = v.assignTo("reflect.Value.Call", targ, (*interface{})(addr))
- if v.flag&flagIndir == 0 {
- storeIword(addr, iword(v.val), n)
+ if v.flag&flagIndir != 0 {
+ memmove(addr, v.ptr, n)
+ } else if targ.pointers() {
+ *(*unsafe.Pointer)(addr) = v.ptr
} else {
- memmove(addr, v.val, n)
+ storeScalar(addr, v.scalar, n)
}
off += n
}
- off = (off + ptrSize - 1) &^ (ptrSize - 1)
// Call.
- call(fn, ptr, uint32(size))
+ call(fn, args, uint32(frametype.size), uint32(retOffset))
+
+ // For testing; see TestCallMethodJump.
+ if callGC {
+ runtime.GC()
+ }
// Copy return values out of args.
- //
- // TODO(rsc): revisit like above.
ret := make([]Value, nout)
+ off = retOffset
for i := 0; i < nout; i++ {
tv := t.Out(i)
a := uintptr(tv.Align())
off = (off + a - 1) &^ (a - 1)
fl := flagIndir | flag(tv.Kind())<<flagKindShift
- ret[i] = Value{tv.common(), unsafe.Pointer(uintptr(ptr) + off), fl}
+ ret[i] = Value{tv.common(), unsafe.Pointer(uintptr(args) + off), 0, fl}
off += tv.Size()
}
@@ -512,18 +605,20 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer) {
for _, arg := range ftyp.in {
typ := arg
off += -off & uintptr(typ.align-1)
- v := Value{typ, nil, flag(typ.Kind()) << flagKindShift}
- if typ.size <= ptrSize {
- // value fits in word.
- v.val = unsafe.Pointer(loadIword(unsafe.Pointer(uintptr(ptr)+off), typ.size))
- } else {
+ addr := unsafe.Pointer(uintptr(ptr) + off)
+ v := Value{typ, nil, 0, flag(typ.Kind()) << flagKindShift}
+ if typ.size > ptrSize {
// value does not fit in word.
// Must make a copy, because f might keep a reference to it,
// and we cannot let f keep a reference to the stack frame
// after this function returns, not even a read-only reference.
- v.val = unsafe_New(typ)
- memmove(v.val, unsafe.Pointer(uintptr(ptr)+off), typ.size)
+ v.ptr = unsafe_New(typ)
+ memmove(v.ptr, addr, typ.size)
v.flag |= flagIndir
+ } else if typ.pointers() {
+ v.ptr = *(*unsafe.Pointer)(addr)
+ } else {
+ v.scalar = loadScalar(addr, typ.size)
}
in = append(in, v)
off += typ.size
@@ -538,6 +633,9 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer) {
// Copy results back into argument frame.
if len(ftyp.out) > 0 {
off += -off & (ptrSize - 1)
+ if runtime.GOARCH == "amd64p32" {
+ off = align(off, 8)
+ }
for i, arg := range ftyp.out {
typ := arg
v := out[i]
@@ -552,10 +650,12 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer) {
}
off += -off & uintptr(typ.align-1)
addr := unsafe.Pointer(uintptr(ptr) + off)
- if v.flag&flagIndir == 0 {
- storeIword(addr, iword(v.val), typ.size)
+ if v.flag&flagIndir != 0 {
+ memmove(addr, v.ptr, typ.size)
+ } else if typ.pointers() {
+ *(*unsafe.Pointer)(addr) = v.ptr
} else {
- memmove(addr, v.val, typ.size)
+ storeScalar(addr, v.scalar, typ.size)
}
off += typ.size
}
@@ -566,7 +666,10 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer) {
// described by v. The Value v may or may not have the
// flagMethod bit set, so the kind cached in v.flag should
// not be used.
-func methodReceiver(op string, v Value, methodIndex int) (t *rtype, fn unsafe.Pointer, rcvr iword) {
+// The return value rcvrtype gives the method's actual receiver type.
+// The return value t gives the method type signature (without the receiver).
+// The return value fn is a pointer to the method code.
+func methodReceiver(op string, v Value, methodIndex int) (rcvrtype, t *rtype, fn unsafe.Pointer) {
i := methodIndex
if v.typ.Kind() == Interface {
tt := (*interfaceType)(unsafe.Pointer(v.typ))
@@ -577,14 +680,15 @@ func methodReceiver(op string, v Value, methodIndex int) (t *rtype, fn unsafe.Po
if m.pkgPath != nil {
panic("reflect: " + op + " of unexported method")
}
- t = m.typ
- iface := (*nonEmptyInterface)(v.val)
+ iface := (*nonEmptyInterface)(v.ptr)
if iface.itab == nil {
panic("reflect: " + op + " of method on nil interface value")
}
+ rcvrtype = iface.itab.typ
fn = unsafe.Pointer(&iface.itab.fun[i])
- rcvr = iface.word
+ t = m.typ
} else {
+ rcvrtype = v.typ
ut := v.typ.uncommon()
if ut == nil || i < 0 || i >= len(ut.methods) {
panic("reflect: internal error: invalid method index")
@@ -595,58 +699,41 @@ func methodReceiver(op string, v Value, methodIndex int) (t *rtype, fn unsafe.Po
}
fn = unsafe.Pointer(&m.ifn)
t = m.mtyp
- rcvr = v.iword()
}
return
}
+// v is a method receiver. Store at p the word which is used to
+// encode that receiver at the start of the argument list.
+// Reflect uses the "interface" calling convention for
+// methods, which always uses one word to record the receiver.
+func storeRcvr(v Value, p unsafe.Pointer) {
+ t := v.typ
+ if t.Kind() == Interface {
+ // the interface data word becomes the receiver word
+ iface := (*nonEmptyInterface)(v.ptr)
+ *(*unsafe.Pointer)(p) = unsafe.Pointer(iface.word)
+ } else if v.flag&flagIndir != 0 {
+ if t.size > ptrSize {
+ *(*unsafe.Pointer)(p) = v.ptr
+ } else if t.pointers() {
+ *(*unsafe.Pointer)(p) = *(*unsafe.Pointer)(v.ptr)
+ } else {
+ *(*uintptr)(p) = loadScalar(v.ptr, t.size)
+ }
+ } else if t.pointers() {
+ *(*unsafe.Pointer)(p) = v.ptr
+ } else {
+ *(*uintptr)(p) = v.scalar
+ }
+}
+
// align returns the result of rounding x up to a multiple of n.
// n must be a power of two.
func align(x, n uintptr) uintptr {
return (x + n - 1) &^ (n - 1)
}
-// frameSize returns the sizes of the argument and result frame
-// for a function of the given type. The rcvr bool specifies whether
-// a one-word receiver should be included in the total.
-func frameSize(t *rtype, rcvr bool) (total, in, outOffset, out uintptr) {
- if rcvr {
- // extra word for receiver interface word
- total += ptrSize
- }
-
- nin := t.NumIn()
- in = -total
- for i := 0; i < nin; i++ {
- tv := t.In(i)
- total = align(total, uintptr(tv.Align()))
- total += tv.Size()
- }
- in += total
- total = align(total, ptrSize)
- nout := t.NumOut()
- outOffset = total
- out = -total
- for i := 0; i < nout; i++ {
- tv := t.Out(i)
- total = align(total, uintptr(tv.Align()))
- total += tv.Size()
- }
- out += total
-
- // total must be > 0 in order for &args[0] to be valid.
- // the argument copying is going to round it up to
- // a multiple of ptrSize anyway, so make it ptrSize to begin with.
- if total < ptrSize {
- total = ptrSize
- }
-
- // round to pointer
- total = align(total, ptrSize)
-
- return
-}
-
// callMethod is the call implementation used by a function returned
// by makeMethodValue (used by v.Method(i).Interface()).
// It is a streamlined version of the usual reflect call: the caller has
@@ -659,24 +746,31 @@ func frameSize(t *rtype, rcvr bool) (total, in, outOffset, out uintptr) {
// so that the linker can make it work correctly for panic and recover.
// The gc compilers know to do that for the name "reflect.callMethod".
func callMethod(ctxt *methodValue, frame unsafe.Pointer) {
- t, fn, rcvr := methodReceiver("call", ctxt.rcvr, ctxt.method)
- total, in, outOffset, out := frameSize(t, true)
-
- // Copy into args.
- //
- // TODO(rsc): This will need to be updated for any new garbage collector.
- // For now make everything look like a pointer by allocating
- // a []unsafe.Pointer.
- args := make([]unsafe.Pointer, total/ptrSize)
- args[0] = unsafe.Pointer(rcvr)
- base := unsafe.Pointer(&args[0])
- memmove(unsafe.Pointer(uintptr(base)+ptrSize), frame, in)
+ rcvr := ctxt.rcvr
+ rcvrtype, t, fn := methodReceiver("call", rcvr, ctxt.method)
+ frametype, argSize, retOffset := funcLayout(t, rcvrtype)
+
+ // Make a new frame that is one word bigger so we can store the receiver.
+ args := unsafe_New(frametype)
+
+ // Copy in receiver and rest of args.
+ storeRcvr(rcvr, args)
+ memmove(unsafe.Pointer(uintptr(args)+ptrSize), frame, argSize-ptrSize)
// Call.
- call(fn, unsafe.Pointer(&args[0]), uint32(total))
+ call(fn, args, uint32(frametype.size), uint32(retOffset))
- // Copy return values.
- memmove(unsafe.Pointer(uintptr(frame)+outOffset-ptrSize), unsafe.Pointer(uintptr(base)+outOffset), out)
+ // Copy return values. On amd64p32, the beginning of return values
+ // is 64-bit aligned, so the caller's frame layout (which doesn't have
+ // a receiver) is different from the layout of the fn call, which has
+ // a receiver.
+ // Ignore any changes to args and just copy return values.
+ callerRetOffset := retOffset - ptrSize
+ if runtime.GOARCH == "amd64p32" {
+ callerRetOffset = align(argSize-ptrSize, 8)
+ }
+ memmove(unsafe.Pointer(uintptr(frame)+callerRetOffset),
+ unsafe.Pointer(uintptr(args)+retOffset), frametype.size-retOffset)
}
// funcName returns the name of f, for use in error messages.
@@ -697,10 +791,10 @@ func (v Value) Cap() int {
case Array:
return v.typ.Len()
case Chan:
- return int(chancap(v.iword()))
+ return int(chancap(v.pointer()))
case Slice:
// Slice is always bigger than a word; assume flagIndir.
- return (*SliceHeader)(v.val).Cap
+ return (*sliceHeader)(v.ptr).Cap
}
panic(&ValueError{"reflect.Value.Cap", k})
}
@@ -710,7 +804,7 @@ func (v Value) Cap() int {
func (v Value) Close() {
v.mustBe(Chan)
v.mustBeExported()
- chanclose(v.iword())
+ chanclose(v.pointer())
}
// Complex returns v's underlying value, as a complex128.
@@ -720,12 +814,12 @@ func (v Value) Complex() complex128 {
switch k {
case Complex64:
if v.flag&flagIndir != 0 {
- return complex128(*(*complex64)(v.val))
+ return complex128(*(*complex64)(v.ptr))
}
- return complex128(*(*complex64)(unsafe.Pointer(&v.val)))
+ return complex128(*(*complex64)(unsafe.Pointer(&v.scalar)))
case Complex128:
// complex128 is always bigger than a word; assume flagIndir.
- return *(*complex128)(v.val)
+ return *(*complex128)(v.ptr)
}
panic(&ValueError{"reflect.Value.Complex", k})
}
@@ -738,48 +832,31 @@ func (v Value) Elem() Value {
k := v.kind()
switch k {
case Interface:
- var (
- typ *rtype
- val unsafe.Pointer
- )
+ var eface interface{}
if v.typ.NumMethod() == 0 {
- eface := (*emptyInterface)(v.val)
- if eface.typ == nil {
- // nil interface value
- return Value{}
- }
- typ = eface.typ
- val = unsafe.Pointer(eface.word)
+ eface = *(*interface{})(v.ptr)
} else {
- iface := (*nonEmptyInterface)(v.val)
- if iface.itab == nil {
- // nil interface value
- return Value{}
- }
- typ = iface.itab.typ
- val = unsafe.Pointer(iface.word)
- }
- fl := v.flag & flagRO
- fl |= flag(typ.Kind()) << flagKindShift
- if typ.size > ptrSize {
- fl |= flagIndir
+ eface = (interface{})(*(*interface {
+ M()
+ })(v.ptr))
}
- return Value{typ, val, fl}
-
+ x := unpackEface(eface)
+ x.flag |= v.flag & flagRO
+ return x
case Ptr:
- val := v.val
+ ptr := v.ptr
if v.flag&flagIndir != 0 {
- val = *(*unsafe.Pointer)(val)
+ ptr = *(*unsafe.Pointer)(ptr)
}
// The returned value's address is v's value.
- if val == nil {
+ if ptr == nil {
return Value{}
}
tt := (*ptrType)(unsafe.Pointer(v.typ))
typ := tt.elem
fl := v.flag&flagRO | flagIndir | flagAddr
fl |= flag(typ.Kind() << flagKindShift)
- return Value{typ, val, fl}
+ return Value{typ, ptr, 0, fl}
}
panic(&ValueError{"reflect.Value.Elem", k})
}
@@ -803,20 +880,26 @@ func (v Value) Field(i int) Value {
}
fl |= flag(typ.Kind()) << flagKindShift
- var val unsafe.Pointer
+ var ptr unsafe.Pointer
+ var scalar uintptr
switch {
case fl&flagIndir != 0:
// Indirect. Just bump pointer.
- val = unsafe.Pointer(uintptr(v.val) + field.offset)
+ ptr = unsafe.Pointer(uintptr(v.ptr) + field.offset)
+ case typ.pointers():
+ if field.offset != 0 {
+ panic("field access of ptr value isn't at offset 0")
+ }
+ ptr = v.ptr
case bigEndian:
- // Direct. Discard leading bytes.
- val = unsafe.Pointer(uintptr(v.val) << (field.offset * 8))
+ // Must be scalar. Discard leading bytes.
+ scalar = v.scalar << (field.offset * 8)
default:
- // Direct. Discard leading bytes.
- val = unsafe.Pointer(uintptr(v.val) >> (field.offset * 8))
+ // Must be scalar. Discard leading bytes.
+ scalar = v.scalar >> (field.offset * 8)
}
- return Value{typ, val, fl}
+ return Value{typ, ptr, scalar, fl}
}
// FieldByIndex returns the nested field corresponding to index.
@@ -825,7 +908,10 @@ func (v Value) FieldByIndex(index []int) Value {
v.mustBe(Struct)
for i, x := range index {
if i > 0 {
- if v.Kind() == Ptr && v.Elem().Kind() == Struct {
+ if v.Kind() == Ptr && v.typ.Elem().Kind() == Struct {
+ if v.IsNil() {
+ panic("reflect: indirection through nil pointer to embedded struct")
+ }
v = v.Elem()
}
}
@@ -864,14 +950,14 @@ func (v Value) Float() float64 {
switch k {
case Float32:
if v.flag&flagIndir != 0 {
- return float64(*(*float32)(v.val))
+ return float64(*(*float32)(v.ptr))
}
- return float64(*(*float32)(unsafe.Pointer(&v.val)))
+ return float64(*(*float32)(unsafe.Pointer(&v.scalar)))
case Float64:
if v.flag&flagIndir != 0 {
- return *(*float64)(v.val)
+ return *(*float64)(v.ptr)
}
- return *(*float64)(unsafe.Pointer(&v.val))
+ return *(*float64)(unsafe.Pointer(&v.scalar))
}
panic(&ValueError{"reflect.Value.Float", k})
}
@@ -894,41 +980,48 @@ func (v Value) Index(i int) Value {
offset := uintptr(i) * typ.size
var val unsafe.Pointer
+ var scalar uintptr
switch {
case fl&flagIndir != 0:
// Indirect. Just bump pointer.
- val = unsafe.Pointer(uintptr(v.val) + offset)
+ val = unsafe.Pointer(uintptr(v.ptr) + offset)
+ case typ.pointers():
+ if offset != 0 {
+ panic("can't Index(i) with i!=0 on ptrLike value")
+ }
+ val = v.ptr
case bigEndian:
// Direct. Discard leading bytes.
- val = unsafe.Pointer(uintptr(v.val) << (offset * 8))
+ scalar = v.scalar << (offset * 8)
default:
// Direct. Discard leading bytes.
- val = unsafe.Pointer(uintptr(v.val) >> (offset * 8))
+ scalar = v.scalar >> (offset * 8)
}
- return Value{typ, val, fl}
+ return Value{typ, val, scalar, fl}
case Slice:
// Element flag same as Elem of Ptr.
// Addressable, indirect, possibly read-only.
fl := flagAddr | flagIndir | v.flag&flagRO
- s := (*SliceHeader)(v.val)
+ s := (*sliceHeader)(v.ptr)
if i < 0 || i >= s.Len {
panic("reflect: slice index out of range")
}
tt := (*sliceType)(unsafe.Pointer(v.typ))
typ := tt.elem
fl |= flag(typ.Kind()) << flagKindShift
- val := unsafe.Pointer(s.Data + uintptr(i)*typ.size)
- return Value{typ, val, fl}
+ val := unsafe.Pointer(uintptr(s.Data) + uintptr(i)*typ.size)
+ return Value{typ, val, 0, fl}
case String:
fl := v.flag&flagRO | flag(Uint8<<flagKindShift)
- s := (*StringHeader)(v.val)
+ s := (*stringHeader)(v.ptr)
if i < 0 || i >= s.Len {
panic("reflect: string index out of range")
}
- val := *(*byte)(unsafe.Pointer(s.Data + uintptr(i)))
- return Value{uint8Type, unsafe.Pointer(uintptr(val)), fl}
+ b := uintptr(0)
+ *(*byte)(unsafe.Pointer(&b)) = *(*byte)(unsafe.Pointer(uintptr(s.Data) + uintptr(i)))
+ return Value{uint8Type, nil, b, fl}
}
panic(&ValueError{"reflect.Value.Index", k})
}
@@ -939,11 +1032,11 @@ func (v Value) Int() int64 {
k := v.kind()
var p unsafe.Pointer
if v.flag&flagIndir != 0 {
- p = v.val
+ p = v.ptr
} else {
- // The escape analysis is good enough that &v.val
+ // The escape analysis is good enough that &v.scalar
// does not trigger a heap allocation.
- p = unsafe.Pointer(&v.val)
+ p = unsafe.Pointer(&v.scalar)
}
switch k {
case Int:
@@ -991,51 +1084,42 @@ func valueInterface(v Value, safe bool) interface{} {
v = makeMethodValue("Interface", v)
}
- k := v.kind()
- if k == Interface {
+ if v.kind() == Interface {
// Special case: return the element inside the interface.
// Empty interface has one layout, all interfaces with
// methods have a second layout.
if v.NumMethod() == 0 {
- return *(*interface{})(v.val)
+ return *(*interface{})(v.ptr)
}
return *(*interface {
M()
- })(v.val)
- }
-
- // Non-interface value.
- var eface emptyInterface
- eface.typ = v.typ
- eface.word = v.iword()
-
- // Don't need to allocate if v is not addressable or fits in one word.
- if v.flag&flagAddr != 0 && v.typ.size > ptrSize {
- // eface.word is a pointer to the actual data,
- // which might be changed. We need to return
- // a pointer to unchanging data, so make a copy.
- ptr := unsafe_New(v.typ)
- memmove(ptr, unsafe.Pointer(eface.word), v.typ.size)
- eface.word = iword(ptr)
+ })(v.ptr)
}
- return *(*interface{})(unsafe.Pointer(&eface))
+ // TODO: pass safe to packEface so we don't need to copy if safe==true?
+ return packEface(v)
}
// InterfaceData returns the interface v's value as a uintptr pair.
// It panics if v's Kind is not Interface.
func (v Value) InterfaceData() [2]uintptr {
+ // TODO: deprecate this
v.mustBe(Interface)
// We treat this as a read operation, so we allow
// it even for unexported data, because the caller
// has to import "unsafe" to turn it into something
// that can be abused.
// Interface value is always bigger than a word; assume flagIndir.
- return *(*[2]uintptr)(v.val)
+ return *(*[2]uintptr)(v.ptr)
}
-// IsNil returns true if v is a nil value.
-// It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice.
+// IsNil reports whether its argument v is nil. The argument must be
+// a chan, func, interface, map, pointer, or slice value; if it is
+// not, IsNil panics. Note that IsNil is not always equivalent to a
+// regular comparison with nil in Go. For example, if v was created
+// by calling ValueOf with an uninitialized interface variable i,
+// i==nil will be true but v.IsNil will panic as v will be the zero
+// Value.
func (v Value) IsNil() bool {
k := v.kind()
switch k {
@@ -1043,7 +1127,7 @@ func (v Value) IsNil() bool {
if v.flag&flagMethod != 0 {
return false
}
- ptr := v.val
+ ptr := v.ptr
if v.flag&flagIndir != 0 {
ptr = *(*unsafe.Pointer)(ptr)
}
@@ -1051,7 +1135,7 @@ func (v Value) IsNil() bool {
case Interface, Slice:
// Both interface and slice are nil if first word is 0.
// Both are always bigger than a word; assume flagIndir.
- return *(*unsafe.Pointer)(v.val) == nil
+ return *(*unsafe.Pointer)(v.ptr) == nil
}
panic(&ValueError{"reflect.Value.IsNil", k})
}
@@ -1080,15 +1164,15 @@ func (v Value) Len() int {
tt := (*arrayType)(unsafe.Pointer(v.typ))
return int(tt.len)
case Chan:
- return chanlen(v.iword())
+ return chanlen(v.pointer())
case Map:
- return maplen(v.iword())
+ return maplen(v.pointer())
case Slice:
// Slice is bigger than a word; assume flagIndir.
- return (*SliceHeader)(v.val).Len
+ return (*sliceHeader)(v.ptr).Len
case String:
// String is bigger than a word; assume flagIndir.
- return (*StringHeader)(v.val).Len
+ return (*stringHeader)(v.ptr).Len
}
panic(&ValueError{"reflect.Value.Len", k})
}
@@ -1110,17 +1194,32 @@ func (v Value) MapIndex(key Value) Value {
// of unexported fields.
key = key.assignTo("reflect.Value.MapIndex", tt.key, nil)
- word, ok := mapaccess(v.typ, v.iword(), key.iword())
- if !ok {
+ var k unsafe.Pointer
+ if key.flag&flagIndir != 0 {
+ k = key.ptr
+ } else if key.typ.pointers() {
+ k = unsafe.Pointer(&key.ptr)
+ } else {
+ k = unsafe.Pointer(&key.scalar)
+ }
+ e := mapaccess(v.typ, v.pointer(), k)
+ if e == nil {
return Value{}
}
typ := tt.elem
fl := (v.flag | key.flag) & flagRO
+ fl |= flag(typ.Kind()) << flagKindShift
if typ.size > ptrSize {
- fl |= flagIndir
+ // Copy result so future changes to the map
+ // won't change the underlying value.
+ c := unsafe_New(typ)
+ memmove(c, e, typ.size)
+ return Value{typ, c, 0, fl | flagIndir}
+ } else if typ.pointers() {
+ return Value{typ, *(*unsafe.Pointer)(e), 0, fl}
+ } else {
+ return Value{typ, nil, loadScalar(e, typ.size), fl}
}
- fl |= flag(typ.Kind()) << flagKindShift
- return Value{typ, unsafe.Pointer(word), fl}
}
// MapKeys returns a slice containing all the keys present in the map,
@@ -1132,13 +1231,9 @@ func (v Value) MapKeys() []Value {
tt := (*mapType)(unsafe.Pointer(v.typ))
keyType := tt.key
- fl := v.flag & flagRO
- fl |= flag(keyType.Kind()) << flagKindShift
- if keyType.size > ptrSize {
- fl |= flagIndir
- }
+ fl := v.flag&flagRO | flag(keyType.Kind())<<flagKindShift
- m := v.iword()
+ m := v.pointer()
mlen := int(0)
if m != nil {
mlen = maplen(m)
@@ -1147,11 +1242,24 @@ func (v Value) MapKeys() []Value {
a := make([]Value, mlen)
var i int
for i = 0; i < len(a); i++ {
- keyWord, ok := mapiterkey(it)
- if !ok {
+ key := mapiterkey(it)
+ if key == nil {
+ // Someone deleted an entry from the map since we
+ // called maplen above. It's a data race, but nothing
+ // we can do about it.
break
}
- a[i] = Value{keyType, unsafe.Pointer(keyWord), fl}
+ if keyType.size > ptrSize {
+ // Copy result so future changes to the map
+ // won't change the underlying value.
+ c := unsafe_New(keyType)
+ memmove(c, key, keyType.size)
+ a[i] = Value{keyType, c, 0, fl | flagIndir}
+ } else if keyType.pointers() {
+ a[i] = Value{keyType, *(*unsafe.Pointer)(key), 0, fl}
+ } else {
+ a[i] = Value{keyType, nil, loadScalar(key, keyType.size), fl}
+ }
mapiternext(it)
}
return a[:i]
@@ -1174,7 +1282,7 @@ func (v Value) Method(i int) Value {
fl := v.flag & (flagRO | flagIndir)
fl |= flag(Func) << flagKindShift
fl |= flag(i)<<flagMethodShift | flagMethod
- return Value{v.typ, v.val, fl}
+ return Value{v.typ, v.ptr, v.scalar, fl}
}
// NumMethod returns the number of methods in the value's method set.
@@ -1284,15 +1392,16 @@ func (v Value) OverflowUint(x uint64) bool {
// code pointer, but not necessarily enough to identify a
// single function uniquely. The only guarantee is that the
// result is zero if and only if v is a nil func Value.
+//
+// If v's Kind is Slice, the returned pointer is to the first
+// element of the slice. If the slice is nil the returned value
+// is 0. If the slice is empty but non-nil the return value is non-zero.
func (v Value) Pointer() uintptr {
+ // TODO: deprecate
k := v.kind()
switch k {
case Chan, Map, Ptr, UnsafePointer:
- p := v.val
- if v.flag&flagIndir != 0 {
- p = *(*unsafe.Pointer)(p)
- }
- return uintptr(p)
+ return uintptr(v.pointer())
case Func:
if v.flag&flagMethod != 0 {
// As the doc comment says, the returned pointer is an
@@ -1304,10 +1413,7 @@ func (v Value) Pointer() uintptr {
f := methodValueCall
return **(**uintptr)(unsafe.Pointer(&f))
}
- p := v.val
- if v.flag&flagIndir != 0 {
- p = *(*unsafe.Pointer)(p)
- }
+ p := v.pointer()
// Non-nil func value points at data block.
// First word of data block is actual code.
if p != nil {
@@ -1316,7 +1422,7 @@ func (v Value) Pointer() uintptr {
return uintptr(p)
case Slice:
- return (*SliceHeader)(v.val).Data
+ return (*SliceHeader)(v.ptr).Data
}
panic(&ValueError{"reflect.Value.Pointer", k})
}
@@ -1339,14 +1445,21 @@ func (v Value) recv(nb bool) (val Value, ok bool) {
if ChanDir(tt.dir)&RecvDir == 0 {
panic("reflect: recv on send-only channel")
}
- word, selected, ok := chanrecv(v.typ, v.iword(), nb)
- if selected {
- typ := tt.elem
- fl := flag(typ.Kind()) << flagKindShift
- if typ.size > ptrSize {
- fl |= flagIndir
- }
- val = Value{typ, unsafe.Pointer(word), fl}
+ t := tt.elem
+ val = Value{t, nil, 0, flag(t.Kind()) << flagKindShift}
+ var p unsafe.Pointer
+ if t.size > ptrSize {
+ p = unsafe_New(t)
+ val.ptr = p
+ val.flag |= flagIndir
+ } else if t.pointers() {
+ p = unsafe.Pointer(&val.ptr)
+ } else {
+ p = unsafe.Pointer(&val.scalar)
+ }
+ selected, ok := chanrecv(v.typ, v.pointer(), nb, p)
+ if !selected {
+ val = Value{}
}
return
}
@@ -1369,7 +1482,15 @@ func (v Value) send(x Value, nb bool) (selected bool) {
}
x.mustBeExported()
x = x.assignTo("reflect.Value.Send", tt.elem, nil)
- return chansend(v.typ, v.iword(), x.iword(), nb)
+ var p unsafe.Pointer
+ if x.flag&flagIndir != 0 {
+ p = x.ptr
+ } else if x.typ.pointers() {
+ p = unsafe.Pointer(&x.ptr)
+ } else {
+ p = unsafe.Pointer(&x.scalar)
+ }
+ return chansend(v.typ, v.pointer(), p, nb)
}
// Set assigns x to the value v.
@@ -1380,13 +1501,15 @@ func (v Value) Set(x Value) {
x.mustBeExported() // do not let unexported x leak
var target *interface{}
if v.kind() == Interface {
- target = (*interface{})(v.val)
+ target = (*interface{})(v.ptr)
}
x = x.assignTo("reflect.Set", v.typ, target)
if x.flag&flagIndir != 0 {
- memmove(v.val, x.val, v.typ.size)
+ memmove(v.ptr, x.ptr, v.typ.size)
+ } else if x.typ.pointers() {
+ *(*unsafe.Pointer)(v.ptr) = x.ptr
} else {
- storeIword(v.val, iword(x.val), v.typ.size)
+ memmove(v.ptr, unsafe.Pointer(&x.scalar), v.typ.size)
}
}
@@ -1395,7 +1518,7 @@ func (v Value) Set(x Value) {
func (v Value) SetBool(x bool) {
v.mustBeAssignable()
v.mustBe(Bool)
- *(*bool)(v.val) = x
+ *(*bool)(v.ptr) = x
}
// SetBytes sets v's underlying value.
@@ -1406,7 +1529,7 @@ func (v Value) SetBytes(x []byte) {
if v.typ.Elem().Kind() != Uint8 {
panic("reflect.Value.SetBytes of non-byte slice")
}
- *(*[]byte)(v.val) = x
+ *(*[]byte)(v.ptr) = x
}
// setRunes sets v's underlying value.
@@ -1417,7 +1540,7 @@ func (v Value) setRunes(x []rune) {
if v.typ.Elem().Kind() != Int32 {
panic("reflect.Value.setRunes of non-rune slice")
}
- *(*[]rune)(v.val) = x
+ *(*[]rune)(v.ptr) = x
}
// SetComplex sets v's underlying value to x.
@@ -1428,9 +1551,9 @@ func (v Value) SetComplex(x complex128) {
default:
panic(&ValueError{"reflect.Value.SetComplex", k})
case Complex64:
- *(*complex64)(v.val) = complex64(x)
+ *(*complex64)(v.ptr) = complex64(x)
case Complex128:
- *(*complex128)(v.val) = x
+ *(*complex128)(v.ptr) = x
}
}
@@ -1442,9 +1565,9 @@ func (v Value) SetFloat(x float64) {
default:
panic(&ValueError{"reflect.Value.SetFloat", k})
case Float32:
- *(*float32)(v.val) = float32(x)
+ *(*float32)(v.ptr) = float32(x)
case Float64:
- *(*float64)(v.val) = x
+ *(*float64)(v.ptr) = x
}
}
@@ -1456,15 +1579,15 @@ func (v Value) SetInt(x int64) {
default:
panic(&ValueError{"reflect.Value.SetInt", k})
case Int:
- *(*int)(v.val) = int(x)
+ *(*int)(v.ptr) = int(x)
case Int8:
- *(*int8)(v.val) = int8(x)
+ *(*int8)(v.ptr) = int8(x)
case Int16:
- *(*int16)(v.val) = int16(x)
+ *(*int16)(v.ptr) = int16(x)
case Int32:
- *(*int32)(v.val) = int32(x)
+ *(*int32)(v.ptr) = int32(x)
case Int64:
- *(*int64)(v.val) = x
+ *(*int64)(v.ptr) = x
}
}
@@ -1474,7 +1597,7 @@ func (v Value) SetInt(x int64) {
func (v Value) SetLen(n int) {
v.mustBeAssignable()
v.mustBe(Slice)
- s := (*SliceHeader)(v.val)
+ s := (*sliceHeader)(v.ptr)
if n < 0 || n > int(s.Cap) {
panic("reflect: slice length out of range in SetLen")
}
@@ -1487,7 +1610,7 @@ func (v Value) SetLen(n int) {
func (v Value) SetCap(n int) {
v.mustBeAssignable()
v.mustBe(Slice)
- s := (*SliceHeader)(v.val)
+ s := (*sliceHeader)(v.ptr)
if n < int(s.Len) || n > int(s.Cap) {
panic("reflect: slice capacity out of range in SetCap")
}
@@ -1497,6 +1620,7 @@ func (v Value) SetCap(n int) {
// SetMapIndex sets the value associated with key in the map v to val.
// It panics if v's Kind is not Map.
// If val is the zero Value, SetMapIndex deletes the key from the map.
+// Otherwise if v holds a nil map, SetMapIndex will panic.
// As in Go, key's value must be assignable to the map's key type,
// and val's value must be assignable to the map's value type.
func (v Value) SetMapIndex(key, val Value) {
@@ -1505,11 +1629,29 @@ func (v Value) SetMapIndex(key, val Value) {
key.mustBeExported()
tt := (*mapType)(unsafe.Pointer(v.typ))
key = key.assignTo("reflect.Value.SetMapIndex", tt.key, nil)
- if val.typ != nil {
- val.mustBeExported()
- val = val.assignTo("reflect.Value.SetMapIndex", tt.elem, nil)
+ var k unsafe.Pointer
+ if key.flag&flagIndir != 0 {
+ k = key.ptr
+ } else if key.typ.pointers() {
+ k = unsafe.Pointer(&key.ptr)
+ } else {
+ k = unsafe.Pointer(&key.scalar)
+ }
+ if val.typ == nil {
+ mapdelete(v.typ, v.pointer(), k)
+ return
+ }
+ val.mustBeExported()
+ val = val.assignTo("reflect.Value.SetMapIndex", tt.elem, nil)
+ var e unsafe.Pointer
+ if val.flag&flagIndir != 0 {
+ e = val.ptr
+ } else if val.typ.pointers() {
+ e = unsafe.Pointer(&val.ptr)
+ } else {
+ e = unsafe.Pointer(&val.scalar)
}
- mapassign(v.typ, v.iword(), key.iword(), val.iword(), val.typ != nil)
+ mapassign(v.typ, v.pointer(), k, e)
}
// SetUint sets v's underlying value to x.
@@ -1520,17 +1662,17 @@ func (v Value) SetUint(x uint64) {
default:
panic(&ValueError{"reflect.Value.SetUint", k})
case Uint:
- *(*uint)(v.val) = uint(x)
+ *(*uint)(v.ptr) = uint(x)
case Uint8:
- *(*uint8)(v.val) = uint8(x)
+ *(*uint8)(v.ptr) = uint8(x)
case Uint16:
- *(*uint16)(v.val) = uint16(x)
+ *(*uint16)(v.ptr) = uint16(x)
case Uint32:
- *(*uint32)(v.val) = uint32(x)
+ *(*uint32)(v.ptr) = uint32(x)
case Uint64:
- *(*uint64)(v.val) = x
+ *(*uint64)(v.ptr) = x
case Uintptr:
- *(*uintptr)(v.val) = uintptr(x)
+ *(*uintptr)(v.ptr) = uintptr(x)
}
}
@@ -1539,7 +1681,7 @@ func (v Value) SetUint(x uint64) {
func (v Value) SetPointer(x unsafe.Pointer) {
v.mustBeAssignable()
v.mustBe(UnsafePointer)
- *(*unsafe.Pointer)(v.val) = x
+ *(*unsafe.Pointer)(v.ptr) = x
}
// SetString sets v's underlying value to x.
@@ -1547,7 +1689,7 @@ func (v Value) SetPointer(x unsafe.Pointer) {
func (v Value) SetString(x string) {
v.mustBeAssignable()
v.mustBe(String)
- *(*string)(v.val) = x
+ *(*string)(v.ptr) = x
}
// Slice returns v[i:j].
@@ -1570,24 +1712,21 @@ func (v Value) Slice(i, j int) Value {
tt := (*arrayType)(unsafe.Pointer(v.typ))
cap = int(tt.len)
typ = (*sliceType)(unsafe.Pointer(tt.slice))
- base = v.val
+ base = v.ptr
case Slice:
typ = (*sliceType)(unsafe.Pointer(v.typ))
- s := (*SliceHeader)(v.val)
+ s := (*sliceHeader)(v.ptr)
base = unsafe.Pointer(s.Data)
cap = s.Cap
case String:
- s := (*StringHeader)(v.val)
+ s := (*stringHeader)(v.ptr)
if i < 0 || j < i || j > s.Len {
panic("reflect.Value.Slice: string slice index out of bounds")
}
- var x string
- val := (*StringHeader)(unsafe.Pointer(&x))
- val.Data = s.Data + uintptr(i)
- val.Len = j - i
- return Value{v.typ, unsafe.Pointer(&x), v.flag}
+ t := stringHeader{unsafe.Pointer(uintptr(s.Data) + uintptr(i)), j - i}
+ return Value{v.typ, unsafe.Pointer(&t), 0, v.flag}
}
if i < 0 || j < i || j > cap {
@@ -1597,14 +1736,14 @@ func (v Value) Slice(i, j int) Value {
// Declare slice so that gc can see the base pointer in it.
var x []unsafe.Pointer
- // Reinterpret as *SliceHeader to edit.
- s := (*SliceHeader)(unsafe.Pointer(&x))
- s.Data = uintptr(base) + uintptr(i)*typ.elem.Size()
+ // Reinterpret as *sliceHeader to edit.
+ s := (*sliceHeader)(unsafe.Pointer(&x))
+ s.Data = unsafe.Pointer(uintptr(base) + uintptr(i)*typ.elem.Size())
s.Len = j - i
s.Cap = cap - i
fl := v.flag&flagRO | flagIndir | flag(Slice)<<flagKindShift
- return Value{typ.common(), unsafe.Pointer(&x), fl}
+ return Value{typ.common(), unsafe.Pointer(&x), 0, fl}
}
// Slice3 is the 3-index form of the slice operation: it returns v[i:j:k].
@@ -1622,17 +1761,17 @@ func (v Value) Slice3(i, j, k int) Value {
case Array:
if v.flag&flagAddr == 0 {
- panic("reflect.Value.Slice: slice of unaddressable array")
+ panic("reflect.Value.Slice3: slice of unaddressable array")
}
tt := (*arrayType)(unsafe.Pointer(v.typ))
cap = int(tt.len)
typ = (*sliceType)(unsafe.Pointer(tt.slice))
- base = v.val
+ base = v.ptr
case Slice:
typ = (*sliceType)(unsafe.Pointer(v.typ))
- s := (*SliceHeader)(v.val)
- base = unsafe.Pointer(s.Data)
+ s := (*sliceHeader)(v.ptr)
+ base = s.Data
cap = s.Cap
}
@@ -1644,14 +1783,14 @@ func (v Value) Slice3(i, j, k int) Value {
// can see the base pointer in it.
var x []unsafe.Pointer
- // Reinterpret as *SliceHeader to edit.
- s := (*SliceHeader)(unsafe.Pointer(&x))
- s.Data = uintptr(base) + uintptr(i)*typ.elem.Size()
+ // Reinterpret as *sliceHeader to edit.
+ s := (*sliceHeader)(unsafe.Pointer(&x))
+ s.Data = unsafe.Pointer(uintptr(base) + uintptr(i)*typ.elem.Size())
s.Len = j - i
s.Cap = k - i
fl := v.flag&flagRO | flagIndir | flag(Slice)<<flagKindShift
- return Value{typ.common(), unsafe.Pointer(&x), fl}
+ return Value{typ.common(), unsafe.Pointer(&x), 0, fl}
}
// String returns the string v's underlying value, as a string.
@@ -1663,7 +1802,7 @@ func (v Value) String() string {
case Invalid:
return "<invalid Value>"
case String:
- return *(*string)(v.val)
+ return *(*string)(v.ptr)
}
// If you call String on a reflect.Value of other type, it's better to
// print something than to panic. Useful in debugging.
@@ -1672,9 +1811,9 @@ func (v Value) String() string {
// TryRecv attempts to receive a value from the channel v but will not block.
// It panics if v's Kind is not Chan.
-// If the receive cannot finish without blocking, x is the zero Value.
-// The boolean ok is true if the value x corresponds to a send
-// on the channel, false if it is a zero value received because the channel is closed.
+// If the receive delivers a value, x is the transferred value and ok is true.
+// If the receive cannot finish without blocking, x is the zero Value and ok is false.
+// If the channel is closed, x is the zero value for the channel's element type and ok is false.
func (v Value) TryRecv() (x Value, ok bool) {
v.mustBe(Chan)
v.mustBeExported()
@@ -1729,11 +1868,11 @@ func (v Value) Uint() uint64 {
k := v.kind()
var p unsafe.Pointer
if v.flag&flagIndir != 0 {
- p = v.val
+ p = v.ptr
} else {
- // The escape analysis is good enough that &v.val
+ // The escape analysis is good enough that &v.scalar
// does not trigger a heap allocation.
- p = unsafe.Pointer(&v.val)
+ p = unsafe.Pointer(&v.scalar)
}
switch k {
case Uint:
@@ -1756,13 +1895,14 @@ func (v Value) Uint() uint64 {
// It is for advanced clients that also import the "unsafe" package.
// It panics if v is not addressable.
func (v Value) UnsafeAddr() uintptr {
+ // TODO: deprecate
if v.typ == nil {
panic(&ValueError{"reflect.Value.UnsafeAddr", Invalid})
}
if v.flag&flagAddr == 0 {
panic("reflect.Value.UnsafeAddr of unaddressable value")
}
- return uintptr(v.val)
+ return uintptr(v.ptr)
}
// StringHeader is the runtime representation of a string.
@@ -1776,6 +1916,12 @@ type StringHeader struct {
Len int
}
+// stringHeader is a safe version of StringHeader used within this package.
+type stringHeader struct {
+ Data unsafe.Pointer
+ Len int
+}
+
// SliceHeader is the runtime representation of a slice.
// It cannot be used safely or portably and its representation may
// change in a later release.
@@ -1788,6 +1934,13 @@ type SliceHeader struct {
Cap int
}
+// sliceHeader is a safe version of SliceHeader used within this package.
+type sliceHeader struct {
+ Data unsafe.Pointer
+ Len int
+ Cap int
+}
+
func typesMustMatch(what string, t1, t2 Type) {
if t1 != t2 {
panic(what + ": " + t1.String() + " != " + t2.String())
@@ -1876,6 +2029,8 @@ func Copy(dst, src Value) int {
// If sk is an in-line array, cannot take its address.
// Instead, copy element by element.
+ // TODO: memmove would be ok for this (sa = unsafe.Pointer(&v.scalar))
+ // if we teach the compiler that ptrs don't escape from memmove.
if src.flag&flagIndir == 0 {
for i := 0; i < n; i++ {
dst.Index(i).Set(src.Index(i))
@@ -1886,14 +2041,14 @@ func Copy(dst, src Value) int {
// Copy via memmove.
var da, sa unsafe.Pointer
if dk == Array {
- da = dst.val
+ da = dst.ptr
} else {
- da = unsafe.Pointer((*SliceHeader)(dst.val).Data)
+ da = (*sliceHeader)(dst.ptr).Data
}
if sk == Array {
- sa = src.val
+ sa = src.ptr
} else {
- sa = unsafe.Pointer((*SliceHeader)(src.val).Data)
+ sa = (*sliceHeader)(src.ptr).Data
}
memmove(da, sa, uintptr(n)*de.Size())
return n
@@ -1902,17 +2057,18 @@ func Copy(dst, src Value) int {
// A runtimeSelect is a single case passed to rselect.
// This must match ../runtime/chan.c:/runtimeSelect
type runtimeSelect struct {
- dir uintptr // 0, SendDir, or RecvDir
- typ *rtype // channel type
- ch iword // interface word for channel
- val iword // interface word for value (for SendDir)
+ dir uintptr // 0, SendDir, or RecvDir
+ typ *rtype // channel type
+ ch unsafe.Pointer // channel
+ val unsafe.Pointer // ptr to data (SendDir) or ptr to receive buffer (RecvDir)
}
-// rselect runs a select. It returns the index of the chosen case,
-// and if the case was a receive, the interface word of the received
-// value and the conventional OK bool to indicate whether the receive
-// corresponds to a sent value.
-func rselect([]runtimeSelect) (chosen int, recv iword, recvOK bool)
+// rselect runs a select. It returns the index of the chosen case.
+// If the case was a receive, val is filled in with the received value.
+// The conventional OK bool indicates whether the receive corresponds
+// to a sent value.
+//go:noescape
+func rselect([]runtimeSelect) (chosen int, recvOK bool)
// A SelectDir describes the communication direction of a select case.
type SelectDir int
@@ -1992,7 +2148,7 @@ func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
if ChanDir(tt.dir)&SendDir == 0 {
panic("reflect.Select: SendDir case using recv-only channel")
}
- rc.ch = ch.iword()
+ rc.ch = ch.pointer()
rc.typ = &tt.rtype
v := c.Send
if !v.IsValid() {
@@ -2000,7 +2156,13 @@ func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
}
v.mustBeExported()
v = v.assignTo("reflect.Select", tt.elem, nil)
- rc.val = v.iword()
+ if v.flag&flagIndir != 0 {
+ rc.val = v.ptr
+ } else if v.typ.pointers() {
+ rc.val = unsafe.Pointer(&v.ptr)
+ } else {
+ rc.val = unsafe.Pointer(&v.scalar)
+ }
case SelectRecv:
if c.Send.IsValid() {
@@ -2013,23 +2175,28 @@ func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
ch.mustBe(Chan)
ch.mustBeExported()
tt := (*chanType)(unsafe.Pointer(ch.typ))
- rc.typ = &tt.rtype
if ChanDir(tt.dir)&RecvDir == 0 {
panic("reflect.Select: RecvDir case using send-only channel")
}
- rc.ch = ch.iword()
+ rc.ch = ch.pointer()
+ rc.typ = &tt.rtype
+ rc.val = unsafe_New(tt.elem)
}
}
- chosen, word, recvOK := rselect(runcases)
+ chosen, recvOK = rselect(runcases)
if runcases[chosen].dir == uintptr(SelectRecv) {
tt := (*chanType)(unsafe.Pointer(runcases[chosen].typ))
- typ := tt.elem
- fl := flag(typ.Kind()) << flagKindShift
- if typ.size > ptrSize {
- fl |= flagIndir
+ t := tt.elem
+ p := runcases[chosen].val
+ fl := flag(t.Kind()) << flagKindShift
+ if t.size > ptrSize {
+ recv = Value{t, p, 0, fl | flagIndir}
+ } else if t.pointers() {
+ recv = Value{t, *(*unsafe.Pointer)(p), 0, fl}
+ } else {
+ recv = Value{t, nil, loadScalar(p, t.size), fl}
}
- recv = Value{typ, unsafe.Pointer(word), fl}
}
return chosen, recv, recvOK
}
@@ -2058,16 +2225,8 @@ func MakeSlice(typ Type, len, cap int) Value {
panic("reflect.MakeSlice: len > cap")
}
- // Declare slice so that gc can see the base pointer in it.
- var x []unsafe.Pointer
-
- // Reinterpret as *SliceHeader to edit.
- s := (*SliceHeader)(unsafe.Pointer(&x))
- s.Data = uintptr(unsafe_NewArray(typ.Elem().(*rtype), cap))
- s.Len = len
- s.Cap = cap
-
- return Value{typ.common(), unsafe.Pointer(&x), flagIndir | flag(Slice)<<flagKindShift}
+ s := sliceHeader{unsafe_NewArray(typ.Elem().(*rtype), cap), len, cap}
+ return Value{typ.common(), unsafe.Pointer(&s), 0, flagIndir | flag(Slice)<<flagKindShift}
}
// MakeChan creates a new channel with the specified type and buffer size.
@@ -2082,7 +2241,7 @@ func MakeChan(typ Type, buffer int) Value {
panic("reflect.MakeChan: unidirectional channel type")
}
ch := makechan(typ.(*rtype), uint64(buffer))
- return Value{typ.common(), unsafe.Pointer(ch), flag(Chan) << flagKindShift}
+ return Value{typ.common(), ch, 0, flag(Chan) << flagKindShift}
}
// MakeMap creates a new map of the specified type.
@@ -2091,7 +2250,7 @@ func MakeMap(typ Type) Value {
panic("reflect.MakeMap of non-map type")
}
m := makemap(typ.(*rtype))
- return Value{typ.common(), unsafe.Pointer(m), flag(Map) << flagKindShift}
+ return Value{typ.common(), m, 0, flag(Map) << flagKindShift}
}
// Indirect returns the value that v points to.
@@ -2112,21 +2271,13 @@ func ValueOf(i interface{}) Value {
}
// TODO(rsc): Eliminate this terrible hack.
- // In the call to packValue, eface.typ doesn't escape,
- // and eface.word is an integer. So it looks like
- // i (= eface) doesn't escape. But really it does,
- // because eface.word is actually a pointer.
+ // In the call to unpackEface, i.typ doesn't escape,
+ // and i.word is an integer. So it looks like
+ // i doesn't escape. But really it does,
+ // because i.word is actually a pointer.
escapes(i)
- // For an interface value with the noAddr bit set,
- // the representation is identical to an empty interface.
- eface := *(*emptyInterface)(unsafe.Pointer(&i))
- typ := eface.typ
- fl := flag(typ.Kind()) << flagKindShift
- if typ.size > ptrSize {
- fl |= flagIndir
- }
- return Value{typ, unsafe.Pointer(eface.word), fl}
+ return unpackEface(i)
}
// Zero returns a Value representing the zero value for the specified type.
@@ -2141,27 +2292,27 @@ func Zero(typ Type) Value {
t := typ.common()
fl := flag(t.Kind()) << flagKindShift
if t.size <= ptrSize {
- return Value{t, nil, fl}
+ return Value{t, nil, 0, fl}
}
- return Value{t, unsafe_New(typ.(*rtype)), fl | flagIndir}
+ return Value{t, unsafe_New(typ.(*rtype)), 0, fl | flagIndir}
}
// New returns a Value representing a pointer to a new zero value
-// for the specified type. That is, the returned Value's Type is PtrTo(t).
+// for the specified type. That is, the returned Value's Type is PtrTo(typ).
func New(typ Type) Value {
if typ == nil {
panic("reflect: New(nil)")
}
ptr := unsafe_New(typ.(*rtype))
fl := flag(Ptr) << flagKindShift
- return Value{typ.common().ptrTo(), ptr, fl}
+ return Value{typ.common().ptrTo(), ptr, 0, fl}
}
// NewAt returns a Value representing a pointer to a value of the
// specified type, using p as that pointer.
func NewAt(typ Type, p unsafe.Pointer) Value {
fl := flag(Ptr) << flagKindShift
- return Value{typ.common().ptrTo(), p, fl}
+ return Value{typ.common().ptrTo(), p, 0, fl}
}
// assignTo returns a value v that can be assigned directly to typ.
@@ -2179,7 +2330,7 @@ func (v Value) assignTo(context string, dst *rtype, target *interface{}) Value {
v.typ = dst
fl := v.flag & (flagRO | flagAddr | flagIndir)
fl |= flag(dst.Kind()) << flagKindShift
- return Value{dst, v.val, fl}
+ return Value{dst, v.ptr, v.scalar, fl}
case implements(dst, v.typ):
if target == nil {
@@ -2191,7 +2342,7 @@ func (v Value) assignTo(context string, dst *rtype, target *interface{}) Value {
} else {
ifaceE2I(dst, x, unsafe.Pointer(target))
}
- return Value{dst, unsafe.Pointer(target), flagIndir | flag(Interface)<<flagKindShift}
+ return Value{dst, unsafe.Pointer(target), 0, flagIndir | flag(Interface)<<flagKindShift}
}
// Failed.
@@ -2303,20 +2454,20 @@ func makeInt(f flag, bits uint64, t Type) Value {
// Assume ptrSize >= 4, so this must be uint64.
ptr := unsafe_New(typ)
*(*uint64)(unsafe.Pointer(ptr)) = bits
- return Value{typ, ptr, f | flagIndir | flag(typ.Kind())<<flagKindShift}
+ return Value{typ, ptr, 0, f | flagIndir | flag(typ.Kind())<<flagKindShift}
}
- var w iword
+ var s uintptr
switch typ.size {
case 1:
- *(*uint8)(unsafe.Pointer(&w)) = uint8(bits)
+ *(*uint8)(unsafe.Pointer(&s)) = uint8(bits)
case 2:
- *(*uint16)(unsafe.Pointer(&w)) = uint16(bits)
+ *(*uint16)(unsafe.Pointer(&s)) = uint16(bits)
case 4:
- *(*uint32)(unsafe.Pointer(&w)) = uint32(bits)
+ *(*uint32)(unsafe.Pointer(&s)) = uint32(bits)
case 8:
- *(*uint64)(unsafe.Pointer(&w)) = uint64(bits)
+ *(*uint64)(unsafe.Pointer(&s)) = uint64(bits)
}
- return Value{typ, unsafe.Pointer(w), f | flag(typ.Kind())<<flagKindShift}
+ return Value{typ, nil, s, f | flag(typ.Kind())<<flagKindShift}
}
// makeFloat returns a Value of type t equal to v (possibly truncated to float32),
@@ -2327,17 +2478,17 @@ func makeFloat(f flag, v float64, t Type) Value {
// Assume ptrSize >= 4, so this must be float64.
ptr := unsafe_New(typ)
*(*float64)(unsafe.Pointer(ptr)) = v
- return Value{typ, ptr, f | flagIndir | flag(typ.Kind())<<flagKindShift}
+ return Value{typ, ptr, 0, f | flagIndir | flag(typ.Kind())<<flagKindShift}
}
- var w iword
+ var s uintptr
switch typ.size {
case 4:
- *(*float32)(unsafe.Pointer(&w)) = float32(v)
+ *(*float32)(unsafe.Pointer(&s)) = float32(v)
case 8:
- *(*float64)(unsafe.Pointer(&w)) = v
+ *(*float64)(unsafe.Pointer(&s)) = v
}
- return Value{typ, unsafe.Pointer(w), f | flag(typ.Kind())<<flagKindShift}
+ return Value{typ, nil, s, f | flag(typ.Kind())<<flagKindShift}
}
// makeComplex returns a Value of type t equal to v (possibly truncated to complex64),
@@ -2352,13 +2503,13 @@ func makeComplex(f flag, v complex128, t Type) Value {
case 16:
*(*complex128)(unsafe.Pointer(ptr)) = v
}
- return Value{typ, ptr, f | flagIndir | flag(typ.Kind())<<flagKindShift}
+ return Value{typ, ptr, 0, f | flagIndir | flag(typ.Kind())<<flagKindShift}
}
// Assume ptrSize <= 8 so this must be complex64.
- var w iword
- *(*complex64)(unsafe.Pointer(&w)) = complex64(v)
- return Value{typ, unsafe.Pointer(w), f | flag(typ.Kind())<<flagKindShift}
+ var s uintptr
+ *(*complex64)(unsafe.Pointer(&s)) = complex64(v)
+ return Value{typ, nil, s, f | flag(typ.Kind())<<flagKindShift}
}
func makeString(f flag, v string, t Type) Value {
@@ -2461,15 +2612,15 @@ func cvtStringRunes(v Value, t Type) Value {
func cvtDirect(v Value, typ Type) Value {
f := v.flag
t := typ.common()
- val := v.val
+ ptr := v.ptr
if f&flagAddr != 0 {
// indirect, mutable word - make a copy
- ptr := unsafe_New(t)
- memmove(ptr, val, t.size)
- val = ptr
+ c := unsafe_New(t)
+ memmove(c, ptr, t.size)
+ ptr = c
f &^= flagAddr
}
- return Value{t, val, v.flag&flagRO | f}
+ return Value{t, ptr, v.scalar, v.flag&flagRO | f} // v.flag&flagRO|f == f?
}
// convertOp: concrete -> interface
@@ -2481,7 +2632,7 @@ func cvtT2I(v Value, typ Type) Value {
} else {
ifaceE2I(typ.(*rtype), x, unsafe.Pointer(target))
}
- return Value{typ.common(), unsafe.Pointer(target), v.flag&flagRO | flagIndir | flag(Interface)<<flagKindShift}
+ return Value{typ.common(), unsafe.Pointer(target), 0, v.flag&flagRO | flagIndir | flag(Interface)<<flagKindShift}
}
// convertOp: interface -> interface
@@ -2495,22 +2646,27 @@ func cvtI2I(v Value, typ Type) Value {
}
// implemented in ../pkg/runtime
-func chancap(ch iword) int
-func chanclose(ch iword)
-func chanlen(ch iword) int
-func chanrecv(t *rtype, ch iword, nb bool) (val iword, selected, received bool)
-func chansend(t *rtype, ch iword, val iword, nb bool) bool
-
-func makechan(typ *rtype, size uint64) (ch iword)
-func makemap(t *rtype) (m iword)
-func mapaccess(t *rtype, m iword, key iword) (val iword, ok bool)
-func mapassign(t *rtype, m iword, key, val iword, ok bool)
-func mapiterinit(t *rtype, m iword) *byte
-func mapiterkey(it *byte) (key iword, ok bool)
-func mapiternext(it *byte)
-func maplen(m iword) int
-
-func call(fn, arg unsafe.Pointer, n uint32)
+func chancap(ch unsafe.Pointer) int
+func chanclose(ch unsafe.Pointer)
+func chanlen(ch unsafe.Pointer) int
+
+//go:noescape
+func chanrecv(t *rtype, ch unsafe.Pointer, nb bool, val unsafe.Pointer) (selected, received bool)
+
+//go:noescape
+func chansend(t *rtype, ch unsafe.Pointer, val unsafe.Pointer, nb bool) bool
+
+func makechan(typ *rtype, size uint64) (ch unsafe.Pointer)
+func makemap(t *rtype) (m unsafe.Pointer)
+func mapaccess(t *rtype, m unsafe.Pointer, key unsafe.Pointer) (val unsafe.Pointer)
+func mapassign(t *rtype, m unsafe.Pointer, key, val unsafe.Pointer)
+func mapdelete(t *rtype, m unsafe.Pointer, key unsafe.Pointer)
+func mapiterinit(t *rtype, m unsafe.Pointer) unsafe.Pointer
+func mapiterkey(it unsafe.Pointer) (key unsafe.Pointer)
+func mapiternext(it unsafe.Pointer)
+func maplen(m unsafe.Pointer) int
+
+func call(fn, arg unsafe.Pointer, n uint32, retoffset uint32)
func ifaceE2I(t *rtype, src interface{}, dst unsafe.Pointer)
// Dummy annotation marking that the value x escapes,
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-21 14:26:54 +0000