blob: 816ccc627fccb71ddc1e8648bd8f222ce2f5b7ff [file] [log] [blame]
// Copyright 2009 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.
package reflectdata
import (
"encoding/binary"
"fmt"
"internal/abi"
"os"
"sort"
"strings"
"sync"
"cmd/compile/internal/base"
"cmd/compile/internal/bitvec"
"cmd/compile/internal/compare"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
"cmd/compile/internal/rttype"
"cmd/compile/internal/staticdata"
"cmd/compile/internal/typebits"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/gcprog"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/src"
)
type ptabEntry struct {
s *types.Sym
t *types.Type
}
// runtime interface and reflection data structures
var (
// protects signatset and signatslice
signatmu sync.Mutex
// Tracking which types need runtime type descriptor
signatset = make(map[*types.Type]struct{})
// Queue of types wait to be generated runtime type descriptor
signatslice []typeAndStr
gcsymmu sync.Mutex // protects gcsymset and gcsymslice
gcsymset = make(map[*types.Type]struct{})
)
type typeSig struct {
name *types.Sym
isym *obj.LSym
tsym *obj.LSym
type_ *types.Type
mtype *types.Type
}
func commonSize() int { return int(rttype.Type.Size()) } // Sizeof(runtime._type{})
func uncommonSize(t *types.Type) int { // Sizeof(runtime.uncommontype{})
if t.Sym() == nil && len(methods(t)) == 0 {
return 0
}
return int(rttype.UncommonType.Size())
}
func makefield(name string, t *types.Type) *types.Field {
sym := (*types.Pkg)(nil).Lookup(name)
return types.NewField(src.NoXPos, sym, t)
}
// MapBucketType makes the map bucket type given the type of the map.
func MapBucketType(t *types.Type) *types.Type {
// Builds a type representing a Bucket structure for
// the given map type. This type is not visible to users -
// we include only enough information to generate a correct GC
// program for it.
// Make sure this stays in sync with runtime/map.go.
//
// A "bucket" is a "struct" {
// tophash [abi.MapBucketCount]uint8
// keys [abi.MapBucketCount]keyType
// elems [abi.MapBucketCount]elemType
// overflow *bucket
// }
if t.MapType().Bucket != nil {
return t.MapType().Bucket
}
keytype := t.Key()
elemtype := t.Elem()
types.CalcSize(keytype)
types.CalcSize(elemtype)
if keytype.Size() > abi.MapMaxKeyBytes {
keytype = types.NewPtr(keytype)
}
if elemtype.Size() > abi.MapMaxElemBytes {
elemtype = types.NewPtr(elemtype)
}
field := make([]*types.Field, 0, 5)
// The first field is: uint8 topbits[BUCKETSIZE].
arr := types.NewArray(types.Types[types.TUINT8], abi.MapBucketCount)
field = append(field, makefield("topbits", arr))
arr = types.NewArray(keytype, abi.MapBucketCount)
arr.SetNoalg(true)
keys := makefield("keys", arr)
field = append(field, keys)
arr = types.NewArray(elemtype, abi.MapBucketCount)
arr.SetNoalg(true)
elems := makefield("elems", arr)
field = append(field, elems)
// If keys and elems have no pointers, the map implementation
// can keep a list of overflow pointers on the side so that
// buckets can be marked as having no pointers.
// Arrange for the bucket to have no pointers by changing
// the type of the overflow field to uintptr in this case.
// See comment on hmap.overflow in runtime/map.go.
otyp := types.Types[types.TUNSAFEPTR]
if !elemtype.HasPointers() && !keytype.HasPointers() {
otyp = types.Types[types.TUINTPTR]
}
overflow := makefield("overflow", otyp)
field = append(field, overflow)
// link up fields
bucket := types.NewStruct(field[:])
bucket.SetNoalg(true)
types.CalcSize(bucket)
// Check invariants that map code depends on.
if !types.IsComparable(t.Key()) {
base.Fatalf("unsupported map key type for %v", t)
}
if abi.MapBucketCount < 8 {
base.Fatalf("bucket size %d too small for proper alignment %d", abi.MapBucketCount, 8)
}
if uint8(keytype.Alignment()) > abi.MapBucketCount {
base.Fatalf("key align too big for %v", t)
}
if uint8(elemtype.Alignment()) > abi.MapBucketCount {
base.Fatalf("elem align %d too big for %v, BUCKETSIZE=%d", elemtype.Alignment(), t, abi.MapBucketCount)
}
if keytype.Size() > abi.MapMaxKeyBytes {
base.Fatalf("key size too large for %v", t)
}
if elemtype.Size() > abi.MapMaxElemBytes {
base.Fatalf("elem size too large for %v", t)
}
if t.Key().Size() > abi.MapMaxKeyBytes && !keytype.IsPtr() {
base.Fatalf("key indirect incorrect for %v", t)
}
if t.Elem().Size() > abi.MapMaxElemBytes && !elemtype.IsPtr() {
base.Fatalf("elem indirect incorrect for %v", t)
}
if keytype.Size()%keytype.Alignment() != 0 {
base.Fatalf("key size not a multiple of key align for %v", t)
}
if elemtype.Size()%elemtype.Alignment() != 0 {
base.Fatalf("elem size not a multiple of elem align for %v", t)
}
if uint8(bucket.Alignment())%uint8(keytype.Alignment()) != 0 {
base.Fatalf("bucket align not multiple of key align %v", t)
}
if uint8(bucket.Alignment())%uint8(elemtype.Alignment()) != 0 {
base.Fatalf("bucket align not multiple of elem align %v", t)
}
if keys.Offset%keytype.Alignment() != 0 {
base.Fatalf("bad alignment of keys in bmap for %v", t)
}
if elems.Offset%elemtype.Alignment() != 0 {
base.Fatalf("bad alignment of elems in bmap for %v", t)
}
// Double-check that overflow field is final memory in struct,
// with no padding at end.
if overflow.Offset != bucket.Size()-int64(types.PtrSize) {
base.Fatalf("bad offset of overflow in bmap for %v, overflow.Offset=%d, bucket.Size()-int64(types.PtrSize)=%d",
t, overflow.Offset, bucket.Size()-int64(types.PtrSize))
}
t.MapType().Bucket = bucket
bucket.StructType().Map = t
return bucket
}
var hmapType *types.Type
// MapType returns a type interchangeable with runtime.hmap.
// Make sure this stays in sync with runtime/map.go.
func MapType() *types.Type {
if hmapType != nil {
return hmapType
}
// build a struct:
// type hmap struct {
// count int
// flags uint8
// B uint8
// noverflow uint16
// hash0 uint32
// buckets unsafe.Pointer
// oldbuckets unsafe.Pointer
// nevacuate uintptr
// extra unsafe.Pointer // *mapextra
// }
// must match runtime/map.go:hmap.
fields := []*types.Field{
makefield("count", types.Types[types.TINT]),
makefield("flags", types.Types[types.TUINT8]),
makefield("B", types.Types[types.TUINT8]),
makefield("noverflow", types.Types[types.TUINT16]),
makefield("hash0", types.Types[types.TUINT32]), // Used in walk.go for OMAKEMAP.
makefield("buckets", types.Types[types.TUNSAFEPTR]), // Used in walk.go for OMAKEMAP.
makefield("oldbuckets", types.Types[types.TUNSAFEPTR]),
makefield("nevacuate", types.Types[types.TUINTPTR]),
makefield("extra", types.Types[types.TUNSAFEPTR]),
}
n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("hmap"))
hmap := types.NewNamed(n)
n.SetType(hmap)
n.SetTypecheck(1)
hmap.SetUnderlying(types.NewStruct(fields))
types.CalcSize(hmap)
// The size of hmap should be 48 bytes on 64 bit
// and 28 bytes on 32 bit platforms.
if size := int64(8 + 5*types.PtrSize); hmap.Size() != size {
base.Fatalf("hmap size not correct: got %d, want %d", hmap.Size(), size)
}
hmapType = hmap
return hmap
}
var hiterType *types.Type
// MapIterType returns a type interchangeable with runtime.hiter.
// Make sure this stays in sync with runtime/map.go.
func MapIterType() *types.Type {
if hiterType != nil {
return hiterType
}
hmap := MapType()
// build a struct:
// type hiter struct {
// key unsafe.Pointer // *Key
// elem unsafe.Pointer // *Elem
// t unsafe.Pointer // *MapType
// h *hmap
// buckets unsafe.Pointer
// bptr unsafe.Pointer // *bmap
// overflow unsafe.Pointer // *[]*bmap
// oldoverflow unsafe.Pointer // *[]*bmap
// startBucket uintptr
// offset uint8
// wrapped bool
// B uint8
// i uint8
// bucket uintptr
// checkBucket uintptr
// }
// must match runtime/map.go:hiter.
fields := []*types.Field{
makefield("key", types.Types[types.TUNSAFEPTR]), // Used in range.go for TMAP.
makefield("elem", types.Types[types.TUNSAFEPTR]), // Used in range.go for TMAP.
makefield("t", types.Types[types.TUNSAFEPTR]),
makefield("h", types.NewPtr(hmap)),
makefield("buckets", types.Types[types.TUNSAFEPTR]),
makefield("bptr", types.Types[types.TUNSAFEPTR]),
makefield("overflow", types.Types[types.TUNSAFEPTR]),
makefield("oldoverflow", types.Types[types.TUNSAFEPTR]),
makefield("startBucket", types.Types[types.TUINTPTR]),
makefield("offset", types.Types[types.TUINT8]),
makefield("wrapped", types.Types[types.TBOOL]),
makefield("B", types.Types[types.TUINT8]),
makefield("i", types.Types[types.TUINT8]),
makefield("bucket", types.Types[types.TUINTPTR]),
makefield("checkBucket", types.Types[types.TUINTPTR]),
}
// build iterator struct holding the above fields
n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("hiter"))
hiter := types.NewNamed(n)
n.SetType(hiter)
n.SetTypecheck(1)
hiter.SetUnderlying(types.NewStruct(fields))
types.CalcSize(hiter)
if hiter.Size() != int64(12*types.PtrSize) {
base.Fatalf("hash_iter size not correct %d %d", hiter.Size(), 12*types.PtrSize)
}
hiterType = hiter
return hiter
}
// methods returns the methods of the non-interface type t, sorted by name.
// Generates stub functions as needed.
func methods(t *types.Type) []*typeSig {
if t.HasShape() {
// Shape types have no methods.
return nil
}
// method type
mt := types.ReceiverBaseType(t)
if mt == nil {
return nil
}
typecheck.CalcMethods(mt)
// make list of methods for t,
// generating code if necessary.
var ms []*typeSig
for _, f := range mt.AllMethods() {
if f.Sym == nil {
base.Fatalf("method with no sym on %v", mt)
}
if !f.IsMethod() {
base.Fatalf("non-method on %v method %v %v", mt, f.Sym, f)
}
if f.Type.Recv() == nil {
base.Fatalf("receiver with no type on %v method %v %v", mt, f.Sym, f)
}
if f.Nointerface() && !t.IsFullyInstantiated() {
// Skip creating method wrappers if f is nointerface. But, if
// t is an instantiated type, we still have to call
// methodWrapper, because methodWrapper generates the actual
// generic method on the type as well.
continue
}
// get receiver type for this particular method.
// if pointer receiver but non-pointer t and
// this is not an embedded pointer inside a struct,
// method does not apply.
if !types.IsMethodApplicable(t, f) {
continue
}
sig := &typeSig{
name: f.Sym,
isym: methodWrapper(t, f, true),
tsym: methodWrapper(t, f, false),
type_: typecheck.NewMethodType(f.Type, t),
mtype: typecheck.NewMethodType(f.Type, nil),
}
if f.Nointerface() {
// In the case of a nointerface method on an instantiated
// type, don't actually append the typeSig.
continue
}
ms = append(ms, sig)
}
return ms
}
// imethods returns the methods of the interface type t, sorted by name.
func imethods(t *types.Type) []*typeSig {
var methods []*typeSig
for _, f := range t.AllMethods() {
if f.Type.Kind() != types.TFUNC || f.Sym == nil {
continue
}
if f.Sym.IsBlank() {
base.Fatalf("unexpected blank symbol in interface method set")
}
if n := len(methods); n > 0 {
last := methods[n-1]
if !last.name.Less(f.Sym) {
base.Fatalf("sigcmp vs sortinter %v %v", last.name, f.Sym)
}
}
sig := &typeSig{
name: f.Sym,
mtype: f.Type,
type_: typecheck.NewMethodType(f.Type, nil),
}
methods = append(methods, sig)
// NOTE(rsc): Perhaps an oversight that
// IfaceType.Method is not in the reflect data.
// Generate the method body, so that compiled
// code can refer to it.
methodWrapper(t, f, false)
}
return methods
}
func dimportpath(p *types.Pkg) {
if p.Pathsym != nil {
return
}
if p == types.LocalPkg && base.Ctxt.Pkgpath == "" {
panic("missing pkgpath")
}
// If we are compiling the runtime package, there are two runtime packages around
// -- localpkg and Pkgs.Runtime. We don't want to produce import path symbols for
// both of them, so just produce one for localpkg.
if base.Ctxt.Pkgpath == "runtime" && p == ir.Pkgs.Runtime {
return
}
s := base.Ctxt.Lookup("type:.importpath." + p.Prefix + ".")
ot := dnameData(s, 0, p.Path, "", nil, false, false)
objw.Global(s, int32(ot), obj.DUPOK|obj.RODATA)
s.Set(obj.AttrContentAddressable, true)
p.Pathsym = s
}
func dgopkgpath(c rttype.Cursor, pkg *types.Pkg) {
c = c.Field("Bytes")
if pkg == nil {
c.WritePtr(nil)
return
}
dimportpath(pkg)
c.WritePtr(pkg.Pathsym)
}
// dgopkgpathOff writes an offset relocation to the pkg path symbol to c.
func dgopkgpathOff(c rttype.Cursor, pkg *types.Pkg) {
if pkg == nil {
c.WriteInt32(0)
return
}
dimportpath(pkg)
c.WriteSymPtrOff(pkg.Pathsym, false)
}
// dnameField dumps a reflect.name for a struct field.
func dnameField(c rttype.Cursor, spkg *types.Pkg, ft *types.Field) {
if !types.IsExported(ft.Sym.Name) && ft.Sym.Pkg != spkg {
base.Fatalf("package mismatch for %v", ft.Sym)
}
nsym := dname(ft.Sym.Name, ft.Note, nil, types.IsExported(ft.Sym.Name), ft.Embedded != 0)
c.Field("Bytes").WritePtr(nsym)
}
// dnameData writes the contents of a reflect.name into s at offset ot.
func dnameData(s *obj.LSym, ot int, name, tag string, pkg *types.Pkg, exported, embedded bool) int {
if len(name) >= 1<<29 {
base.Fatalf("name too long: %d %s...", len(name), name[:1024])
}
if len(tag) >= 1<<29 {
base.Fatalf("tag too long: %d %s...", len(tag), tag[:1024])
}
var nameLen [binary.MaxVarintLen64]byte
nameLenLen := binary.PutUvarint(nameLen[:], uint64(len(name)))
var tagLen [binary.MaxVarintLen64]byte
tagLenLen := binary.PutUvarint(tagLen[:], uint64(len(tag)))
// Encode name and tag. See reflect/type.go for details.
var bits byte
l := 1 + nameLenLen + len(name)
if exported {
bits |= 1 << 0
}
if len(tag) > 0 {
l += tagLenLen + len(tag)
bits |= 1 << 1
}
if pkg != nil {
bits |= 1 << 2
}
if embedded {
bits |= 1 << 3
}
b := make([]byte, l)
b[0] = bits
copy(b[1:], nameLen[:nameLenLen])
copy(b[1+nameLenLen:], name)
if len(tag) > 0 {
tb := b[1+nameLenLen+len(name):]
copy(tb, tagLen[:tagLenLen])
copy(tb[tagLenLen:], tag)
}
ot = int(s.WriteBytes(base.Ctxt, int64(ot), b))
if pkg != nil {
c := rttype.NewCursor(s, int64(ot), types.Types[types.TUINT32])
dgopkgpathOff(c, pkg)
ot += 4
}
return ot
}
var dnameCount int
// dname creates a reflect.name for a struct field or method.
func dname(name, tag string, pkg *types.Pkg, exported, embedded bool) *obj.LSym {
// Write out data as "type:." to signal two things to the
// linker, first that when dynamically linking, the symbol
// should be moved to a relro section, and second that the
// contents should not be decoded as a type.
sname := "type:.namedata."
if pkg == nil {
// In the common case, share data with other packages.
if name == "" {
if exported {
sname += "-noname-exported." + tag
} else {
sname += "-noname-unexported." + tag
}
} else {
if exported {
sname += name + "." + tag
} else {
sname += name + "-" + tag
}
}
} else {
// TODO(mdempsky): We should be able to share these too (except
// maybe when dynamic linking).
sname = fmt.Sprintf("%s%s.%d", sname, types.LocalPkg.Prefix, dnameCount)
dnameCount++
}
if embedded {
sname += ".embedded"
}
s := base.Ctxt.Lookup(sname)
if len(s.P) > 0 {
return s
}
ot := dnameData(s, 0, name, tag, pkg, exported, embedded)
objw.Global(s, int32(ot), obj.DUPOK|obj.RODATA)
s.Set(obj.AttrContentAddressable, true)
return s
}
// dextratype dumps the fields of a runtime.uncommontype.
// dataAdd is the offset in bytes after the header where the
// backing array of the []method field should be written.
func dextratype(lsym *obj.LSym, off int64, t *types.Type, dataAdd int) {
m := methods(t)
if t.Sym() == nil && len(m) == 0 {
base.Fatalf("extra requested of type with no extra info %v", t)
}
noff := types.RoundUp(off, int64(types.PtrSize))
if noff != off {
base.Fatalf("unexpected alignment in dextratype for %v", t)
}
for _, a := range m {
writeType(a.type_)
}
c := rttype.NewCursor(lsym, off, rttype.UncommonType)
dgopkgpathOff(c.Field("PkgPath"), typePkg(t))
dataAdd += uncommonSize(t)
mcount := len(m)
if mcount != int(uint16(mcount)) {
base.Fatalf("too many methods on %v: %d", t, mcount)
}
xcount := sort.Search(mcount, func(i int) bool { return !types.IsExported(m[i].name.Name) })
if dataAdd != int(uint32(dataAdd)) {
base.Fatalf("methods are too far away on %v: %d", t, dataAdd)
}
c.Field("Mcount").WriteUint16(uint16(mcount))
c.Field("Xcount").WriteUint16(uint16(xcount))
c.Field("Moff").WriteUint32(uint32(dataAdd))
// Note: there is an unused uint32 field here.
// Write the backing array for the []method field.
array := rttype.NewArrayCursor(lsym, off+int64(dataAdd), rttype.Method, mcount)
for i, a := range m {
exported := types.IsExported(a.name.Name)
var pkg *types.Pkg
if !exported && a.name.Pkg != typePkg(t) {
pkg = a.name.Pkg
}
nsym := dname(a.name.Name, "", pkg, exported, false)
e := array.Elem(i)
e.Field("Name").WriteSymPtrOff(nsym, false)
dmethodptrOff(e.Field("Mtyp"), writeType(a.mtype))
dmethodptrOff(e.Field("Ifn"), a.isym)
dmethodptrOff(e.Field("Tfn"), a.tsym)
}
}
func typePkg(t *types.Type) *types.Pkg {
tsym := t.Sym()
if tsym == nil {
switch t.Kind() {
case types.TARRAY, types.TSLICE, types.TPTR, types.TCHAN:
if t.Elem() != nil {
tsym = t.Elem().Sym()
}
}
}
if tsym != nil && tsym.Pkg != types.BuiltinPkg {
return tsym.Pkg
}
return nil
}
func dmethodptrOff(c rttype.Cursor, x *obj.LSym) {
c.WriteInt32(0)
r := c.Reloc()
r.Sym = x
r.Type = objabi.R_METHODOFF
}
var kinds = []abi.Kind{
types.TINT: abi.Int,
types.TUINT: abi.Uint,
types.TINT8: abi.Int8,
types.TUINT8: abi.Uint8,
types.TINT16: abi.Int16,
types.TUINT16: abi.Uint16,
types.TINT32: abi.Int32,
types.TUINT32: abi.Uint32,
types.TINT64: abi.Int64,
types.TUINT64: abi.Uint64,
types.TUINTPTR: abi.Uintptr,
types.TFLOAT32: abi.Float32,
types.TFLOAT64: abi.Float64,
types.TBOOL: abi.Bool,
types.TSTRING: abi.String,
types.TPTR: abi.Pointer,
types.TSTRUCT: abi.Struct,
types.TINTER: abi.Interface,
types.TCHAN: abi.Chan,
types.TMAP: abi.Map,
types.TARRAY: abi.Array,
types.TSLICE: abi.Slice,
types.TFUNC: abi.Func,
types.TCOMPLEX64: abi.Complex64,
types.TCOMPLEX128: abi.Complex128,
types.TUNSAFEPTR: abi.UnsafePointer,
}
var (
memhashvarlen *obj.LSym
memequalvarlen *obj.LSym
)
// dcommontype dumps the contents of a reflect.rtype (runtime._type) to c.
func dcommontype(c rttype.Cursor, t *types.Type) {
types.CalcSize(t)
eqfunc := geneq(t)
sptrWeak := true
var sptr *obj.LSym
if !t.IsPtr() || t.IsPtrElem() {
tptr := types.NewPtr(t)
if t.Sym() != nil || methods(tptr) != nil {
sptrWeak = false
}
sptr = writeType(tptr)
}
gcsym, useGCProg, ptrdata := dgcsym(t, true)
delete(gcsymset, t)
// ../../../../reflect/type.go:/^type.rtype
// actual type structure
// type rtype struct {
// size uintptr
// ptrdata uintptr
// hash uint32
// tflag tflag
// align uint8
// fieldAlign uint8
// kind uint8
// equal func(unsafe.Pointer, unsafe.Pointer) bool
// gcdata *byte
// str nameOff
// ptrToThis typeOff
// }
c.Field("Size_").WriteUintptr(uint64(t.Size()))
c.Field("PtrBytes").WriteUintptr(uint64(ptrdata))
c.Field("Hash").WriteUint32(types.TypeHash(t))
var tflag abi.TFlag
if uncommonSize(t) != 0 {
tflag |= abi.TFlagUncommon
}
if t.Sym() != nil && t.Sym().Name != "" {
tflag |= abi.TFlagNamed
}
if compare.IsRegularMemory(t) {
tflag |= abi.TFlagRegularMemory
}
exported := false
p := t.NameString()
// If we're writing out type T,
// we are very likely to write out type *T as well.
// Use the string "*T"[1:] for "T", so that the two
// share storage. This is a cheap way to reduce the
// amount of space taken up by reflect strings.
if !strings.HasPrefix(p, "*") {
p = "*" + p
tflag |= abi.TFlagExtraStar
if t.Sym() != nil {
exported = types.IsExported(t.Sym().Name)
}
} else {
if t.Elem() != nil && t.Elem().Sym() != nil {
exported = types.IsExported(t.Elem().Sym().Name)
}
}
if tflag != abi.TFlag(uint8(tflag)) {
// this should optimize away completely
panic("Unexpected change in size of abi.TFlag")
}
c.Field("TFlag").WriteUint8(uint8(tflag))
// runtime (and common sense) expects alignment to be a power of two.
i := int(uint8(t.Alignment()))
if i == 0 {
i = 1
}
if i&(i-1) != 0 {
base.Fatalf("invalid alignment %d for %v", uint8(t.Alignment()), t)
}
c.Field("Align_").WriteUint8(uint8(t.Alignment()))
c.Field("FieldAlign_").WriteUint8(uint8(t.Alignment()))
kind := kinds[t.Kind()]
if types.IsDirectIface(t) {
kind |= abi.KindDirectIface
}
if useGCProg {
kind |= abi.KindGCProg
}
c.Field("Kind_").WriteUint8(uint8(kind))
c.Field("Equal").WritePtr(eqfunc)
c.Field("GCData").WritePtr(gcsym)
nsym := dname(p, "", nil, exported, false)
c.Field("Str").WriteSymPtrOff(nsym, false)
c.Field("PtrToThis").WriteSymPtrOff(sptr, sptrWeak)
}
// TrackSym returns the symbol for tracking use of field/method f, assumed
// to be a member of struct/interface type t.
func TrackSym(t *types.Type, f *types.Field) *obj.LSym {
return base.PkgLinksym("go:track", t.LinkString()+"."+f.Sym.Name, obj.ABI0)
}
func TypeSymPrefix(prefix string, t *types.Type) *types.Sym {
p := prefix + "." + t.LinkString()
s := types.TypeSymLookup(p)
// This function is for looking up type-related generated functions
// (e.g. eq and hash). Make sure they are indeed generated.
signatmu.Lock()
NeedRuntimeType(t)
signatmu.Unlock()
//print("algsym: %s -> %+S\n", p, s);
return s
}
func TypeSym(t *types.Type) *types.Sym {
if t == nil || (t.IsPtr() && t.Elem() == nil) || t.IsUntyped() {
base.Fatalf("TypeSym %v", t)
}
if t.Kind() == types.TFUNC && t.Recv() != nil {
base.Fatalf("misuse of method type: %v", t)
}
s := types.TypeSym(t)
signatmu.Lock()
NeedRuntimeType(t)
signatmu.Unlock()
return s
}
func TypeLinksymPrefix(prefix string, t *types.Type) *obj.LSym {
return TypeSymPrefix(prefix, t).Linksym()
}
func TypeLinksymLookup(name string) *obj.LSym {
return types.TypeSymLookup(name).Linksym()
}
func TypeLinksym(t *types.Type) *obj.LSym {
lsym := TypeSym(t).Linksym()
signatmu.Lock()
if lsym.Extra == nil {
ti := lsym.NewTypeInfo()
ti.Type = t
}
signatmu.Unlock()
return lsym
}
// TypePtrAt returns an expression that evaluates to the
// *runtime._type value for t.
func TypePtrAt(pos src.XPos, t *types.Type) *ir.AddrExpr {
return typecheck.LinksymAddr(pos, TypeLinksym(t), types.Types[types.TUINT8])
}
// ITabLsym returns the LSym representing the itab for concrete type typ implementing
// interface iface. A dummy tab will be created in the unusual case where typ doesn't
// implement iface. Normally, this wouldn't happen, because the typechecker would
// have reported a compile-time error. This situation can only happen when the
// destination type of a type assert or a type in a type switch is parameterized, so
// it may sometimes, but not always, be a type that can't implement the specified
// interface.
func ITabLsym(typ, iface *types.Type) *obj.LSym {
s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
lsym := s.Linksym()
if !existed {
writeITab(lsym, typ, iface, true)
}
return lsym
}
// ITabAddrAt returns an expression that evaluates to the
// *runtime.itab value for concrete type typ implementing interface
// iface.
func ITabAddrAt(pos src.XPos, typ, iface *types.Type) *ir.AddrExpr {
s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
lsym := s.Linksym()
if !existed {
writeITab(lsym, typ, iface, false)
}
return typecheck.LinksymAddr(pos, lsym, types.Types[types.TUINT8])
}
// needkeyupdate reports whether map updates with t as a key
// need the key to be updated.
func needkeyupdate(t *types.Type) bool {
switch t.Kind() {
case types.TBOOL, types.TINT, types.TUINT, types.TINT8, types.TUINT8, types.TINT16, types.TUINT16, types.TINT32, types.TUINT32,
types.TINT64, types.TUINT64, types.TUINTPTR, types.TPTR, types.TUNSAFEPTR, types.TCHAN:
return false
case types.TFLOAT32, types.TFLOAT64, types.TCOMPLEX64, types.TCOMPLEX128, // floats and complex can be +0/-0
types.TINTER,
types.TSTRING: // strings might have smaller backing stores
return true
case types.TARRAY:
return needkeyupdate(t.Elem())
case types.TSTRUCT:
for _, t1 := range t.Fields() {
if needkeyupdate(t1.Type) {
return true
}
}
return false
default:
base.Fatalf("bad type for map key: %v", t)
return true
}
}
// hashMightPanic reports whether the hash of a map key of type t might panic.
func hashMightPanic(t *types.Type) bool {
switch t.Kind() {
case types.TINTER:
return true
case types.TARRAY:
return hashMightPanic(t.Elem())
case types.TSTRUCT:
for _, t1 := range t.Fields() {
if hashMightPanic(t1.Type) {
return true
}
}
return false
default:
return false
}
}
// formalType replaces predeclared aliases with real types.
// They've been separate internally to make error messages
// better, but we have to merge them in the reflect tables.
func formalType(t *types.Type) *types.Type {
switch t {
case types.AnyType, types.ByteType, types.RuneType:
return types.Types[t.Kind()]
}
return t
}
func writeType(t *types.Type) *obj.LSym {
t = formalType(t)
if t.IsUntyped() {
base.Fatalf("writeType %v", t)
}
s := types.TypeSym(t)
lsym := s.Linksym()
// special case (look for runtime below):
// when compiling package runtime,
// emit the type structures for int, float, etc.
tbase := t
if t.IsPtr() && t.Sym() == nil && t.Elem().Sym() != nil {
tbase = t.Elem()
}
if tbase.Kind() == types.TFORW {
base.Fatalf("unresolved defined type: %v", tbase)
}
// This is a fake type we generated for our builtin pseudo-runtime
// package. We'll emit a description for the real type while
// compiling package runtime, so we don't need or want to emit one
// from this fake type.
if sym := tbase.Sym(); sym != nil && sym.Pkg == ir.Pkgs.Runtime {
return lsym
}
if s.Siggen() {
return lsym
}
s.SetSiggen(true)
if !NeedEmit(tbase) {
if i := typecheck.BaseTypeIndex(t); i >= 0 {
lsym.Pkg = tbase.Sym().Pkg.Prefix
lsym.SymIdx = int32(i)
lsym.Set(obj.AttrIndexed, true)
}
// TODO(mdempsky): Investigate whether this still happens.
// If we know we don't need to emit code for a type,
// we should have a link-symbol index for it.
// See also TODO in NeedEmit.
return lsym
}
// Type layout Written by Marker
// +--------------------------------+ - 0
// | abi/internal.Type | dcommontype
// +--------------------------------+ - A
// | additional type-dependent | code in the switch below
// | fields, e.g. |
// | abi/internal.ArrayType.Len |
// +--------------------------------+ - B
// | internal/abi.UncommonType | dextratype
// | This section is optional, |
// | if type has a name or methods |
// +--------------------------------+ - C
// | variable-length data | code in the switch below
// | referenced by |
// | type-dependent fields, e.g. |
// | abi/internal.StructType.Fields |
// | dataAdd = size of this section |
// +--------------------------------+ - D
// | method list, if any | dextratype
// +--------------------------------+ - E
// UncommonType section is included if we have a name or a method.
extra := t.Sym() != nil || len(methods(t)) != 0
// Decide the underlying type of the descriptor, and remember
// the size we need for variable-length data.
var rt *types.Type
dataAdd := 0
switch t.Kind() {
default:
rt = rttype.Type
case types.TARRAY:
rt = rttype.ArrayType
case types.TSLICE:
rt = rttype.SliceType
case types.TCHAN:
rt = rttype.ChanType
case types.TFUNC:
rt = rttype.FuncType
dataAdd = (t.NumRecvs() + t.NumParams() + t.NumResults()) * types.PtrSize
case types.TINTER:
rt = rttype.InterfaceType
dataAdd = len(imethods(t)) * int(rttype.IMethod.Size())
case types.TMAP:
rt = rttype.MapType
case types.TPTR:
rt = rttype.PtrType
// TODO: use rttype.Type for Elem() is ANY?
case types.TSTRUCT:
rt = rttype.StructType
dataAdd = t.NumFields() * int(rttype.StructField.Size())
}
// Compute offsets of each section.
B := rt.Size()
C := B
if extra {
C = B + rttype.UncommonType.Size()
}
D := C + int64(dataAdd)
E := D + int64(len(methods(t)))*rttype.Method.Size()
// Write the runtime._type
c := rttype.NewCursor(lsym, 0, rt)
if rt == rttype.Type {
dcommontype(c, t)
} else {
dcommontype(c.Field("Type"), t)
}
// Write additional type-specific data
// (Both the fixed size and variable-sized sections.)
switch t.Kind() {
case types.TARRAY:
// internal/abi.ArrayType
s1 := writeType(t.Elem())
t2 := types.NewSlice(t.Elem())
s2 := writeType(t2)
c.Field("Elem").WritePtr(s1)
c.Field("Slice").WritePtr(s2)
c.Field("Len").WriteUintptr(uint64(t.NumElem()))
case types.TSLICE:
// internal/abi.SliceType
s1 := writeType(t.Elem())
c.Field("Elem").WritePtr(s1)
case types.TCHAN:
// internal/abi.ChanType
s1 := writeType(t.Elem())
c.Field("Elem").WritePtr(s1)
c.Field("Dir").WriteInt(int64(t.ChanDir()))
case types.TFUNC:
// internal/abi.FuncType
for _, t1 := range t.RecvParamsResults() {
writeType(t1.Type)
}
inCount := t.NumRecvs() + t.NumParams()
outCount := t.NumResults()
if t.IsVariadic() {
outCount |= 1 << 15
}
c.Field("InCount").WriteUint16(uint16(inCount))
c.Field("OutCount").WriteUint16(uint16(outCount))
// Array of rtype pointers follows funcType.
typs := t.RecvParamsResults()
array := rttype.NewArrayCursor(lsym, C, types.Types[types.TUNSAFEPTR], len(typs))
for i, t1 := range typs {
array.Elem(i).WritePtr(writeType(t1.Type))
}
case types.TINTER:
// internal/abi.InterfaceType
m := imethods(t)
n := len(m)
for _, a := range m {
writeType(a.type_)
}
var tpkg *types.Pkg
if t.Sym() != nil && t != types.Types[t.Kind()] && t != types.ErrorType {
tpkg = t.Sym().Pkg
}
dgopkgpath(c.Field("PkgPath"), tpkg)
c.Field("Methods").WriteSlice(lsym, C, int64(n), int64(n))
array := rttype.NewArrayCursor(lsym, C, rttype.IMethod, n)
for i, a := range m {
exported := types.IsExported(a.name.Name)
var pkg *types.Pkg
if !exported && a.name.Pkg != tpkg {
pkg = a.name.Pkg
}
nsym := dname(a.name.Name, "", pkg, exported, false)
e := array.Elem(i)
e.Field("Name").WriteSymPtrOff(nsym, false)
e.Field("Typ").WriteSymPtrOff(writeType(a.type_), false)
}
case types.TMAP:
// internal/abi.MapType
s1 := writeType(t.Key())
s2 := writeType(t.Elem())
s3 := writeType(MapBucketType(t))
hasher := genhash(t.Key())
c.Field("Key").WritePtr(s1)
c.Field("Elem").WritePtr(s2)
c.Field("Bucket").WritePtr(s3)
c.Field("Hasher").WritePtr(hasher)
var flags uint32
// Note: flags must match maptype accessors in ../../../../runtime/type.go
// and maptype builder in ../../../../reflect/type.go:MapOf.
if t.Key().Size() > abi.MapMaxKeyBytes {
c.Field("KeySize").WriteUint8(uint8(types.PtrSize))
flags |= 1 // indirect key
} else {
c.Field("KeySize").WriteUint8(uint8(t.Key().Size()))
}
if t.Elem().Size() > abi.MapMaxElemBytes {
c.Field("ValueSize").WriteUint8(uint8(types.PtrSize))
flags |= 2 // indirect value
} else {
c.Field("ValueSize").WriteUint8(uint8(t.Elem().Size()))
}
c.Field("BucketSize").WriteUint16(uint16(MapBucketType(t).Size()))
if types.IsReflexive(t.Key()) {
flags |= 4 // reflexive key
}
if needkeyupdate(t.Key()) {
flags |= 8 // need key update
}
if hashMightPanic(t.Key()) {
flags |= 16 // hash might panic
}
c.Field("Flags").WriteUint32(flags)
if u := t.Underlying(); u != t {
// If t is a named map type, also keep the underlying map
// type live in the binary. This is important to make sure that
// a named map and that same map cast to its underlying type via
// reflection, use the same hash function. See issue 37716.
r := obj.Addrel(lsym)
r.Sym = writeType(u)
r.Type = objabi.R_KEEP
}
case types.TPTR:
// internal/abi.PtrType
if t.Elem().Kind() == types.TANY {
base.Fatalf("bad pointer base type")
}
s1 := writeType(t.Elem())
c.Field("Elem").WritePtr(s1)
case types.TSTRUCT:
// internal/abi.StructType
fields := t.Fields()
for _, t1 := range fields {
writeType(t1.Type)
}
// All non-exported struct field names within a struct
// type must originate from a single package. By
// identifying and recording that package within the
// struct type descriptor, we can omit that
// information from the field descriptors.
var spkg *types.Pkg
for _, f := range fields {
if !types.IsExported(f.Sym.Name) {
spkg = f.Sym.Pkg
break
}
}
dgopkgpath(c.Field("PkgPath"), spkg)
c.Field("Fields").WriteSlice(lsym, C, int64(len(fields)), int64(len(fields)))
array := rttype.NewArrayCursor(lsym, C, rttype.StructField, len(fields))
for i, f := range fields {
e := array.Elem(i)
dnameField(e.Field("Name"), spkg, f)
e.Field("Typ").WritePtr(writeType(f.Type))
e.Field("Offset").WriteUintptr(uint64(f.Offset))
}
}
// Write the extra info, if any.
if extra {
dextratype(lsym, B, t, dataAdd)
}
// Note: DUPOK is required to ensure that we don't end up with more
// than one type descriptor for a given type, if the type descriptor
// can be defined in multiple packages, that is, unnamed types,
// instantiated types and shape types.
dupok := 0
if tbase.Sym() == nil || tbase.IsFullyInstantiated() || tbase.HasShape() {
dupok = obj.DUPOK
}
objw.Global(lsym, int32(E), int16(dupok|obj.RODATA))
// The linker will leave a table of all the typelinks for
// types in the binary, so the runtime can find them.
//
// When buildmode=shared, all types are in typelinks so the
// runtime can deduplicate type pointers.
keep := base.Ctxt.Flag_dynlink
if !keep && t.Sym() == nil {
// For an unnamed type, we only need the link if the type can
// be created at run time by reflect.PointerTo and similar
// functions. If the type exists in the program, those
// functions must return the existing type structure rather
// than creating a new one.
switch t.Kind() {
case types.TPTR, types.TARRAY, types.TCHAN, types.TFUNC, types.TMAP, types.TSLICE, types.TSTRUCT:
keep = true
}
}
// Do not put Noalg types in typelinks. See issue #22605.
if types.TypeHasNoAlg(t) {
keep = false
}
lsym.Set(obj.AttrMakeTypelink, keep)
return lsym
}
// InterfaceMethodOffset returns the offset of the i-th method in the interface
// type descriptor, ityp.
func InterfaceMethodOffset(ityp *types.Type, i int64) int64 {
// interface type descriptor layout is struct {
// _type // commonSize
// pkgpath // 1 word
// []imethod // 3 words (pointing to [...]imethod below)
// uncommontype // uncommonSize
// [...]imethod
// }
// The size of imethod is 8.
return int64(commonSize()+4*types.PtrSize+uncommonSize(ityp)) + i*8
}
// NeedRuntimeType ensures that a runtime type descriptor is emitted for t.
func NeedRuntimeType(t *types.Type) {
if _, ok := signatset[t]; !ok {
signatset[t] = struct{}{}
signatslice = append(signatslice, typeAndStr{t: t, short: types.TypeSymName(t), regular: t.String()})
}
}
func WriteRuntimeTypes() {
// Process signatslice. Use a loop, as writeType adds
// entries to signatslice while it is being processed.
for len(signatslice) > 0 {
signats := signatslice
// Sort for reproducible builds.
sort.Sort(typesByString(signats))
for _, ts := range signats {
t := ts.t
writeType(t)
if t.Sym() != nil {
writeType(types.NewPtr(t))
}
}
signatslice = signatslice[len(signats):]
}
}
func WriteGCSymbols() {
// Emit GC data symbols.
gcsyms := make([]typeAndStr, 0, len(gcsymset))
for t := range gcsymset {
gcsyms = append(gcsyms, typeAndStr{t: t, short: types.TypeSymName(t), regular: t.String()})
}
sort.Sort(typesByString(gcsyms))
for _, ts := range gcsyms {
dgcsym(ts.t, true)
}
}
// writeITab writes the itab for concrete type typ implementing interface iface. If
// allowNonImplement is true, allow the case where typ does not implement iface, and just
// create a dummy itab with zeroed-out method entries.
func writeITab(lsym *obj.LSym, typ, iface *types.Type, allowNonImplement bool) {
// TODO(mdempsky): Fix methodWrapper, geneq, and genhash (and maybe
// others) to stop clobbering these.
oldpos, oldfn := base.Pos, ir.CurFunc
defer func() { base.Pos, ir.CurFunc = oldpos, oldfn }()
if typ == nil || (typ.IsPtr() && typ.Elem() == nil) || typ.IsUntyped() || iface == nil || !iface.IsInterface() || iface.IsEmptyInterface() {
base.Fatalf("writeITab(%v, %v)", typ, iface)
}
sigs := iface.AllMethods()
entries := make([]*obj.LSym, 0, len(sigs))
// both sigs and methods are sorted by name,
// so we can find the intersection in a single pass
for _, m := range methods(typ) {
if m.name == sigs[0].Sym {
entries = append(entries, m.isym)
if m.isym == nil {
panic("NO ISYM")
}
sigs = sigs[1:]
if len(sigs) == 0 {
break
}
}
}
completeItab := len(sigs) == 0
if !allowNonImplement && !completeItab {
base.Fatalf("incomplete itab")
}
// dump empty itab symbol into i.sym
// type itab struct {
// inter *interfacetype
// _type *_type
// hash uint32 // copy of _type.hash. Used for type switches.
// _ [4]byte
// fun [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
// }
c := rttype.NewCursor(lsym, 0, rttype.ITab)
c.Field("Inter").WritePtr(writeType(iface))
c.Field("Type").WritePtr(writeType(typ))
c.Field("Hash").WriteUint32(types.TypeHash(typ)) // copy of type hash
var delta int64
c = c.Field("Fun")
if !completeItab {
// If typ doesn't implement iface, make method entries be zero.
c.Elem(0).WriteUintptr(0)
} else {
var a rttype.ArrayCursor
a, delta = c.ModifyArray(len(entries))
for i, fn := range entries {
a.Elem(i).WritePtrWeak(fn) // method pointer for each method
}
}
// Nothing writes static itabs, so they are read only.
objw.Global(lsym, int32(rttype.ITab.Size()+delta), int16(obj.DUPOK|obj.RODATA))
lsym.Set(obj.AttrContentAddressable, true)
}
func WritePluginTable() {
ptabs := typecheck.Target.PluginExports
if len(ptabs) == 0 {
return
}
lsym := base.Ctxt.Lookup("go:plugin.tabs")
ot := 0
for _, p := range ptabs {
// Dump ptab symbol into go.pluginsym package.
//
// type ptab struct {
// name nameOff
// typ typeOff // pointer to symbol
// }
nsym := dname(p.Sym().Name, "", nil, true, false)
t := p.Type()
if p.Class != ir.PFUNC {
t = types.NewPtr(t)
}
tsym := writeType(t)
ot = objw.SymPtrOff(lsym, ot, nsym)
ot = objw.SymPtrOff(lsym, ot, tsym)
// Plugin exports symbols as interfaces. Mark their types
// as UsedInIface.
tsym.Set(obj.AttrUsedInIface, true)
}
objw.Global(lsym, int32(ot), int16(obj.RODATA))
lsym = base.Ctxt.Lookup("go:plugin.exports")
ot = 0
for _, p := range ptabs {
ot = objw.SymPtr(lsym, ot, p.Linksym(), 0)
}
objw.Global(lsym, int32(ot), int16(obj.RODATA))
}
// writtenByWriteBasicTypes reports whether typ is written by WriteBasicTypes.
// WriteBasicTypes always writes pointer types; any pointer has been stripped off typ already.
func writtenByWriteBasicTypes(typ *types.Type) bool {
if typ.Sym() == nil && typ.Kind() == types.TFUNC {
// func(error) string
if typ.NumRecvs() == 0 &&
typ.NumParams() == 1 && typ.NumResults() == 1 &&
typ.Param(0).Type == types.ErrorType &&
typ.Result(0).Type == types.Types[types.TSTRING] {
return true
}
}
// Now we have left the basic types plus any and error, plus slices of them.
// Strip the slice.
if typ.Sym() == nil && typ.IsSlice() {
typ = typ.Elem()
}
// Basic types.
sym := typ.Sym()
if sym != nil && (sym.Pkg == types.BuiltinPkg || sym.Pkg == types.UnsafePkg) {
return true
}
// any or error
return (sym == nil && typ.IsEmptyInterface()) || typ == types.ErrorType
}
func WriteBasicTypes() {
// do basic types if compiling package runtime.
// they have to be in at least one package,
// and runtime is always loaded implicitly,
// so this is as good as any.
// another possible choice would be package main,
// but using runtime means fewer copies in object files.
// The code here needs to be in sync with writtenByWriteBasicTypes above.
if base.Ctxt.Pkgpath != "runtime" {
return
}
// Note: always write NewPtr(t) because NeedEmit's caller strips the pointer.
var list []*types.Type
for i := types.Kind(1); i <= types.TBOOL; i++ {
list = append(list, types.Types[i])
}
list = append(list,
types.Types[types.TSTRING],
types.Types[types.TUNSAFEPTR],
types.AnyType,
types.ErrorType)
for _, t := range list {
writeType(types.NewPtr(t))
writeType(types.NewPtr(types.NewSlice(t)))
}
// emit type for func(error) string,
// which is the type of an auto-generated wrapper.
writeType(types.NewPtr(types.NewSignature(nil, []*types.Field{
types.NewField(base.Pos, nil, types.ErrorType),
}, []*types.Field{
types.NewField(base.Pos, nil, types.Types[types.TSTRING]),
})))
}
type typeAndStr struct {
t *types.Type
short string // "short" here means TypeSymName
regular string
}
type typesByString []typeAndStr
func (a typesByString) Len() int { return len(a) }
func (a typesByString) Less(i, j int) bool {
// put named types before unnamed types
if a[i].t.Sym() != nil && a[j].t.Sym() == nil {
return true
}
if a[i].t.Sym() == nil && a[j].t.Sym() != nil {
return false
}
if a[i].short != a[j].short {
return a[i].short < a[j].short
}
// When the only difference between the types is whether
// they refer to byte or uint8, such as **byte vs **uint8,
// the types' NameStrings can be identical.
// To preserve deterministic sort ordering, sort these by String().
//
// TODO(mdempsky): This all seems suspect. Using LinkString would
// avoid naming collisions, and there shouldn't be a reason to care
// about "byte" vs "uint8": they share the same runtime type
// descriptor anyway.
if a[i].regular != a[j].regular {
return a[i].regular < a[j].regular
}
// Identical anonymous interfaces defined in different locations
// will be equal for the above checks, but different in DWARF output.
// Sort by source position to ensure deterministic order.
// See issues 27013 and 30202.
if a[i].t.Kind() == types.TINTER && len(a[i].t.AllMethods()) > 0 {
return a[i].t.AllMethods()[0].Pos.Before(a[j].t.AllMethods()[0].Pos)
}
return false
}
func (a typesByString) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
// GCSym returns a data symbol containing GC information for type t, along
// with a boolean reporting whether the UseGCProg bit should be set in the
// type kind, and the ptrdata field to record in the reflect type information.
// GCSym may be called in concurrent backend, so it does not emit the symbol
// content.
func GCSym(t *types.Type) (lsym *obj.LSym, useGCProg bool, ptrdata int64) {
// Record that we need to emit the GC symbol.
gcsymmu.Lock()
if _, ok := gcsymset[t]; !ok {
gcsymset[t] = struct{}{}
}
gcsymmu.Unlock()
return dgcsym(t, false)
}
// dgcsym returns a data symbol containing GC information for type t, along
// with a boolean reporting whether the UseGCProg bit should be set in the
// type kind, and the ptrdata field to record in the reflect type information.
// When write is true, it writes the symbol data.
func dgcsym(t *types.Type, write bool) (lsym *obj.LSym, useGCProg bool, ptrdata int64) {
ptrdata = types.PtrDataSize(t)
if ptrdata/int64(types.PtrSize) <= abi.MaxPtrmaskBytes*8 {
lsym = dgcptrmask(t, write)
return
}
useGCProg = true
lsym, ptrdata = dgcprog(t, write)
return
}
// dgcptrmask emits and returns the symbol containing a pointer mask for type t.
func dgcptrmask(t *types.Type, write bool) *obj.LSym {
// Bytes we need for the ptrmask.
n := (types.PtrDataSize(t)/int64(types.PtrSize) + 7) / 8
// Runtime wants ptrmasks padded to a multiple of uintptr in size.
n = (n + int64(types.PtrSize) - 1) &^ (int64(types.PtrSize) - 1)
ptrmask := make([]byte, n)
fillptrmask(t, ptrmask)
p := fmt.Sprintf("runtime.gcbits.%x", ptrmask)
lsym := base.Ctxt.Lookup(p)
if write && !lsym.OnList() {
for i, x := range ptrmask {
objw.Uint8(lsym, i, x)
}
objw.Global(lsym, int32(len(ptrmask)), obj.DUPOK|obj.RODATA|obj.LOCAL)
lsym.Set(obj.AttrContentAddressable, true)
}
return lsym
}
// fillptrmask fills in ptrmask with 1s corresponding to the
// word offsets in t that hold pointers.
// ptrmask is assumed to fit at least types.PtrDataSize(t)/PtrSize bits.
func fillptrmask(t *types.Type, ptrmask []byte) {
for i := range ptrmask {
ptrmask[i] = 0
}
if !t.HasPointers() {
return
}
vec := bitvec.New(8 * int32(len(ptrmask)))
typebits.Set(t, 0, vec)
nptr := types.PtrDataSize(t) / int64(types.PtrSize)
for i := int64(0); i < nptr; i++ {
if vec.Get(int32(i)) {
ptrmask[i/8] |= 1 << (uint(i) % 8)
}
}
}
// dgcprog emits and returns the symbol containing a GC program for type t
// along with the size of the data described by the program (in the range
// [types.PtrDataSize(t), t.Width]).
// In practice, the size is types.PtrDataSize(t) except for non-trivial arrays.
// For non-trivial arrays, the program describes the full t.Width size.
func dgcprog(t *types.Type, write bool) (*obj.LSym, int64) {
types.CalcSize(t)
if t.Size() == types.BADWIDTH {
base.Fatalf("dgcprog: %v badwidth", t)
}
lsym := TypeLinksymPrefix(".gcprog", t)
var p gcProg
p.init(lsym, write)
p.emit(t, 0)
offset := p.w.BitIndex() * int64(types.PtrSize)
p.end()
if ptrdata := types.PtrDataSize(t); offset < ptrdata || offset > t.Size() {
base.Fatalf("dgcprog: %v: offset=%d but ptrdata=%d size=%d", t, offset, ptrdata, t.Size())
}
return lsym, offset
}
type gcProg struct {
lsym *obj.LSym
symoff int
w gcprog.Writer
write bool
}
func (p *gcProg) init(lsym *obj.LSym, write bool) {
p.lsym = lsym
p.write = write && !lsym.OnList()
p.symoff = 4 // first 4 bytes hold program length
if !write {
p.w.Init(func(byte) {})
return
}
p.w.Init(p.writeByte)
if base.Debug.GCProg > 0 {
fmt.Fprintf(os.Stderr, "compile: start GCProg for %v\n", lsym)
p.w.Debug(os.Stderr)
}
}
func (p *gcProg) writeByte(x byte) {
p.symoff = objw.Uint8(p.lsym, p.symoff, x)
}
func (p *gcProg) end() {
p.w.End()
if !p.write {
return
}
objw.Uint32(p.lsym, 0, uint32(p.symoff-4))
objw.Global(p.lsym, int32(p.symoff), obj.DUPOK|obj.RODATA|obj.LOCAL)
p.lsym.Set(obj.AttrContentAddressable, true)
if base.Debug.GCProg > 0 {
fmt.Fprintf(os.Stderr, "compile: end GCProg for %v\n", p.lsym)
}
}
func (p *gcProg) emit(t *types.Type, offset int64) {
types.CalcSize(t)
if !t.HasPointers() {
return
}
if t.Size() == int64(types.PtrSize) {
p.w.Ptr(offset / int64(types.PtrSize))
return
}
switch t.Kind() {
default:
base.Fatalf("gcProg.emit: unexpected type %v", t)
case types.TSTRING:
p.w.Ptr(offset / int64(types.PtrSize))
case types.TINTER:
// Note: the first word isn't a pointer. See comment in typebits.Set
p.w.Ptr(offset/int64(types.PtrSize) + 1)
case types.TSLICE:
p.w.Ptr(offset / int64(types.PtrSize))
case types.TARRAY:
if t.NumElem() == 0 {
// should have been handled by haspointers check above
base.Fatalf("gcProg.emit: empty array")
}
// Flatten array-of-array-of-array to just a big array by multiplying counts.
count := t.NumElem()
elem := t.Elem()
for elem.IsArray() {
count *= elem.NumElem()
elem = elem.Elem()
}
if !p.w.ShouldRepeat(elem.Size()/int64(types.PtrSize), count) {
// Cheaper to just emit the bits.
for i := int64(0); i < count; i++ {
p.emit(elem, offset+i*elem.Size())
}
return
}
p.emit(elem, offset)
p.w.ZeroUntil((offset + elem.Size()) / int64(types.PtrSize))
p.w.Repeat(elem.Size()/int64(types.PtrSize), count-1)
case types.TSTRUCT:
for _, t1 := range t.Fields() {
p.emit(t1.Type, offset+t1.Offset)
}
}
}
// ZeroAddr returns the address of a symbol with at least
// size bytes of zeros.
func ZeroAddr(size int64) ir.Node {
if size >= 1<<31 {
base.Fatalf("map elem too big %d", size)
}
if ZeroSize < size {
ZeroSize = size
}
lsym := base.PkgLinksym("go:map", "zero", obj.ABI0)
x := ir.NewLinksymExpr(base.Pos, lsym, types.Types[types.TUINT8])
return typecheck.Expr(typecheck.NodAddr(x))
}
// NeedEmit reports whether typ is a type that we need to emit code
// for (e.g., runtime type descriptors, method wrappers).
func NeedEmit(typ *types.Type) bool {
// TODO(mdempsky): Export data should keep track of which anonymous
// and instantiated types were emitted, so at least downstream
// packages can skip re-emitting them.
//
// Perhaps we can just generalize the linker-symbol indexing to
// track the index of arbitrary types, not just defined types, and
// use its presence to detect this. The same idea would work for
// instantiated generic functions too.
switch sym := typ.Sym(); {
case writtenByWriteBasicTypes(typ):
return base.Ctxt.Pkgpath == "runtime"
case sym == nil:
// Anonymous type; possibly never seen before or ever again.
// Need to emit to be safe (however, see TODO above).
return true
case sym.Pkg == types.LocalPkg:
// Local defined type; our responsibility.
return true
case typ.IsFullyInstantiated():
// Instantiated type; possibly instantiated with unique type arguments.
// Need to emit to be safe (however, see TODO above).
return true
case typ.HasShape():
// Shape type; need to emit even though it lives in the .shape package.
// TODO: make sure the linker deduplicates them (see dupok in writeType above).
return true
default:
// Should have been emitted by an imported package.
return false
}
}
// Generate a wrapper function to convert from
// a receiver of type T to a receiver of type U.
// That is,
//
// func (t T) M() {
// ...
// }
//
// already exists; this function generates
//
// func (u U) M() {
// u.M()
// }
//
// where the types T and U are such that u.M() is valid
// and calls the T.M method.
// The resulting function is for use in method tables.
//
// rcvr - U
// method - M func (t T)(), a TFIELD type struct
//
// Also wraps methods on instantiated generic types for use in itab entries.
// For an instantiated generic type G[int], we generate wrappers like:
// G[int] pointer shaped:
//
// func (x G[int]) f(arg) {
// .inst.G[int].f(dictionary, x, arg)
// }
//
// G[int] not pointer shaped:
//
// func (x *G[int]) f(arg) {
// .inst.G[int].f(dictionary, *x, arg)
// }
//
// These wrappers are always fully stenciled.
func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSym {
if forItab && !types.IsDirectIface(rcvr) {
rcvr = rcvr.PtrTo()
}
newnam := ir.MethodSym(rcvr, method.Sym)
lsym := newnam.Linksym()
// Unified IR creates its own wrappers.
return lsym
}
var ZeroSize int64
// MarkTypeUsedInInterface marks that type t is converted to an interface.
// This information is used in the linker in dead method elimination.
func MarkTypeUsedInInterface(t *types.Type, from *obj.LSym) {
if t.HasShape() {
// Shape types shouldn't be put in interfaces, so we shouldn't ever get here.
base.Fatalf("shape types have no methods %+v", t)
}
MarkTypeSymUsedInInterface(TypeLinksym(t), from)
}
func MarkTypeSymUsedInInterface(tsym *obj.LSym, from *obj.LSym) {
// Emit a marker relocation. The linker will know the type is converted
// to an interface if "from" is reachable.
r := obj.Addrel(from)
r.Sym = tsym
r.Type = objabi.R_USEIFACE
}
// MarkUsedIfaceMethod marks that an interface method is used in the current
// function. n is OCALLINTER node.
func MarkUsedIfaceMethod(n *ir.CallExpr) {
// skip unnamed functions (func _())
if ir.CurFunc.LSym == nil {
return
}
dot := n.Fun.(*ir.SelectorExpr)
ityp := dot.X.Type()
if ityp.HasShape() {
// Here we're calling a method on a generic interface. Something like:
//
// type I[T any] interface { foo() T }
// func f[T any](x I[T]) {
// ... = x.foo()
// }
// f[int](...)
// f[string](...)
//
// In this case, in f we're calling foo on a generic interface.
// Which method could that be? Normally we could match the method
// both by name and by type. But in this case we don't really know
// the type of the method we're calling. It could be func()int
// or func()string. So we match on just the function name, instead
// of both the name and the type used for the non-generic case below.
// TODO: instantiations at least know the shape of the instantiated
// type, and the linker could do more complicated matching using
// some sort of fuzzy shape matching. For now, only use the name
// of the method for matching.
r := obj.Addrel(ir.CurFunc.LSym)
r.Sym = staticdata.StringSymNoCommon(dot.Sel.Name)
r.Type = objabi.R_USENAMEDMETHOD
return
}
tsym := TypeLinksym(ityp)
r := obj.Addrel(ir.CurFunc.LSym)
r.Sym = tsym
// dot.Offset() is the method index * PtrSize (the offset of code pointer
// in itab).
midx := dot.Offset() / int64(types.PtrSize)
r.Add = InterfaceMethodOffset(ityp, midx)
r.Type = objabi.R_USEIFACEMETHOD
}
func deref(t *types.Type) *types.Type {
if t.IsPtr() {
return t.Elem()
}
return t
}