1 files changed, 634 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/types/size.go b/src/cmd/compile/internal/types/size.go
new file mode 100644
index 0000000000..a54c086ded
--- /dev/null
+++ b/src/cmd/compile/internal/types/size.go
@@ -0,0 +1,634 @@
+// 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 types
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+
+	"cmd/compile/internal/base"
+	"cmd/internal/src"
+)
+
+var PtrSize int
+
+var RegSize int
+
+// Slices in the runtime are represented by three components:
+//
+// type slice struct {
+// 	ptr unsafe.Pointer
+// 	len int
+// 	cap int
+// }
+//
+// Strings in the runtime are represented by two components:
+//
+// type string struct {
+// 	ptr unsafe.Pointer
+// 	len int
+// }
+//
+// These variables are the offsets of fields and sizes of these structs.
+var (
+	SlicePtrOffset int64
+	SliceLenOffset int64
+	SliceCapOffset int64
+
+	SliceSize  int64
+	StringSize int64
+)
+
+var SkipSizeForTracing bool
+
+// typePos returns the position associated with t.
+// This is where t was declared or where it appeared as a type expression.
+func typePos(t *Type) src.XPos {
+	if pos := t.Pos(); pos.IsKnown() {
+		return pos
+	}
+	base.Fatalf("bad type: %v", t)
+	panic("unreachable")
+}
+
+// MaxWidth is the maximum size of a value on the target architecture.
+var MaxWidth int64
+
+// CalcSizeDisabled indicates whether it is safe
+// to calculate Types' widths and alignments. See dowidth.
+var CalcSizeDisabled bool
+
+// machine size and rounding alignment is dictated around
+// the size of a pointer, set in betypeinit (see ../amd64/galign.go).
+var defercalc int
+
+func Rnd(o int64, r int64) int64 {
+	if r < 1 || r > 8 || r&(r-1) != 0 {
+		base.Fatalf("rnd %d", r)
+	}
+	return (o + r - 1) &^ (r - 1)
+}
+
+// expandiface computes the method set for interface type t by
+// expanding embedded interfaces.
+func expandiface(t *Type) {
+	seen := make(map[*Sym]*Field)
+	var methods []*Field
+
+	addMethod := func(m *Field, explicit bool) {
+		switch prev := seen[m.Sym]; {
+		case prev == nil:
+			seen[m.Sym] = m
+		case AllowsGoVersion(t.Pkg(), 1, 14) && !explicit && Identical(m.Type, prev.Type):
+			return
+		default:
+			base.ErrorfAt(m.Pos, "duplicate method %s", m.Sym.Name)
+		}
+		methods = append(methods, m)
+	}
+
+	for _, m := range t.Methods().Slice() {
+		if m.Sym == nil {
+			continue
+		}
+
+		CheckSize(m.Type)
+		addMethod(m, true)
+	}
+
+	for _, m := range t.Methods().Slice() {
+		if m.Sym != nil {
+			continue
+		}
+
+		if !m.Type.IsInterface() {
+			base.ErrorfAt(m.Pos, "interface contains embedded non-interface %v", m.Type)
+			m.SetBroke(true)
+			t.SetBroke(true)
+			// Add to fields so that error messages
+			// include the broken embedded type when
+			// printing t.
+			// TODO(mdempsky): Revisit this.
+			methods = append(methods, m)
+			continue
+		}
+
+		// Embedded interface: duplicate all methods
+		// (including broken ones, if any) and add to t's
+		// method set.
+		for _, t1 := range m.Type.Fields().Slice() {
+			// Use m.Pos rather than t1.Pos to preserve embedding position.
+			f := NewField(m.Pos, t1.Sym, t1.Type)
+			addMethod(f, false)
+		}
+	}
+
+	sort.Sort(MethodsByName(methods))
+
+	if int64(len(methods)) >= MaxWidth/int64(PtrSize) {
+		base.ErrorfAt(typePos(t), "interface too large")
+	}
+	for i, m := range methods {
+		m.Offset = int64(i) * int64(PtrSize)
+	}
+
+	// Access fields directly to avoid recursively calling dowidth
+	// within Type.Fields().
+	t.Extra.(*Interface).Fields.Set(methods)
+}
+
+func calcStructOffset(errtype *Type, t *Type, o int64, flag int) int64 {
+	starto := o
+	maxalign := int32(flag)
+	if maxalign < 1 {
+		maxalign = 1
+	}
+	lastzero := int64(0)
+	for _, f := range t.Fields().Slice() {
+		if f.Type == nil {
+			// broken field, just skip it so that other valid fields
+			// get a width.
+			continue
+		}
+
+		CalcSize(f.Type)
+		if int32(f.Type.Align) > maxalign {
+			maxalign = int32(f.Type.Align)
+		}
+		if f.Type.Align > 0 {
+			o = Rnd(o, int64(f.Type.Align))
+		}
+		f.Offset = o
+		if f.Nname != nil {
+			// addrescapes has similar code to update these offsets.
+			// Usually addrescapes runs after widstruct,
+			// in which case we could drop this,
+			// but function closure functions are the exception.
+			// NOTE(rsc): This comment may be stale.
+			// It's possible the ordering has changed and this is
+			// now the common case. I'm not sure.
+			f.Nname.(VarObject).RecordFrameOffset(o)
+		}
+
+		w := f.Type.Width
+		if w < 0 {
+			base.Fatalf("invalid width %d", f.Type.Width)
+		}
+		if w == 0 {
+			lastzero = o
+		}
+		o += w
+		maxwidth := MaxWidth
+		// On 32-bit systems, reflect tables impose an additional constraint
+		// that each field start offset must fit in 31 bits.
+		if maxwidth < 1<<32 {
+			maxwidth = 1<<31 - 1
+		}
+		if o >= maxwidth {
+			base.ErrorfAt(typePos(errtype), "type %L too large", errtype)
+			o = 8 // small but nonzero
+		}
+	}
+
+	// For nonzero-sized structs which end in a zero-sized thing, we add
+	// an extra byte of padding to the type. This padding ensures that
+	// taking the address of the zero-sized thing can't manufacture a
+	// pointer to the next object in the heap. See issue 9401.
+	if flag == 1 && o > starto && o == lastzero {
+		o++
+	}
+
+	// final width is rounded
+	if flag != 0 {
+		o = Rnd(o, int64(maxalign))
+	}
+	t.Align = uint8(maxalign)
+
+	// type width only includes back to first field's offset
+	t.Width = o - starto
+
+	return o
+}
+
+// findTypeLoop searches for an invalid type declaration loop involving
+// type t and reports whether one is found. If so, path contains the
+// loop.
+//
+// path points to a slice used for tracking the sequence of types
+// visited. Using a pointer to a slice allows the slice capacity to
+// grow and limit reallocations.
+func findTypeLoop(t *Type, path *[]*Type) bool {
+	// We implement a simple DFS loop-finding algorithm. This
+	// could be faster, but type cycles are rare.
+
+	if t.Sym() != nil {
+		// Declared type. Check for loops and otherwise
+		// recurse on the type expression used in the type
+		// declaration.
+
+		// Type imported from package, so it can't be part of
+		// a type loop (otherwise that package should have
+		// failed to compile).
+		if t.Sym().Pkg != LocalPkg {
+			return false
+		}
+
+		for i, x := range *path {
+			if x == t {
+				*path = (*path)[i:]
+				return true
+			}
+		}
+
+		*path = append(*path, t)
+		if findTypeLoop(t.Obj().(TypeObject).TypeDefn(), path) {
+			return true
+		}
+		*path = (*path)[:len(*path)-1]
+	} else {
+		// Anonymous type. Recurse on contained types.
+
+		switch t.Kind() {
+		case TARRAY:
+			if findTypeLoop(t.Elem(), path) {
+				return true
+			}
+		case TSTRUCT:
+			for _, f := range t.Fields().Slice() {
+				if findTypeLoop(f.Type, path) {
+					return true
+				}
+			}
+		case TINTER:
+			for _, m := range t.Methods().Slice() {
+				if m.Type.IsInterface() { // embedded interface
+					if findTypeLoop(m.Type, path) {
+						return true
+					}
+				}
+			}
+		}
+	}
+
+	return false
+}
+
+func reportTypeLoop(t *Type) {
+	if t.Broke() {
+		return
+	}
+
+	var l []*Type
+	if !findTypeLoop(t, &l) {
+		base.Fatalf("failed to find type loop for: %v", t)
+	}
+
+	// Rotate loop so that the earliest type declaration is first.
+	i := 0
+	for j, t := range l[1:] {
+		if typePos(t).Before(typePos(l[i])) {
+			i = j + 1
+		}
+	}
+	l = append(l[i:], l[:i]...)
+
+	var msg bytes.Buffer
+	fmt.Fprintf(&msg, "invalid recursive type %v\n", l[0])
+	for _, t := range l {
+		fmt.Fprintf(&msg, "\t%v: %v refers to\n", base.FmtPos(typePos(t)), t)
+		t.SetBroke(true)
+	}
+	fmt.Fprintf(&msg, "\t%v: %v", base.FmtPos(typePos(l[0])), l[0])
+	base.ErrorfAt(typePos(l[0]), msg.String())
+}
+
+// CalcSize calculates and stores the size and alignment for t.
+// If sizeCalculationDisabled is set, and the size/alignment
+// have not already been calculated, it calls Fatal.
+// This is used to prevent data races in the back end.
+func CalcSize(t *Type) {
+	// Calling dowidth when typecheck tracing enabled is not safe.
+	// See issue #33658.
+	if base.EnableTrace && SkipSizeForTracing {
+		return
+	}
+	if PtrSize == 0 {
+
+		// Assume this is a test.
+		return
+	}
+
+	if t == nil {
+		return
+	}
+
+	if t.Width == -2 {
+		reportTypeLoop(t)
+		t.Width = 0
+		t.Align = 1
+		return
+	}
+
+	if t.WidthCalculated() {
+		return
+	}
+
+	if CalcSizeDisabled {
+		if t.Broke() {
+			// break infinite recursion from Fatal call below
+			return
+		}
+		t.SetBroke(true)
+		base.Fatalf("width not calculated: %v", t)
+	}
+
+	// break infinite recursion if the broken recursive type
+	// is referenced again
+	if t.Broke() && t.Width == 0 {
+		return
+	}
+
+	// defer checkwidth calls until after we're done
+	DeferCheckSize()
+
+	lno := base.Pos
+	if pos := t.Pos(); pos.IsKnown() {
+		base.Pos = pos
+	}
+
+	t.Width = -2
+	t.Align = 0 // 0 means use t.Width, below
+
+	et := t.Kind()
+	switch et {
+	case TFUNC, TCHAN, TMAP, TSTRING:
+		break
+
+	// simtype == 0 during bootstrap
+	default:
+		if SimType[t.Kind()] != 0 {
+			et = SimType[t.Kind()]
+		}
+	}
+
+	var w int64
+	switch et {
+	default:
+		base.Fatalf("dowidth: unknown type: %v", t)
+
+	// compiler-specific stuff
+	case TINT8, TUINT8, TBOOL:
+		// bool is int8
+		w = 1
+
+	case TINT16, TUINT16:
+		w = 2
+
+	case TINT32, TUINT32, TFLOAT32:
+		w = 4
+
+	case TINT64, TUINT64, TFLOAT64:
+		w = 8
+		t.Align = uint8(RegSize)
+
+	case TCOMPLEX64:
+		w = 8
+		t.Align = 4
+
+	case TCOMPLEX128:
+		w = 16
+		t.Align = uint8(RegSize)
+
+	case TPTR:
+		w = int64(PtrSize)
+		CheckSize(t.Elem())
+
+	case TUNSAFEPTR:
+		w = int64(PtrSize)
+
+	case TINTER: // implemented as 2 pointers
+		w = 2 * int64(PtrSize)
+		t.Align = uint8(PtrSize)
+		expandiface(t)
+
+	case TCHAN: // implemented as pointer
+		w = int64(PtrSize)
+
+		CheckSize(t.Elem())
+
+		// make fake type to check later to
+		// trigger channel argument check.
+		t1 := NewChanArgs(t)
+		CheckSize(t1)
+
+	case TCHANARGS:
+		t1 := t.ChanArgs()
+		CalcSize(t1) // just in case
+		if t1.Elem().Width >= 1<<16 {
+			base.ErrorfAt(typePos(t1), "channel element type too large (>64kB)")
+		}
+		w = 1 // anything will do
+
+	case TMAP: // implemented as pointer
+		w = int64(PtrSize)
+		CheckSize(t.Elem())
+		CheckSize(t.Key())
+
+	case TFORW: // should have been filled in
+		reportTypeLoop(t)
+		w = 1 // anything will do
+
+	case TANY:
+		// not a real type; should be replaced before use.
+		base.Fatalf("dowidth any")
+
+	case TSTRING:
+		if StringSize == 0 {
+			base.Fatalf("early dowidth string")
+		}
+		w = StringSize
+		t.Align = uint8(PtrSize)
+
+	case TARRAY:
+		if t.Elem() == nil {
+			break
+		}
+
+		CalcSize(t.Elem())
+		if t.Elem().Width != 0 {
+			cap := (uint64(MaxWidth) - 1) / uint64(t.Elem().Width)
+			if uint64(t.NumElem()) > cap {
+				base.ErrorfAt(typePos(t), "type %L larger than address space", t)
+			}
+		}
+		w = t.NumElem() * t.Elem().Width
+		t.Align = t.Elem().Align
+
+	case TSLICE:
+		if t.Elem() == nil {
+			break
+		}
+		w = SliceSize
+		CheckSize(t.Elem())
+		t.Align = uint8(PtrSize)
+
+	case TSTRUCT:
+		if t.IsFuncArgStruct() {
+			base.Fatalf("dowidth fn struct %v", t)
+		}
+		w = calcStructOffset(t, t, 0, 1)
+
+	// make fake type to check later to
+	// trigger function argument computation.
+	case TFUNC:
+		t1 := NewFuncArgs(t)
+		CheckSize(t1)
+		w = int64(PtrSize) // width of func type is pointer
+
+	// function is 3 cated structures;
+	// compute their widths as side-effect.
+	case TFUNCARGS:
+		t1 := t.FuncArgs()
+		w = calcStructOffset(t1, t1.Recvs(), 0, 0)
+		w = calcStructOffset(t1, t1.Params(), w, RegSize)
+		w = calcStructOffset(t1, t1.Results(), w, RegSize)
+		t1.Extra.(*Func).Argwid = w
+		if w%int64(RegSize) != 0 {
+			base.Warn("bad type %v %d\n", t1, w)
+		}
+		t.Align = 1
+	}
+
+	if PtrSize == 4 && w != int64(int32(w)) {
+		base.ErrorfAt(typePos(t), "type %v too large", t)
+	}
+
+	t.Width = w
+	if t.Align == 0 {
+		if w == 0 || w > 8 || w&(w-1) != 0 {
+			base.Fatalf("invalid alignment for %v", t)
+		}
+		t.Align = uint8(w)
+	}
+
+	base.Pos = lno
+
+	ResumeCheckSize()
+}
+
+// CalcStructSize calculates the size of s,
+// filling in s.Width and s.Align,
+// even if size calculation is otherwise disabled.
+func CalcStructSize(s *Type) {
+	s.Width = calcStructOffset(s, s, 0, 1) // sets align
+}
+
+// when a type's width should be known, we call checkwidth
+// to compute it.  during a declaration like
+//
+//	type T *struct { next T }
+//
+// it is necessary to defer the calculation of the struct width
+// until after T has been initialized to be a pointer to that struct.
+// similarly, during import processing structs may be used
+// before their definition.  in those situations, calling
+// defercheckwidth() stops width calculations until
+// resumecheckwidth() is called, at which point all the
+// checkwidths that were deferred are executed.
+// dowidth should only be called when the type's size
+// is needed immediately.  checkwidth makes sure the
+// size is evaluated eventually.
+
+var deferredTypeStack []*Type
+
+func CheckSize(t *Type) {
+	if t == nil {
+		return
+	}
+
+	// function arg structs should not be checked
+	// outside of the enclosing function.
+	if t.IsFuncArgStruct() {
+		base.Fatalf("checkwidth %v", t)
+	}
+
+	if defercalc == 0 {
+		CalcSize(t)
+		return
+	}
+
+	// if type has not yet been pushed on deferredTypeStack yet, do it now
+	if !t.Deferwidth() {
+		t.SetDeferwidth(true)
+		deferredTypeStack = append(deferredTypeStack, t)
+	}
+}
+
+func DeferCheckSize() {
+	defercalc++
+}
+
+func ResumeCheckSize() {
+	if defercalc == 1 {
+		for len(deferredTypeStack) > 0 {
+			t := deferredTypeStack[len(deferredTypeStack)-1]
+			deferredTypeStack = deferredTypeStack[:len(deferredTypeStack)-1]
+			t.SetDeferwidth(false)
+			CalcSize(t)
+		}
+	}
+
+	defercalc--
+}
+
+// PtrDataSize returns the length in bytes of the prefix of t
+// containing pointer data. Anything after this offset is scalar data.
+func PtrDataSize(t *Type) int64 {
+	if !t.HasPointers() {
+		return 0
+	}
+
+	switch t.Kind() {
+	case TPTR,
+		TUNSAFEPTR,
+		TFUNC,
+		TCHAN,
+		TMAP:
+		return int64(PtrSize)
+
+	case TSTRING:
+		// struct { byte *str; intgo len; }
+		return int64(PtrSize)
+
+	case TINTER:
+		// struct { Itab *tab;	void *data; } or
+		// struct { Type *type; void *data; }
+		// Note: see comment in plive.go:onebitwalktype1.
+		return 2 * int64(PtrSize)
+
+	case TSLICE:
+		// struct { byte *array; uintgo len; uintgo cap; }
+		return int64(PtrSize)
+
+	case TARRAY:
+		// haspointers already eliminated t.NumElem() == 0.
+		return (t.NumElem()-1)*t.Elem().Width + PtrDataSize(t.Elem())
+
+	case TSTRUCT:
+		// Find the last field that has pointers.
+		var lastPtrField *Field
+		for _, t1 := range t.Fields().Slice() {
+			if t1.Type.HasPointers() {
+				lastPtrField = t1
+			}
+		}
+		return lastPtrField.Offset + PtrDataSize(lastPtrField.Type)
+
+	default:
+		base.Fatalf("typeptrdata: unexpected type, %v", t)
+		return 0
+	}
+}