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// 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 gc
import (
"cmd/compile/internal/types"
"cmd/internal/obj"
"fmt"
)
type InitEntry struct {
Xoffset int64 // struct, array only
Expr *Node // bytes of run-time computed expressions
}
type InitPlan struct {
E []InitEntry
}
// An InitSchedule is used to decompose assignment statements into
// static and dynamic initialization parts. Static initializations are
// handled by populating variables' linker symbol data, while dynamic
// initializations are accumulated to be executed in order.
type InitSchedule struct {
// out is the ordered list of dynamic initialization
// statements.
out []*Node
initplans map[*Node]*InitPlan
inittemps map[*Node]*Node
}
func (s *InitSchedule) append(n *Node) {
s.out = append(s.out, n)
}
// staticInit adds an initialization statement n to the schedule.
func (s *InitSchedule) staticInit(n *Node) {
if !s.tryStaticInit(n) {
if Debug.P != 0 {
Dump("nonstatic", n)
}
s.append(n)
}
}
// tryStaticInit attempts to statically execute an initialization
// statement and reports whether it succeeded.
func (s *InitSchedule) tryStaticInit(n *Node) bool {
// Only worry about simple "l = r" assignments. Multiple
// variable/expression OAS2 assignments have already been
// replaced by multiple simple OAS assignments, and the other
// OAS2* assignments mostly necessitate dynamic execution
// anyway.
if n.Op != OAS {
return false
}
if n.Left.isBlank() && candiscard(n.Right) {
return true
}
lno := setlineno(n)
defer func() { lineno = lno }()
return s.staticassign(n.Left, n.Right)
}
// like staticassign but we are copying an already
// initialized value r.
func (s *InitSchedule) staticcopy(l *Node, r *Node) bool {
if r.Op != ONAME {
return false
}
if r.Class() == PFUNC {
pfuncsym(l, r)
return true
}
if r.Class() != PEXTERN || r.Sym.Pkg != localpkg {
return false
}
if r.Name.Defn == nil { // probably zeroed but perhaps supplied externally and of unknown value
return false
}
if r.Name.Defn.Op != OAS {
return false
}
if r.Type.IsString() { // perhaps overwritten by cmd/link -X (#34675)
return false
}
orig := r
r = r.Name.Defn.Right
for r.Op == OCONVNOP && !types.Identical(r.Type, l.Type) {
r = r.Left
}
switch r.Op {
case ONAME:
if s.staticcopy(l, r) {
return true
}
// We may have skipped past one or more OCONVNOPs, so
// use conv to ensure r is assignable to l (#13263).
s.append(nod(OAS, l, conv(r, l.Type)))
return true
case OLITERAL:
if isZero(r) {
return true
}
litsym(l, r, int(l.Type.Width))
return true
case OADDR:
if a := r.Left; a.Op == ONAME {
addrsym(l, a)
return true
}
case OPTRLIT:
switch r.Left.Op {
case OARRAYLIT, OSLICELIT, OSTRUCTLIT, OMAPLIT:
// copy pointer
addrsym(l, s.inittemps[r])
return true
}
case OSLICELIT:
// copy slice
a := s.inittemps[r]
slicesym(l, a, r.Right.Int64Val())
return true
case OARRAYLIT, OSTRUCTLIT:
p := s.initplans[r]
n := l.copy()
for i := range p.E {
e := &p.E[i]
n.Xoffset = l.Xoffset + e.Xoffset
n.Type = e.Expr.Type
if e.Expr.Op == OLITERAL {
litsym(n, e.Expr, int(n.Type.Width))
continue
}
ll := n.sepcopy()
if s.staticcopy(ll, e.Expr) {
continue
}
// Requires computation, but we're
// copying someone else's computation.
rr := orig.sepcopy()
rr.Type = ll.Type
rr.Xoffset += e.Xoffset
setlineno(rr)
s.append(nod(OAS, ll, rr))
}
return true
}
return false
}
func (s *InitSchedule) staticassign(l *Node, r *Node) bool {
for r.Op == OCONVNOP {
r = r.Left
}
switch r.Op {
case ONAME:
return s.staticcopy(l, r)
case OLITERAL:
if isZero(r) {
return true
}
litsym(l, r, int(l.Type.Width))
return true
case OADDR:
var nam Node
if stataddr(&nam, r.Left) {
addrsym(l, &nam)
return true
}
fallthrough
case OPTRLIT:
switch r.Left.Op {
case OARRAYLIT, OSLICELIT, OMAPLIT, OSTRUCTLIT:
// Init pointer.
a := staticname(r.Left.Type)
s.inittemps[r] = a
addrsym(l, a)
// Init underlying literal.
if !s.staticassign(a, r.Left) {
s.append(nod(OAS, a, r.Left))
}
return true
}
//dump("not static ptrlit", r);
case OSTR2BYTES:
if l.Class() == PEXTERN && r.Left.Op == OLITERAL {
sval := r.Left.StringVal()
slicebytes(l, sval)
return true
}
case OSLICELIT:
s.initplan(r)
// Init slice.
bound := r.Right.Int64Val()
ta := types.NewArray(r.Type.Elem(), bound)
ta.SetNoalg(true)
a := staticname(ta)
s.inittemps[r] = a
slicesym(l, a, bound)
// Fall through to init underlying array.
l = a
fallthrough
case OARRAYLIT, OSTRUCTLIT:
s.initplan(r)
p := s.initplans[r]
n := l.copy()
for i := range p.E {
e := &p.E[i]
n.Xoffset = l.Xoffset + e.Xoffset
n.Type = e.Expr.Type
if e.Expr.Op == OLITERAL {
litsym(n, e.Expr, int(n.Type.Width))
continue
}
setlineno(e.Expr)
a := n.sepcopy()
if !s.staticassign(a, e.Expr) {
s.append(nod(OAS, a, e.Expr))
}
}
return true
case OMAPLIT:
break
case OCLOSURE:
if hasemptycvars(r) {
if Debug_closure > 0 {
Warnl(r.Pos, "closure converted to global")
}
// Closures with no captured variables are globals,
// so the assignment can be done at link time.
pfuncsym(l, r.Func.Closure.Func.Nname)
return true
}
closuredebugruntimecheck(r)
case OCONVIFACE:
// This logic is mirrored in isStaticCompositeLiteral.
// If you change something here, change it there, and vice versa.
// Determine the underlying concrete type and value we are converting from.
val := r
for val.Op == OCONVIFACE {
val = val.Left
}
if val.Type.IsInterface() {
// val is an interface type.
// If val is nil, we can statically initialize l;
// both words are zero and so there no work to do, so report success.
// If val is non-nil, we have no concrete type to record,
// and we won't be able to statically initialize its value, so report failure.
return Isconst(val, CTNIL)
}
markTypeUsedInInterface(val.Type, l.Sym.Linksym())
var itab *Node
if l.Type.IsEmptyInterface() {
itab = typename(val.Type)
} else {
itab = itabname(val.Type, l.Type)
}
// Create a copy of l to modify while we emit data.
n := l.copy()
// Emit itab, advance offset.
addrsym(n, itab.Left) // itab is an OADDR node
n.Xoffset += int64(Widthptr)
// Emit data.
if isdirectiface(val.Type) {
if Isconst(val, CTNIL) {
// Nil is zero, nothing to do.
return true
}
// Copy val directly into n.
n.Type = val.Type
setlineno(val)
a := n.sepcopy()
if !s.staticassign(a, val) {
s.append(nod(OAS, a, val))
}
} else {
// Construct temp to hold val, write pointer to temp into n.
a := staticname(val.Type)
s.inittemps[val] = a
if !s.staticassign(a, val) {
s.append(nod(OAS, a, val))
}
addrsym(n, a)
}
return true
}
//dump("not static", r);
return false
}
// initContext is the context in which static data is populated.
// It is either in an init function or in any other function.
// Static data populated in an init function will be written either
// zero times (as a readonly, static data symbol) or
// one time (during init function execution).
// Either way, there is no opportunity for races or further modification,
// so the data can be written to a (possibly readonly) data symbol.
// Static data populated in any other function needs to be local to
// that function to allow multiple instances of that function
// to execute concurrently without clobbering each others' data.
type initContext uint8
const (
inInitFunction initContext = iota
inNonInitFunction
)
func (c initContext) String() string {
if c == inInitFunction {
return "inInitFunction"
}
return "inNonInitFunction"
}
// from here down is the walk analysis
// of composite literals.
// most of the work is to generate
// data statements for the constant
// part of the composite literal.
var statuniqgen int // name generator for static temps
// staticname returns a name backed by a (writable) static data symbol.
// Use readonlystaticname for read-only node.
func staticname(t *types.Type) *Node {
// Don't use lookupN; it interns the resulting string, but these are all unique.
n := newname(lookup(fmt.Sprintf("%s%d", obj.StaticNamePref, statuniqgen)))
statuniqgen++
addvar(n, t, PEXTERN)
n.Sym.Linksym().Set(obj.AttrLocal, true)
return n
}
// readonlystaticname returns a name backed by a (writable) static data symbol.
func readonlystaticname(t *types.Type) *Node {
n := staticname(t)
n.MarkReadonly()
n.Sym.Linksym().Set(obj.AttrContentAddressable, true)
return n
}
func (n *Node) isSimpleName() bool {
return n.Op == ONAME && n.Class() != PAUTOHEAP && n.Class() != PEXTERN
}
func litas(l *Node, r *Node, init *Nodes) {
a := nod(OAS, l, r)
a = typecheck(a, ctxStmt)
a = walkexpr(a, init)
init.Append(a)
}
// initGenType is a bitmap indicating the types of generation that will occur for a static value.
type initGenType uint8
const (
initDynamic initGenType = 1 << iota // contains some dynamic values, for which init code will be generated
initConst // contains some constant values, which may be written into data symbols
)
// getdyn calculates the initGenType for n.
// If top is false, getdyn is recursing.
func getdyn(n *Node, top bool) initGenType {
switch n.Op {
default:
if n.isGoConst() {
return initConst
}
return initDynamic
case OSLICELIT:
if !top {
return initDynamic
}
if n.Right.Int64Val()/4 > int64(n.List.Len()) {
// <25% of entries have explicit values.
// Very rough estimation, it takes 4 bytes of instructions
// to initialize 1 byte of result. So don't use a static
// initializer if the dynamic initialization code would be
// smaller than the static value.
// See issue 23780.
return initDynamic
}
case OARRAYLIT, OSTRUCTLIT:
}
var mode initGenType
for _, n1 := range n.List.Slice() {
switch n1.Op {
case OKEY:
n1 = n1.Right
case OSTRUCTKEY:
n1 = n1.Left
}
mode |= getdyn(n1, false)
if mode == initDynamic|initConst {
break
}
}
return mode
}
// isStaticCompositeLiteral reports whether n is a compile-time constant.
func isStaticCompositeLiteral(n *Node) bool {
switch n.Op {
case OSLICELIT:
return false
case OARRAYLIT:
for _, r := range n.List.Slice() {
if r.Op == OKEY {
r = r.Right
}
if !isStaticCompositeLiteral(r) {
return false
}
}
return true
case OSTRUCTLIT:
for _, r := range n.List.Slice() {
if r.Op != OSTRUCTKEY {
Fatalf("isStaticCompositeLiteral: rhs not OSTRUCTKEY: %v", r)
}
if !isStaticCompositeLiteral(r.Left) {
return false
}
}
return true
case OLITERAL:
return true
case OCONVIFACE:
// See staticassign's OCONVIFACE case for comments.
val := n
for val.Op == OCONVIFACE {
val = val.Left
}
if val.Type.IsInterface() {
return Isconst(val, CTNIL)
}
if isdirectiface(val.Type) && Isconst(val, CTNIL) {
return true
}
return isStaticCompositeLiteral(val)
}
return false
}
// initKind is a kind of static initialization: static, dynamic, or local.
// Static initialization represents literals and
// literal components of composite literals.
// Dynamic initialization represents non-literals and
// non-literal components of composite literals.
// LocalCode initialization represents initialization
// that occurs purely in generated code local to the function of use.
// Initialization code is sometimes generated in passes,
// first static then dynamic.
type initKind uint8
const (
initKindStatic initKind = iota + 1
initKindDynamic
initKindLocalCode
)
// fixedlit handles struct, array, and slice literals.
// TODO: expand documentation.
func fixedlit(ctxt initContext, kind initKind, n *Node, var_ *Node, init *Nodes) {
isBlank := var_ == nblank
var splitnode func(*Node) (a *Node, value *Node)
switch n.Op {
case OARRAYLIT, OSLICELIT:
var k int64
splitnode = func(r *Node) (*Node, *Node) {
if r.Op == OKEY {
k = indexconst(r.Left)
if k < 0 {
Fatalf("fixedlit: invalid index %v", r.Left)
}
r = r.Right
}
a := nod(OINDEX, var_, nodintconst(k))
k++
if isBlank {
a = nblank
}
return a, r
}
case OSTRUCTLIT:
splitnode = func(r *Node) (*Node, *Node) {
if r.Op != OSTRUCTKEY {
Fatalf("fixedlit: rhs not OSTRUCTKEY: %v", r)
}
if r.Sym.IsBlank() || isBlank {
return nblank, r.Left
}
setlineno(r)
return nodSym(ODOT, var_, r.Sym), r.Left
}
default:
Fatalf("fixedlit bad op: %v", n.Op)
}
for _, r := range n.List.Slice() {
a, value := splitnode(r)
if a == nblank && candiscard(value) {
continue
}
switch value.Op {
case OSLICELIT:
if (kind == initKindStatic && ctxt == inNonInitFunction) || (kind == initKindDynamic && ctxt == inInitFunction) {
slicelit(ctxt, value, a, init)
continue
}
case OARRAYLIT, OSTRUCTLIT:
fixedlit(ctxt, kind, value, a, init)
continue
}
islit := value.isGoConst()
if (kind == initKindStatic && !islit) || (kind == initKindDynamic && islit) {
continue
}
// build list of assignments: var[index] = expr
setlineno(a)
a = nod(OAS, a, value)
a = typecheck(a, ctxStmt)
switch kind {
case initKindStatic:
genAsStatic(a)
case initKindDynamic, initKindLocalCode:
a = orderStmtInPlace(a, map[string][]*Node{})
a = walkstmt(a)
init.Append(a)
default:
Fatalf("fixedlit: bad kind %d", kind)
}
}
}
func isSmallSliceLit(n *Node) bool {
if n.Op != OSLICELIT {
return false
}
r := n.Right
return smallintconst(r) && (n.Type.Elem().Width == 0 || r.Int64Val() <= smallArrayBytes/n.Type.Elem().Width)
}
func slicelit(ctxt initContext, n *Node, var_ *Node, init *Nodes) {
// make an array type corresponding the number of elements we have
t := types.NewArray(n.Type.Elem(), n.Right.Int64Val())
dowidth(t)
if ctxt == inNonInitFunction {
// put everything into static array
vstat := staticname(t)
fixedlit(ctxt, initKindStatic, n, vstat, init)
fixedlit(ctxt, initKindDynamic, n, vstat, init)
// copy static to slice
var_ = typecheck(var_, ctxExpr|ctxAssign)
var nam Node
if !stataddr(&nam, var_) || nam.Class() != PEXTERN {
Fatalf("slicelit: %v", var_)
}
slicesym(&nam, vstat, t.NumElem())
return
}
// recipe for var = []t{...}
// 1. make a static array
// var vstat [...]t
// 2. assign (data statements) the constant part
// vstat = constpart{}
// 3. make an auto pointer to array and allocate heap to it
// var vauto *[...]t = new([...]t)
// 4. copy the static array to the auto array
// *vauto = vstat
// 5. for each dynamic part assign to the array
// vauto[i] = dynamic part
// 6. assign slice of allocated heap to var
// var = vauto[:]
//
// an optimization is done if there is no constant part
// 3. var vauto *[...]t = new([...]t)
// 5. vauto[i] = dynamic part
// 6. var = vauto[:]
// if the literal contains constants,
// make static initialized array (1),(2)
var vstat *Node
mode := getdyn(n, true)
if mode&initConst != 0 && !isSmallSliceLit(n) {
if ctxt == inInitFunction {
vstat = readonlystaticname(t)
} else {
vstat = staticname(t)
}
fixedlit(ctxt, initKindStatic, n, vstat, init)
}
// make new auto *array (3 declare)
vauto := temp(types.NewPtr(t))
// set auto to point at new temp or heap (3 assign)
var a *Node
if x := prealloc[n]; x != nil {
// temp allocated during order.go for dddarg
if !types.Identical(t, x.Type) {
panic("dotdotdot base type does not match order's assigned type")
}
if vstat == nil {
a = nod(OAS, x, nil)
a = typecheck(a, ctxStmt)
init.Append(a) // zero new temp
} else {
// Declare that we're about to initialize all of x.
// (Which happens at the *vauto = vstat below.)
init.Append(nod(OVARDEF, x, nil))
}
a = nod(OADDR, x, nil)
} else if n.Esc == EscNone {
a = temp(t)
if vstat == nil {
a = nod(OAS, temp(t), nil)
a = typecheck(a, ctxStmt)
init.Append(a) // zero new temp
a = a.Left
} else {
init.Append(nod(OVARDEF, a, nil))
}
a = nod(OADDR, a, nil)
} else {
a = nod(ONEW, nil, nil)
a.List.Set1(typenod(t))
}
a = nod(OAS, vauto, a)
a = typecheck(a, ctxStmt)
a = walkexpr(a, init)
init.Append(a)
if vstat != nil {
// copy static to heap (4)
a = nod(ODEREF, vauto, nil)
a = nod(OAS, a, vstat)
a = typecheck(a, ctxStmt)
a = walkexpr(a, init)
init.Append(a)
}
// put dynamics into array (5)
var index int64
for _, value := range n.List.Slice() {
if value.Op == OKEY {
index = indexconst(value.Left)
if index < 0 {
Fatalf("slicelit: invalid index %v", value.Left)
}
value = value.Right
}
a := nod(OINDEX, vauto, nodintconst(index))
a.SetBounded(true)
index++
// TODO need to check bounds?
switch value.Op {
case OSLICELIT:
break
case OARRAYLIT, OSTRUCTLIT:
k := initKindDynamic
if vstat == nil {
// Generate both static and dynamic initializations.
// See issue #31987.
k = initKindLocalCode
}
fixedlit(ctxt, k, value, a, init)
continue
}
if vstat != nil && value.isGoConst() { // already set by copy from static value
continue
}
// build list of vauto[c] = expr
setlineno(value)
a = nod(OAS, a, value)
a = typecheck(a, ctxStmt)
a = orderStmtInPlace(a, map[string][]*Node{})
a = walkstmt(a)
init.Append(a)
}
// make slice out of heap (6)
a = nod(OAS, var_, nod(OSLICE, vauto, nil))
a = typecheck(a, ctxStmt)
a = orderStmtInPlace(a, map[string][]*Node{})
a = walkstmt(a)
init.Append(a)
}
func maplit(n *Node, m *Node, init *Nodes) {
// make the map var
a := nod(OMAKE, nil, nil)
a.Esc = n.Esc
a.List.Set2(typenod(n.Type), nodintconst(int64(n.List.Len())))
litas(m, a, init)
entries := n.List.Slice()
// The order pass already removed any dynamic (runtime-computed) entries.
// All remaining entries are static. Double-check that.
for _, r := range entries {
if !isStaticCompositeLiteral(r.Left) || !isStaticCompositeLiteral(r.Right) {
Fatalf("maplit: entry is not a literal: %v", r)
}
}
if len(entries) > 25 {
// For a large number of entries, put them in an array and loop.
// build types [count]Tindex and [count]Tvalue
tk := types.NewArray(n.Type.Key(), int64(len(entries)))
te := types.NewArray(n.Type.Elem(), int64(len(entries)))
tk.SetNoalg(true)
te.SetNoalg(true)
dowidth(tk)
dowidth(te)
// make and initialize static arrays
vstatk := readonlystaticname(tk)
vstate := readonlystaticname(te)
datak := nod(OARRAYLIT, nil, nil)
datae := nod(OARRAYLIT, nil, nil)
for _, r := range entries {
datak.List.Append(r.Left)
datae.List.Append(r.Right)
}
fixedlit(inInitFunction, initKindStatic, datak, vstatk, init)
fixedlit(inInitFunction, initKindStatic, datae, vstate, init)
// loop adding structure elements to map
// for i = 0; i < len(vstatk); i++ {
// map[vstatk[i]] = vstate[i]
// }
i := temp(types.Types[TINT])
rhs := nod(OINDEX, vstate, i)
rhs.SetBounded(true)
kidx := nod(OINDEX, vstatk, i)
kidx.SetBounded(true)
lhs := nod(OINDEX, m, kidx)
zero := nod(OAS, i, nodintconst(0))
cond := nod(OLT, i, nodintconst(tk.NumElem()))
incr := nod(OAS, i, nod(OADD, i, nodintconst(1)))
body := nod(OAS, lhs, rhs)
loop := nod(OFOR, cond, incr)
loop.Nbody.Set1(body)
loop.Ninit.Set1(zero)
loop = typecheck(loop, ctxStmt)
loop = walkstmt(loop)
init.Append(loop)
return
}
// For a small number of entries, just add them directly.
// Build list of var[c] = expr.
// Use temporaries so that mapassign1 can have addressable key, elem.
// TODO(josharian): avoid map key temporaries for mapfast_* assignments with literal keys.
tmpkey := temp(m.Type.Key())
tmpelem := temp(m.Type.Elem())
for _, r := range entries {
index, elem := r.Left, r.Right
setlineno(index)
a := nod(OAS, tmpkey, index)
a = typecheck(a, ctxStmt)
a = walkstmt(a)
init.Append(a)
setlineno(elem)
a = nod(OAS, tmpelem, elem)
a = typecheck(a, ctxStmt)
a = walkstmt(a)
init.Append(a)
setlineno(tmpelem)
a = nod(OAS, nod(OINDEX, m, tmpkey), tmpelem)
a = typecheck(a, ctxStmt)
a = walkstmt(a)
init.Append(a)
}
a = nod(OVARKILL, tmpkey, nil)
a = typecheck(a, ctxStmt)
init.Append(a)
a = nod(OVARKILL, tmpelem, nil)
a = typecheck(a, ctxStmt)
init.Append(a)
}
func anylit(n *Node, var_ *Node, init *Nodes) {
t := n.Type
switch n.Op {
default:
Fatalf("anylit: not lit, op=%v node=%v", n.Op, n)
case ONAME:
a := nod(OAS, var_, n)
a = typecheck(a, ctxStmt)
init.Append(a)
case OPTRLIT:
if !t.IsPtr() {
Fatalf("anylit: not ptr")
}
var r *Node
if n.Right != nil {
// n.Right is stack temporary used as backing store.
init.Append(nod(OAS, n.Right, nil)) // zero backing store, just in case (#18410)
r = nod(OADDR, n.Right, nil)
r = typecheck(r, ctxExpr)
} else {
r = nod(ONEW, nil, nil)
r.SetTypecheck(1)
r.Type = t
r.Esc = n.Esc
}
r = walkexpr(r, init)
a := nod(OAS, var_, r)
a = typecheck(a, ctxStmt)
init.Append(a)
var_ = nod(ODEREF, var_, nil)
var_ = typecheck(var_, ctxExpr|ctxAssign)
anylit(n.Left, var_, init)
case OSTRUCTLIT, OARRAYLIT:
if !t.IsStruct() && !t.IsArray() {
Fatalf("anylit: not struct/array")
}
if var_.isSimpleName() && n.List.Len() > 4 {
// lay out static data
vstat := readonlystaticname(t)
ctxt := inInitFunction
if n.Op == OARRAYLIT {
ctxt = inNonInitFunction
}
fixedlit(ctxt, initKindStatic, n, vstat, init)
// copy static to var
a := nod(OAS, var_, vstat)
a = typecheck(a, ctxStmt)
a = walkexpr(a, init)
init.Append(a)
// add expressions to automatic
fixedlit(inInitFunction, initKindDynamic, n, var_, init)
break
}
var components int64
if n.Op == OARRAYLIT {
components = t.NumElem()
} else {
components = int64(t.NumFields())
}
// initialization of an array or struct with unspecified components (missing fields or arrays)
if var_.isSimpleName() || int64(n.List.Len()) < components {
a := nod(OAS, var_, nil)
a = typecheck(a, ctxStmt)
a = walkexpr(a, init)
init.Append(a)
}
fixedlit(inInitFunction, initKindLocalCode, n, var_, init)
case OSLICELIT:
slicelit(inInitFunction, n, var_, init)
case OMAPLIT:
if !t.IsMap() {
Fatalf("anylit: not map")
}
maplit(n, var_, init)
}
}
func oaslit(n *Node, init *Nodes) bool {
if n.Left == nil || n.Right == nil {
// not a special composite literal assignment
return false
}
if n.Left.Type == nil || n.Right.Type == nil {
// not a special composite literal assignment
return false
}
if !n.Left.isSimpleName() {
// not a special composite literal assignment
return false
}
if !types.Identical(n.Left.Type, n.Right.Type) {
// not a special composite literal assignment
return false
}
switch n.Right.Op {
default:
// not a special composite literal assignment
return false
case OSTRUCTLIT, OARRAYLIT, OSLICELIT, OMAPLIT:
if vmatch1(n.Left, n.Right) {
// not a special composite literal assignment
return false
}
anylit(n.Right, n.Left, init)
}
n.Op = OEMPTY
n.Right = nil
return true
}
func getlit(lit *Node) int {
if smallintconst(lit) {
return int(lit.Int64Val())
}
return -1
}
// stataddr sets nam to the static address of n and reports whether it succeeded.
func stataddr(nam *Node, n *Node) bool {
if n == nil {
return false
}
switch n.Op {
case ONAME:
*nam = *n
return true
case ODOT:
if !stataddr(nam, n.Left) {
break
}
nam.Xoffset += n.Xoffset
nam.Type = n.Type
return true
case OINDEX:
if n.Left.Type.IsSlice() {
break
}
if !stataddr(nam, n.Left) {
break
}
l := getlit(n.Right)
if l < 0 {
break
}
// Check for overflow.
if n.Type.Width != 0 && thearch.MAXWIDTH/n.Type.Width <= int64(l) {
break
}
nam.Xoffset += int64(l) * n.Type.Width
nam.Type = n.Type
return true
}
return false
}
func (s *InitSchedule) initplan(n *Node) {
if s.initplans[n] != nil {
return
}
p := new(InitPlan)
s.initplans[n] = p
switch n.Op {
default:
Fatalf("initplan")
case OARRAYLIT, OSLICELIT:
var k int64
for _, a := range n.List.Slice() {
if a.Op == OKEY {
k = indexconst(a.Left)
if k < 0 {
Fatalf("initplan arraylit: invalid index %v", a.Left)
}
a = a.Right
}
s.addvalue(p, k*n.Type.Elem().Width, a)
k++
}
case OSTRUCTLIT:
for _, a := range n.List.Slice() {
if a.Op != OSTRUCTKEY {
Fatalf("initplan structlit")
}
if a.Sym.IsBlank() {
continue
}
s.addvalue(p, a.Xoffset, a.Left)
}
case OMAPLIT:
for _, a := range n.List.Slice() {
if a.Op != OKEY {
Fatalf("initplan maplit")
}
s.addvalue(p, -1, a.Right)
}
}
}
func (s *InitSchedule) addvalue(p *InitPlan, xoffset int64, n *Node) {
// special case: zero can be dropped entirely
if isZero(n) {
return
}
// special case: inline struct and array (not slice) literals
if isvaluelit(n) {
s.initplan(n)
q := s.initplans[n]
for _, qe := range q.E {
// qe is a copy; we are not modifying entries in q.E
qe.Xoffset += xoffset
p.E = append(p.E, qe)
}
return
}
// add to plan
p.E = append(p.E, InitEntry{Xoffset: xoffset, Expr: n})
}
func isZero(n *Node) bool {
switch n.Op {
case OLITERAL:
switch u := n.Val().U.(type) {
default:
Dump("unexpected literal", n)
Fatalf("isZero")
case *NilVal:
return true
case string:
return u == ""
case bool:
return !u
case *Mpint:
return u.CmpInt64(0) == 0
case *Mpflt:
return u.CmpFloat64(0) == 0
case *Mpcplx:
return u.Real.CmpFloat64(0) == 0 && u.Imag.CmpFloat64(0) == 0
}
case OARRAYLIT:
for _, n1 := range n.List.Slice() {
if n1.Op == OKEY {
n1 = n1.Right
}
if !isZero(n1) {
return false
}
}
return true
case OSTRUCTLIT:
for _, n1 := range n.List.Slice() {
if !isZero(n1.Left) {
return false
}
}
return true
}
return false
}
func isvaluelit(n *Node) bool {
return n.Op == OARRAYLIT || n.Op == OSTRUCTLIT
}
func genAsStatic(as *Node) {
if as.Left.Type == nil {
Fatalf("genAsStatic as.Left not typechecked")
}
var nam Node
if !stataddr(&nam, as.Left) || (nam.Class() != PEXTERN && as.Left != nblank) {
Fatalf("genAsStatic: lhs %v", as.Left)
}
switch {
case as.Right.Op == OLITERAL:
litsym(&nam, as.Right, int(as.Right.Type.Width))
case as.Right.Op == ONAME && as.Right.Class() == PFUNC:
pfuncsym(&nam, as.Right)
default:
Fatalf("genAsStatic: rhs %v", as.Right)
}
}