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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 walk
import (
"go/constant"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/src"
)
// walkAssign walks an OAS (AssignExpr) or OASOP (AssignOpExpr) node.
func walkAssign(init *ir.Nodes, n ir.Node) ir.Node {
init.Append(ir.TakeInit(n)...)
var left, right ir.Node
switch n.Op() {
case ir.OAS:
n := n.(*ir.AssignStmt)
left, right = n.X, n.Y
case ir.OASOP:
n := n.(*ir.AssignOpStmt)
left, right = n.X, n.Y
}
// Recognize m[k] = append(m[k], ...) so we can reuse
// the mapassign call.
var mapAppend *ir.CallExpr
if left.Op() == ir.OINDEXMAP && right.Op() == ir.OAPPEND {
left := left.(*ir.IndexExpr)
mapAppend = right.(*ir.CallExpr)
if !ir.SameSafeExpr(left, mapAppend.Args[0]) {
base.Fatalf("not same expressions: %v != %v", left, mapAppend.Args[0])
}
}
left = walkExpr(left, init)
left = safeExpr(left, init)
if mapAppend != nil {
mapAppend.Args[0] = left
}
if n.Op() == ir.OASOP {
// Rewrite x op= y into x = x op y.
n = ir.NewAssignStmt(base.Pos, left, typecheck.Expr(ir.NewBinaryExpr(base.Pos, n.(*ir.AssignOpStmt).AsOp, left, right)))
} else {
n.(*ir.AssignStmt).X = left
}
as := n.(*ir.AssignStmt)
if oaslit(as, init) {
return ir.NewBlockStmt(as.Pos(), nil)
}
if as.Y == nil {
// TODO(austin): Check all "implicit zeroing"
return as
}
if !base.Flag.Cfg.Instrumenting && ir.IsZero(as.Y) {
return as
}
switch as.Y.Op() {
default:
as.Y = walkExpr(as.Y, init)
case ir.ORECV:
// x = <-c; as.Left is x, as.Right.Left is c.
// order.stmt made sure x is addressable.
recv := as.Y.(*ir.UnaryExpr)
recv.X = walkExpr(recv.X, init)
n1 := typecheck.NodAddr(as.X)
r := recv.X // the channel
return mkcall1(chanfn("chanrecv1", 2, r.Type()), nil, init, r, n1)
case ir.OAPPEND:
// x = append(...)
call := as.Y.(*ir.CallExpr)
if call.Type().Elem().NotInHeap() {
base.Errorf("%v can't be allocated in Go; it is incomplete (or unallocatable)", call.Type().Elem())
}
var r ir.Node
switch {
case isAppendOfMake(call):
// x = append(y, make([]T, y)...)
r = extendSlice(call, init)
case call.IsDDD:
r = appendSlice(call, init) // also works for append(slice, string).
default:
r = walkAppend(call, init, as)
}
as.Y = r
if r.Op() == ir.OAPPEND {
r := r.(*ir.CallExpr)
// Left in place for back end.
// Do not add a new write barrier.
// Set up address of type for back end.
r.X = reflectdata.AppendElemRType(base.Pos, r)
return as
}
// Otherwise, lowered for race detector.
// Treat as ordinary assignment.
}
if as.X != nil && as.Y != nil {
return convas(as, init)
}
return as
}
// walkAssignDotType walks an OAS2DOTTYPE node.
func walkAssignDotType(n *ir.AssignListStmt, init *ir.Nodes) ir.Node {
walkExprListSafe(n.Lhs, init)
n.Rhs[0] = walkExpr(n.Rhs[0], init)
return n
}
// walkAssignFunc walks an OAS2FUNC node.
func walkAssignFunc(init *ir.Nodes, n *ir.AssignListStmt) ir.Node {
init.Append(ir.TakeInit(n)...)
r := n.Rhs[0]
walkExprListSafe(n.Lhs, init)
r = walkExpr(r, init)
if ir.IsIntrinsicCall(r.(*ir.CallExpr)) {
n.Rhs = []ir.Node{r}
return n
}
init.Append(r)
ll := ascompatet(n.Lhs, r.Type())
return ir.NewBlockStmt(src.NoXPos, ll)
}
// walkAssignList walks an OAS2 node.
func walkAssignList(init *ir.Nodes, n *ir.AssignListStmt) ir.Node {
init.Append(ir.TakeInit(n)...)
return ir.NewBlockStmt(src.NoXPos, ascompatee(ir.OAS, n.Lhs, n.Rhs))
}
// walkAssignMapRead walks an OAS2MAPR node.
func walkAssignMapRead(init *ir.Nodes, n *ir.AssignListStmt) ir.Node {
init.Append(ir.TakeInit(n)...)
r := n.Rhs[0].(*ir.IndexExpr)
walkExprListSafe(n.Lhs, init)
r.X = walkExpr(r.X, init)
r.Index = walkExpr(r.Index, init)
t := r.X.Type()
fast := mapfast(t)
key := mapKeyArg(fast, r, r.Index, false)
// from:
// a,b = m[i]
// to:
// var,b = mapaccess2*(t, m, i)
// a = *var
a := n.Lhs[0]
var call *ir.CallExpr
if w := t.Elem().Size(); w <= zeroValSize {
fn := mapfn(mapaccess2[fast], t, false)
call = mkcall1(fn, fn.Type().Results(), init, reflectdata.IndexMapRType(base.Pos, r), r.X, key)
} else {
fn := mapfn("mapaccess2_fat", t, true)
z := reflectdata.ZeroAddr(w)
call = mkcall1(fn, fn.Type().Results(), init, reflectdata.IndexMapRType(base.Pos, r), r.X, key, z)
}
// mapaccess2* returns a typed bool, but due to spec changes,
// the boolean result of i.(T) is now untyped so we make it the
// same type as the variable on the lhs.
if ok := n.Lhs[1]; !ir.IsBlank(ok) && ok.Type().IsBoolean() {
call.Type().Field(1).Type = ok.Type()
}
n.Rhs = []ir.Node{call}
n.SetOp(ir.OAS2FUNC)
// don't generate a = *var if a is _
if ir.IsBlank(a) {
return walkExpr(typecheck.Stmt(n), init)
}
var_ := typecheck.Temp(types.NewPtr(t.Elem()))
var_.SetTypecheck(1)
var_.MarkNonNil() // mapaccess always returns a non-nil pointer
n.Lhs[0] = var_
init.Append(walkExpr(n, init))
as := ir.NewAssignStmt(base.Pos, a, ir.NewStarExpr(base.Pos, var_))
return walkExpr(typecheck.Stmt(as), init)
}
// walkAssignRecv walks an OAS2RECV node.
func walkAssignRecv(init *ir.Nodes, n *ir.AssignListStmt) ir.Node {
init.Append(ir.TakeInit(n)...)
r := n.Rhs[0].(*ir.UnaryExpr) // recv
walkExprListSafe(n.Lhs, init)
r.X = walkExpr(r.X, init)
var n1 ir.Node
if ir.IsBlank(n.Lhs[0]) {
n1 = typecheck.NodNil()
} else {
n1 = typecheck.NodAddr(n.Lhs[0])
}
fn := chanfn("chanrecv2", 2, r.X.Type())
ok := n.Lhs[1]
call := mkcall1(fn, types.Types[types.TBOOL], init, r.X, n1)
return typecheck.Stmt(ir.NewAssignStmt(base.Pos, ok, call))
}
// walkReturn walks an ORETURN node.
func walkReturn(n *ir.ReturnStmt) ir.Node {
fn := ir.CurFunc
fn.NumReturns++
if len(n.Results) == 0 {
return n
}
results := fn.Type().Results().FieldSlice()
dsts := make([]ir.Node, len(results))
for i, v := range results {
// TODO(mdempsky): typecheck should have already checked the result variables.
dsts[i] = typecheck.AssignExpr(v.Nname.(*ir.Name))
}
n.Results = ascompatee(n.Op(), dsts, n.Results)
return n
}
// check assign type list to
// an expression list. called in
//
// expr-list = func()
func ascompatet(nl ir.Nodes, nr *types.Type) []ir.Node {
if len(nl) != nr.NumFields() {
base.Fatalf("ascompatet: assignment count mismatch: %d = %d", len(nl), nr.NumFields())
}
var nn ir.Nodes
for i, l := range nl {
if ir.IsBlank(l) {
continue
}
r := nr.Field(i)
// Order should have created autotemps of the appropriate type for
// us to store results into.
if tmp, ok := l.(*ir.Name); !ok || !tmp.AutoTemp() || !types.Identical(tmp.Type(), r.Type) {
base.FatalfAt(l.Pos(), "assigning %v to %+v", r.Type, l)
}
res := ir.NewResultExpr(base.Pos, nil, types.BADWIDTH)
res.Index = int64(i)
res.SetType(r.Type)
res.SetTypecheck(1)
nn.Append(ir.NewAssignStmt(base.Pos, l, res))
}
return nn
}
// check assign expression list to
// an expression list. called in
//
// expr-list = expr-list
func ascompatee(op ir.Op, nl, nr []ir.Node) []ir.Node {
// cannot happen: should have been rejected during type checking
if len(nl) != len(nr) {
base.Fatalf("assignment operands mismatch: %+v / %+v", ir.Nodes(nl), ir.Nodes(nr))
}
var assigned ir.NameSet
var memWrite, deferResultWrite bool
// affected reports whether expression n could be affected by
// the assignments applied so far.
affected := func(n ir.Node) bool {
if deferResultWrite {
return true
}
return ir.Any(n, func(n ir.Node) bool {
if n.Op() == ir.ONAME && assigned.Has(n.(*ir.Name)) {
return true
}
if memWrite && readsMemory(n) {
return true
}
return false
})
}
// If a needed expression may be affected by an
// earlier assignment, make an early copy of that
// expression and use the copy instead.
var early ir.Nodes
save := func(np *ir.Node) {
if n := *np; affected(n) {
*np = copyExpr(n, n.Type(), &early)
}
}
var late ir.Nodes
for i, lorig := range nl {
l, r := lorig, nr[i]
// Do not generate 'x = x' during return. See issue 4014.
if op == ir.ORETURN && ir.SameSafeExpr(l, r) {
continue
}
// Save subexpressions needed on left side.
// Drill through non-dereferences.
for {
// If an expression has init statements, they must be evaluated
// before any of its saved sub-operands (#45706).
// TODO(mdempsky): Disallow init statements on lvalues.
init := ir.TakeInit(l)
walkStmtList(init)
early.Append(init...)
switch ll := l.(type) {
case *ir.IndexExpr:
if ll.X.Type().IsArray() {
save(&ll.Index)
l = ll.X
continue
}
case *ir.ParenExpr:
l = ll.X
continue
case *ir.SelectorExpr:
if ll.Op() == ir.ODOT {
l = ll.X
continue
}
}
break
}
var name *ir.Name
switch l.Op() {
default:
base.Fatalf("unexpected lvalue %v", l.Op())
case ir.ONAME:
name = l.(*ir.Name)
case ir.OINDEX, ir.OINDEXMAP:
l := l.(*ir.IndexExpr)
save(&l.X)
save(&l.Index)
case ir.ODEREF:
l := l.(*ir.StarExpr)
save(&l.X)
case ir.ODOTPTR:
l := l.(*ir.SelectorExpr)
save(&l.X)
}
// Save expression on right side.
save(&r)
appendWalkStmt(&late, convas(ir.NewAssignStmt(base.Pos, lorig, r), &late))
// Check for reasons why we may need to compute later expressions
// before this assignment happens.
if name == nil {
// Not a direct assignment to a declared variable.
// Conservatively assume any memory access might alias.
memWrite = true
continue
}
if name.Class == ir.PPARAMOUT && ir.CurFunc.HasDefer() {
// Assignments to a result parameter in a function with defers
// becomes visible early if evaluation of any later expression
// panics (#43835).
deferResultWrite = true
continue
}
if sym := types.OrigSym(name.Sym()); sym == nil || sym.IsBlank() {
// We can ignore assignments to blank or anonymous result parameters.
// These can't appear in expressions anyway.
continue
}
if name.Addrtaken() || !name.OnStack() {
// Global variable, heap escaped, or just addrtaken.
// Conservatively assume any memory access might alias.
memWrite = true
continue
}
// Local, non-addrtaken variable.
// Assignments can only alias with direct uses of this variable.
assigned.Add(name)
}
early.Append(late.Take()...)
return early
}
// readsMemory reports whether the evaluation n directly reads from
// memory that might be written to indirectly.
func readsMemory(n ir.Node) bool {
switch n.Op() {
case ir.ONAME:
n := n.(*ir.Name)
if n.Class == ir.PFUNC {
return false
}
return n.Addrtaken() || !n.OnStack()
case ir.OADD,
ir.OAND,
ir.OANDAND,
ir.OANDNOT,
ir.OBITNOT,
ir.OCONV,
ir.OCONVIFACE,
ir.OCONVIDATA,
ir.OCONVNOP,
ir.ODIV,
ir.ODOT,
ir.ODOTTYPE,
ir.OLITERAL,
ir.OLSH,
ir.OMOD,
ir.OMUL,
ir.ONEG,
ir.ONIL,
ir.OOR,
ir.OOROR,
ir.OPAREN,
ir.OPLUS,
ir.ORSH,
ir.OSUB,
ir.OXOR:
return false
}
// Be conservative.
return true
}
// expand append(l1, l2...) to
//
// init {
// s := l1
// newLen := s.len + l2.len
// // Compare as uint so growslice can panic on overflow.
// if uint(newLen) <= uint(s.cap) {
// s = s[:newLen]
// } else {
// s = growslice(s.ptr, s.len, s.cap, l2.len, T)
// }
// memmove(&s[s.len-l2.len], &l2[0], l2.len*sizeof(T))
// }
// s
//
// l2 is allowed to be a string.
func appendSlice(n *ir.CallExpr, init *ir.Nodes) ir.Node {
walkAppendArgs(n, init)
l1 := n.Args[0]
l2 := n.Args[1]
l2 = cheapExpr(l2, init)
n.Args[1] = l2
var nodes ir.Nodes
// var s []T
s := typecheck.Temp(l1.Type())
nodes.Append(ir.NewAssignStmt(base.Pos, s, l1)) // s = l1
elemtype := s.Type().Elem()
// Decompose slice.
oldPtr := ir.NewUnaryExpr(base.Pos, ir.OSPTR, s)
oldLen := ir.NewUnaryExpr(base.Pos, ir.OLEN, s)
oldCap := ir.NewUnaryExpr(base.Pos, ir.OCAP, s)
// Number of elements we are adding
num := ir.NewUnaryExpr(base.Pos, ir.OLEN, l2)
// newLen := oldLen + num
newLen := typecheck.Temp(types.Types[types.TINT])
nodes.Append(ir.NewAssignStmt(base.Pos, newLen, ir.NewBinaryExpr(base.Pos, ir.OADD, oldLen, num)))
// if uint(newLen) <= uint(oldCap)
nif := ir.NewIfStmt(base.Pos, nil, nil, nil)
nuint := typecheck.Conv(newLen, types.Types[types.TUINT])
scapuint := typecheck.Conv(oldCap, types.Types[types.TUINT])
nif.Cond = ir.NewBinaryExpr(base.Pos, ir.OLE, nuint, scapuint)
nif.Likely = true
// then { s = s[:newLen] }
slice := ir.NewSliceExpr(base.Pos, ir.OSLICE, s, nil, newLen, nil)
slice.SetBounded(true)
nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, s, slice)}
// func growslice(oldPtr unsafe.Pointer, newLen, oldCap, num int, et *_type) []T
fn := typecheck.LookupRuntime("growslice")
fn = typecheck.SubstArgTypes(fn, elemtype, elemtype)
// else { s = growslice(oldPtr, newLen, oldCap, num, T) }
call := mkcall1(fn, s.Type(), nif.PtrInit(), oldPtr, newLen, oldCap, num, reflectdata.TypePtr(elemtype))
nif.Else = []ir.Node{ir.NewAssignStmt(base.Pos, s, call)}
nodes.Append(nif)
// Index to start copying into s.
// idx = newLen - len(l2)
// We use this expression instead of oldLen because it avoids
// a spill/restore of oldLen.
// Note: this doesn't work optimally currently because
// the compiler optimizer undoes this arithmetic.
idx := ir.NewBinaryExpr(base.Pos, ir.OSUB, newLen, ir.NewUnaryExpr(base.Pos, ir.OLEN, l2))
var ncopy ir.Node
if elemtype.HasPointers() {
// copy(s[idx:], l2)
slice := ir.NewSliceExpr(base.Pos, ir.OSLICE, s, idx, nil, nil)
slice.SetType(s.Type())
slice.SetBounded(true)
ir.CurFunc.SetWBPos(n.Pos())
// instantiate typedslicecopy(typ *type, dstPtr *any, dstLen int, srcPtr *any, srcLen int) int
fn := typecheck.LookupRuntime("typedslicecopy")
fn = typecheck.SubstArgTypes(fn, l1.Type().Elem(), l2.Type().Elem())
ptr1, len1 := backingArrayPtrLen(cheapExpr(slice, &nodes))
ptr2, len2 := backingArrayPtrLen(l2)
ncopy = mkcall1(fn, types.Types[types.TINT], &nodes, reflectdata.AppendElemRType(base.Pos, n), ptr1, len1, ptr2, len2)
} else if base.Flag.Cfg.Instrumenting && !base.Flag.CompilingRuntime {
// rely on runtime to instrument:
// copy(s[idx:], l2)
// l2 can be a slice or string.
slice := ir.NewSliceExpr(base.Pos, ir.OSLICE, s, idx, nil, nil)
slice.SetType(s.Type())
slice.SetBounded(true)
ptr1, len1 := backingArrayPtrLen(cheapExpr(slice, &nodes))
ptr2, len2 := backingArrayPtrLen(l2)
fn := typecheck.LookupRuntime("slicecopy")
fn = typecheck.SubstArgTypes(fn, ptr1.Type().Elem(), ptr2.Type().Elem())
ncopy = mkcall1(fn, types.Types[types.TINT], &nodes, ptr1, len1, ptr2, len2, ir.NewInt(elemtype.Size()))
} else {
// memmove(&s[idx], &l2[0], len(l2)*sizeof(T))
ix := ir.NewIndexExpr(base.Pos, s, idx)
ix.SetBounded(true)
addr := typecheck.NodAddr(ix)
sptr := ir.NewUnaryExpr(base.Pos, ir.OSPTR, l2)
nwid := cheapExpr(typecheck.Conv(ir.NewUnaryExpr(base.Pos, ir.OLEN, l2), types.Types[types.TUINTPTR]), &nodes)
nwid = ir.NewBinaryExpr(base.Pos, ir.OMUL, nwid, ir.NewInt(elemtype.Size()))
// instantiate func memmove(to *any, frm *any, length uintptr)
fn := typecheck.LookupRuntime("memmove")
fn = typecheck.SubstArgTypes(fn, elemtype, elemtype)
ncopy = mkcall1(fn, nil, &nodes, addr, sptr, nwid)
}
ln := append(nodes, ncopy)
typecheck.Stmts(ln)
walkStmtList(ln)
init.Append(ln...)
return s
}
// isAppendOfMake reports whether n is of the form append(x, make([]T, y)...).
// isAppendOfMake assumes n has already been typechecked.
func isAppendOfMake(n ir.Node) bool {
if base.Flag.N != 0 || base.Flag.Cfg.Instrumenting {
return false
}
if n.Typecheck() == 0 {
base.Fatalf("missing typecheck: %+v", n)
}
if n.Op() != ir.OAPPEND {
return false
}
call := n.(*ir.CallExpr)
if !call.IsDDD || len(call.Args) != 2 || call.Args[1].Op() != ir.OMAKESLICE {
return false
}
mk := call.Args[1].(*ir.MakeExpr)
if mk.Cap != nil {
return false
}
// y must be either an integer constant or the largest possible positive value
// of variable y needs to fit into an uint.
// typecheck made sure that constant arguments to make are not negative and fit into an int.
// The care of overflow of the len argument to make will be handled by an explicit check of int(len) < 0 during runtime.
y := mk.Len
if !ir.IsConst(y, constant.Int) && y.Type().Size() > types.Types[types.TUINT].Size() {
return false
}
return true
}
// extendSlice rewrites append(l1, make([]T, l2)...) to
//
// init {
// if l2 >= 0 { // Empty if block here for more meaningful node.SetLikely(true)
// } else {
// panicmakeslicelen()
// }
// s := l1
// n := len(s) + l2
// // Compare n and s as uint so growslice can panic on overflow of len(s) + l2.
// // cap is a positive int and n can become negative when len(s) + l2
// // overflows int. Interpreting n when negative as uint makes it larger
// // than cap(s). growslice will check the int n arg and panic if n is
// // negative. This prevents the overflow from being undetected.
// if uint(n) <= uint(cap(s)) {
// s = s[:n]
// } else {
// s = growslice(T, s.ptr, n, s.cap, l2, T)
// }
// // clear the new portion of the underlying array.
// hp := &s[len(s)-l2]
// hn := l2 * sizeof(T)
// memclr(hp, hn)
// }
// s
//
// if T has pointers, the final memclr can go inside the "then" branch, as
// growslice will have done the clearing for us.
func extendSlice(n *ir.CallExpr, init *ir.Nodes) ir.Node {
// isAppendOfMake made sure all possible positive values of l2 fit into an uint.
// The case of l2 overflow when converting from e.g. uint to int is handled by an explicit
// check of l2 < 0 at runtime which is generated below.
l2 := typecheck.Conv(n.Args[1].(*ir.MakeExpr).Len, types.Types[types.TINT])
l2 = typecheck.Expr(l2)
n.Args[1] = l2 // walkAppendArgs expects l2 in n.List.Second().
walkAppendArgs(n, init)
l1 := n.Args[0]
l2 = n.Args[1] // re-read l2, as it may have been updated by walkAppendArgs
var nodes []ir.Node
// if l2 >= 0 (likely happens), do nothing
nifneg := ir.NewIfStmt(base.Pos, ir.NewBinaryExpr(base.Pos, ir.OGE, l2, ir.NewInt(0)), nil, nil)
nifneg.Likely = true
// else panicmakeslicelen()
nifneg.Else = []ir.Node{mkcall("panicmakeslicelen", nil, init)}
nodes = append(nodes, nifneg)
// s := l1
s := typecheck.Temp(l1.Type())
nodes = append(nodes, ir.NewAssignStmt(base.Pos, s, l1))
elemtype := s.Type().Elem()
// n := s.len + l2
nn := typecheck.Temp(types.Types[types.TINT])
nodes = append(nodes, ir.NewAssignStmt(base.Pos, nn, ir.NewBinaryExpr(base.Pos, ir.OADD, ir.NewUnaryExpr(base.Pos, ir.OLEN, s), l2)))
// if uint(n) <= uint(s.cap)
nuint := typecheck.Conv(nn, types.Types[types.TUINT])
capuint := typecheck.Conv(ir.NewUnaryExpr(base.Pos, ir.OCAP, s), types.Types[types.TUINT])
nif := ir.NewIfStmt(base.Pos, ir.NewBinaryExpr(base.Pos, ir.OLE, nuint, capuint), nil, nil)
nif.Likely = true
// then { s = s[:n] }
nt := ir.NewSliceExpr(base.Pos, ir.OSLICE, s, nil, nn, nil)
nt.SetBounded(true)
nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, s, nt)}
// instantiate growslice(oldPtr *any, newLen, oldCap, num int, typ *type) []any
fn := typecheck.LookupRuntime("growslice")
fn = typecheck.SubstArgTypes(fn, elemtype, elemtype)
// else { s = growslice(s.ptr, n, s.cap, l2, T) }
nif.Else = []ir.Node{
ir.NewAssignStmt(base.Pos, s, mkcall1(fn, s.Type(), nif.PtrInit(),
ir.NewUnaryExpr(base.Pos, ir.OSPTR, s),
nn,
ir.NewUnaryExpr(base.Pos, ir.OCAP, s),
l2,
reflectdata.TypePtr(elemtype))),
}
nodes = append(nodes, nif)
// hp := &s[s.len - l2]
// TODO: &s[s.len] - hn?
ix := ir.NewIndexExpr(base.Pos, s, ir.NewBinaryExpr(base.Pos, ir.OSUB, ir.NewUnaryExpr(base.Pos, ir.OLEN, s), l2))
ix.SetBounded(true)
hp := typecheck.ConvNop(typecheck.NodAddr(ix), types.Types[types.TUNSAFEPTR])
// hn := l2 * sizeof(elem(s))
hn := typecheck.Conv(ir.NewBinaryExpr(base.Pos, ir.OMUL, l2, ir.NewInt(elemtype.Size())), types.Types[types.TUINTPTR])
clrname := "memclrNoHeapPointers"
hasPointers := elemtype.HasPointers()
if hasPointers {
clrname = "memclrHasPointers"
ir.CurFunc.SetWBPos(n.Pos())
}
var clr ir.Nodes
clrfn := mkcall(clrname, nil, &clr, hp, hn)
clr.Append(clrfn)
if hasPointers {
// growslice will have cleared the new entries, so only
// if growslice isn't called do we need to do the zeroing ourselves.
nif.Body = append(nif.Body, clr...)
} else {
nodes = append(nodes, clr...)
}
typecheck.Stmts(nodes)
walkStmtList(nodes)
init.Append(nodes...)
return s
}