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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 (
"fmt"
"go/constant"
"strings"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/staticdata"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/obj"
"cmd/internal/objabi"
)
// The result of walkExpr MUST be assigned back to n, e.g.
// n.Left = walkExpr(n.Left, init)
func walkExpr(n ir.Node, init *ir.Nodes) ir.Node {
if n == nil {
return n
}
if n, ok := n.(ir.InitNode); ok && init == n.PtrInit() {
// not okay to use n->ninit when walking n,
// because we might replace n with some other node
// and would lose the init list.
base.Fatalf("walkExpr init == &n->ninit")
}
if len(n.Init()) != 0 {
walkStmtList(n.Init())
init.Append(ir.TakeInit(n)...)
}
lno := ir.SetPos(n)
if base.Flag.LowerW > 1 {
ir.Dump("before walk expr", n)
}
if n.Typecheck() != 1 {
base.Fatalf("missed typecheck: %+v", n)
}
if n.Type().IsUntyped() {
base.Fatalf("expression has untyped type: %+v", n)
}
n = walkExpr1(n, init)
// Eagerly compute sizes of all expressions for the back end.
if typ := n.Type(); typ != nil && typ.Kind() != types.TBLANK && !typ.IsFuncArgStruct() {
types.CheckSize(typ)
}
if n, ok := n.(*ir.Name); ok && n.Heapaddr != nil {
types.CheckSize(n.Heapaddr.Type())
}
if ir.IsConst(n, constant.String) {
// Emit string symbol now to avoid emitting
// any concurrently during the backend.
_ = staticdata.StringSym(n.Pos(), constant.StringVal(n.Val()))
}
if base.Flag.LowerW != 0 && n != nil {
ir.Dump("after walk expr", n)
}
base.Pos = lno
return n
}
func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
switch n.Op() {
default:
ir.Dump("walk", n)
base.Fatalf("walkExpr: switch 1 unknown op %+v", n.Op())
panic("unreachable")
case ir.ONONAME, ir.OGETG:
return n
case ir.OTYPE, ir.ONAME, ir.OLITERAL, ir.ONIL, ir.OLINKSYMOFFSET:
// TODO(mdempsky): Just return n; see discussion on CL 38655.
// Perhaps refactor to use Node.mayBeShared for these instead.
// If these return early, make sure to still call
// StringSym for constant strings.
return n
case ir.OMETHEXPR:
// TODO(mdempsky): Do this right after type checking.
n := n.(*ir.SelectorExpr)
return n.FuncName()
case ir.ONOT, ir.ONEG, ir.OPLUS, ir.OBITNOT, ir.OREAL, ir.OIMAG, ir.OSPTR, ir.OITAB, ir.OIDATA:
n := n.(*ir.UnaryExpr)
n.X = walkExpr(n.X, init)
return n
case ir.ODOTMETH, ir.ODOTINTER:
n := n.(*ir.SelectorExpr)
n.X = walkExpr(n.X, init)
return n
case ir.OADDR:
n := n.(*ir.AddrExpr)
n.X = walkExpr(n.X, init)
return n
case ir.ODEREF:
n := n.(*ir.StarExpr)
n.X = walkExpr(n.X, init)
return n
case ir.OEFACE, ir.OAND, ir.OANDNOT, ir.OSUB, ir.OMUL, ir.OADD, ir.OOR, ir.OXOR, ir.OLSH, ir.ORSH:
n := n.(*ir.BinaryExpr)
n.X = walkExpr(n.X, init)
n.Y = walkExpr(n.Y, init)
return n
case ir.ODOT, ir.ODOTPTR:
n := n.(*ir.SelectorExpr)
return walkDot(n, init)
case ir.ODOTTYPE, ir.ODOTTYPE2:
n := n.(*ir.TypeAssertExpr)
return walkDotType(n, init)
case ir.OLEN, ir.OCAP:
n := n.(*ir.UnaryExpr)
return walkLenCap(n, init)
case ir.OCOMPLEX:
n := n.(*ir.BinaryExpr)
n.X = walkExpr(n.X, init)
n.Y = walkExpr(n.Y, init)
return n
case ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
n := n.(*ir.BinaryExpr)
return walkCompare(n, init)
case ir.OANDAND, ir.OOROR:
n := n.(*ir.LogicalExpr)
return walkLogical(n, init)
case ir.OPRINT, ir.OPRINTN:
return walkPrint(n.(*ir.CallExpr), init)
case ir.OPANIC:
n := n.(*ir.UnaryExpr)
return mkcall("gopanic", nil, init, n.X)
case ir.ORECOVER:
n := n.(*ir.CallExpr)
return mkcall("gorecover", n.Type(), init, typecheck.NodAddr(ir.RegFP))
case ir.OCFUNC:
return n
case ir.OCALLINTER, ir.OCALLFUNC, ir.OCALLMETH:
n := n.(*ir.CallExpr)
return walkCall(n, init)
case ir.OAS, ir.OASOP:
return walkAssign(init, n)
case ir.OAS2:
n := n.(*ir.AssignListStmt)
return walkAssignList(init, n)
// a,b,... = fn()
case ir.OAS2FUNC:
n := n.(*ir.AssignListStmt)
return walkAssignFunc(init, n)
// x, y = <-c
// order.stmt made sure x is addressable or blank.
case ir.OAS2RECV:
n := n.(*ir.AssignListStmt)
return walkAssignRecv(init, n)
// a,b = m[i]
case ir.OAS2MAPR:
n := n.(*ir.AssignListStmt)
return walkAssignMapRead(init, n)
case ir.ODELETE:
n := n.(*ir.CallExpr)
return walkDelete(init, n)
case ir.OAS2DOTTYPE:
n := n.(*ir.AssignListStmt)
return walkAssignDotType(n, init)
case ir.OCONVIFACE:
n := n.(*ir.ConvExpr)
return walkConvInterface(n, init)
case ir.OCONV, ir.OCONVNOP:
n := n.(*ir.ConvExpr)
return walkConv(n, init)
case ir.ODIV, ir.OMOD:
n := n.(*ir.BinaryExpr)
return walkDivMod(n, init)
case ir.OINDEX:
n := n.(*ir.IndexExpr)
return walkIndex(n, init)
case ir.OINDEXMAP:
n := n.(*ir.IndexExpr)
return walkIndexMap(n, init)
case ir.ORECV:
base.Fatalf("walkExpr ORECV") // should see inside OAS only
panic("unreachable")
case ir.OSLICEHEADER:
n := n.(*ir.SliceHeaderExpr)
return walkSliceHeader(n, init)
case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
n := n.(*ir.SliceExpr)
return walkSlice(n, init)
case ir.ONEW:
n := n.(*ir.UnaryExpr)
return walkNew(n, init)
case ir.OADDSTR:
return walkAddString(n.(*ir.AddStringExpr), init)
case ir.OAPPEND:
// order should make sure we only see OAS(node, OAPPEND), which we handle above.
base.Fatalf("append outside assignment")
panic("unreachable")
case ir.OCOPY:
return walkCopy(n.(*ir.BinaryExpr), init, base.Flag.Cfg.Instrumenting && !base.Flag.CompilingRuntime)
case ir.OCLOSE:
n := n.(*ir.UnaryExpr)
return walkClose(n, init)
case ir.OMAKECHAN:
n := n.(*ir.MakeExpr)
return walkMakeChan(n, init)
case ir.OMAKEMAP:
n := n.(*ir.MakeExpr)
return walkMakeMap(n, init)
case ir.OMAKESLICE:
n := n.(*ir.MakeExpr)
return walkMakeSlice(n, init)
case ir.OMAKESLICECOPY:
n := n.(*ir.MakeExpr)
return walkMakeSliceCopy(n, init)
case ir.ORUNESTR:
n := n.(*ir.ConvExpr)
return walkRuneToString(n, init)
case ir.OBYTES2STR, ir.ORUNES2STR:
n := n.(*ir.ConvExpr)
return walkBytesRunesToString(n, init)
case ir.OBYTES2STRTMP:
n := n.(*ir.ConvExpr)
return walkBytesToStringTemp(n, init)
case ir.OSTR2BYTES:
n := n.(*ir.ConvExpr)
return walkStringToBytes(n, init)
case ir.OSTR2BYTESTMP:
n := n.(*ir.ConvExpr)
return walkStringToBytesTemp(n, init)
case ir.OSTR2RUNES:
n := n.(*ir.ConvExpr)
return walkStringToRunes(n, init)
case ir.OARRAYLIT, ir.OSLICELIT, ir.OMAPLIT, ir.OSTRUCTLIT, ir.OPTRLIT:
return walkCompLit(n, init)
case ir.OSEND:
n := n.(*ir.SendStmt)
return walkSend(n, init)
case ir.OCLOSURE:
return walkClosure(n.(*ir.ClosureExpr), init)
case ir.OCALLPART:
return walkCallPart(n.(*ir.SelectorExpr), init)
}
// No return! Each case must return (or panic),
// to avoid confusion about what gets returned
// in the presence of type assertions.
}
// walk the whole tree of the body of an
// expression or simple statement.
// the types expressions are calculated.
// compile-time constants are evaluated.
// complex side effects like statements are appended to init
func walkExprList(s []ir.Node, init *ir.Nodes) {
for i := range s {
s[i] = walkExpr(s[i], init)
}
}
func walkExprListCheap(s []ir.Node, init *ir.Nodes) {
for i, n := range s {
s[i] = cheapExpr(n, init)
s[i] = walkExpr(s[i], init)
}
}
func walkExprListSafe(s []ir.Node, init *ir.Nodes) {
for i, n := range s {
s[i] = safeExpr(n, init)
s[i] = walkExpr(s[i], init)
}
}
// return side-effect free and cheap n, appending side effects to init.
// result may not be assignable.
func cheapExpr(n ir.Node, init *ir.Nodes) ir.Node {
switch n.Op() {
case ir.ONAME, ir.OLITERAL, ir.ONIL:
return n
}
return copyExpr(n, n.Type(), init)
}
// return side effect-free n, appending side effects to init.
// result is assignable if n is.
func safeExpr(n ir.Node, init *ir.Nodes) ir.Node {
if n == nil {
return nil
}
if len(n.Init()) != 0 {
walkStmtList(n.Init())
init.Append(ir.TakeInit(n)...)
}
switch n.Op() {
case ir.ONAME, ir.OLITERAL, ir.ONIL, ir.OLINKSYMOFFSET:
return n
case ir.OLEN, ir.OCAP:
n := n.(*ir.UnaryExpr)
l := safeExpr(n.X, init)
if l == n.X {
return n
}
a := ir.Copy(n).(*ir.UnaryExpr)
a.X = l
return walkExpr(typecheck.Expr(a), init)
case ir.ODOT, ir.ODOTPTR:
n := n.(*ir.SelectorExpr)
l := safeExpr(n.X, init)
if l == n.X {
return n
}
a := ir.Copy(n).(*ir.SelectorExpr)
a.X = l
return walkExpr(typecheck.Expr(a), init)
case ir.ODEREF:
n := n.(*ir.StarExpr)
l := safeExpr(n.X, init)
if l == n.X {
return n
}
a := ir.Copy(n).(*ir.StarExpr)
a.X = l
return walkExpr(typecheck.Expr(a), init)
case ir.OINDEX, ir.OINDEXMAP:
n := n.(*ir.IndexExpr)
l := safeExpr(n.X, init)
r := safeExpr(n.Index, init)
if l == n.X && r == n.Index {
return n
}
a := ir.Copy(n).(*ir.IndexExpr)
a.X = l
a.Index = r
return walkExpr(typecheck.Expr(a), init)
case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
n := n.(*ir.CompLitExpr)
if isStaticCompositeLiteral(n) {
return n
}
}
// make a copy; must not be used as an lvalue
if ir.IsAddressable(n) {
base.Fatalf("missing lvalue case in safeExpr: %v", n)
}
return cheapExpr(n, init)
}
func copyExpr(n ir.Node, t *types.Type, init *ir.Nodes) ir.Node {
l := typecheck.Temp(t)
appendWalkStmt(init, ir.NewAssignStmt(base.Pos, l, n))
return l
}
func walkAddString(n *ir.AddStringExpr, init *ir.Nodes) ir.Node {
c := len(n.List)
if c < 2 {
base.Fatalf("walkAddString count %d too small", c)
}
buf := typecheck.NodNil()
if n.Esc() == ir.EscNone {
sz := int64(0)
for _, n1 := range n.List {
if n1.Op() == ir.OLITERAL {
sz += int64(len(ir.StringVal(n1)))
}
}
// Don't allocate the buffer if the result won't fit.
if sz < tmpstringbufsize {
// Create temporary buffer for result string on stack.
buf = stackBufAddr(tmpstringbufsize, types.Types[types.TUINT8])
}
}
// build list of string arguments
args := []ir.Node{buf}
for _, n2 := range n.List {
args = append(args, typecheck.Conv(n2, types.Types[types.TSTRING]))
}
var fn string
if c <= 5 {
// small numbers of strings use direct runtime helpers.
// note: order.expr knows this cutoff too.
fn = fmt.Sprintf("concatstring%d", c)
} else {
// large numbers of strings are passed to the runtime as a slice.
fn = "concatstrings"
t := types.NewSlice(types.Types[types.TSTRING])
// args[1:] to skip buf arg
slice := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(t), args[1:])
slice.Prealloc = n.Prealloc
args = []ir.Node{buf, slice}
slice.SetEsc(ir.EscNone)
}
cat := typecheck.LookupRuntime(fn)
r := ir.NewCallExpr(base.Pos, ir.OCALL, cat, nil)
r.Args = args
r1 := typecheck.Expr(r)
r1 = walkExpr(r1, init)
r1.SetType(n.Type())
return r1
}
// walkCall walks an OCALLFUNC, OCALLINTER, or OCALLMETH node.
func walkCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
if n.Op() == ir.OCALLINTER || n.Op() == ir.OCALLMETH {
// We expect both interface call reflect.Type.Method and concrete
// call reflect.(*rtype).Method.
usemethod(n)
}
if n.Op() == ir.OCALLINTER {
reflectdata.MarkUsedIfaceMethod(n)
}
if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.OCLOSURE {
directClosureCall(n)
}
walkCall1(n, init)
return n
}
func walkCall1(n *ir.CallExpr, init *ir.Nodes) {
if n.Walked() {
return // already walked
}
n.SetWalked(true)
// If this is a method call t.M(...),
// rewrite into a function call T.M(t, ...).
// TODO(mdempsky): Do this right after type checking.
if n.Op() == ir.OCALLMETH {
withRecv := make([]ir.Node, len(n.Args)+1)
dot := n.X.(*ir.SelectorExpr)
withRecv[0] = dot.X
copy(withRecv[1:], n.Args)
n.Args = withRecv
dot = ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym)
n.SetOp(ir.OCALLFUNC)
n.X = typecheck.Expr(dot)
}
args := n.Args
params := n.X.Type().Params()
n.X = walkExpr(n.X, init)
walkExprList(args, init)
for i, arg := range args {
// Validate argument and parameter types match.
param := params.Field(i)
if !types.Identical(arg.Type(), param.Type) {
base.FatalfAt(n.Pos(), "assigning %L to parameter %v (type %v)", arg, param.Sym, param.Type)
}
// For any argument whose evaluation might require a function call,
// store that argument into a temporary variable,
// to prevent that calls from clobbering arguments already on the stack.
if mayCall(arg) {
// assignment of arg to Temp
tmp := typecheck.Temp(param.Type)
init.Append(convas(typecheck.Stmt(ir.NewAssignStmt(base.Pos, tmp, arg)).(*ir.AssignStmt), init))
// replace arg with temp
args[i] = tmp
}
}
n.Args = args
}
// walkDivMod walks an ODIV or OMOD node.
func walkDivMod(n *ir.BinaryExpr, init *ir.Nodes) ir.Node {
n.X = walkExpr(n.X, init)
n.Y = walkExpr(n.Y, init)
// rewrite complex div into function call.
et := n.X.Type().Kind()
if types.IsComplex[et] && n.Op() == ir.ODIV {
t := n.Type()
call := mkcall("complex128div", types.Types[types.TCOMPLEX128], init, typecheck.Conv(n.X, types.Types[types.TCOMPLEX128]), typecheck.Conv(n.Y, types.Types[types.TCOMPLEX128]))
return typecheck.Conv(call, t)
}
// Nothing to do for float divisions.
if types.IsFloat[et] {
return n
}
// rewrite 64-bit div and mod on 32-bit architectures.
// TODO: Remove this code once we can introduce
// runtime calls late in SSA processing.
if types.RegSize < 8 && (et == types.TINT64 || et == types.TUINT64) {
if n.Y.Op() == ir.OLITERAL {
// Leave div/mod by constant powers of 2 or small 16-bit constants.
// The SSA backend will handle those.
switch et {
case types.TINT64:
c := ir.Int64Val(n.Y)
if c < 0 {
c = -c
}
if c != 0 && c&(c-1) == 0 {
return n
}
case types.TUINT64:
c := ir.Uint64Val(n.Y)
if c < 1<<16 {
return n
}
if c != 0 && c&(c-1) == 0 {
return n
}
}
}
var fn string
if et == types.TINT64 {
fn = "int64"
} else {
fn = "uint64"
}
if n.Op() == ir.ODIV {
fn += "div"
} else {
fn += "mod"
}
return mkcall(fn, n.Type(), init, typecheck.Conv(n.X, types.Types[et]), typecheck.Conv(n.Y, types.Types[et]))
}
return n
}
// walkDot walks an ODOT or ODOTPTR node.
func walkDot(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
usefield(n)
n.X = walkExpr(n.X, init)
return n
}
// walkDotType walks an ODOTTYPE or ODOTTYPE2 node.
func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
n.X = walkExpr(n.X, init)
// Set up interface type addresses for back end.
if !n.Type().IsInterface() && !n.X.Type().IsEmptyInterface() {
n.Itab = reflectdata.ITabAddr(n.Type(), n.X.Type())
}
return n
}
// walkIndex walks an OINDEX node.
func walkIndex(n *ir.IndexExpr, init *ir.Nodes) ir.Node {
n.X = walkExpr(n.X, init)
// save the original node for bounds checking elision.
// If it was a ODIV/OMOD walk might rewrite it.
r := n.Index
n.Index = walkExpr(n.Index, init)
// if range of type cannot exceed static array bound,
// disable bounds check.
if n.Bounded() {
return n
}
t := n.X.Type()
if t != nil && t.IsPtr() {
t = t.Elem()
}
if t.IsArray() {
n.SetBounded(bounded(r, t.NumElem()))
if base.Flag.LowerM != 0 && n.Bounded() && !ir.IsConst(n.Index, constant.Int) {
base.Warn("index bounds check elided")
}
if ir.IsSmallIntConst(n.Index) && !n.Bounded() {
base.Errorf("index out of bounds")
}
} else if ir.IsConst(n.X, constant.String) {
n.SetBounded(bounded(r, int64(len(ir.StringVal(n.X)))))
if base.Flag.LowerM != 0 && n.Bounded() && !ir.IsConst(n.Index, constant.Int) {
base.Warn("index bounds check elided")
}
if ir.IsSmallIntConst(n.Index) && !n.Bounded() {
base.Errorf("index out of bounds")
}
}
if ir.IsConst(n.Index, constant.Int) {
if v := n.Index.Val(); constant.Sign(v) < 0 || ir.ConstOverflow(v, types.Types[types.TINT]) {
base.Errorf("index out of bounds")
}
}
return n
}
// walkIndexMap walks an OINDEXMAP node.
func walkIndexMap(n *ir.IndexExpr, init *ir.Nodes) ir.Node {
// Replace m[k] with *map{access1,assign}(maptype, m, &k)
n.X = walkExpr(n.X, init)
n.Index = walkExpr(n.Index, init)
map_ := n.X
key := n.Index
t := map_.Type()
var call *ir.CallExpr
if n.Assigned {
// This m[k] expression is on the left-hand side of an assignment.
fast := mapfast(t)
if fast == mapslow {
// standard version takes key by reference.
// order.expr made sure key is addressable.
key = typecheck.NodAddr(key)
}
call = mkcall1(mapfn(mapassign[fast], t), nil, init, reflectdata.TypePtr(t), map_, key)
} else {
// m[k] is not the target of an assignment.
fast := mapfast(t)
if fast == mapslow {
// standard version takes key by reference.
// order.expr made sure key is addressable.
key = typecheck.NodAddr(key)
}
if w := t.Elem().Width; w <= zeroValSize {
call = mkcall1(mapfn(mapaccess1[fast], t), types.NewPtr(t.Elem()), init, reflectdata.TypePtr(t), map_, key)
} else {
z := reflectdata.ZeroAddr(w)
call = mkcall1(mapfn("mapaccess1_fat", t), types.NewPtr(t.Elem()), init, reflectdata.TypePtr(t), map_, key, z)
}
}
call.SetType(types.NewPtr(t.Elem()))
call.MarkNonNil() // mapaccess1* and mapassign always return non-nil pointers.
star := ir.NewStarExpr(base.Pos, call)
star.SetType(t.Elem())
star.SetTypecheck(1)
return star
}
// walkLogical walks an OANDAND or OOROR node.
func walkLogical(n *ir.LogicalExpr, init *ir.Nodes) ir.Node {
n.X = walkExpr(n.X, init)
// cannot put side effects from n.Right on init,
// because they cannot run before n.Left is checked.
// save elsewhere and store on the eventual n.Right.
var ll ir.Nodes
n.Y = walkExpr(n.Y, &ll)
n.Y = ir.InitExpr(ll, n.Y)
return n
}
// walkSend walks an OSEND node.
func walkSend(n *ir.SendStmt, init *ir.Nodes) ir.Node {
n1 := n.Value
n1 = typecheck.AssignConv(n1, n.Chan.Type().Elem(), "chan send")
n1 = walkExpr(n1, init)
n1 = typecheck.NodAddr(n1)
return mkcall1(chanfn("chansend1", 2, n.Chan.Type()), nil, init, n.Chan, n1)
}
// walkSlice walks an OSLICE, OSLICEARR, OSLICESTR, OSLICE3, or OSLICE3ARR node.
func walkSlice(n *ir.SliceExpr, init *ir.Nodes) ir.Node {
checkSlice := ir.ShouldCheckPtr(ir.CurFunc, 1) && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
if checkSlice {
conv := n.X.(*ir.ConvExpr)
conv.X = walkExpr(conv.X, init)
} else {
n.X = walkExpr(n.X, init)
}
n.Low = walkExpr(n.Low, init)
if n.Low != nil && ir.IsZero(n.Low) {
// Reduce x[0:j] to x[:j] and x[0:j:k] to x[:j:k].
n.Low = nil
}
n.High = walkExpr(n.High, init)
n.Max = walkExpr(n.Max, init)
if checkSlice {
n.X = walkCheckPtrAlignment(n.X.(*ir.ConvExpr), init, n.Max)
}
if n.Op().IsSlice3() {
if n.Max != nil && n.Max.Op() == ir.OCAP && ir.SameSafeExpr(n.X, n.Max.(*ir.UnaryExpr).X) {
// Reduce x[i:j:cap(x)] to x[i:j].
if n.Op() == ir.OSLICE3 {
n.SetOp(ir.OSLICE)
} else {
n.SetOp(ir.OSLICEARR)
}
return reduceSlice(n)
}
return n
}
return reduceSlice(n)
}
// walkSliceHeader walks an OSLICEHEADER node.
func walkSliceHeader(n *ir.SliceHeaderExpr, init *ir.Nodes) ir.Node {
n.Ptr = walkExpr(n.Ptr, init)
n.Len = walkExpr(n.Len, init)
n.Cap = walkExpr(n.Cap, init)
return n
}
// TODO(josharian): combine this with its caller and simplify
func reduceSlice(n *ir.SliceExpr) ir.Node {
if n.High != nil && n.High.Op() == ir.OLEN && ir.SameSafeExpr(n.X, n.High.(*ir.UnaryExpr).X) {
// Reduce x[i:len(x)] to x[i:].
n.High = nil
}
if (n.Op() == ir.OSLICE || n.Op() == ir.OSLICESTR) && n.Low == nil && n.High == nil {
// Reduce x[:] to x.
if base.Debug.Slice > 0 {
base.Warn("slice: omit slice operation")
}
return n.X
}
return n
}
// return 1 if integer n must be in range [0, max), 0 otherwise
func bounded(n ir.Node, max int64) bool {
if n.Type() == nil || !n.Type().IsInteger() {
return false
}
sign := n.Type().IsSigned()
bits := int32(8 * n.Type().Width)
if ir.IsSmallIntConst(n) {
v := ir.Int64Val(n)
return 0 <= v && v < max
}
switch n.Op() {
case ir.OAND, ir.OANDNOT:
n := n.(*ir.BinaryExpr)
v := int64(-1)
switch {
case ir.IsSmallIntConst(n.X):
v = ir.Int64Val(n.X)
case ir.IsSmallIntConst(n.Y):
v = ir.Int64Val(n.Y)
if n.Op() == ir.OANDNOT {
v = ^v
if !sign {
v &= 1<<uint(bits) - 1
}
}
}
if 0 <= v && v < max {
return true
}
case ir.OMOD:
n := n.(*ir.BinaryExpr)
if !sign && ir.IsSmallIntConst(n.Y) {
v := ir.Int64Val(n.Y)
if 0 <= v && v <= max {
return true
}
}
case ir.ODIV:
n := n.(*ir.BinaryExpr)
if !sign && ir.IsSmallIntConst(n.Y) {
v := ir.Int64Val(n.Y)
for bits > 0 && v >= 2 {
bits--
v >>= 1
}
}
case ir.ORSH:
n := n.(*ir.BinaryExpr)
if !sign && ir.IsSmallIntConst(n.Y) {
v := ir.Int64Val(n.Y)
if v > int64(bits) {
return true
}
bits -= int32(v)
}
}
if !sign && bits <= 62 && 1<<uint(bits) <= max {
return true
}
return false
}
// usemethod checks interface method calls for uses of reflect.Type.Method.
func usemethod(n *ir.CallExpr) {
t := n.X.Type()
// Looking for either of:
// Method(int) reflect.Method
// MethodByName(string) (reflect.Method, bool)
//
// TODO(crawshaw): improve precision of match by working out
// how to check the method name.
if n := t.NumParams(); n != 1 {
return
}
if n := t.NumResults(); n != 1 && n != 2 {
return
}
p0 := t.Params().Field(0)
res0 := t.Results().Field(0)
var res1 *types.Field
if t.NumResults() == 2 {
res1 = t.Results().Field(1)
}
if res1 == nil {
if p0.Type.Kind() != types.TINT {
return
}
} else {
if !p0.Type.IsString() {
return
}
if !res1.Type.IsBoolean() {
return
}
}
// Don't mark reflect.(*rtype).Method, etc. themselves in the reflect package.
// Those functions may be alive via the itab, which should not cause all methods
// alive. We only want to mark their callers.
if base.Ctxt.Pkgpath == "reflect" {
switch ir.CurFunc.Nname.Sym().Name { // TODO: is there a better way than hardcoding the names?
case "(*rtype).Method", "(*rtype).MethodByName", "(*interfaceType).Method", "(*interfaceType).MethodByName":
return
}
}
// Note: Don't rely on res0.Type.String() since its formatting depends on multiple factors
// (including global variables such as numImports - was issue #19028).
// Also need to check for reflect package itself (see Issue #38515).
if s := res0.Type.Sym(); s != nil && s.Name == "Method" && types.IsReflectPkg(s.Pkg) {
ir.CurFunc.SetReflectMethod(true)
// The LSym is initialized at this point. We need to set the attribute on the LSym.
ir.CurFunc.LSym.Set(obj.AttrReflectMethod, true)
}
}
func usefield(n *ir.SelectorExpr) {
if objabi.Fieldtrack_enabled == 0 {
return
}
switch n.Op() {
default:
base.Fatalf("usefield %v", n.Op())
case ir.ODOT, ir.ODOTPTR:
break
}
field := n.Selection
if field == nil {
base.Fatalf("usefield %v %v without paramfld", n.X.Type(), n.Sel)
}
if field.Sym != n.Sel {
base.Fatalf("field inconsistency: %v != %v", field.Sym, n.Sel)
}
if !strings.Contains(field.Note, "go:\"track\"") {
return
}
outer := n.X.Type()
if outer.IsPtr() {
outer = outer.Elem()
}
if outer.Sym() == nil {
base.Errorf("tracked field must be in named struct type")
}
if !types.IsExported(field.Sym.Name) {
base.Errorf("tracked field must be exported (upper case)")
}
sym := reflectdata.TrackSym(outer, field)
if ir.CurFunc.FieldTrack == nil {
ir.CurFunc.FieldTrack = make(map[*obj.LSym]struct{})
}
ir.CurFunc.FieldTrack[sym] = struct{}{}
}