golang order 代码
文件路径：/src/cmd/compile/internal/walk/order.go
/ Copyright 2012 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"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/staticinit"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/objabi"
"cmd/internal/src"
)
/ Rewrite tree to use separate statements to enforce
/ order of evaluation. Makes walk easier, because it
/ can (after this runs) reorder at will within an expression.
/
/ Rewrite m[k] op= r into m[k] = m[k] op r if op is / or %.
/
/ Introduce temporaries as needed by runtime routines.
/ For example, the map runtime routines take the map key
/ by reference, so make sure all map keys are addressable
/ by copying them to temporaries as needed.
/ The same is true for channel operations.
/
/ Arrange that map index expressions only appear in direct
/ assignments x = m[k] or m[k] = x, never in larger expressions.
/
/ Arrange that receive expressions only appear in direct assignments
/ x = <-c or as standalone statements <-c, never in larger expressions.
/ TODO(rsc): The temporary introduction during multiple assignments
/ should be moved into this file, so that the temporaries can be cleaned
/ and so that conversions implicit in the OAS2FUNC and OAS2RECV
/ nodes can be made explicit and then have their temporaries cleaned.
/ TODO(rsc): Goto and multilevel break/continue can jump over
/ inserted VARKILL annotations. Work out a way to handle these.
/ The current implementation is safe, in that it will execute correctly.
/ But it won't reuse temporaries as aggressively as it might, and
/ it can result in unnecessary zeroing of those variables in the function
/ prologue.
/ orderState holds state during the ordering process.
type orderState struct {
out []ir.Node / list of generated statements
temp []*ir.Name / stack of temporary variables
free map[string][]*ir.Name / free list of unused temporaries, by type.LinkString().
edit func(ir.Node) ir.Node / cached closure of o.exprNoLHS
}
/ Order rewrites fn.Nbody to apply the ordering constraints
/ described in the comment at the top of the file.
func order(fn *ir.Func) {
if base.Flag.W > 1 {
s := fmt.Sprintf("\nbefore order %v", fn.Sym())
ir.DumpList(s, fn.Body)
}
ir.SetPos(fn) / Set reasonable position for instrumenting code. See issue 53688.
orderBlock(&fn.Body, map[string][]*ir.Name{})
}
/ append typechecks stmt and appends it to out.
func (o *orderState) append(stmt ir.Node) {
o.out = append(o.out, typecheck.Stmt(stmt))
}
/ newTemp allocates a new temporary with the given type,
/ pushes it onto the temp stack, and returns it.
/ If clear is true, newTemp emits code to zero the temporary.
func (o *orderState) newTemp(t *types.Type, clear bool) *ir.Name {
var v *ir.Name
key := t.LinkString()
if a := o.free[key]; len(a) > 0 {
v = a[len(a)-1]
if !types.Identical(t, v.Type()) {
base.Fatalf("expected %L to have type %v", v, t)
}
o.free[key] = a[:len(a)-1]
} else {
v = typecheck.Temp(t)
}
if clear {
o.append(ir.NewAssignStmt(base.Pos, v, nil))
}
o.temp = append(o.temp, v)
return v
}
/ copyExpr behaves like newTemp but also emits
/ code to initialize the temporary to the value n.
func (o *orderState) copyExpr(n ir.Node) *ir.Name {
return o.copyExpr1(n, false)
}
/ copyExprClear is like copyExpr but clears the temp before assignment.
/ It is provided for use when the evaluation of tmp = n turns into
/ a function call that is passed a pointer to the temporary as the output space.
/ If the call blocks before tmp has been written,
/ the garbage collector will still treat the temporary as live,
/ so we must zero it before entering that call.
/ Today, this only happens for channel receive operations.
/ (The other candidate would be map access, but map access
/ returns a pointer to the result data instead of taking a pointer
/ to be filled in.)
func (o *orderState) copyExprClear(n ir.Node) *ir.Name {
return o.copyExpr1(n, true)
}
func (o *orderState) copyExpr1(n ir.Node, clear bool) *ir.Name {
t := n.Type()
v := o.newTemp(t, clear)
o.append(ir.NewAssignStmt(base.Pos, v, n))
return v
}
/ cheapExpr returns a cheap version of n.
/ The definition of cheap is that n is a variable or constant.
/ If not, cheapExpr allocates a new tmp, emits tmp = n,
/ and then returns tmp.
func (o *orderState) cheapExpr(n ir.Node) ir.Node {
if n == nil {
return nil
}
switch n.Op() {
case ir.ONAME, ir.OLITERAL, ir.ONIL:
return n
case ir.OLEN, ir.OCAP:
n := n.(*ir.UnaryExpr)
l := o.cheapExpr(n.X)
if l == n.X {
return n
}
a := ir.SepCopy(n).(*ir.UnaryExpr)
a.X = l
return typecheck.Expr(a)
}
return o.copyExpr(n)
}
/ safeExpr returns a safe version of n.
/ The definition of safe is that n can appear multiple times
/ without violating the semantics of the original program,
/ and that assigning to the safe version has the same effect
/ as assigning to the original n.
/
/ The intended use is to apply to x when rewriting x += y into x = x + y.
func (o *orderState) safeExpr(n ir.Node) ir.Node {
switch n.Op() {
case ir.ONAME, ir.OLITERAL, ir.ONIL:
return n
case ir.OLEN, ir.OCAP:
n := n.(*ir.UnaryExpr)
l := o.safeExpr(n.X)
if l == n.X {
return n
}
a := ir.SepCopy(n).(*ir.UnaryExpr)
a.X = l
return typecheck.Expr(a)
case ir.ODOT:
n := n.(*ir.SelectorExpr)
l := o.safeExpr(n.X)
if l == n.X {
return n
}
a := ir.SepCopy(n).(*ir.SelectorExpr)
a.X = l
return typecheck.Expr(a)
case ir.ODOTPTR:
n := n.(*ir.SelectorExpr)
l := o.cheapExpr(n.X)
if l == n.X {
return n
}
a := ir.SepCopy(n).(*ir.SelectorExpr)
a.X = l
return typecheck.Expr(a)
case ir.ODEREF:
n := n.(*ir.StarExpr)
l := o.cheapExpr(n.X)
if l == n.X {
return n
}
a := ir.SepCopy(n).(*ir.StarExpr)
a.X = l
return typecheck.Expr(a)
case ir.OINDEX, ir.OINDEXMAP:
n := n.(*ir.IndexExpr)
var l ir.Node
if n.X.Type().IsArray() {
l = o.safeExpr(n.X)
} else {
l = o.cheapExpr(n.X)
}
r := o.cheapExpr(n.Index)
if l == n.X && r == n.Index {
return n
}
a := ir.SepCopy(n).(*ir.IndexExpr)
a.X = l
a.Index = r
return typecheck.Expr(a)
default:
base.Fatalf("order.safeExpr %v", n.Op())
return nil / not reached
}
}
/ isaddrokay reports whether it is okay to pass n's address to runtime routines.
/ Taking the address of a variable makes the liveness and optimization analyses
/ lose track of where the variable's lifetime ends. To avoid hurting the analyses
/ of ordinary stack variables, those are not 'isaddrokay'. Temporaries are okay,
/ because we emit explicit VARKILL instructions marking the end of those
/ temporaries' lifetimes.
func isaddrokay(n ir.Node) bool {
return ir.IsAddressable(n) && (n.Op() != ir.ONAME || n.(*ir.Name).Class == ir.PEXTERN || ir.IsAutoTmp(n))
}
/ addrTemp ensures that n is okay to pass by address to runtime routines.
/ If the original argument n is not okay, addrTemp creates a tmp, emits
/ tmp = n, and then returns tmp.
/ The result of addrTemp MUST be assigned back to n, e.g.
/
/ n.Left = o.addrTemp(n.Left)
func (o *orderState) addrTemp(n ir.Node) ir.Node {
if n.Op() == ir.OLITERAL || n.Op() == ir.ONIL {
/ TODO: expand this to all static composite literal nodes?
n = typecheck.DefaultLit(n, nil)
types.CalcSize(n.Type())
vstat := readonlystaticname(n.Type())
var s staticinit.Schedule
s.StaticAssign(vstat, 0, n, n.Type())
if s.Out != nil {
base.Fatalf("staticassign of const generated code: %+v", n)
}
vstat = typecheck.Expr(vstat).(*ir.Name)
return vstat
}
if isaddrokay(n) {
return n
}
return o.copyExpr(n)
}
/ mapKeyTemp prepares n to be a key in a map runtime call and returns n.
/ It should only be used for map runtime calls which have *_fast* versions.
func (o *orderState) mapKeyTemp(t *types.Type, n ir.Node) ir.Node {
/ Most map calls need to take the address of the key.
/ Exception: map*_fast* calls. See golang.org/issue/19015.
alg := mapfast(t)
if alg == mapslow {
return o.addrTemp(n)
}
var kt *types.Type
switch alg {
case mapfast32:
kt = types.Types[types.TUINT32]
case mapfast64:
kt = types.Types[types.TUINT64]
case mapfast32ptr, mapfast64ptr:
kt = types.Types[types.TUNSAFEPTR]
case mapfaststr:
kt = types.Types[types.TSTRING]
}
nt := n.Type()
switch {
case nt == kt:
return n
case nt.Kind() == kt.Kind(), nt.IsPtrShaped() && kt.IsPtrShaped():
/ can directly convert (e.g. named type to underlying type, or one pointer to another)
return typecheck.Expr(ir.NewConvExpr(n.Pos(), ir.OCONVNOP, kt, n))
case nt.IsInteger() && kt.IsInteger():
/ can directly convert (e.g. int32 to uint32)
if n.Op() == ir.OLITERAL && nt.IsSigned() {
/ avoid constant overflow error
n = ir.NewConstExpr(constant.MakeUint64(uint64(ir.Int64Val(n))), n)
n.SetType(kt)
return n
}
return typecheck.Expr(ir.NewConvExpr(n.Pos(), ir.OCONV, kt, n))
default:
/ Unsafe cast through memory.
/ We'll need to do a load with type kt. Create a temporary of type kt to
/ ensure sufficient alignment. nt may be under-aligned.
if uint8(kt.Alignment()) < uint8(nt.Alignment()) {
base.Fatalf("mapKeyTemp: key type is not sufficiently aligned, kt=%v nt=%v", kt, nt)
}
tmp := o.newTemp(kt, true)
/ *(*nt)(&tmp) = n
var e ir.Node = typecheck.NodAddr(tmp)
e = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, nt.PtrTo(), e)
e = ir.NewStarExpr(n.Pos(), e)
o.append(ir.NewAssignStmt(base.Pos, e, n))
return tmp
}
}
/ mapKeyReplaceStrConv replaces OBYTES2STR by OBYTES2STRTMP
/ in n to avoid string allocations for keys in map lookups.
/ Returns a bool that signals if a modification was made.
/
/ For:
/
/ x = m[string(k)]
/ x = m[T1{... Tn{..., string(k), ...}]
/
/ where k is []byte, T1 to Tn is a nesting of struct and array literals,
/ the allocation of backing bytes for the string can be avoided
/ by reusing the []byte backing array. These are special cases
/ for avoiding allocations when converting byte slices to strings.
/ It would be nice to handle these generally, but because
/ []byte keys are not allowed in maps, the use of string(k)
/ comes up in important cases in practice. See issue 3512.
func mapKeyReplaceStrConv(n ir.Node) bool {
var replaced bool
switch n.Op() {
case ir.OBYTES2STR:
n := n.(*ir.ConvExpr)
n.SetOp(ir.OBYTES2STRTMP)
replaced = true
case ir.OSTRUCTLIT:
n := n.(*ir.CompLitExpr)
for _, elem := range n.List {
elem := elem.(*ir.StructKeyExpr)
if mapKeyReplaceStrConv(elem.Value) {
replaced = true
}
}
case ir.OARRAYLIT:
n := n.(*ir.CompLitExpr)
for _, elem := range n.List {
if elem.Op() == ir.OKEY {
elem = elem.(*ir.KeyExpr).Value
}
if mapKeyReplaceStrConv(elem) {
replaced = true
}
}
}
return replaced
}
type ordermarker int
/ markTemp returns the top of the temporary variable stack.
func (o *orderState) markTemp() ordermarker {
return ordermarker(len(o.temp))
}
/ popTemp pops temporaries off the stack until reaching the mark,
/ which must have been returned by markTemp.
func (o *orderState) popTemp(mark ordermarker) {
for _, n := range o.temp[mark:] {
key := n.Type().LinkString()
o.free[key] = append(o.free[key], n)
}
o.temp = o.temp[:mark]
}
/ cleanTempNoPop emits VARKILL instructions to *out
/ for each temporary above the mark on the temporary stack.
/ It does not pop the temporaries from the stack.
func (o *orderState) cleanTempNoPop(mark ordermarker) []ir.Node {
var out []ir.Node
for i := len(o.temp) - 1; i >= int(mark); i-- {
n := o.temp[i]
out = append(out, typecheck.Stmt(ir.NewUnaryExpr(base.Pos, ir.OVARKILL, n)))
}
return out
}
/ cleanTemp emits VARKILL instructions for each temporary above the
/ mark on the temporary stack and removes them from the stack.
func (o *orderState) cleanTemp(top ordermarker) {
o.out = append(o.out, o.cleanTempNoPop(top)...)
o.popTemp(top)
}
/ stmtList orders each of the statements in the list.
func (o *orderState) stmtList(l ir.Nodes) {
s := l
for i := range s {
orderMakeSliceCopy(s[i:])
o.stmt(s[i])
}
}
/ orderMakeSliceCopy matches the pattern:
/
/ m = OMAKESLICE([]T, x); OCOPY(m, s)
/
/ and rewrites it to:
/
/ m = OMAKESLICECOPY([]T, x, s); nil
func orderMakeSliceCopy(s []ir.Node) {
if base.Flag.N != 0 || base.Flag.Cfg.Instrumenting {
return
}
if len(s) < 2 || s[0] == nil || s[0].Op() != ir.OAS || s[1] == nil || s[1].Op() != ir.OCOPY {
return
}
as := s[0].(*ir.AssignStmt)
cp := s[1].(*ir.BinaryExpr)
if as.Y == nil || as.Y.Op() != ir.OMAKESLICE || ir.IsBlank(as.X) ||
as.X.Op() != ir.ONAME || cp.X.Op() != ir.ONAME || cp.Y.Op() != ir.ONAME ||
as.X.Name() != cp.X.Name() || cp.X.Name() == cp.Y.Name() {
/ The line above this one is correct with the differing equality operators:
/ we want as.X and cp.X to be the same name,
/ but we want the initial data to be coming from a different name.
return
}
mk := as.Y.(*ir.MakeExpr)
if mk.Esc() == ir.EscNone || mk.Len == nil || mk.Cap != nil {
return
}
mk.SetOp(ir.OMAKESLICECOPY)
mk.Cap = cp.Y
/ Set bounded when m = OMAKESLICE([]T, len(s)); OCOPY(m, s)
mk.SetBounded(mk.Len.Op() == ir.OLEN && ir.SameSafeExpr(mk.Len.(*ir.UnaryExpr).X, cp.Y))
as.Y = typecheck.Expr(mk)
s[1] = nil / remove separate copy call
}
/ edge inserts coverage instrumentation for libfuzzer.
func (o *orderState) edge() {
if base.Debug.Libfuzzer == 0 {
return
}
/ Create a new uint8 counter to be allocated in section __sancov_cntrs
counter := staticinit.StaticName(types.Types[types.TUINT8])
counter.SetLibfuzzer8BitCounter(true)
/ As well as setting SetLibfuzzer8BitCounter, we preemptively set the
/ symbol type to SLIBFUZZER_8BIT_COUNTER so that the race detector
/ instrumentation pass (which does not have access to the flags set by
/ SetLibfuzzer8BitCounter) knows to ignore them. This information is
/ lost by the time it reaches the compile step, so SetLibfuzzer8BitCounter
/ is still necessary.
counter.Linksym().Type = objabi.SLIBFUZZER_8BIT_COUNTER
/ We guarantee that the counter never becomes zero again once it has been
/ incremented once. This implementation follows the NeverZero optimization
/ presented by the paper:
/ "AFL++: Combining Incremental Steps of Fuzzing Research"
/ The NeverZero policy avoids the overflow to 0 by setting the counter to one
/ after it reaches 255 and so, if an edge is executed at least one time, the entry is
/ never 0.
/ Another policy presented in the paper is the Saturated Counters policy which
/ freezes the counter when it reaches the value of 255. However, a range
/ of experiments showed that that decreases overall performance.
o.append(ir.NewIfStmt(base.Pos,
ir.NewBinaryExpr(base.Pos, ir.OEQ, counter, ir.NewInt(0xff)),
[]ir.Node{ir.NewAssignStmt(base.Pos, counter, ir.NewInt(1))},
[]ir.Node{ir.NewAssignOpStmt(base.Pos, ir.OADD, counter, ir.NewInt(1))}))
}
/ orderBlock orders the block of statements in n into a new slice,
/ and then replaces the old slice in n with the new slice.
/ free is a map that can be used to obtain temporary variables by type.
func orderBlock(n *ir.Nodes, free map[string][]*ir.Name) {
if len(*n) != 0 {
/ Set reasonable position for instrumenting code. See issue 53688.
/ It would be nice if ir.Nodes had a position (the opening {, probably),
/ but it doesn't. So we use the first statement's position instead.
ir.SetPos((*n)[0])
}
var order orderState
order.free = free
mark := order.markTemp()
order.edge()
order.stmtList(*n)
order.cleanTemp(mark)
*n = order.out
}
/ exprInPlace orders the side effects in *np and
/ leaves them as the init list of the final *np.
/ The result of exprInPlace MUST be assigned back to n, e.g.
/
/ n.Left = o.exprInPlace(n.Left)
func (o *orderState) exprInPlace(n ir.Node) ir.Node {
var order orderState
order.free = o.free
n = order.expr(n, nil)
n = ir.InitExpr(order.out, n)
/ insert new temporaries from order
/ at head of outer list.
o.temp = append(o.temp, order.temp...)
return n
}
/ orderStmtInPlace orders the side effects of the single statement *np
/ and replaces it with the resulting statement list.
/ The result of orderStmtInPlace MUST be assigned back to n, e.g.
/
/ n.Left = orderStmtInPlace(n.Left)
/
/ free is a map that can be used to obtain temporary variables by type.
func orderStmtInPlace(n ir.Node, free map[string][]*ir.Name) ir.Node {
var order orderState
order.free = free
mark := order.markTemp()
order.stmt(n)
order.cleanTemp(mark)
return ir.NewBlockStmt(src.NoXPos, order.out)
}
/ init moves n's init list to o.out.
func (o *orderState) init(n ir.Node) {
if ir.MayBeShared(n) {
/ For concurrency safety, don't mutate potentially shared nodes.
/ First, ensure that no work is required here.
if len(n.Init()) > 0 {
base.Fatalf("order.init shared node with ninit")
}
return
}
o.stmtList(ir.TakeInit(n))
}
/ call orders the call expression n.
/ n.Op is OCALLFUNC/OCALLINTER or a builtin like OCOPY.
func (o *orderState) call(nn ir.Node) {
if len(nn.Init()) > 0 {
/ Caller should have already called o.init(nn).
base.Fatalf("%v with unexpected ninit", nn.Op())
}
if nn.Op() == ir.OCALLMETH {
base.FatalfAt(nn.Pos(), "OCALLMETH missed by typecheck")
}
/ Builtin functions.
if nn.Op() != ir.OCALLFUNC && nn.Op() != ir.OCALLINTER {
switch n := nn.(type) {
default:
base.Fatalf("unexpected call: %+v", n)
case *ir.UnaryExpr:
n.X = o.expr(n.X, nil)
case *ir.ConvExpr:
n.X = o.expr(n.X, nil)
case *ir.BinaryExpr:
n.X = o.expr(n.X, nil)
n.Y = o.expr(n.Y, nil)
case *ir.MakeExpr:
n.Len = o.expr(n.Len, nil)
n.Cap = o.expr(n.Cap, nil)
case *ir.CallExpr:
o.exprList(n.Args)
}
return
}
n := nn.(*ir.CallExpr)
typecheck.FixVariadicCall(n)
if isFuncPCIntrinsic(n) && isIfaceOfFunc(n.Args[0]) {
/ For internal/abi.FuncPCABIxxx(fn), if fn is a defined function,
/ do not introduce temporaries here, so it is easier to rewrite it
/ to symbol address reference later in walk.
return
}
n.X = o.expr(n.X, nil)
o.exprList(n.Args)
}
/ mapAssign appends n to o.out.
func (o *orderState) mapAssign(n ir.Node) {
switch n.Op() {
default:
base.Fatalf("order.mapAssign %v", n.Op())
case ir.OAS:
n := n.(*ir.AssignStmt)
if n.X.Op() == ir.OINDEXMAP {
n.Y = o.safeMapRHS(n.Y)
}
o.out = append(o.out, n)
case ir.OASOP:
n := n.(*ir.AssignOpStmt)
if n.X.Op() == ir.OINDEXMAP {
n.Y = o.safeMapRHS(n.Y)
}
o.out = append(o.out, n)
}
}
func (o *orderState) safeMapRHS(r ir.Node) ir.Node {
/ Make sure we evaluate the RHS before starting the map insert.
/ We need to make sure the RHS won't panic. See issue 22881.
if r.Op() == ir.OAPPEND {
r := r.(*ir.CallExpr)
s := r.Args[1:]
for i, n := range s {
s[i] = o.cheapExpr(n)
}
return r
}
return o.cheapExpr(r)
}
/ stmt orders the statement n, appending to o.out.
/ Temporaries created during the statement are cleaned
/ up using VARKILL instructions as possible.
func (o *orderState) stmt(n ir.Node) {
if n == nil {
return
}
lno := ir.SetPos(n)
o.init(n)
switch n.Op() {
default:
base.Fatalf("order.stmt %v", n.Op())
case ir.OVARKILL, ir.OVARLIVE, ir.OINLMARK:
o.out = append(o.out, n)
case ir.OAS:
n := n.(*ir.AssignStmt)
t := o.markTemp()
n.X = o.expr(n.X, nil)
n.Y = o.expr(n.Y, n.X)
o.mapAssign(n)
o.cleanTemp(t)
case ir.OASOP:
n := n.(*ir.AssignOpStmt)
t := o.markTemp()
n.X = o.expr(n.X, nil)
n.Y = o.expr(n.Y, nil)
if base.Flag.Cfg.Instrumenting || n.X.Op() == ir.OINDEXMAP && (n.AsOp == ir.ODIV || n.AsOp == ir.OMOD) {
/ Rewrite m[k] op= r into m[k] = m[k] op r so
/ that we can ensure that if op panics
/ because r is zero, the panic happens before
/ the map assignment.
/ DeepCopy is a big hammer here, but safeExpr
/ makes sure there is nothing too deep being copied.
l1 := o.safeExpr(n.X)
l2 := ir.DeepCopy(src.NoXPos, l1)
if l2.Op() == ir.OINDEXMAP {
l2 := l2.(*ir.IndexExpr)
l2.Assigned = false
}
l2 = o.copyExpr(l2)
r := o.expr(typecheck.Expr(ir.NewBinaryExpr(n.Pos(), n.AsOp, l2, n.Y)), nil)
as := typecheck.Stmt(ir.NewAssignStmt(n.Pos(), l1, r))
o.mapAssign(as)
o.cleanTemp(t)
return
}
o.mapAssign(n)
o.cleanTemp(t)
case ir.OAS2:
n := n.(*ir.AssignListStmt)
t := o.markTemp()
o.exprList(n.Lhs)
o.exprList(n.Rhs)
o.out = append(o.out, n)
o.cleanTemp(t)
/ Special: avoid copy of func call n.Right
case ir.OAS2FUNC:
n := n.(*ir.AssignListStmt)
t := o.markTemp()
o.exprList(n.Lhs)
call := n.Rhs[0]
o.init(call)
if ic, ok := call.(*ir.InlinedCallExpr); ok {
o.stmtList(ic.Body)
n.SetOp(ir.OAS2)
n.Rhs = ic.ReturnVars
o.exprList(n.Rhs)
o.out = append(o.out, n)
} else {
o.call(call)
o.as2func(n)
}
o.cleanTemp(t)
/ Special: use temporary variables to hold result,
/ so that runtime can take address of temporary.
/ No temporary for blank assignment.
/
/ OAS2MAPR: make sure key is addressable if needed,
/ and make sure OINDEXMAP is not copied out.
case ir.OAS2DOTTYPE, ir.OAS2RECV, ir.OAS2MAPR:
n := n.(*ir.AssignListStmt)
t := o.markTemp()
o.exprList(n.Lhs)
switch r := n.Rhs[0]; r.Op() {
case ir.ODOTTYPE2:
r := r.(*ir.TypeAssertExpr)
r.X = o.expr(r.X, nil)
case ir.ODYNAMICDOTTYPE2:
r := r.(*ir.DynamicTypeAssertExpr)
r.X = o.expr(r.X, nil)
r.RType = o.expr(r.RType, nil)
r.ITab = o.expr(r.ITab, nil)
case ir.ORECV:
r := r.(*ir.UnaryExpr)
r.X = o.expr(r.X, nil)
case ir.OINDEXMAP:
r := r.(*ir.IndexExpr)
r.X = o.expr(r.X, nil)
r.Index = o.expr(r.Index, nil)
/ See similar conversion for OINDEXMAP below.
_ = mapKeyReplaceStrConv(r.Index)
r.Index = o.mapKeyTemp(r.X.Type(), r.Index)
default:
base.Fatalf("order.stmt: %v", r.Op())
}
o.as2ok(n)
o.cleanTemp(t)
/ Special: does not save n onto out.
case ir.OBLOCK:
n := n.(*ir.BlockStmt)
o.stmtList(n.List)
/ Special: n->left is not an expression; save as is.
case ir.OBREAK,
ir.OCONTINUE,
ir.ODCL,
ir.ODCLCONST,
ir.ODCLTYPE,
ir.OFALL,
ir.OGOTO,
ir.OLABEL,
ir.OTAILCALL:
o.out = append(o.out, n)
/ Special: handle call arguments.
case ir.OCALLFUNC, ir.OCALLINTER:
n := n.(*ir.CallExpr)
t := o.markTemp()
o.call(n)
o.out = append(o.out, n)
o.cleanTemp(t)
case ir.OINLCALL:
n := n.(*ir.InlinedCallExpr)
o.stmtList(n.Body)
/ discard results; double-check for no side effects
for _, result := range n.ReturnVars {
if staticinit.AnySideEffects(result) {
base.FatalfAt(result.Pos(), "inlined call result has side effects: %v", result)
}
}
case ir.OCHECKNIL, ir.OCLOSE, ir.OPANIC, ir.ORECV:
n := n.(*ir.UnaryExpr)
t := o.markTemp()
n.X = o.expr(n.X, nil)
o.out = append(o.out, n)
o.cleanTemp(t)
case ir.OCOPY:
n := n.(*ir.BinaryExpr)
t := o.markTemp()
n.X = o.expr(n.X, nil)
n.Y = o.expr(n.Y, nil)
o.out = append(o.out, n)
o.cleanTemp(t)
case ir.OPRINT, ir.OPRINTN, ir.ORECOVERFP:
n := n.(*ir.CallExpr)
t := o.markTemp()
o.call(n)
o.out = append(o.out, n)
o.cleanTemp(t)
/ Special: order arguments to inner call but not call itself.
case ir.ODEFER, ir.OGO:
n := n.(*ir.GoDeferStmt)
t := o.markTemp()
o.init(n.Call)
o.call(n.Call)
o.out = append(o.out, n)
o.cleanTemp(t)
case ir.ODELETE:
n := n.(*ir.CallExpr)
t := o.markTemp()
n.Args[0] = o.expr(n.Args[0], nil)
n.Args[1] = o.expr(n.Args[1], nil)
n.Args[1] = o.mapKeyTemp(n.Args[0].Type(), n.Args[1])
o.out = append(o.out, n)
o.cleanTemp(t)
/ Clean temporaries from condition evaluation at
/ beginning of loop body and after for statement.
case ir.OFOR:
n := n.(*ir.ForStmt)
t := o.markTemp()
n.Cond = o.exprInPlace(n.Cond)
n.Body.Prepend(o.cleanTempNoPop(t)...)
orderBlock(&n.Body, o.free)
n.Post = orderStmtInPlace(n.Post, o.free)
o.out = append(o.out, n)
o.cleanTemp(t)
/ Clean temporaries from condition at
/ beginning of both branches.
case ir.OIF:
n := n.(*ir.IfStmt)
t := o.markTemp()
n.Cond = o.exprInPlace(n.Cond)
n.Body.Prepend(o.cleanTempNoPop(t)...)
n.Else.Prepend(o.cleanTempNoPop(t)...)
o.popTemp(t)
orderBlock(&n.Body, o.free)
orderBlock(&n.Else, o.free)
o.out = append(o.out, n)
case ir.ORANGE:
/ n.Right is the expression being ranged over.
/ order it, and then make a copy if we need one.
/ We almost always do, to ensure that we don't
/ see any value changes made during the loop.
/ Usually the copy is cheap (e.g., array pointer,
/ chan, slice, string are all tiny).
/ The exception is ranging over an array value
/ (not a slice, not a pointer to array),
/ which must make a copy to avoid seeing updates made during
/ the range body. Ranging over an array value is uncommon though.
/ Mark []byte(str) range expression to reuse string backing storage.
/ It is safe because the storage cannot be mutated.
n := n.(*ir.RangeStmt)
if n.X.Op() == ir.OSTR2BYTES {
n.X.(*ir.ConvExpr).SetOp(ir.OSTR2BYTESTMP)
}
t := o.markTemp()
n.X = o.expr(n.X, nil)
orderBody := true
xt := typecheck.RangeExprType(n.X.Type())
switch xt.Kind() {
default:
base.Fatalf("order.stmt range %v", n.Type())
case types.TARRAY, types.TSLICE:
if n.Value == nil || ir.IsBlank(n.Value) {
/ for i := range x will only use x once, to compute len(x).
/ No need to copy it.
break
}
fallthrough
case types.TCHAN, types.TSTRING:
/ chan, string, slice, array ranges use value multiple times.
/ make copy.
r := n.X
if r.Type().IsString() && r.Type() != types.Types[types.TSTRING] {
r = ir.NewConvExpr(base.Pos, ir.OCONV, nil, r)
r.SetType(types.Types[types.TSTRING])
r = typecheck.Expr(r)
}
n.X = o.copyExpr(r)
case types.TMAP:
if isMapClear(n) {
/ Preserve the body of the map clear pattern so it can
/ be detected during walk. The loop body will not be used
/ when optimizing away the range loop to a runtime call.
orderBody = false
break
}
/ copy the map value in case it is a map literal.
/ TODO(rsc): Make tmp = literal expressions reuse tmp.
/ For maps tmp is just one word so it hardly matters.
r := n.X
n.X = o.copyExpr(r)
/ n.Prealloc is the temp for the iterator.
/ MapIterType contains pointers and needs to be zeroed.
n.Prealloc = o.newTemp(reflectdata.MapIterType(xt), true)
}
n.Key = o.exprInPlace(n.Key)
n.Value = o.exprInPlace(n.Value)
if orderBody {
orderBlock(&n.Body, o.free)
}
o.out = append(o.out, n)
o.cleanTemp(t)
case ir.ORETURN:
n := n.(*ir.ReturnStmt)
o.exprList(n.Results)
o.out = append(o.out, n)
/ Special: clean case temporaries in each block entry.
/ Select must enter one of its blocks, so there is no
/ need for a cleaning at the end.
/ Doubly special: evaluation order for select is stricter
/ than ordinary expressions. Even something like p.c
/ has to be hoisted into a temporary, so that it cannot be
/ reordered after the channel evaluation for a different
/ case (if p were nil, then the timing of the fault would
/ give this away).
case ir.OSELECT:
n := n.(*ir.SelectStmt)
t := o.markTemp()
for _, ncas := range n.Cases {
r := ncas.Comm
ir.SetPos(ncas)
/ Append any new body prologue to ninit.
/ The next loop will insert ninit into nbody.
if len(ncas.Init()) != 0 {
base.Fatalf("order select ninit")
}
if r == nil {
continue
}
switch r.Op() {
default:
ir.Dump("select case", r)
base.Fatalf("unknown op in select %v", r.Op())
case ir.OSELRECV2:
/ case x, ok = <-c
r := r.(*ir.AssignListStmt)
recv := r.Rhs[0].(*ir.UnaryExpr)
recv.X = o.expr(recv.X, nil)
if !ir.IsAutoTmp(recv.X) {
recv.X = o.copyExpr(recv.X)
}
init := ir.TakeInit(r)
colas := r.Def
do := func(i int, t *types.Type) {
n := r.Lhs[i]
if ir.IsBlank(n) {
return
}
/ If this is case x := <-ch or case x, y := <-ch, the case has
/ the ODCL nodes to declare x and y. We want to delay that
/ declaration (and possible allocation) until inside the case body.
/ Delete the ODCL nodes here and recreate them inside the body below.
if colas {
if len(init) > 0 && init[0].Op() == ir.ODCL && init[0].(*ir.Decl).X == n {
init = init[1:]
/ iimport may have added a default initialization assignment,
/ due to how it handles ODCL statements.
if len(init) > 0 && init[0].Op() == ir.OAS && init[0].(*ir.AssignStmt).X == n {
init = init[1:]
}
}
dcl := typecheck.Stmt(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
ncas.PtrInit().Append(dcl)
}
tmp := o.newTemp(t, t.HasPointers())
as := typecheck.Stmt(ir.NewAssignStmt(base.Pos, n, typecheck.Conv(tmp, n.Type())))
ncas.PtrInit().Append(as)
r.Lhs[i] = tmp
}
do(0, recv.X.Type().Elem())
do(1, types.Types[types.TBOOL])
if len(init) != 0 {
ir.DumpList("ninit", r.Init())
base.Fatalf("ninit on select recv")
}
orderBlock(ncas.PtrInit(), o.free)
case ir.OSEND:
r := r.(*ir.SendStmt)
if len(r.Init()) != 0 {
ir.DumpList("ninit", r.Init())
base.Fatalf("ninit on select send")
}
/ case c <- x
/ r->left is c, r->right is x, both are always evaluated.
r.Chan = o.expr(r.Chan, nil)
if !ir.IsAutoTmp(r.Chan) {
r.Chan = o.copyExpr(r.Chan)
}
r.Value = o.expr(r.Value, nil)
if !ir.IsAutoTmp(r.Value) {
r.Value = o.copyExpr(r.Value)
}
}
}
/ Now that we have accumulated all the temporaries, clean them.
/ Also insert any ninit queued during the previous loop.
/ (The temporary cleaning must follow that ninit work.)
for _, cas := range n.Cases {
orderBlock(&cas.Body, o.free)
cas.Body.Prepend(o.cleanTempNoPop(t)...)
/ TODO(mdempsky): Is this actually necessary?
/ walkSelect appears to walk Ninit.
cas.Body.Prepend(ir.TakeInit(cas)...)
}
o.out = append(o.out, n)
o.popTemp(t)
/ Special: value being sent is passed as a pointer; make it addressable.
case ir.OSEND:
n := n.(*ir.SendStmt)
t := o.markTemp()
n.Chan = o.expr(n.Chan, nil)
n.Value = o.expr(n.Value, nil)
if base.Flag.Cfg.Instrumenting {
/ Force copying to the stack so that (chan T)(nil) <- x
/ is still instrumented as a read of x.
n.Value = o.copyExpr(n.Value)
} else {
n.Value = o.addrTemp(n.Value)
}
o.out = append(o.out, n)
o.cleanTemp(t)
/ TODO(rsc): Clean temporaries more aggressively.
/ Note that because walkSwitch will rewrite some of the
/ switch into a binary search, this is not as easy as it looks.
/ (If we ran that code here we could invoke order.stmt on
/ the if-else chain instead.)
/ For now just clean all the temporaries at the end.
/ In practice that's fine.
case ir.OSWITCH:
n := n.(*ir.SwitchStmt)
if base.Debug.Libfuzzer != 0 && !hasDefaultCase(n) {
/ Add empty "default:" case for instrumentation.
n.Cases = append(n.Cases, ir.NewCaseStmt(base.Pos, nil, nil))
}
t := o.markTemp()
n.Tag = o.expr(n.Tag, nil)
for _, ncas := range n.Cases {
o.exprListInPlace(ncas.List)
orderBlock(&ncas.Body, o.free)
}
o.out = append(o.out, n)
o.cleanTemp(t)
}
base.Pos = lno
}
func hasDefaultCase(n *ir.SwitchStmt) bool {
for _, ncas := range n.Cases {
if len(ncas.List) == 0 {
return true
}
}
return false
}
/ exprList orders the expression list l into o.
func (o *orderState) exprList(l ir.Nodes) {
s := l
for i := range s {
s[i] = o.expr(s[i], nil)
}
}
/ exprListInPlace orders the expression list l but saves
/ the side effects on the individual expression ninit lists.
func (o *orderState) exprListInPlace(l ir.Nodes) {
s := l
for i := range s {
s[i] = o.exprInPlace(s[i])
}
}
func (o *orderState) exprNoLHS(n ir.Node) ir.Node {
return o.expr(n, nil)
}
/ expr orders a single expression, appending side
/ effects to o.out as needed.
/ If this is part of an assignment lhs = *np, lhs is given.
/ Otherwise lhs == nil. (When lhs != nil it may be possible
/ to avoid copying the result of the expression to a temporary.)
/ The result of expr MUST be assigned back to n, e.g.
/
/ n.Left = o.expr(n.Left, lhs)
func (o *orderState) expr(n, lhs ir.Node) ir.Node {
if n == nil {
return n
}
lno := ir.SetPos(n)
n = o.expr1(n, lhs)
base.Pos = lno
return n
}
func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
o.init(n)
switch n.Op() {
default:
if o.edit == nil {
o.edit = o.exprNoLHS / create closure once
}
ir.EditChildren(n, o.edit)
return n
/ Addition of strings turns into a function call.
/ Allocate a temporary to hold the strings.
/ Fewer than 5 strings use direct runtime helpers.
case ir.OADDSTR:
n := n.(*ir.AddStringExpr)
o.exprList(n.List)
if len(n.List) > 5 {
t := types.NewArray(types.Types[types.TSTRING], int64(len(n.List)))
n.Prealloc = o.newTemp(t, false)
}
/ Mark string(byteSlice) arguments to reuse byteSlice backing
/ buffer during conversion. String concatenation does not
/ memorize the strings for later use, so it is safe.
/ However, we can do it only if there is at least one non-empty string literal.
/ Otherwise if all other arguments are empty strings,
/ concatstrings will return the reference to the temp string
/ to the caller.
hasbyte := false
haslit := false
for _, n1 := range n.List {
hasbyte = hasbyte || n1.Op() == ir.OBYTES2STR
haslit = haslit || n1.Op() == ir.OLITERAL && len(ir.StringVal(n1)) != 0
}
if haslit && hasbyte {
for _, n2 := range n.List {
if n2.Op() == ir.OBYTES2STR {
n2 := n2.(*ir.ConvExpr)
n2.SetOp(ir.OBYTES2STRTMP)
}
}
}
return n
case ir.OINDEXMAP:
n := n.(*ir.IndexExpr)
n.X = o.expr(n.X, nil)
n.Index = o.expr(n.Index, nil)
needCopy := false
if !n.Assigned {
/ Enforce that any []byte slices we are not copying
/ can not be changed before the map index by forcing
/ the map index to happen immediately following the
/ conversions. See copyExpr a few lines below.
needCopy = mapKeyReplaceStrConv(n.Index)
if base.Flag.Cfg.Instrumenting {
/ Race detector needs the copy.
needCopy = true
}
}
/ key must be addressable
n.Index = o.mapKeyTemp(n.X.Type(), n.Index)
if needCopy {
return o.copyExpr(n)
}
return n
/ concrete type (not interface) argument might need an addressable
/ temporary to pass to the runtime conversion routine.
case ir.OCONVIFACE, ir.OCONVIDATA:
n := n.(*ir.ConvExpr)
n.X = o.expr(n.X, nil)
if n.X.Type().IsInterface() {
return n
}
if _, _, needsaddr := dataWordFuncName(n.X.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
/ Need a temp if we need to pass the address to the conversion function.
/ We also process static composite literal node here, making a named static global
/ whose address we can put directly in an interface (see OCONVIFACE/OCONVIDATA case in walk).
n.X = o.addrTemp(n.X)
}
return n
case ir.OCONVNOP:
n := n.(*ir.ConvExpr)
if n.X.Op() == ir.OCALLMETH {
base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
}
if n.Type().IsKind(types.TUNSAFEPTR) && n.X.Type().IsKind(types.TUINTPTR) && (n.X.Op() == ir.OCALLFUNC || n.X.Op() == ir.OCALLINTER) {
call := n.X.(*ir.CallExpr)
/ When reordering unsafe.Pointer(f()) into a separate
/ statement, the conversion and function call must stay
/ together. See golang.org/issue/15329.
o.init(call)
o.call(call)
if lhs == nil || lhs.Op() != ir.ONAME || base.Flag.Cfg.Instrumenting {
return o.copyExpr(n)
}
} else {
n.X = o.expr(n.X, nil)
}
return n
case ir.OANDAND, ir.OOROR:
/ ... = LHS && RHS
/
/ var r bool
/ r = LHS
/ if r { / or !r, for OROR
/ r = RHS
/ }
/ ... = r
n := n.(*ir.LogicalExpr)
r := o.newTemp(n.Type(), false)
/ Evaluate left-hand side.
lhs := o.expr(n.X, nil)
o.out = append(o.out, typecheck.Stmt(ir.NewAssignStmt(base.Pos, r, lhs)))
/ Evaluate right-hand side, save generated code.
saveout := o.out
o.out = nil
t := o.markTemp()
o.edge()
rhs := o.expr(n.Y, nil)
o.out = append(o.out, typecheck.Stmt(ir.NewAssignStmt(base.Pos, r, rhs)))
o.cleanTemp(t)
gen := o.out
o.out = saveout
/ If left-hand side doesn't cause a short-circuit, issue right-hand side.
nif := ir.NewIfStmt(base.Pos, r, nil, nil)
if n.Op() == ir.OANDAND {
nif.Body = gen
} else {
nif.Else = gen
}
o.out = append(o.out, nif)
return r
case ir.OCALLMETH:
base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
panic("unreachable")
case ir.OCALLFUNC,
ir.OCALLINTER,
ir.OCAP,
ir.OCOMPLEX,
ir.OCOPY,
ir.OIMAG,
ir.OLEN,
ir.OMAKECHAN,
ir.OMAKEMAP,
ir.OMAKESLICE,
ir.OMAKESLICECOPY,
ir.ONEW,
ir.OREAL,
ir.ORECOVERFP,
ir.OSTR2BYTES,
ir.OSTR2BYTESTMP,
ir.OSTR2RUNES:
if isRuneCount(n) {
/ len([]rune(s)) is rewritten to runtime.countrunes(s) later.
conv := n.(*ir.UnaryExpr).X.(*ir.ConvExpr)
conv.X = o.expr(conv.X, nil)
} else {
o.call(n)
}
if lhs == nil || lhs.Op() != ir.ONAME || base.Flag.Cfg.Instrumenting {
return o.copyExpr(n)
}
return n
case ir.OINLCALL:
n := n.(*ir.InlinedCallExpr)
o.stmtList(n.Body)
return n.SingleResult()
case ir.OAPPEND:
/ Check for append(x, make([]T, y)...) .
n := n.(*ir.CallExpr)
if isAppendOfMake(n) {
n.Args[0] = o.expr(n.Args[0], nil) / order x
mk := n.Args[1].(*ir.MakeExpr)
mk.Len = o.expr(mk.Len, nil) / order y
} else {
o.exprList(n.Args)
}
if lhs == nil || lhs.Op() != ir.ONAME && !ir.SameSafeExpr(lhs, n.Args[0]) {
return o.copyExpr(n)
}
return n
case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
n := n.(*ir.SliceExpr)
n.X = o.expr(n.X, nil)
n.Low = o.cheapExpr(o.expr(n.Low, nil))
n.High = o.cheapExpr(o.expr(n.High, nil))
n.Max = o.cheapExpr(o.expr(n.Max, nil))
if lhs == nil || lhs.Op() != ir.ONAME && !ir.SameSafeExpr(lhs, n.X) {
return o.copyExpr(n)
}
return n
case ir.OCLOSURE:
n := n.(*ir.ClosureExpr)
if n.Transient() && len(n.Func.ClosureVars) > 0 {
n.Prealloc = o.newTemp(typecheck.ClosureType(n), false)
}
return n
case ir.OMETHVALUE:
n := n.(*ir.SelectorExpr)
n.X = o.expr(n.X, nil)
if n.Transient() {
t := typecheck.MethodValueType(n)
n.Prealloc = o.newTemp(t, false)
}
return n
case ir.OSLICELIT:
n := n.(*ir.CompLitExpr)
o.exprList(n.List)
if n.Transient() {
t := types.NewArray(n.Type().Elem(), n.Len)
n.Prealloc = o.newTemp(t, false)
}
return n
case ir.ODOTTYPE, ir.ODOTTYPE2:
n := n.(*ir.TypeAssertExpr)
n.X = o.expr(n.X, nil)
if !types.IsDirectIface(n.Type()) || base.Flag.Cfg.Instrumenting {
return o.copyExprClear(n)
}
return n
case ir.ORECV:
n := n.(*ir.UnaryExpr)
n.X = o.expr(n.X, nil)
return o.copyExprClear(n)
case ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
n := n.(*ir.BinaryExpr)
n.X = o.expr(n.X, nil)
n.Y = o.expr(n.Y, nil)
t := n.X.Type()
switch {
case t.IsString():
/ Mark string(byteSlice) arguments to reuse byteSlice backing
/ buffer during conversion. String comparison does not
/ memorize the strings for later use, so it is safe.
if n.X.Op() == ir.OBYTES2STR {
n.X.(*ir.ConvExpr).SetOp(ir.OBYTES2STRTMP)
}
if n.Y.Op() == ir.OBYTES2STR {
n.Y.(*ir.ConvExpr).SetOp(ir.OBYTES2STRTMP)
}
case t.IsStruct() || t.IsArray():
/ for complex comparisons, we need both args to be
/ addressable so we can pass them to the runtime.
n.X = o.addrTemp(n.X)
n.Y = o.addrTemp(n.Y)
}
return n
case ir.OMAPLIT:
/ Order map by converting:
/ map[int]int{
/ a(): b(),
/ c(): d(),
/ e(): f(),
/ }
/ to
/ m := map[int]int{}
/ m[a()] = b()
/ m[c()] = d()
/ m[e()] = f()
/ Then order the result.
/ Without this special case, order would otherwise compute all
/ the keys and values before storing any of them to the map.
/ See issue 26552.
n := n.(*ir.CompLitExpr)
entries := n.List
statics := entries[:0]
var dynamics []*ir.KeyExpr
for _, r := range entries {
r := r.(*ir.KeyExpr)
if !isStaticCompositeLiteral(r.Key) || !isStaticCompositeLiteral(r.Value) {
dynamics = append(dynamics, r)
continue
}
/ Recursively ordering some static entries can change them to dynamic;
/ e.g., OCONVIFACE nodes. See #31777.
r = o.expr(r, nil).(*ir.KeyExpr)
if !isStaticCompositeLiteral(r.Key) || !isStaticCompositeLiteral(r.Value) {
dynamics = append(dynamics, r)
continue
}
statics = append(statics, r)
}
n.List = statics
if len(dynamics) == 0 {
return n
}
/ Emit the creation of the map (with all its static entries).
m := o.newTemp(n.Type(), false)
as := ir.NewAssignStmt(base.Pos, m, n)
typecheck.Stmt(as)
o.stmt(as)
/ Emit eval+insert of dynamic entries, one at a time.
for _, r := range dynamics {
as := ir.NewAssignStmt(base.Pos, ir.NewIndexExpr(base.Pos, m, r.Key), r.Value)
typecheck.Stmt(as) / Note: this converts the OINDEX to an OINDEXMAP
o.stmt(as)
}
/ Remember that we issued these assignments so we can include that count
/ in the map alloc hint.
/ We're assuming here that all the keys in the map literal are distinct.
/ If any are equal, this will be an overcount. Probably not worth accounting
/ for that, as equal keys in map literals are rare, and at worst we waste
/ a bit of space.
n.Len += int64(len(dynamics))
return m
}
/ No return - type-assertions above. Each case must return for itself.
}
/ as2func orders OAS2FUNC nodes. It creates temporaries to ensure left-to-right assignment.
/ The caller should order the right-hand side of the assignment before calling order.as2func.
/ It rewrites,
/
/ a, b, a = ...
/
/ as
/
/ tmp1, tmp2, tmp3 = ...
/ a, b, a = tmp1, tmp2, tmp3
/
/ This is necessary to ensure left to right assignment order.
func (o *orderState) as2func(n *ir.AssignListStmt) {
results := n.Rhs[0].Type()
as := ir.NewAssignListStmt(n.Pos(), ir.OAS2, nil, nil)
for i, nl := range n.Lhs {
if !ir.IsBlank(nl) {
typ := results.Field(i).Type
tmp := o.newTemp(typ, typ.HasPointers())
n.Lhs[i] = tmp
as.Lhs = append(as.Lhs, nl)
as.Rhs = append(as.Rhs, tmp)
}
}
o.out = append(o.out, n)
o.stmt(typecheck.Stmt(as))
}
/ as2ok orders OAS2XXX with ok.
/ Just like as2func, this also adds temporaries to ensure left-to-right assignment.
func (o *orderState) as2ok(n *ir.AssignListStmt) {
as := ir.NewAssignListStmt(n.Pos(), ir.OAS2, nil, nil)
do := func(i int, typ *types.Type) {
if nl := n.Lhs[i]; !ir.IsBlank(nl) {
var tmp ir.Node = o.newTemp(typ, typ.HasPointers())
n.Lhs[i] = tmp
as.Lhs = append(as.Lhs, nl)
if i == 1 {
/ The "ok" result is an untyped boolean according to the Go
/ spec. We need to explicitly convert it to the LHS type in
/ case the latter is a defined boolean type (#8475).
tmp = typecheck.Conv(tmp, nl.Type())
}
as.Rhs = append(as.Rhs, tmp)
}
}
do(0, n.Rhs[0].Type())
do(1, types.Types[types.TBOOL])
o.out = append(o.out, n)
o.stmt(typecheck.Stmt(as))
}
/ isFuncPCIntrinsic returns whether n is a direct call of internal/abi.FuncPCABIxxx functions.
func isFuncPCIntrinsic(n *ir.CallExpr) bool {
if n.Op() != ir.OCALLFUNC || n.X.Op() != ir.ONAME {
return false
}
fn := n.X.(*ir.Name).Sym()
return (fn.Name == "FuncPCABI0" || fn.Name == "FuncPCABIInternal") &&
(fn.Pkg.Path == "internal/abi" || fn.Pkg == types.LocalPkg && base.Ctxt.Pkgpath == "internal/abi")
}
/ isIfaceOfFunc returns whether n is an interface conversion from a direct reference of a func.
func isIfaceOfFunc(n ir.Node) bool {
return n.Op() == ir.OCONVIFACE && n.(*ir.ConvExpr).X.Op() == ir.ONAME && n.(*ir.ConvExpr).X.(*ir.Name).Class == ir.PFUNC
}