Current File : //usr/local/go/src/cmd/compile/internal/noder/expr.go
// Copyright 2021 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 noder
import (
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/syntax"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/compile/internal/types2"
"cmd/internal/src"
)
func (g *irgen) expr(expr syntax.Expr) ir.Node {
if expr == nil {
return nil
}
if expr, ok := expr.(*syntax.Name); ok && expr.Value == "_" {
return ir.BlankNode
}
tv, ok := g.info.Types[expr]
if !ok {
base.FatalfAt(g.pos(expr), "missing type for %v (%T)", expr, expr)
}
switch {
case tv.IsBuiltin():
// Qualified builtins, such as unsafe.Add and unsafe.Slice.
if expr, ok := expr.(*syntax.SelectorExpr); ok {
if name, ok := expr.X.(*syntax.Name); ok {
if _, ok := g.info.Uses[name].(*types2.PkgName); ok {
return g.use(expr.Sel)
}
}
}
return g.use(expr.(*syntax.Name))
case tv.IsType():
return ir.TypeNode(g.typ(tv.Type))
case tv.IsValue(), tv.IsVoid():
// ok
default:
base.FatalfAt(g.pos(expr), "unrecognized type-checker result")
}
// The gc backend expects all expressions to have a concrete type, and
// types2 mostly satisfies this expectation already. But there are a few
// cases where the Go spec doesn't require converting to concrete type,
// and so types2 leaves them untyped. So we need to fix those up here.
typ := tv.Type
if basic, ok := typ.(*types2.Basic); ok && basic.Info()&types2.IsUntyped != 0 {
switch basic.Kind() {
case types2.UntypedNil:
// ok; can appear in type switch case clauses
// TODO(mdempsky): Handle as part of type switches instead?
case types2.UntypedBool:
typ = types2.Typ[types2.Bool] // expression in "if" or "for" condition
case types2.UntypedString:
typ = types2.Typ[types2.String] // argument to "append" or "copy" calls
default:
base.FatalfAt(g.pos(expr), "unexpected untyped type: %v", basic)
}
}
// Constant expression.
if tv.Value != nil {
return Const(g.pos(expr), g.typ(typ), tv.Value)
}
n := g.expr0(typ, expr)
if n.Typecheck() != 1 && n.Typecheck() != 3 {
base.FatalfAt(g.pos(expr), "missed typecheck: %+v", n)
}
if !g.match(n.Type(), typ, tv.HasOk()) {
base.FatalfAt(g.pos(expr), "expected %L to have type %v", n, typ)
}
return n
}
func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
pos := g.pos(expr)
switch expr := expr.(type) {
case *syntax.Name:
if _, isNil := g.info.Uses[expr].(*types2.Nil); isNil {
return Nil(pos, g.typ(typ))
}
return g.use(expr)
case *syntax.CompositeLit:
return g.compLit(typ, expr)
case *syntax.FuncLit:
return g.funcLit(typ, expr)
case *syntax.AssertExpr:
return Assert(pos, g.expr(expr.X), g.typeExpr(expr.Type))
case *syntax.CallExpr:
fun := g.expr(expr.Fun)
// The key for the Inferred map is the CallExpr (if inferring
// types required the function arguments) or the IndexExpr below
// (if types could be inferred without the function arguments).
if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
// This is the case where inferring types required the
// types of the function arguments.
targs := make([]ir.Node, len(inferred.Targs))
for i, targ := range inferred.Targs {
targs[i] = ir.TypeNode(g.typ(targ))
}
if fun.Op() == ir.OFUNCINST {
// Replace explicit type args with the full list that
// includes the additional inferred type args
fun.(*ir.InstExpr).Targs = targs
} else {
// Create a function instantiation here, given
// there are only inferred type args (e.g.
// min(5,6), where min is a generic function)
inst := ir.NewInstExpr(pos, ir.OFUNCINST, fun, targs)
typed(fun.Type(), inst)
fun = inst
}
}
return Call(pos, g.typ(typ), fun, g.exprs(expr.ArgList), expr.HasDots)
case *syntax.IndexExpr:
var targs []ir.Node
if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
// This is the partial type inference case where the types
// can be inferred from other type arguments without using
// the types of the function arguments.
targs = make([]ir.Node, len(inferred.Targs))
for i, targ := range inferred.Targs {
targs[i] = ir.TypeNode(g.typ(targ))
}
} else if _, ok := expr.Index.(*syntax.ListExpr); ok {
targs = g.exprList(expr.Index)
} else {
index := g.expr(expr.Index)
if index.Op() != ir.OTYPE {
// This is just a normal index expression
return Index(pos, g.typ(typ), g.expr(expr.X), index)
}
// This is generic function instantiation with a single type
targs = []ir.Node{index}
}
// This is a generic function instantiation (e.g. min[int]).
// Generic type instantiation is handled in the type
// section of expr() above (using g.typ).
x := g.expr(expr.X)
if x.Op() != ir.ONAME || x.Type().Kind() != types.TFUNC {
panic("Incorrect argument for generic func instantiation")
}
n := ir.NewInstExpr(pos, ir.OFUNCINST, x, targs)
typed(g.typ(typ), n)
return n
case *syntax.ParenExpr:
return g.expr(expr.X) // skip parens; unneeded after parse+typecheck
case *syntax.SelectorExpr:
// Qualified identifier.
if name, ok := expr.X.(*syntax.Name); ok {
if _, ok := g.info.Uses[name].(*types2.PkgName); ok {
return g.use(expr.Sel)
}
}
return g.selectorExpr(pos, typ, expr)
case *syntax.SliceExpr:
return Slice(pos, g.typ(typ), g.expr(expr.X), g.expr(expr.Index[0]), g.expr(expr.Index[1]), g.expr(expr.Index[2]))
case *syntax.Operation:
if expr.Y == nil {
return Unary(pos, g.typ(typ), g.op(expr.Op, unOps[:]), g.expr(expr.X))
}
switch op := g.op(expr.Op, binOps[:]); op {
case ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
return Compare(pos, g.typ(typ), op, g.expr(expr.X), g.expr(expr.Y))
default:
return Binary(pos, op, g.typ(typ), g.expr(expr.X), g.expr(expr.Y))
}
default:
g.unhandled("expression", expr)
panic("unreachable")
}
}
// selectorExpr resolves the choice of ODOT, ODOTPTR, OCALLPART (eventually
// ODOTMETH & ODOTINTER), and OMETHEXPR and deals with embedded fields here rather
// than in typecheck.go.
func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.SelectorExpr) ir.Node {
x := g.expr(expr.X)
if x.Type().HasTParam() {
// Leave a method call on a type param as an OXDOT, since it can
// only be fully transformed once it has an instantiated type.
n := ir.NewSelectorExpr(pos, ir.OXDOT, x, typecheck.Lookup(expr.Sel.Value))
typed(g.typ(typ), n)
return n
}
selinfo := g.info.Selections[expr]
// Everything up to the last selection is an implicit embedded field access,
// and the last selection is determined by selinfo.Kind().
index := selinfo.Index()
embeds, last := index[:len(index)-1], index[len(index)-1]
origx := x
for _, ix := range embeds {
x = Implicit(DotField(pos, x, ix))
}
kind := selinfo.Kind()
if kind == types2.FieldVal {
return DotField(pos, x, last)
}
// TODO(danscales,mdempsky): Interface method sets are not sorted the
// same between types and types2. In particular, using "last" here
// without conversion will likely fail if an interface contains
// unexported methods from two different packages (due to cross-package
// interface embedding).
var n ir.Node
method2 := selinfo.Obj().(*types2.Func)
if kind == types2.MethodExpr {
// OMETHEXPR is unusual in using directly the node and type of the
// original OTYPE node (origx) before passing through embedded
// fields, even though the method is selected from the type
// (x.Type()) reached after following the embedded fields. We will
// actually drop any ODOT nodes we created due to the embedded
// fields.
n = MethodExpr(pos, origx, x.Type(), last)
} else {
// Add implicit addr/deref for method values, if needed.
if x.Type().IsInterface() {
n = DotMethod(pos, x, last)
} else {
recvType2 := method2.Type().(*types2.Signature).Recv().Type()
_, wantPtr := recvType2.(*types2.Pointer)
havePtr := x.Type().IsPtr()
if havePtr != wantPtr {
if havePtr {
x = Implicit(Deref(pos, x.Type().Elem(), x))
} else {
x = Implicit(Addr(pos, x))
}
}
recvType2Base := recvType2
if wantPtr {
recvType2Base = types2.AsPointer(recvType2).Elem()
}
if len(types2.AsNamed(recvType2Base).TParams()) > 0 {
// recvType2 is the original generic type that is
// instantiated for this method call.
// selinfo.Recv() is the instantiated type
recvType2 = recvType2Base
// method is the generic method associated with the gen type
method := g.obj(types2.AsNamed(recvType2).Method(last))
n = ir.NewSelectorExpr(pos, ir.OCALLPART, x, method.Sym())
n.(*ir.SelectorExpr).Selection = types.NewField(pos, method.Sym(), method.Type())
n.(*ir.SelectorExpr).Selection.Nname = method
typed(method.Type(), n)
// selinfo.Targs() are the types used to
// instantiate the type of receiver
targs2 := getTargs(selinfo)
targs := make([]ir.Node, len(targs2))
for i, targ2 := range targs2 {
targs[i] = ir.TypeNode(g.typ(targ2))
}
// Create function instantiation with the type
// args for the receiver type for the method call.
n = ir.NewInstExpr(pos, ir.OFUNCINST, n, targs)
typed(g.typ(typ), n)
return n
}
if !g.match(x.Type(), recvType2, false) {
base.FatalfAt(pos, "expected %L to have type %v", x, recvType2)
} else {
n = DotMethod(pos, x, last)
}
}
}
if have, want := n.Sym(), g.selector(method2); have != want {
base.FatalfAt(pos, "bad Sym: have %v, want %v", have, want)
}
return n
}
// getTargs gets the targs associated with the receiver of a selected method
func getTargs(selinfo *types2.Selection) []types2.Type {
r := selinfo.Recv()
if p := types2.AsPointer(r); p != nil {
r = p.Elem()
}
n := types2.AsNamed(r)
if n == nil {
base.Fatalf("Incorrect type for selinfo %v", selinfo)
}
return n.TArgs()
}
func (g *irgen) exprList(expr syntax.Expr) []ir.Node {
switch expr := expr.(type) {
case nil:
return nil
case *syntax.ListExpr:
return g.exprs(expr.ElemList)
default:
return []ir.Node{g.expr(expr)}
}
}
func (g *irgen) exprs(exprs []syntax.Expr) []ir.Node {
nodes := make([]ir.Node, len(exprs))
for i, expr := range exprs {
nodes[i] = g.expr(expr)
}
return nodes
}
func (g *irgen) compLit(typ types2.Type, lit *syntax.CompositeLit) ir.Node {
if ptr, ok := typ.Underlying().(*types2.Pointer); ok {
n := ir.NewAddrExpr(g.pos(lit), g.compLit(ptr.Elem(), lit))
n.SetOp(ir.OPTRLIT)
return typed(g.typ(typ), n)
}
_, isStruct := typ.Underlying().(*types2.Struct)
exprs := make([]ir.Node, len(lit.ElemList))
for i, elem := range lit.ElemList {
switch elem := elem.(type) {
case *syntax.KeyValueExpr:
if isStruct {
exprs[i] = ir.NewStructKeyExpr(g.pos(elem), g.name(elem.Key.(*syntax.Name)), g.expr(elem.Value))
} else {
exprs[i] = ir.NewKeyExpr(g.pos(elem), g.expr(elem.Key), g.expr(elem.Value))
}
default:
exprs[i] = g.expr(elem)
}
}
n := ir.NewCompLitExpr(g.pos(lit), ir.OCOMPLIT, nil, exprs)
typed(g.typ(typ), n)
return transformCompLit(n)
}
func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
fn := ir.NewFunc(g.pos(expr))
fn.SetIsHiddenClosure(ir.CurFunc != nil)
fn.Nname = ir.NewNameAt(g.pos(expr), typecheck.ClosureName(ir.CurFunc))
ir.MarkFunc(fn.Nname)
typ := g.typ(typ2)
fn.Nname.Func = fn
fn.Nname.Defn = fn
typed(typ, fn.Nname)
fn.SetTypecheck(1)
fn.OClosure = ir.NewClosureExpr(g.pos(expr), fn)
typed(typ, fn.OClosure)
g.funcBody(fn, nil, expr.Type, expr.Body)
ir.FinishCaptureNames(fn.Pos(), ir.CurFunc, fn)
// TODO(mdempsky): ir.CaptureName should probably handle
// copying these fields from the canonical variable.
for _, cv := range fn.ClosureVars {
cv.SetType(cv.Canonical().Type())
cv.SetTypecheck(1)
cv.SetWalkdef(1)
}
g.target.Decls = append(g.target.Decls, fn)
return fn.OClosure
}
func (g *irgen) typeExpr(typ syntax.Expr) *types.Type {
n := g.expr(typ)
if n.Op() != ir.OTYPE {
base.FatalfAt(g.pos(typ), "expected type: %L", n)
}
return n.Type()
}
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