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[dev.typeparams] cmd/compile: refactor SelectorExpr code into helpers

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This CL refactors the SelectorExpr-handling code added in CL 285373
into helper functions that can eventually be reused by iimport.

Change-Id: I15b4a96c242f63cb370d7492ed08168550724f47
Reviewed-on: https://go-review.googlesource.com/c/go/+/285953
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2021-01-22 13:29:59 -08:00
parent 1946a77e69
commit 2b95c28b18
2 changed files with 126 additions and 87 deletions
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123
src/cmd/compile/internal/noder/expr.go
View File

@ -107,7 +107,7 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
}
}
return g.selectorExpr(pos, typ, expr)
return g.selectorExpr(pos, expr)
case *syntax.SliceExpr:
return Slice(pos, g.expr(expr.X), g.expr(expr.Index[0]), g.expr(expr.Index[1]), g.expr(expr.Index[2]))
@ -131,88 +131,55 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
// 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)
func (g *irgen) selectorExpr(pos src.XPos, expr *syntax.SelectorExpr) ir.Node {
selinfo := g.info.Selections[expr]
nindex := len(selinfo.Index())
// Iterate through the selections from types2. If nindex > 1, then we will
// create extra nodes to deal with embedded fields.
for i := 0; i < nindex; i++ {
var f *types.Field
var n *ir.SelectorExpr
// 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]
op := ir.ODOT
index := selinfo.Index()[i]
xt := x.Type()
origxt := xt
if xt.IsPtr() && !xt.Elem().IsInterface() {
// Get to the base type, but remember that we skipped the ptr
xt = xt.Elem()
op = ir.ODOTPTR
}
types.CalcSize(xt)
// Everything up to the last selection is an embedded field
// access, and the last selection is determined by selinfo.Kind().
if i < nindex-1 || selinfo.Kind() == types2.FieldVal {
f = xt.Field(index)
sym := f.Sym
n = ir.NewSelectorExpr(pos, op, x, sym)
if i < nindex-1 {
n.SetImplicit(true)
typed(f.Type, n)
}
} else if selinfo.Kind() == types2.MethodExpr {
var ms *types.Fields
if xt.IsInterface() {
// TODO(danscales,mdempsky): interface method sets
// are not sorted the same between types and
// types2. In particular, this will likely fail if
// an interface contains unexported methods from
// two different packages (due to cross-package
// interface embedding).
ms = xt.Fields()
} else {
mt := types.ReceiverBaseType(xt)
ms = mt.Methods()
}
f = ms.Slice()[index]
n = ir.NewSelectorExpr(pos, ir.OMETHEXPR, x, f.Sym)
} else { // types.MethodVal
if xt.IsInterface() {
f = xt.Field(index)
} else {
f = xt.Methods().Slice()[index]
rcvr := f.Type.Recv().Type
if rcvr.IsPtr() && types.Identical(rcvr.Elem(), origxt) {
addr := typecheck.NodAddrAt(pos, x)
addr.SetImplicit(true)
typed(xt.PtrTo(), addr)
x = addr
} else if op == ir.ODOTPTR && !rcvr.IsPtr() {
star := ir.NewStarExpr(pos, x)
star.SetImplicit(true)
typed(xt, star)
x = star
}
}
// We will change OCALLPART to ODOTMETH or ODOTINTER in
// Call() if n is actually called.
n = ir.NewSelectorExpr(pos, ir.OCALLPART, x, f.Sym)
}
n.Selection = f
x = n
x := g.expr(expr.X)
for _, ix := range embeds {
x = Implicit(DotField(pos, x, ix))
}
// We don't set type on x for the last index (i == nindex - 1), since that
// is the actual selection (ignoring embedded fields) and may be an
// OMETHEXPR or OCALLPART operation. In those cases, the type to set on the
// node will be different from the type derived from the field/method
// selection. Instead for the last index, we always set the type (at the
// end of the function) from g.typ(typ).
typed(g.typ(typ), x)
types.CalcSize(x.Type())
return x
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).
method := selinfo.Obj().(*types2.Func)
// Add implicit addr/deref for method values, if needed.
if kind == types2.MethodVal && !x.Type().IsInterface() {
recvTyp := method.Type().(*types2.Signature).Recv().Type()
_, wantPtr := recvTyp.(*types2.Pointer)
havePtr := x.Type().IsPtr()
if havePtr != wantPtr {
if havePtr {
x = Implicit(Deref(pos, x))
} else {
x = Implicit(Addr(pos, x))
}
}
if !g.match(x.Type(), recvTyp, false) {
base.FatalfAt(pos, "expected %L to have type %v", x, recvTyp)
}
}
n := DotMethod(pos, x, last)
if have, want := n.Sym(), g.selector(method); have != want {
base.FatalfAt(pos, "bad Sym: have %v, want %v", have, want)
}
return n
}
func (g *irgen) exprList(expr syntax.Expr) []ir.Node {

90
src/cmd/compile/internal/noder/helpers.go
View File

@ -5,11 +5,13 @@
package noder
import (
"go/constant"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/src"
"go/constant"
)
// Helpers for constructing typed IR nodes.
@ -21,6 +23,17 @@ import (
// results, rather than leaving the caller responsible for using
// typecheck.Expr or typecheck.Stmt.
type ImplicitNode interface {
ir.Node
SetImplicit(x bool)
}
// Implicit returns n after marking it as Implicit.
func Implicit(n ImplicitNode) ImplicitNode {
n.SetImplicit(true)
return n
}
// typed returns n after setting its type to typ.
func typed(typ *types.Type, n ir.Node) ir.Node {
n.SetType(typ)
@ -40,6 +53,13 @@ func Nil(pos src.XPos, typ *types.Type) ir.Node {
// Expressions
func Addr(pos src.XPos, x ir.Node) *ir.AddrExpr {
// TODO(mdempsky): Avoid typecheck.Expr. Probably just need to set OPTRLIT when appropriate.
n := typecheck.Expr(typecheck.NodAddrAt(pos, x)).(*ir.AddrExpr)
typed(types.NewPtr(x.Type()), n)
return n
}
func Assert(pos src.XPos, x ir.Node, typ *types.Type) ir.Node {
return typed(typ, ir.NewTypeAssertExpr(pos, x, nil))
}
@ -109,6 +129,58 @@ func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) ir.Node {
return typed(typ, n)
}
func Deref(pos src.XPos, x ir.Node) *ir.StarExpr {
n := ir.NewStarExpr(pos, x)
typed(x.Type().Elem(), n)
return n
}
func DotField(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
op, typ := ir.ODOT, x.Type()
if typ.IsPtr() {
op, typ = ir.ODOTPTR, typ.Elem()
}
if !typ.IsStruct() {
base.FatalfAt(pos, "DotField of non-struct: %L", x)
}
// TODO(mdempsky): This is the backend's responsibility.
types.CalcSize(typ)
field := typ.Field(index)
return dot(pos, field.Type, op, x, field)
}
func DotMethod(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
method := method(x.Type(), index)
// Method expression.
// TODO(mdempsky): Handle with a separate helper?
if x.Op() == ir.OTYPE {
typ := typecheck.NewMethodType(method.Type, x.Type())
return dot(pos, typ, ir.OMETHEXPR, x, method)
}
// Method value.
typ := typecheck.NewMethodType(method.Type, nil)
return dot(pos, typ, ir.OCALLPART, x, method)
}
func dot(pos src.XPos, typ *types.Type, op ir.Op, x ir.Node, selection *types.Field) *ir.SelectorExpr {
n := ir.NewSelectorExpr(pos, op, x, selection.Sym)
n.Selection = selection
typed(typ, n)
return n
}
// TODO(mdempsky): Move to package types.
func method(typ *types.Type, index int) *types.Field {
if typ.IsInterface() {
return typ.Field(index)
}
return types.ReceiverBaseType(typ).Methods().Index(index)
}
func Index(pos src.XPos, x, index ir.Node) ir.Node {
// TODO(mdempsky): Avoid typecheck.Expr.
return typecheck.Expr(ir.NewIndexExpr(pos, x, index))
@ -124,18 +196,18 @@ func Slice(pos src.XPos, x, low, high, max ir.Node) ir.Node {
}
func Unary(pos src.XPos, op ir.Op, x ir.Node) ir.Node {
typ := x.Type()
switch op {
case ir.OADDR:
// TODO(mdempsky): Avoid typecheck.Expr. Probably just need to set OPTRLIT as needed.
return typed(types.NewPtr(typ), typecheck.Expr(typecheck.NodAddrAt(pos, x)))
return Addr(pos, x)
case ir.ODEREF:
return typed(typ.Elem(), ir.NewStarExpr(pos, x))
case ir.ORECV:
return typed(typ.Elem(), ir.NewUnaryExpr(pos, op, x))
default:
return typed(typ, ir.NewUnaryExpr(pos, op, x))
return Deref(pos, x)
}
typ := x.Type()
if op == ir.ORECV {
typ = typ.Elem()
}
return typed(typ, ir.NewUnaryExpr(pos, op, x))
}
// Statements