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[dev.unified] cmd/compile: extract nil handling from exprType

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Type switches are the only context where exprType was used and `nilOK`
was true. It'll simplify subsequent dictionary work somewhat if
exprType doesn't need to worry about `nil`, so extract this logic and
move it into switchStmt instead.

Change-Id: I3d810f465173f5bb2e2dee7bbc7843fff6a62ee5
Reviewed-on: https://go-review.googlesource.com/c/go/+/419474
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Matthew Dempsky 2022-07-25 12:21:21 -07:00
parent 92798176e7
commit 831fdf1dff
2 changed files with 26 additions and 21 deletions
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18
src/cmd/compile/internal/noder/reader.go
View file

@ -1547,7 +1547,11 @@ func (r *reader) switchStmt(label *types.Sym) ir.Node {
cases = nil // TODO(mdempsky): Unclear if this matters.
}
for i := range cases {
cases[i] = r.exprType(true)
if r.Bool() { // case nil
cases[i] = typecheck.Expr(types.BuiltinPkg.Lookup("nil").Def.(*ir.NilExpr))
} else {
cases[i] = r.exprType()
}
}
} else {
cases = r.exprList()
@ -1734,7 +1738,7 @@ func (r *reader) expr() (res ir.Node) {
case exprAssert:
x := r.expr()
pos := r.pos()
typ := r.exprType(false)
typ := r.exprType()
srcRType := r.rtype(pos)
// TODO(mdempsky): Always emit ODYNAMICDOTTYPE for uniformity?
@ -1800,7 +1804,7 @@ func (r *reader) expr() (res ir.Node) {
case exprMake:
pos := r.pos()
typ := r.exprType(false)
typ := r.exprType()
extra := r.exprs()
n := typecheck.Expr(ir.NewCallExpr(pos, ir.OMAKE, nil, append([]ir.Node{typ}, extra...))).(*ir.MakeExpr)
n.RType = r.rtype(pos)
@ -1808,7 +1812,7 @@ func (r *reader) expr() (res ir.Node) {
case exprNew:
pos := r.pos()
typ := r.exprType(false)
typ := r.exprType()
return typecheck.Expr(ir.NewUnaryExpr(pos, ir.ONEW, typ))
case exprConvert:
@ -2043,13 +2047,9 @@ func (r *reader) convRTTI(pos src.XPos) (typeWord, srcRType ir.Node) {
return
}
func (r *reader) exprType(nilOK bool) ir.Node {
func (r *reader) exprType() ir.Node {
r.Sync(pkgbits.SyncExprType)
if nilOK && r.Bool() {
return typecheck.Expr(types.BuiltinPkg.Lookup("nil").Def.(*ir.NilExpr))
}
pos := r.pos()
setBasePos(pos)

29
src/cmd/compile/internal/noder/writer.go
View file

@ -1464,7 +1464,10 @@ func (w *writer) switchStmt(stmt *syntax.SwitchStmt) {
if iface != nil {
w.Len(len(cases))
for _, cas := range cases {
w.exprType(iface, cas, true)
if w.Bool(isNil(w.p.info, cas)) {
continue
}
w.exprType(iface, cas)
}
} else {
// As if w.exprList(clause.Cases),
@ -1642,7 +1645,7 @@ func (w *writer) expr(expr syntax.Expr) {
w.Code(exprAssert)
w.expr(expr.X)
w.pos(expr)
w.exprType(iface, expr.Type, false)
w.exprType(iface, expr.Type)
w.rtype(iface)
case *syntax.Operation:
@ -1702,7 +1705,7 @@ func (w *writer) expr(expr syntax.Expr) {
w.Code(exprMake)
w.pos(expr)
w.exprType(nil, expr.ArgList[0], false)
w.exprType(nil, expr.ArgList[0])
w.exprs(expr.ArgList[1:])
typ := w.p.typeOf(expr)
@ -1725,7 +1728,7 @@ func (w *writer) expr(expr syntax.Expr) {
w.Code(exprNew)
w.pos(expr)
w.exprType(nil, expr.ArgList[0], false)
w.exprType(nil, expr.ArgList[0])
return
case "append":
@ -1960,21 +1963,15 @@ func (w *writer) convRTTI(src, dst types2.Type) {
w.typ(dst)
}
func (w *writer) exprType(iface types2.Type, typ syntax.Expr, nilOK bool) {
func (w *writer) exprType(iface types2.Type, typ syntax.Expr) {
base.Assertf(iface == nil || isInterface(iface), "%v must be nil or an interface type", iface)
tv, ok := w.p.info.Types[typ]
assert(ok)
w.Sync(pkgbits.SyncExprType)
if nilOK && w.Bool(tv.IsNil()) {
return
}
assert(tv.IsType())
info := w.p.typIdx(tv.Type, w.dict)
w.Sync(pkgbits.SyncExprType)
w.pos(typ)
if w.Bool(info.derived && iface != nil && !iface.Underlying().(*types2.Interface).Empty()) {
@ -2386,6 +2383,14 @@ func isMultiValueExpr(info *types2.Info, expr syntax.Expr) bool {
return false
}
// isNil reports whether expr is a (possibly parenthesized) reference
// to the predeclared nil value.
func isNil(info *types2.Info, expr syntax.Expr) bool {
tv, ok := info.Types[expr]
assert(ok)
return tv.IsNil()
}
// recvBase returns the base type for the given receiver parameter.
func recvBase(recv *types2.Var) *types2.Named {
typ := recv.Type()