1
0
mirror of https://github.com/golang/go synced 2024-11-22 16:25:07 -07:00

[dev.typeparams] cmd/compile: fix crawling of embeddable types

In reflectdata, we have a hack to only apply inlining for (*T).M
wrappers generated around T.M. This was a hack because I didn't
understand at the time why other cases were failing.

But I understand now: during export, we generally skip exporting the
inline bodies for unexported methods (unless they're reachable through
some other exported method). But it doesn't take into account that
embedding a type requires generating wrappers for promoted methods,
including imported, unexported methods.

For example:

	package a
	type T struct{}
	func (T) m() {} // previously omitted by exported

	package b
	import "./a"
	type U struct { a.T } // needs U.m -> T.m wrapper

This CL adds extra logic to the crawler to recognize that T is an
exported type directly reachable by the user, so *all* of its methods
need to be re-exported.

This finally allows simplifying reflectdata.methodWrapper to always
call inline.InlineCalls.

Change-Id: I25031d41fd6b6cd69d31c6a864b5329cdb5780e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/327872
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Matthew Dempsky 2021-06-14 19:21:14 -07:00
parent 8f95eaddd3
commit 132ea56d29
2 changed files with 81 additions and 18 deletions

View File

@ -1795,20 +1795,24 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
return lsym
}
// Only generate (*T).M wrappers for T.M in T's own package, except for
// instantiated methods.
if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type &&
rcvr.Elem().Sym() != nil && rcvr.Elem().Sym().Pkg != types.LocalPkg &&
!rcvr.Elem().IsFullyInstantiated() {
return lsym
// imported reports whether typ is a defined type that was declared
// in an imported package, and therefore must have been compiled in
// that package.
importedType := func(typ *types.Type) bool {
return typ.Sym() != nil && typ.Sym().Pkg != types.LocalPkg &&
// Exception: need wrapper for error.Error (#29304).
// TODO(mdempsky): Put this in package runtime, like we do for
// the type descriptors for predeclared types.
typ != types.ErrorType &&
// Exception: parameterized types may have been instantiated
// with new type arguments, so we don't assume they've been
// compiled before.
!typ.IsFullyInstantiated()
}
// Only generate I.M wrappers for I in I's own package
// but keep doing it for error.Error (was issue #29304)
// and methods of instantiated interfaces.
if rcvr.IsInterface() && rcvr != types.ErrorType &&
rcvr.Sym() != nil && rcvr.Sym().Pkg != types.LocalPkg &&
!rcvr.IsFullyInstantiated() {
if importedType(rcvr) || rcvr.IsPtr() && importedType(rcvr.Elem()) {
return lsym
}
@ -1922,9 +1926,16 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
ir.CurFunc = fn
typecheck.Stmts(fn.Body)
// Inline calls within (*T).M wrappers. This is safe because we only
// generate those wrappers within the same compilation unit as (T).M.
// TODO(mdempsky): Investigate why we can't enable this more generally.
// TODO(mdempsky): Make this unconditional. The exporter now
// includes all of the inline bodies we need, and the "importedType"
// logic above now correctly suppresses compiling out-of-package
// types that we might not have inline bodies for. The only problem
// now is that the extra inlining can now introduce further new
// itabs, and gc.dumpdata's ad hoc compile loop doesn't handle this.
//
// CL 327871 will address this by writing itabs and generating
// wrappers as part of the loop, so we won't have to worry about
// "itabs changed after compile functions loop" errors anymore.
if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type && rcvr.Elem().Sym() != nil {
inline.InlineCalls(fn)
}

View File

@ -15,14 +15,18 @@ import (
// callable by importers are marked with ExportInline so that
// iexport.go knows to re-export their inline body.
func crawlExports(exports []*ir.Name) {
p := crawler{marked: make(map[*types.Type]bool)}
p := crawler{
marked: make(map[*types.Type]bool),
embedded: make(map[*types.Type]bool),
}
for _, n := range exports {
p.markObject(n)
}
}
type crawler struct {
marked map[*types.Type]bool // types already seen by markType
marked map[*types.Type]bool // types already seen by markType
embedded map[*types.Type]bool // types already seen by markEmbed
}
// markObject visits a reachable object.
@ -31,6 +35,12 @@ func (p *crawler) markObject(n *ir.Name) {
p.markInlBody(n)
}
// If a declared type name is reachable, users can embed it in their
// own types, which makes even its unexported methods reachable.
if n.Op() == ir.OTYPE {
p.markEmbed(n.Type())
}
p.markType(n.Type())
}
@ -46,7 +56,7 @@ func (p *crawler) markType(t *types.Type) {
}
p.marked[t] = true
// If this is a named type, mark all of its associated
// If this is a defined type, mark all of its associated
// methods. Skip interface types because t.Methods contains
// only their unexpanded method set (i.e., exclusive of
// interface embeddings), and the switch statement below
@ -107,6 +117,48 @@ func (p *crawler) markType(t *types.Type) {
}
}
// markEmbed is similar to markType, but handles finding methods that
// need to be re-exported because t can be embedded in user code
// (possibly transitively).
func (p *crawler) markEmbed(t *types.Type) {
if t.IsPtr() {
// Defined pointer type; not allowed to embed anyway.
if t.Sym() != nil {
return
}
t = t.Elem()
}
if t.IsInstantiatedGeneric() {
// Re-instantiated types don't add anything new, so don't follow them.
return
}
if p.embedded[t] {
return
}
p.embedded[t] = true
// If t is a defined type, then re-export all of its methods. Unlike
// in markType, we include even unexported methods here, because we
// still need to generate wrappers for them, even if the user can't
// refer to them directly.
if t.Sym() != nil && t.Kind() != types.TINTER {
for _, m := range t.Methods().Slice() {
p.markObject(m.Nname.(*ir.Name))
}
}
// If t is a struct, recursively visit its embedded fields.
if t.IsStruct() {
for _, f := range t.FieldSlice() {
if f.Embedded != 0 {
p.markEmbed(f.Type)
}
}
}
}
// markInlBody marks n's inline body for export and recursively
// ensures all called functions are marked too.
func (p *crawler) markInlBody(n *ir.Name) {