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[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>
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@ -1795,20 +1795,24 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
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return lsym
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}
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// Only generate (*T).M wrappers for T.M in T's own package, except for
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// instantiated methods.
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if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type &&
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rcvr.Elem().Sym() != nil && rcvr.Elem().Sym().Pkg != types.LocalPkg &&
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!rcvr.Elem().IsFullyInstantiated() {
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return lsym
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// imported reports whether typ is a defined type that was declared
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// in an imported package, and therefore must have been compiled in
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// that package.
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importedType := func(typ *types.Type) bool {
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return typ.Sym() != nil && typ.Sym().Pkg != types.LocalPkg &&
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// Exception: need wrapper for error.Error (#29304).
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// TODO(mdempsky): Put this in package runtime, like we do for
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// the type descriptors for predeclared types.
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typ != types.ErrorType &&
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// Exception: parameterized types may have been instantiated
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// with new type arguments, so we don't assume they've been
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// compiled before.
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!typ.IsFullyInstantiated()
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}
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// Only generate I.M wrappers for I in I's own package
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// but keep doing it for error.Error (was issue #29304)
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// and methods of instantiated interfaces.
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if rcvr.IsInterface() && rcvr != types.ErrorType &&
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rcvr.Sym() != nil && rcvr.Sym().Pkg != types.LocalPkg &&
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!rcvr.IsFullyInstantiated() {
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if importedType(rcvr) || rcvr.IsPtr() && importedType(rcvr.Elem()) {
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return lsym
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}
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@ -1922,9 +1926,16 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
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ir.CurFunc = fn
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typecheck.Stmts(fn.Body)
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// Inline calls within (*T).M wrappers. This is safe because we only
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// generate those wrappers within the same compilation unit as (T).M.
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// TODO(mdempsky): Investigate why we can't enable this more generally.
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// TODO(mdempsky): Make this unconditional. The exporter now
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// includes all of the inline bodies we need, and the "importedType"
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// logic above now correctly suppresses compiling out-of-package
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// types that we might not have inline bodies for. The only problem
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// now is that the extra inlining can now introduce further new
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// itabs, and gc.dumpdata's ad hoc compile loop doesn't handle this.
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//
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// CL 327871 will address this by writing itabs and generating
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// wrappers as part of the loop, so we won't have to worry about
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// "itabs changed after compile functions loop" errors anymore.
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if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type && rcvr.Elem().Sym() != nil {
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inline.InlineCalls(fn)
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}
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@ -15,14 +15,18 @@ import (
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// callable by importers are marked with ExportInline so that
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// iexport.go knows to re-export their inline body.
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func crawlExports(exports []*ir.Name) {
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p := crawler{marked: make(map[*types.Type]bool)}
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p := crawler{
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marked: make(map[*types.Type]bool),
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embedded: make(map[*types.Type]bool),
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}
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for _, n := range exports {
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p.markObject(n)
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}
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}
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type crawler struct {
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marked map[*types.Type]bool // types already seen by markType
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marked map[*types.Type]bool // types already seen by markType
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embedded map[*types.Type]bool // types already seen by markEmbed
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}
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// markObject visits a reachable object.
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@ -31,6 +35,12 @@ func (p *crawler) markObject(n *ir.Name) {
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p.markInlBody(n)
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}
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// If a declared type name is reachable, users can embed it in their
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// own types, which makes even its unexported methods reachable.
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if n.Op() == ir.OTYPE {
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p.markEmbed(n.Type())
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}
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p.markType(n.Type())
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}
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@ -46,7 +56,7 @@ func (p *crawler) markType(t *types.Type) {
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}
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p.marked[t] = true
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// If this is a named type, mark all of its associated
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// If this is a defined type, mark all of its associated
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// methods. Skip interface types because t.Methods contains
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// only their unexpanded method set (i.e., exclusive of
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// interface embeddings), and the switch statement below
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@ -107,6 +117,48 @@ func (p *crawler) markType(t *types.Type) {
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}
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}
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// markEmbed is similar to markType, but handles finding methods that
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// need to be re-exported because t can be embedded in user code
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// (possibly transitively).
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func (p *crawler) markEmbed(t *types.Type) {
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if t.IsPtr() {
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// Defined pointer type; not allowed to embed anyway.
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if t.Sym() != nil {
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return
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}
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t = t.Elem()
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}
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if t.IsInstantiatedGeneric() {
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// Re-instantiated types don't add anything new, so don't follow them.
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return
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}
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if p.embedded[t] {
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return
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}
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p.embedded[t] = true
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// If t is a defined type, then re-export all of its methods. Unlike
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// in markType, we include even unexported methods here, because we
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// still need to generate wrappers for them, even if the user can't
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// refer to them directly.
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if t.Sym() != nil && t.Kind() != types.TINTER {
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for _, m := range t.Methods().Slice() {
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p.markObject(m.Nname.(*ir.Name))
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}
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}
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// If t is a struct, recursively visit its embedded fields.
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if t.IsStruct() {
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for _, f := range t.FieldSlice() {
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if f.Embedded != 0 {
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p.markEmbed(f.Type)
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}
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}
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}
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}
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// markInlBody marks n's inline body for export and recursively
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// ensures all called functions are marked too.
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func (p *crawler) markInlBody(n *ir.Name) {
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