From 110343e4a2a953a581e34e91e51cef08856b0b0a Mon Sep 17 00:00:00 2001 From: Dan Scales Date: Thu, 5 Aug 2021 10:17:40 -0700 Subject: [dev.typeparams] cmd/compile: cleanup wrapper code for generics Simple change - added some comments, but also removed some TODO comments which are now done or no longer a question. Cleaned up the initial check for generic methods. The one remaining TODO that really needs to be done is generating dictionary wrappers for any methods involving embedded fields. Given we are not doing this, I think this would only affect if a struct with an embedded field with methods was converted to an interface containing the embedded method, and then the method was called via that interface. Change-Id: I6a8a2885de33ad60b313c1899b659daef7550dfb Reviewed-on: https://go-review.googlesource.com/c/go/+/340260 Trust: Dan Scales Run-TryBot: Dan Scales Reviewed-by: Keith Randall --- src/cmd/compile/internal/reflectdata/reflect.go | 52 +++++++++++++------------ 1 file changed, 27 insertions(+), 25 deletions(-) diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go index a8df7a1a24..b04e4d684f 100644 --- a/src/cmd/compile/internal/reflectdata/reflect.go +++ b/src/cmd/compile/internal/reflectdata/reflect.go @@ -303,6 +303,7 @@ func MapIterType(t *types.Type) *types.Type { // Generates stub functions as needed. func methods(t *types.Type) []*typeSig { if t.HasShape() { + // Shape types have no methods. return nil } // method type @@ -1228,9 +1229,8 @@ func InterfaceMethodOffset(ityp *types.Type, i int64) int64 { // NeedRuntimeType ensures that a runtime type descriptor is emitted for t. func NeedRuntimeType(t *types.Type) { if t.HasTParam() { - // Generic types don't have a runtime type descriptor (but will - // have a dictionary) - // TODO: also shape type here? + // Generic types don't really exist at run-time and have no runtime + // type descriptor. But we do write out shape types. return } if _, ok := signatset[t]; !ok { @@ -1786,26 +1786,28 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy if forItab && !types.IsDirectIface(rcvr) { rcvr = rcvr.PtrTo() } + generic := false - if !types.IsInterfaceMethod(method.Type) && - (len(rcvr.RParams()) > 0 || - rcvr.IsPtr() && len(rcvr.Elem().RParams()) > 0) { // TODO: right detection? - // Don't need dictionary if we are reaching a method (possibly via - // an embedded field) which is an interface method. - // TODO: check that we do the right thing when method is an interface method. - generic = true - - targs := rcvr.RParams() - if rcvr.IsPtr() { - targs = rcvr.Elem().RParams() - } - // TODO: why do shape-instantiated types exist? - for _, t := range targs { - if t.HasShape() { - base.Fatalf("method on type instantiated with shapes targ:%+v rcvr:%+v", t, rcvr) + // We don't need a dictionary if we are reaching a method (possibly via an + // embedded field) which is an interface method. + if !types.IsInterfaceMethod(method.Type) { + rcvr1 := rcvr + if rcvr1.IsPtr() { + rcvr1 = rcvr.Elem() + } + if len(rcvr1.RParams()) > 0 { + // If rcvr has rparams, remember method as generic, which + // means we need to add a dictionary to the wrapper. + generic = true + targs := rcvr1.RParams() + for _, t := range targs { + if t.HasShape() { + base.Fatalf("method on type instantiated with shapes targ:%+v rcvr:%+v", t, rcvr) + } } } } + newnam := ir.MethodSym(rcvr, method.Sym) lsym := newnam.Linksym() if newnam.Siggen() { @@ -1818,6 +1820,8 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy return lsym } + // For generic methods, we need to generate the wrapper even if the receiver + // types are identical, because we want to add the dictionary. if !generic && types.Identical(rcvr, method.Type.Recv().Type) { return lsym } @@ -1890,7 +1894,7 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy if generic { var args []ir.Node var targs []*types.Type - if rcvr.IsPtr() { // TODO: correct condition? + if rcvr.IsPtr() { targs = rcvr.Elem().RParams() } else { targs = rcvr.RParams() @@ -1899,10 +1903,9 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy fmt.Printf("%s\n", ir.MethodSym(orig, method.Sym).Name) panic("multiple .inst.") } - // Temporary fix: the wrapper for an auto-generated - // pointer/non-pointer receiver method should share the - // same dictionary as the corresponding original - // (user-written) method. + // The wrapper for an auto-generated pointer/non-pointer + // receiver method should share the same dictionary as the + // corresponding original (user-written) method. baseOrig := orig if baseOrig.IsPtr() && !method.Type.Recv().Type.IsPtr() { baseOrig = baseOrig.Elem() @@ -2058,7 +2061,6 @@ func getDictionary(gf *types.Sym, targs []*types.Type) ir.Node { // Note: treat dictionary pointers as uintptrs, so they aren't pointers // with respect to GC. That saves on stack scanning work, write barriers, etc. // We can get away with it because dictionaries are global variables. - // TODO: use a cast, or is typing directly ok? np.SetType(types.Types[types.TUINTPTR]) np.SetTypecheck(1) return np -- cgit v1.2.3-54-g00ecf