cmd/compile/internal/noder: explicitly handle function instantiations

This CL changes unified IR to explicitly handle function
instantiations within expression handling, rather than leaving it to
the underlying object reading logic.

Change-Id: I009a56013fbe9fbc4dabf80eea98993d34af4272
Reviewed-on: https://go-review.googlesource.com/c/go/+/421817
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 20 insertions, 18 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 4bdce25cca..1c4323b67a 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -558,24 +558,7 @@ var objReader = map[*types.Sym]pkgReaderIndex{}
 // obj reads an instantiated object reference from the bitstream.
 func (r *reader) obj() ir.Node {
 	r.Sync(pkgbits.SyncObject)
-
-	if r.Bool() {
-		idx := r.Len()
-		obj := r.dict.funcsObj[idx]
-		if obj == nil {
-			fn := r.dict.funcs[idx]
-			targs := make([]*types.Type, len(fn.explicits))
-			for i, targ := range fn.explicits {
-				targs[i] = r.p.typIdx(targ, r.dict, true)
-			}
-
-			obj = r.p.objIdx(fn.idx, nil, targs)
-			assert(r.dict.funcsObj[idx] == nil)
-			r.dict.funcsObj[idx] = obj
-		}
-		return obj
-	}
-
+	assert(!r.Bool()) // TODO(mdempsky): Remove; was derived func inst.
 	idx := r.Reloc(pkgbits.RelocObj)
 
 	explicits := make([]*types.Type, r.Len())
@@ -1860,6 +1843,25 @@ func (r *reader) expr() (res ir.Node) {
 		// TODO(mdempsky): Handle builtins directly in exprCall, like method calls?
 		return typecheck.Callee(r.obj())
 
+	case exprFuncInst:
+		if r.Bool() {
+			idx := r.Len()
+			obj := r.dict.funcsObj[idx]
+			if obj == nil {
+				fn := r.dict.funcs[idx]
+				targs := make([]*types.Type, len(fn.explicits))
+				for i, targ := range fn.explicits {
+					targs[i] = r.p.typIdx(targ, r.dict, true)
+				}
+
+				obj = r.p.objIdx(fn.idx, nil, targs)
+				assert(r.dict.funcsObj[idx] == nil)
+				r.dict.funcsObj[idx] = obj
+			}
+			return obj
+		}
+		return r.obj()
+
 	case exprConst:
 		pos := r.pos()
 		typ := r.typ()