cmd/gc, runtime: refactor interface inlining decision into compiler
We need to change the interface value representation for
concurrent garbage collection, so that there is no ambiguity
about whether the data word holds a pointer or scalar.
This CL does NOT make any representation changes.
Instead, it removes representation assumptions from
various pieces of code throughout the tree.
The isdirectiface function in cmd/gc/subr.c is now
the only place that decides that policy.
The policy propagates out from there in the reflect
metadata, as a new flag in the internal kind value.
A follow-up CL will change the representation by
changing the isdirectiface function. If that CL causes
problems, it will be easy to roll back.
Update #8405.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/129090043
diff --git a/src/pkg/runtime/typekind.go b/src/pkg/runtime/typekind.go
new file mode 100644
index 0000000..5985536
--- /dev/null
+++ b/src/pkg/runtime/typekind.go
@@ -0,0 +1,44 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+const (
+ kindBool = 1 + iota
+ kindInt
+ kindInt8
+ kindInt16
+ kindInt32
+ kindInt64
+ kindUint
+ kindUint8
+ kindUint16
+ kindUint32
+ kindUint64
+ kindUintptr
+ kindFloat32
+ kindFloat64
+ kindComplex64
+ kindComplex128
+ kindArray
+ kindChan
+ kindFunc
+ kindInterface
+ kindMap
+ kindPtr
+ kindSlice
+ kindString
+ kindStruct
+ kindUnsafePointer
+
+ kindDirectIface = 1 << 5
+ kindGCProg = 1 << 6 // Type.gc points to GC program
+ kindNoPointers = 1 << 7
+ kindMask = (1 << 5) - 1
+)
+
+// isDirectIface reports whether t is stored directly in an interface value.
+func isDirectIface(t *_type) bool {
+ return t.kind&kindDirectIface != 0
+}
