runtime: implement string ops in Go
Also implement go:nosplit annotation. Not really needed
for now, but we'll definitely need it for other conversions.
benchmark old ns/op new ns/op delta
BenchmarkRuneIterate 534 474 -11.24%
BenchmarkRuneIterate2 535 470 -12.15%
LGTM=bradfitz
R=golang-codereviews, dave, bradfitz, minux
CC=golang-codereviews
https://golang.org/cl/93380044
diff --git a/src/pkg/runtime/stubs.go b/src/pkg/runtime/stubs.go
new file mode 100644
index 0000000..b19b0e0
--- /dev/null
+++ b/src/pkg/runtime/stubs.go
@@ -0,0 +1,30 @@
+// 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
+
+import "unsafe"
+
+// Declarations for runtime services implemented in C or assembly.
+// C implementations of these functions are in stubs.goc.
+// Assembly implementations are in various files, see comments with
+// each function.
+
+// rawstring allocates storage for a new string. The returned
+// string and byte slice both refer to the same storage.
+// The storage is not zeroed. Callers should use
+// b to set the string contents and then drop b.
+func rawstring(size int) (string, []byte)
+
+// rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
+func rawbyteslice(size int) []byte
+
+// rawruneslice allocates a new rune slice. The rune slice is not zeroed.
+func rawruneslice(size int) []rune
+
+//go:noescape
+func gogetcallerpc(p unsafe.Pointer) uintptr
+
+//go:noescape
+func racereadrangepc(addr unsafe.Pointer, len int, callpc, pc uintptr)
