runtime: add support for linux/arm64

Change-Id: Ibda6a5bedaff57fd161d63fc04ad260931d34413
Reviewed-on: https://go-review.googlesource.com/7142
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/runtime/lfstack_linux_arm64.go b/src/runtime/lfstack_linux_arm64.go
new file mode 100644
index 0000000000..54cae39fbc
--- /dev/null
+++ b/src/runtime/lfstack_linux_arm64.go
@@ -0,0 +1,25 @@
+// 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"
+
+// In addition to the 16 bits taken from the top, we can take 3 from the
+// bottom, because node must be pointer-aligned, giving a total of 19 bits
+// of count.
+const (
+	addrBits = 48
+	cntBits  = 64 - addrBits + 3
+)
+
+func lfstackPack(node *lfnode, cnt uintptr) uint64 {
+	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
+}
+
+func lfstackUnpack(val uint64) (node *lfnode, cnt uintptr) {
+	node = (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
+	cnt = uintptr(val & (1<<cntBits - 1))
+	return
+}