runtime: merge lfstack{Pack,Unpack} into one file

Merge the remaining lfstack{Pack,Unpack} implemetations into one file.

unsafe.Sizeof(uintptr(0)) == 4 is a constant comparison so this branch
folds away at compile time.

Dmitry confirmed that the upper 17 bits of an address will be zero for a
user mode pointer, so there is no need to sign extend on amd64 during
unpack, so we can reuse the same implementation as all othe 64 bit
archs.

Change-Id: I99f589416d8b181ccde5364c9c2e78e4a5efc7f1
Reviewed-on: https://go-review.googlesource.com/21597
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

1 files changed, 0 insertions, 33 deletions

diff --git a/src/runtime/lfstack_64bit.go b/src/runtime/lfstack_64bit.go
deleted file mode 100644
index 07c2a141f0..0000000000
--- a/src/runtime/lfstack_64bit.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// 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.
-
-// +build arm64 mips64 mips64le ppc64 ppc64le
-
-package runtime
-
-import "unsafe"
-
-// On ppc64, Linux limits the user address space to 46 bits (see
-// TASK_SIZE_USER64 in the Linux kernel).  This has grown over time,
-// so here we allow 48 bit addresses.
-//
-// On mips64, Linux limits the user address space to 40 bits (see
-// TASK_SIZE64 in the Linux kernel).  This has grown over time,
-// so here we allow 48 bit addresses.
-//
-// 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) *lfnode {
-	return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
-}