From 9cc9e95b288648d796d92f0b92cb713b35f20062 Mon Sep 17 00:00:00 2001 From: Dave Cheney Date: Thu, 7 Apr 2016 14:05:06 +0000 Subject: Revert "runtime: merge lfstack{Pack,Unpack} into one file" This broke solaris, which apparently does use the upper 17 bits of the address space. This reverts commit 3b02c5b1b66df9cdb23d5a3243bb37b2c312ea1b. Change-Id: Iedfe54abd0384960845468205f20191a97751c0b Reviewed-on: https://go-review.googlesource.com/21652 Reviewed-by: Dave Cheney --- src/runtime/lfstack_amd64.go | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 src/runtime/lfstack_amd64.go (limited to 'src/runtime/lfstack_amd64.go') diff --git a/src/runtime/lfstack_amd64.go b/src/runtime/lfstack_amd64.go new file mode 100644 index 0000000000..6397e1d47f --- /dev/null +++ b/src/runtime/lfstack_amd64.go @@ -0,0 +1,22 @@ +// 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" + +// On AMD64, virtual addresses are 48-bit numbers sign extended to 64. +// We shift the address left 16 to eliminate the sign extended part and make +// room in the bottom for the count. +// 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. + +func lfstackPack(node *lfnode, cnt uintptr) uint64 { + return uint64(uintptr(unsafe.Pointer(node)))<<16 | uint64(cnt&(1<<19-1)) +} + +func lfstackUnpack(val uint64) *lfnode { + return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> 19 << 3))) +} -- cgit v1.3-6-g1900