From: Dave Cheney Date: Wed, 6 Apr 2016 21:29:22 +0000 (+1000) Subject: runtime: merge lfstack{Pack,Unpack} into one file X-Git-Tag: go1.7beta1~839 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=3b02c5b1b66df9cdb23d5a3243bb37b2c312ea1b;p=gostls13.git 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 TryBot-Result: Gobot Gobot Reviewed-by: Minux Ma --- diff --git a/src/runtime/lfstack.go b/src/runtime/lfstack.go index 1261f54d97..8a2d519402 100644 --- a/src/runtime/lfstack.go +++ b/src/runtime/lfstack.go @@ -41,3 +41,38 @@ func lfstackpop(head *uint64) unsafe.Pointer { } } } + +const ( + addrBits = 48 + cntBits = 64 - addrBits + 3 +) + +func lfstackPack(node *lfnode, cnt uintptr) uint64 { + if unsafe.Sizeof(uintptr(0)) == 4 { + // On 32-bit systems, the stored uint64 has a 32-bit pointer and 32-bit count. + return uint64(uintptr(unsafe.Pointer(node)))<<32 | uint64(cnt) + } + // 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. + // + // 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. + return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<> 32))) + } + return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3))) +} diff --git a/src/runtime/lfstack_32bit.go b/src/runtime/lfstack_32bit.go deleted file mode 100644 index 2f59e0212e..0000000000 --- a/src/runtime/lfstack_32bit.go +++ /dev/null @@ -1,19 +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 386 arm nacl - -package runtime - -import "unsafe" - -// On 32-bit systems, the stored uint64 has a 32-bit pointer and 32-bit count. - -func lfstackPack(node *lfnode, cnt uintptr) uint64 { - return uint64(uintptr(unsafe.Pointer(node)))<<32 | uint64(cnt) -} - -func lfstackUnpack(val uint64) *lfnode { - return (*lfnode)(unsafe.Pointer(uintptr(val >> 32))) -} 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 << 3))) -} diff --git a/src/runtime/lfstack_amd64.go b/src/runtime/lfstack_amd64.go deleted file mode 100644 index 6397e1d47f..0000000000 --- a/src/runtime/lfstack_amd64.go +++ /dev/null @@ -1,22 +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. - -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))) -}