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

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This broke solaris, which apparently does use the upper 17 bits of the address space.

This reverts commit 3b02c5b1b6.

Change-Id: Iedfe54abd0384960845468205f20191a97751c0b
Reviewed-on: https://go-review.googlesource.com/21652
Reviewed-by: Dave Cheney <dave@cheney.net>
This commit is contained in:
Dave Cheney 2016-04-07 14:05:06 +00:00
parent 8448d3aace
commit 9cc9e95b28
4 changed files with 74 additions and 35 deletions
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35
src/runtime/lfstack.go
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@ -41,38 +41,3 @@ 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<<cntBits-1))
}
func lfstackUnpack(val uint64) *lfnode {
if unsafe.Sizeof(uintptr(0)) == 4 {
return (*lfnode)(unsafe.Pointer(uintptr(val >> 32)))
}
return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
}

19
src/runtime/lfstack_32bit.go Normal file
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@ -0,0 +1,19 @@
// 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)))
}

33
src/runtime/lfstack_64bit.go Normal file
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@ -0,0 +1,33 @@
// 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)))
}

22
src/runtime/lfstack_amd64.go Normal file
View File

@ -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)))
}