gcc/libgo/go/runtime/lfstack_64bit.go
Ian Lance Taylor e0f69f36ea libgo: change build procedure to use build tags
Previously the libgo Makefile explicitly listed the set of files to
    compile for each package.  For packages that use build tags, this
    required a lot of awkward automake conditionals in the Makefile.
    
    This CL changes the build to look at the build tags in the files.
    The new shell script libgo/match.sh does the matching.  This required
    adjusting a lot of build tags, and removing some files that are never
    used.  I verified that the exact same sets of files are compiled on
    amd64 GNU/Linux.  I also tested the build on i386 Solaris.
    
    Writing match.sh revealed some bugs in the build tag handling that
    already exists, in a slightly different form, in the gotest shell
    script.  This CL fixes those problems as well.
    
    The old code used automake conditionals to handle systems that were
    missing strerror_r and wait4.  Rather than deal with those in Go, those
    functions are now implemented in runtime/go-nosys.c when necessary, so
    the Go code can simply assume that they exist.
    
    The os testsuite looked for dir_unix.go, which was never built for gccgo
    and has now been removed.  I changed the testsuite to look for dir.go
    instead.
    
    Reviewed-on: https://go-review.googlesource.com/25546

From-SVN: r239189
2016-08-06 00:36:33 +00:00

51 lines
1.8 KiB
Go

// 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 ignore
// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x
package runtime
import "unsafe"
const (
// addrBits is the number of bits needed to represent a virtual address.
//
// In Linux the user address space for each architecture is limited as
// follows (taken from the processor.h file for the architecture):
//
// Architecture Name Maximum Value (exclusive)
// ---------------------------------------------------------------------
// arm64 TASK_SIZE_64 Depends on configuration.
// ppc64{,le} TASK_SIZE_USER64 0x400000000000UL (46 bit addresses)
// mips64{,le} TASK_SIZE64 0x010000000000UL (40 bit addresses)
// s390x TASK_SIZE 0x020000000000UL (41 bit addresses)
//
// These values may increase over time.
//
// 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.
addrBits = 48
// 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.
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 {
if GOARCH == "amd64" {
// amd64 systems can place the stack above the VA hole, so we need to sign extend
// val before unpacking.
return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> cntBits << 3)))
}
return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
}