syscall: delete the "use" function and calls in non-generated files.

Delete use stub from asm.s, leaving only a dummy file.
Deleting the file causes Windows build to fail.

Fixes #16607

Change-Id: Ic5a55e042e588f1e1bc6605a3d309d1eabdeb288
Reviewed-on: https://go-review.googlesource.com/36716
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/syscall/asm.s

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "textflag.h"
-
-TEXT ·use(SB),NOSPLIT,$0
-	RET
+// Dummy asm file to keep Windows building.
+// TODO(sameer): delete this after updating go tool
+// per Ian's comment in golang.org/cl/36716

src/syscall/dll_windows.go

@@ -87,7 +87,6 @@ func (d *DLL) FindProc(name string) (proc *Proc, err error) {
 		return nil, err
 	}
 	a, e := getprocaddress(uintptr(d.Handle), namep)
-	use(unsafe.Pointer(namep))
 	if e != 0 {
 		return nil, &DLLError{
 			Err:     e,

src/syscall/syscall.go

@@ -26,8 +26,6 @@
 //
 package syscall
 
-import "unsafe"
-
 //go:generate go run mksyscall_windows.go -systemdll -output zsyscall_windows.go syscall_windows.go security_windows.go
 
 // StringByteSlice converts a string to a NUL-terminated []byte,
@@ -98,11 +96,3 @@ func (tv *Timeval) Nano() int64 {
 // Getpagesize is provided by the runtime.
 
 func Getpagesize() int
-
-// use is a no-op, but the compiler cannot see that it is.
-// Calling use(p) ensures that p is kept live until that point.
-// This was needed until Go 1.6 to call syscall.Syscall correctly.
-// As of Go 1.6 the compiler handles that case automatically.
-// The uses and definition of use can be removed early in the Go 1.7 cycle.
-//go:noescape
-func use(p unsafe.Pointer)

src/syscall/syscall_darwin.go

@@ -127,7 +127,6 @@ func getAttrList(path string, attrList attrList, attrBuf []byte, options uint) (
 		uintptr(options),
 		0,
 	)
-	use(unsafe.Pointer(_p0))
 	if e1 != 0 {
 		return nil, e1
 	}
@@ -180,7 +179,6 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 		bufsize = unsafe.Sizeof(Statfs_t{}) * uintptr(len(buf))
 	}
 	r0, _, e1 := Syscall(SYS_GETFSSTAT64, uintptr(_p0), bufsize, uintptr(flags))
-	use(unsafe.Pointer(_p0))
 	n = int(r0)
 	if e1 != 0 {
 		err = e1

src/syscall/syscall_dragonfly.go

@@ -100,7 +100,6 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 		bufsize = unsafe.Sizeof(Statfs_t{}) * uintptr(len(buf))
 	}
 	r0, _, e1 := Syscall(SYS_GETFSSTAT, uintptr(_p0), bufsize, uintptr(flags))
-	use(unsafe.Pointer(_p0))
 	n = int(r0)
 	if e1 != 0 {
 		err = e1

src/syscall/syscall_freebsd.go

@@ -113,7 +113,6 @@ func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
 		bufsize = unsafe.Sizeof(Statfs_t{}) * uintptr(len(buf))
 	}
 	r0, _, e1 := Syscall(SYS_GETFSSTAT, uintptr(_p0), bufsize, uintptr(flags))
-	use(unsafe.Pointer(_p0))
 	n = int(r0)
 	if e1 != 0 {
 		err = e1

src/syscall/syscall_linux.go

@@ -127,7 +127,6 @@ func Futimesat(dirfd int, path string, tv []Timeval) (err error) {
 		return err
 	}
 	err = futimesat(dirfd, pathp, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
-	use(unsafe.Pointer(pathp))
 	return err
 }
 
@@ -790,7 +789,6 @@ func Mount(source string, target string, fstype string, flags uintptr, data stri
 		return err
 	}
 	err = mount(source, target, fstype, flags, datap)
-	use(unsafe.Pointer(datap))
 	return err
 }
 

src/syscall/syscall_linux_386.go

@@ -354,7 +354,6 @@ func Statfs(path string, buf *Statfs_t) (err error) {
 		return err
 	}
 	_, _, e := Syscall(SYS_STATFS64, uintptr(unsafe.Pointer(pathp)), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
-	use(unsafe.Pointer(pathp))
 	if e != 0 {
 		err = e
 	}

src/syscall/syscall_linux_arm.go

@@ -123,7 +123,6 @@ func Statfs(path string, buf *Statfs_t) (err error) {
 		return err
 	}
 	_, _, e := Syscall(SYS_STATFS64, uintptr(unsafe.Pointer(pathp)), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
-	use(unsafe.Pointer(pathp))
 	if e != 0 {
 		err = e
 	}

src/syscall/syscall_linux_mipsx.go

@@ -72,7 +72,6 @@ func Syscall9(trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr,
 
 func Fstatfs(fd int, buf *Statfs_t) (err error) {
 	_, _, e := Syscall(SYS_FSTATFS64, uintptr(fd), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
-	use(unsafe.Pointer(buf))
 	if e != 0 {
 		err = errnoErr(e)
 	}
@@ -85,7 +84,6 @@ func Statfs(path string, buf *Statfs_t) (err error) {
 		return err
 	}
 	_, _, e := Syscall(SYS_STATFS64, uintptr(unsafe.Pointer(p)), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
-	use(unsafe.Pointer(p))
 	if e != 0 {
 		err = errnoErr(e)
 	}

src/syscall/syscall_linux_s390x.go

@@ -96,7 +96,6 @@ func Pipe2(p []int, flags int) (err error) {
 func mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error) {
 	mmap_args := [6]uintptr{addr, length, uintptr(prot), uintptr(flags), uintptr(fd), uintptr(offset)}
 	r0, _, e1 := Syscall(SYS_MMAP, uintptr(unsafe.Pointer(&mmap_args[0])), 0, 0)
-	use(unsafe.Pointer(&mmap_args[0]))
 	xaddr = uintptr(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)

src/syscall/syscall_plan9.go

@@ -251,9 +251,7 @@ func Unmount(name, old string) (err error) {
 			return err
 		}
 		r0, _, e = Syscall(SYS_UNMOUNT, uintptr(unsafe.Pointer(namep)), oldptr, 0)
-		use(unsafe.Pointer(namep))
 	}
-	use(unsafe.Pointer(oldp))
 
 	if int32(r0) == -1 {
 		err = e