runtime: deduplicate Windows stdcall

There is no need to have a dedicated stdcall variant for each
number of arguments. Instead, we can use a variadic function
that accepts any number of arguments and handles them uniformly.

While here, improve documentation of syscall_syscalln to make it clear
that it should not be used within the runtime package.

Change-Id: I022afc7f28d969fd7307bb2b1f4594246ac38d18
Reviewed-on: https://go-review.googlesource.com/c/go/+/691215
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Mark Freeman <mark@golang.org>

Author: qmuntal

src/runtime/export_windows_test.go

@@ -18,7 +18,7 @@ var (
 
 func NumberOfProcessors() int32 {
 	var info systeminfo
-	stdcall1(_GetSystemInfo, uintptr(unsafe.Pointer(&info)))
+	stdcall(_GetSystemInfo, uintptr(unsafe.Pointer(&info)))
 	return int32(info.dwnumberofprocessors)
 }
 

src/runtime/mem_windows.go

@@ -26,11 +26,11 @@ const (
 //
 //go:nosplit
 func sysAllocOS(n uintptr, _ string) unsafe.Pointer {
-	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
+	return unsafe.Pointer(stdcall(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
 }
 
 func sysUnusedOS(v unsafe.Pointer, n uintptr) {
-	r := stdcall3(_VirtualFree, uintptr(v), n, _MEM_DECOMMIT)
+	r := stdcall(_VirtualFree, uintptr(v), n, _MEM_DECOMMIT)
 	if r != 0 {
 		return
 	}
@@ -46,7 +46,7 @@ func sysUnusedOS(v unsafe.Pointer, n uintptr) {
 	// in the worst case, but that's fast enough.
 	for n > 0 {
 		small := n
-		for small >= 4096 && stdcall3(_VirtualFree, uintptr(v), small, _MEM_DECOMMIT) == 0 {
+		for small >= 4096 && stdcall(_VirtualFree, uintptr(v), small, _MEM_DECOMMIT) == 0 {
 			small /= 2
 			small &^= 4096 - 1
 		}
@@ -60,7 +60,7 @@ func sysUnusedOS(v unsafe.Pointer, n uintptr) {
 }
 
 func sysUsedOS(v unsafe.Pointer, n uintptr) {
-	p := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
+	p := stdcall(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
 	if p == uintptr(v) {
 		return
 	}
@@ -71,7 +71,7 @@ func sysUsedOS(v unsafe.Pointer, n uintptr) {
 	k := n
 	for k > 0 {
 		small := k
-		for small >= 4096 && stdcall4(_VirtualAlloc, uintptr(v), small, _MEM_COMMIT, _PAGE_READWRITE) == 0 {
+		for small >= 4096 && stdcall(_VirtualAlloc, uintptr(v), small, _MEM_COMMIT, _PAGE_READWRITE) == 0 {
 			small /= 2
 			small &^= 4096 - 1
 		}
@@ -105,7 +105,7 @@ func sysHugePageCollapseOS(v unsafe.Pointer, n uintptr) {
 //
 //go:nosplit
 func sysFreeOS(v unsafe.Pointer, n uintptr) {
-	r := stdcall3(_VirtualFree, uintptr(v), 0, _MEM_RELEASE)
+	r := stdcall(_VirtualFree, uintptr(v), 0, _MEM_RELEASE)
 	if r == 0 {
 		print("runtime: VirtualFree of ", n, " bytes failed with errno=", getlasterror(), "\n")
 		throw("runtime: failed to release pages")
@@ -121,13 +121,13 @@ func sysReserveOS(v unsafe.Pointer, n uintptr, _ string) unsafe.Pointer {
 	// v is just a hint.
 	// First try at v.
 	// This will fail if any of [v, v+n) is already reserved.
-	v = unsafe.Pointer(stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_RESERVE, _PAGE_READWRITE))
+	v = unsafe.Pointer(stdcall(_VirtualAlloc, uintptr(v), n, _MEM_RESERVE, _PAGE_READWRITE))
 	if v != nil {
 		return v
 	}
 
 	// Next let the kernel choose the address.
-	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_RESERVE, _PAGE_READWRITE))
+	return unsafe.Pointer(stdcall(_VirtualAlloc, 0, n, _MEM_RESERVE, _PAGE_READWRITE))
 }
 
 func sysMapOS(v unsafe.Pointer, n uintptr, _ string) {

src/runtime/netpoll_windows.go

@@ -102,7 +102,7 @@ var (
 )
 
 func netpollinit() {
-	iocphandle = stdcall4(_CreateIoCompletionPort, _INVALID_HANDLE_VALUE, 0, 0, _DWORD_MAX)
+	iocphandle = stdcall(_CreateIoCompletionPort, _INVALID_HANDLE_VALUE, 0, 0, _DWORD_MAX)
 	if iocphandle == 0 {
 		println("runtime: CreateIoCompletionPort failed (errno=", getlasterror(), ")")
 		throw("runtime: netpollinit failed")
@@ -115,7 +115,7 @@ func netpollIsPollDescriptor(fd uintptr) bool {
 
 func netpollopen(fd uintptr, pd *pollDesc) int32 {
 	key := packNetpollKey(netpollSourceReady, pd)
-	if stdcall4(_CreateIoCompletionPort, fd, iocphandle, key, 0) == 0 {
+	if stdcall(_CreateIoCompletionPort, fd, iocphandle, key, 0) == 0 {
 		return int32(getlasterror())
 	}
 	return 0
@@ -137,7 +137,7 @@ func netpollBreak() {
 	}
 
 	key := packNetpollKey(netpollSourceBreak, nil)
-	if stdcall4(_PostQueuedCompletionStatus, iocphandle, 0, key, 0) == 0 {
+	if stdcall(_PostQueuedCompletionStatus, iocphandle, 0, key, 0) == 0 {
 		println("runtime: netpoll: PostQueuedCompletionStatus failed (errno=", getlasterror(), ")")
 		throw("runtime: netpoll: PostQueuedCompletionStatus failed")
 	}
@@ -197,7 +197,7 @@ func netpoll(delay int64) (gList, int32) {
 	if delay != 0 {
 		mp.blocked = true
 	}
-	if stdcall6(_GetQueuedCompletionStatusEx, iocphandle, uintptr(unsafe.Pointer(&entries[0])), uintptr(n), uintptr(unsafe.Pointer(&n)), uintptr(wait), 0) == 0 {
+	if stdcall(_GetQueuedCompletionStatusEx, iocphandle, uintptr(unsafe.Pointer(&entries[0])), uintptr(n), uintptr(unsafe.Pointer(&n)), uintptr(wait), 0) == 0 {
 		mp.blocked = false
 		errno := getlasterror()
 		if errno == _WAIT_TIMEOUT {
@@ -256,20 +256,20 @@ func netpollQueueTimer(delay int64) (signaled bool) {
 	// such as a netpollBreak, so we can get to this point with a timer that hasn't
 	// expired yet. In this case, the completion packet can still be picked up by
 	// another thread, so defer the cancellation until it is really necessary.
-	errno := stdcall2(_NtCancelWaitCompletionPacket, mp.waitIocpHandle, 1)
+	errno := stdcall(_NtCancelWaitCompletionPacket, mp.waitIocpHandle, 1)
 	switch errno {
 	case STATUS_CANCELLED:
 		// STATUS_CANCELLED is returned when the associated timer has already expired,
 		// in which automatically cancels the wait completion packet.
 		fallthrough
 	case STATUS_SUCCESS:
 		dt := -delay / 100 // relative sleep (negative), 100ns units
-		if stdcall6(_SetWaitableTimer, mp.waitIocpTimer, uintptr(unsafe.Pointer(&dt)), 0, 0, 0, 0) == 0 {
+		if stdcall(_SetWaitableTimer, mp.waitIocpTimer, uintptr(unsafe.Pointer(&dt)), 0, 0, 0, 0) == 0 {
 			println("runtime: SetWaitableTimer failed; errno=", getlasterror())
 			throw("runtime: netpoll failed")
 		}
 		key := packNetpollKey(netpollSourceTimer, nil)
-		if errno := stdcall8(_NtAssociateWaitCompletionPacket, mp.waitIocpHandle, iocphandle, mp.waitIocpTimer, key, 0, 0, 0, uintptr(unsafe.Pointer(&signaled))); errno != 0 {
+		if errno := stdcall(_NtAssociateWaitCompletionPacket, mp.waitIocpHandle, iocphandle, mp.waitIocpTimer, key, 0, 0, 0, uintptr(unsafe.Pointer(&signaled))); errno != 0 {
 			println("runtime: NtAssociateWaitCompletionPacket failed; errno=", errno)
 			throw("runtime: netpoll failed")
 		}