runtime: do not calculate asmstdcall address every time we make syscall

Change-Id: If3c8c9035e12d41647ae4982883f6a979313ea9d
Reviewed-on: https://go-review.googlesource.com/8682Reviewed-by: Minux Ma <minux@golang.org>

src/runtime/os1_windows.go

@@ -94,6 +94,12 @@ var (
 	_GetQueuedCompletionStatusEx stdFunction
 )
 
+// Call a Windows function with stdcall conventions,
+// and switch to os stack during the call.
+func asmstdcall(fn unsafe.Pointer)
+
+var asmstdcallAddr unsafe.Pointer
+
 func loadOptionalSyscalls() {
 	var buf [50]byte // large enough for longest string
 	strtoptr := func(s string) uintptr {
@@ -157,6 +163,8 @@ func getVersion() (major, minor byte) {
 }
 
 func osinit() {
+	asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall))
+
 	setBadSignalMsg()
 
 	loadOptionalSyscalls()
@@ -391,7 +399,7 @@ func stdcall(fn stdFunction) uintptr {
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp(unsafe.Pointer(&fn))
 	}
-	asmcgocall(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&mp.libcall))
+	asmcgocall(asmstdcallAddr, unsafe.Pointer(&mp.libcall))
 	mp.libcallsp = 0
 	return mp.libcall.r1
 }

src/runtime/os2_windows.go

@@ -4,12 +4,6 @@
 
 package runtime
 
-import "unsafe"
-
-// Call a Windows function with stdcall conventions,
-// and switch to os stack during the call.
-func asmstdcall(fn unsafe.Pointer)
-
 func getlasterror() uint32
 func setlasterror(err uint32)
 

src/runtime/syscall_windows.go

@@ -95,7 +95,7 @@ func syscall_loadlibrary(filename *uint16) (handle, err uintptr) {
 	c.fn = getLoadLibrary()
 	c.n = 1
 	c.args = uintptr(unsafe.Pointer(&filename))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	handle = c.r1
 	if handle == 0 {
 		err = c.err
@@ -110,7 +110,7 @@ func syscall_getprocaddress(handle uintptr, procname *byte) (outhandle, err uint
 	c.fn = getGetProcAddress()
 	c.n = 2
 	c.args = uintptr(unsafe.Pointer(&handle))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	outhandle = c.r1
 	if outhandle == 0 {
 		err = c.err
@@ -125,7 +125,7 @@ func syscall_Syscall(fn, nargs, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	c.fn = fn
 	c.n = nargs
 	c.args = uintptr(unsafe.Pointer(&a1))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	return c.r1, c.r2, c.err
 }
 
@@ -136,7 +136,7 @@ func syscall_Syscall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err ui
 	c.fn = fn
 	c.n = nargs
 	c.args = uintptr(unsafe.Pointer(&a1))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	return c.r1, c.r2, c.err
 }
 
@@ -147,7 +147,7 @@ func syscall_Syscall9(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1
 	c.fn = fn
 	c.n = nargs
 	c.args = uintptr(unsafe.Pointer(&a1))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	return c.r1, c.r2, c.err
 }
 
@@ -158,7 +158,7 @@ func syscall_Syscall12(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11,
 	c.fn = fn
 	c.n = nargs
 	c.args = uintptr(unsafe.Pointer(&a1))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	return c.r1, c.r2, c.err
 }
 
@@ -169,6 +169,6 @@ func syscall_Syscall15(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11,
 	c.fn = fn
 	c.n = nargs
 	c.args = uintptr(unsafe.Pointer(&a1))
-	cgocall_errno(unsafe.Pointer(funcPC(asmstdcall)), unsafe.Pointer(&c))
+	cgocall_errno(asmstdcallAddr, unsafe.Pointer(&c))
 	return c.r1, c.r2, c.err
 }