// we can use it to catch exceptions from C code.
		// TODO: use a more generic approach to identify which calls need an exception handler.
		exceptionHandler = ctxt.Lookup("runtime.sehtramp")
		if exceptionHandler == nil {
			ctxt.Diag("missing runtime.sehtramp\n")
			return
		}
		flags = UNW_FLAG_EHANDLER
	}

	// Fow now we only support operations which are encoded
	// using a single 2-byte node, so the number of nodes

	MOVQ	$const_callbackVEH, DX
	JMP	sigtramp<>(SB)

TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
	// PExceptionPointers already on CX
	MOVQ	$const_callbackFirstVCH, DX
	JMP	sigtramp<>(SB)

TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
	// PExceptionPointers already on CX
	MOVQ	$const_callbackLastVCH, DX
	JMP	sigtramp<>(SB)

TEXT runtime·sehtramp(SB),NOSPLIT,$40-0

	}
}

// in sys_windows_386.s, sys_windows_amd64.s, sys_windows_arm.s, and sys_windows_arm64.s
func exceptiontramp()
func firstcontinuetramp()
func lastcontinuetramp()
func sehtramp()
func sigresume()

func initExceptionHandler() {
	stdcall2(_AddVectoredExceptionHandler, 1, abi.FuncPCABI0(exceptiontramp))
	if GOARCH == "386" {
		// use SetUnhandledExceptionFilter for windows-386.

	ADJSP	$32
	// On Windows, asmcgocall_landingpad acts as landing pad for exceptions
	// thrown in the cgo call. Exceptions that reach this function will be
	// handled by runtime.sehtramp thanks to the SEH metadata added
	// by the compiler.
	// Note that runtime.sehtramp can't be attached directly to asmcgocall
	// because its initial stack pointer can be outside the system stack bounds,

#endif

// Call the user's traceback function and then call sigtramp.
// The runtime signal handler will jump to this code.
// We do it this way so that the user's traceback function will be called
// by a C function with proper unwind info.
void
x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(struct cgoTracebackArg*), uintptr_t* cgoCallers, void (*sigtramp)(uintptr_t, void*, void*)) {
	struct cgoTracebackArg arg;

	// Figure out if we are currently in a cgo call.
	// If not, just do usual sigtramp.
	get_tls(CX)
	MOVQ	g(CX),AX
	TESTQ	AX, AX
	JZ	sigtrampnog     // g == nil
	MOVQ	g_m(AX), AX
	TESTQ	AX, AX
	JZ	sigtramp        // g.m == nil
	MOVL	m_ncgo(AX), CX
	TESTL	CX, CX
	JZ	sigtramp        // g.m.ncgo == 0
	MOVQ	m_curg(AX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg == nil
	MOVQ	g_syscallsp(CX), CX

	// Figure out if we are currently in a cgo call.
	// If not, just do usual sigtramp.
	get_tls(CX)
	MOVQ	g(CX),AX
	TESTQ	AX, AX
	JZ	sigtrampnog     // g == nil
	MOVQ	g_m(AX), AX
	TESTQ	AX, AX
	JZ	sigtramp        // g.m == nil
	MOVL	m_ncgo(AX), CX
	TESTL	CX, CX
	JZ	sigtramp        // g.m.ncgo == 0
	MOVQ	m_curg(AX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg == nil
	MOVQ	g_syscallsp(CX), CX

	MOVD	$0, R0

	// If no traceback function, do usual sigtramp.
	MOVD	runtime·cgoTraceback(SB), R6
	CMP	$0, R6
	BEQ	sigtramp

	// If no traceback support function, which means that
	// runtime/cgo was not linked in, do usual sigtramp.
	MOVD	_cgo_callers(SB), R6
	CMP	$0, R6
	BEQ	sigtramp

	// Inspect the g in TLS without clobbering R30/R31 via runtime.load_g.

	// Figure out if we are currently in a cgo call.
	// If not, just do usual sigtramp.
	get_tls(CX)
	MOVQ	g(CX),AX
	TESTQ	AX, AX
	JZ	sigtrampnog     // g == nil
	MOVQ	g_m(AX), AX
	TESTQ	AX, AX
	JZ	sigtramp        // g.m == nil
	MOVL	m_ncgo(AX), CX
	TESTL	CX, CX
	JZ	sigtramp        // g.m.ncgo == 0
	MOVQ	m_curg(AX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg == nil
	MOVQ	g_syscallsp(CX), CX

	MOVD	0(R12), R0
	MOVD	R2, 40(R1)
	MOVD	8(R12), R2
	MOVD	R0, CTR
	BL	(CTR)
	MOVD	40(R1), R2
	BL	runtime·reginit(SB)
	RET


// runtime.sigtramp is a function descriptor to the real sigtramp.
DATA	runtime·sigtramp+0(SB)/8, $sigtramp<>(SB)
DATA	runtime·sigtramp+8(SB)/8, $TOC(SB)
DATA	runtime·sigtramp+16(SB)/8, $0
GLOBL	runtime·sigtramp(SB), NOPTR, $24