}
	if !isShrinkStackSafe(gp) {
		throw("shrinkstack at bad time")
	}
	// Check for self-shrinks while in a libcall. These may have
	// pointers into the stack disguised as uintptrs, but these
	// code paths should all be nosplit.
	if gp == getg().m.curg && gp.m.libcallsp != 0 {
		throw("shrinking stack in libcall")
	}

	if debug.gcshrinkstackoff > 0 {
		return
	}
	f := findfunc(gp.startpc)

		u.initAt(mp.curg.syscallpc, mp.curg.syscallsp, 0, mp.curg, unwindSilentErrors)
	} else if usesLibcall() && mp.libcallg != 0 && mp.libcallpc != 0 && mp.libcallsp != 0 {
		// Libcall, i.e. runtime syscall on windows.
		// Collect Go stack that leads to the call.
		u.initAt(mp.libcallpc, mp.libcallsp, 0, mp.libcallg.ptr(), unwindSilentErrors)
	} else if mp != nil && mp.vdsoSP != 0 {
		// VDSO call, e.g. nanotime1 on Linux.

		releasem(mp)
		return false
	}
	status := readgstatus(gp)
	if status&^_Gscan != _Grunning || gp.syscallsp != 0 {
		releasem(mp)
		return false
	}
	if GOOS == "windows" && mp.libcallsp != 0 {
		releasem(mp)
		return false
	}
	releasem(mp)
	return true
}

// shouldPushSigpanic reports whether pc should be used as sigpanic's