1From f107467179428a0e3ea9e4aa9738ac12ff02822d Mon Sep 17 00:00:00 2001
2From: Colin Watson <cjwatson@debian.org>
3Date: Thu, 24 Feb 2022 16:04:18 +0000
4Subject: [PATCH] Improve detection of -fzero-call-used-regs=all support
5
6GCC doesn't tell us whether this option is supported unless it runs into
7the situation where it would need to emit corresponding code.
8
9Upstream-Status: Backport
10Signed-off-by: Alexander Kanavin <alex@linutronix.de>
11---
12 m4/openssh.m4 | 3 +++
13 1 file changed, 3 insertions(+)
14
15diff --git a/m4/openssh.m4 b/m4/openssh.m4
16index 4f9c3792dc1..8c33c701b8b 100644
17--- a/m4/openssh.m4
18+++ b/m4/openssh.m4
19@@ -14,6 +14,8 @@ AC_DEFUN([OSSH_CHECK_CFLAG_COMPILE], [{
20 	AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
21 #include <stdlib.h>
22 #include <stdio.h>
23+/* Trivial function to help test for -fzero-call-used-regs */
24+void f(int n) {}
25 int main(int argc, char **argv) {
26 	(void)argv;
27 	/* Some math to catch -ftrapv problems in the toolchain */
28@@ -21,6 +23,7 @@ int main(int argc, char **argv) {
29 	float l = i * 2.1;
30 	double m = l / 0.5;
31 	long long int n = argc * 12345LL, o = 12345LL * (long long int)argc;
32+	f(0);
33 	printf("%d %d %d %f %f %lld %lld\n", i, j, k, l, m, n, o);
34 	/*
35 	 * Test fallthrough behaviour.  clang 10's -Wimplicit-fallthrough does
36