From 40e5138fb1e615c927a21d0b3f2e24eca885ede4 Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Thu, 15 Jul 2021 10:39:28 +0200
Subject: [PATCH 36/39] configure: Fix endianess test with LTO

RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 24: v7:  Add support for building qemu-kvm with clang and safe-stack
RH-Commit: [9/11] c4be415076356fe74efab6f74d7b347064bbdb40 (jmaloy/qemu-kvm-centos-jon)
RH-Bugzilla: 1939509 1940132
RH-Acked-by: Danilo Cesar Lemes de Paula <ddepaula@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>

If a user is trying to compile QEMU with link-time optimization
enabled by running the configure script like this:

 .../configure --extra-cflags="-flto"

then the endianess test is failing since the magic values do not
show up in the intermediate object files there. If the host is
a big endian machine (like s390x), the QEMU binary is then unusable
since the corresponding variable "bigendian" is pre-initialized
with "no".

To fix this issue, we should rather create a full binary and look
for the magic strings there instead.
And we really should not continue the build if the endianess check
failed, to make it clear right from the start that something went
wrong here, thus let's also add some "exit 1" statements here
after emitting the error message.

Message-Id: <20210715083928.933806-1-thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 659eb157a55666bf379f5362238a86d855e262e2)
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 configure | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index 83d8af7fe4..dcd9520bed 100755
--- a/configure
+++ b/configure
@@ -2323,24 +2323,27 @@ feature_not_found() {
 # ---
 # big/little endian test
 cat > $TMPC << EOF
+#include <stdio.h>
 short big_endian[] = { 0x4269, 0x4765, 0x4e64, 0x4961, 0x4e00, 0, };
 short little_endian[] = { 0x694c, 0x7454, 0x654c, 0x6e45, 0x6944, 0x6e41, 0, };
-extern int foo(short *, short *);
-int main(int argc, char *argv[]) {
-    return foo(big_endian, little_endian);
+int main(int argc, char *argv[])
+{
+    return printf("%s %s\n", (char *)big_endian, (char *)little_endian);
 }
 EOF
 
-if compile_object ; then
-    if strings -a $TMPO | grep -q BiGeNdIaN ; then
+if compile_prog ; then
+    if strings -a $TMPE | grep -q BiGeNdIaN ; then
         bigendian="yes"
-    elif strings -a $TMPO | grep -q LiTtLeEnDiAn ; then
+    elif strings -a $TMPE | grep -q LiTtLeEnDiAn ; then
         bigendian="no"
     else
         echo big/little test failed
+        exit 1
     fi
 else
     echo big/little test failed
+    exit 1
 fi
 
 ##########################################
-- 
2.27.0