From b25de410a971169497e1f3bf0badbdfd729ffb9c Mon Sep 17 00:00:00 2001
From: Laurent Vivier <lvivier@redhat.com>
Date: Sat, 7 Apr 2018 23:02:58 -0400
Subject: [PATCH] tcg: fix 16-byte vector operations detection
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configure tries to detect if the compiler
supports 16-byte vector operations.

As stated in the comment of the detection
program, there is a problem with the system
compiler on GCC on Centos 7.

This program doesn't actually detect the problem
with GCC on RHEL7 on PPC64LE (Red Hat 4.8.5-28).

This patch updates the test to look more like
it is in QEMU helpers, and now detects the problem.

The error reported is:

CC ppc64-softmmu/accel/tcg/tcg-runtime-gvec.o
..//accel/tcg/tcg-runtime-gvec.c: In function ‘helper_gvec_shl8i’:
../accel/tcg/tcg-runtime-gvec.c:558:26: internal compiler error: in emit_move_insn, at expr.c:3495
*(vec8 *)(d + i) = *(vec8 *)(a + i) << shift;
^
Fixes: db43267 "tcg: Add generic vector expanders"

Backports commit 74912f6dad207bfdd5bfa8c6012c364ea9405fc7 from qemu
---
 qemu/configure | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/qemu/configure b/qemu/configure
index 57aff38a..69b620c4 100755
--- a/qemu/configure
+++ b/qemu/configure
@@ -1166,6 +1166,14 @@ static S2 c2;
 static S4 c4;
 static S8 c8;
 static int i;
+void helper(void *d, void *a, int shift, int i);
+void helper(void *d, void *a, int shift, int i)
+{
+  *(U1 *)(d + i) = *(U1 *)(a + i) << shift;
+  *(U2 *)(d + i) = *(U2 *)(a + i) << shift;
+  *(U4 *)(d + i) = *(U4 *)(a + i) << shift;
+  *(U8 *)(d + i) = *(U8 *)(a + i) << shift;
+}
 int main(void)
 {
   a1 += b1; a2 += b2; a4 += b4; a8 += b8;