[Mesa-dev] [Bug 110884] can't start GDM when building mesa master branch with LTO

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=110884

--- Comment #3 from Thiago Macieira <thiago at kde.org> ---
This patch appears to fix the problem:

>From 49607f0524539cb836065b626bb3d3946061c486 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira at intel.com>
Date: Mon, 10 Jun 2019 19:13:12 -0700
Subject: [PATCH] Attempt at fixing strict aliasing violation in dequeueing
 packets

lp_scene_dequeue() calls util_ringbuffer_dequeue() with a payload that
isn't an array of struct util_packets. When util_ringbuffer_dequeue()
made the direct copy, the compiler discarded because it wasn't writing
the right type.

Signed-off-by: Thiago Macieira <thiago.macieira at intel.com>
---
 src/gallium/auxiliary/util/u_ringbuffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/util/u_ringbuffer.c
b/src/gallium/auxiliary/util/u_ringbuffer.c
index f6bb910671e..cebb908410c 100644
--- a/src/gallium/auxiliary/util/u_ringbuffer.c
+++ b/src/gallium/auxiliary/util/u_ringbuffer.c
@@ -146,7 +146,7 @@ enum pipe_error util_ringbuffer_dequeue( struct
util_ringbuffer *ring,
    /* Copy data from ring:
     */
    for (i = 0; i < ring_packet->dwords; i++) {
-      packet[i] = ring->buf[ring->tail];
+      memcpy(packet + i, ring->buf + ring->tail, sizeof(*packet));
       ring->tail++;
       ring->tail &= ring->mask;
    }
-- 
2.22.0

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