[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 #4 from Marcos Simental <mrkzmrkz at gmail.com> ---
(In reply to Thiago Macieira from comment #3)
> 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

This patch works for me

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