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| author | Solomon Peachy <pizza@shaftnet.org> | 2020-07-24 22:46:05 -0400 |
|---|---|---|
| committer | Solomon Peachy <pizza@shaftnet.org> | 2020-07-25 02:57:35 +0000 |
| commit | 469866b6c90c1de8a8581347a357e33a3dfd908c (patch) | |
| tree | 7a2c90cb606260d171822ac04fbecd0c8cae62ed | |
| parent | 677848cf80a06a2ffacbc99ef8fed4ff9e4ef6d7 (diff) | |
| download | rockbox-469866b.tar.gz rockbox-469866b.zip | |
mpegplayer: Fix aliasing rules violation on multi-core targets
As the PP series has no sense of cache coherency between its multiple
cores, we need to ensure the vo_data structure does not share cachelines
with anything else.
This was previously done by defining a uint8_t array and trying to
access it via typecasting hell, triggering a large pile of aliasing
violation warnings on newer toolchains and/or higher optimization
levels.
Instead of violating the C spec in an undefined-behaviour-sort-of-way,
create a union of the right size and alignment, and make one of its members
the structure we care about. Voila, everyone is happy.
Change-Id: Iad78f8132225437cd4aa10e6e5f6ae58ba996c19
| -rw-r--r-- | apps/plugins/mpegplayer/video_out_rockbox.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/apps/plugins/mpegplayer/video_out_rockbox.c b/apps/plugins/mpegplayer/video_out_rockbox.c index b05a229083..ee5c3400c5 100644 --- a/apps/plugins/mpegplayer/video_out_rockbox.c +++ b/apps/plugins/mpegplayer/video_out_rockbox.c @@ -47,9 +47,11 @@ struct vo_data #if NUM_CORES > 1 /* Cache aligned and padded to avoid clobbering other processors' cacheable * data */ -static uint8_t __vo_data[CACHEALIGN_UP(sizeof(struct vo_data))] - CACHEALIGN_ATTR; -#define vo (*((struct vo_data *)__vo_data)) +static union { + uint8_t __vo_data[CACHEALIGN_UP(sizeof(struct vo_data))]; + struct vo_data vo; +} vo_raw CACHEALIGN_ATTR; +#define vo vo_raw.vo #else static struct vo_data vo; #endif |