Module: Mesa
Branch: master
Commit: c9e33e5cbf6b8b953932f283e1f0abcb6c77eb1f
URL:
http://cgit.freedesktop.org/mesa/mesa/commit/?id=c9e33e5cbf6b8b953932f283e1f0abcb6c77eb1f
Author: Francisco Jerez <curroje...@riseup.net>
Date: Thu Jan 23 22:01:00 2020 -0800
intel/fs/cse: Make HALT instruction act as CSE barrier.
Found by inspection. This seems particularly likely to cause problems
with instructions dependent on the current execution mask like
SHADER_OPCODE_FIND_LIVE_CHANNEL or the FS_OPCODE_LOAD_LIVE_CHANNELS
instruction I'm about to introduce, but one could imagine it leading
to data corruption if CSE ever managed to combine two instructions
before and after the FS_OPCODE_PLACEHOLDER_HALT, since the one before
may not be executed for some channels.
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.olive...@intel.com>
Cc: 20.0 <mesa-sta...@lists.freedesktop.org>
---
src/intel/compiler/brw_fs_cse.cpp | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/src/intel/compiler/brw_fs_cse.cpp
b/src/intel/compiler/brw_fs_cse.cpp
index b7c32f3907f..4751e11bcfe 100644
--- a/src/intel/compiler/brw_fs_cse.cpp
+++ b/src/intel/compiler/brw_fs_cse.cpp
@@ -317,6 +317,16 @@ fs_visitor::opt_cse_local(bblock_t *block, int &ip)
}
}
+ /* Discard jumps aren't represented in the CFG unfortunately, so we need
+ * to make sure that they behave as a CSE barrier, since we lack global
+ * dataflow information. This is particularly likely to cause problems
+ * with instructions dependent on the current execution mask like
+ * SHADER_OPCODE_FIND_LIVE_CHANNEL.
+ */
+ if (inst->opcode == FS_OPCODE_DISCARD_JUMP ||
+ inst->opcode == FS_OPCODE_PLACEHOLDER_HALT)
+ aeb.make_empty();
+
foreach_in_list_safe(aeb_entry, entry, &aeb) {
/* Kill all AEB entries that write a different value to or read from
* the flag register if we just wrote it.
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