Excluding the existing liveout bits is a deviation from the textbook
algorithm. The reason for doing so was to determine if the value
changed, which means the fixed-point algorithm needs to run for another
iteration.
The simpler way to do that is to save the value from step (N-1) and
compare it to the new value at step N.
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index 2970af6..2ab7734 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -194,13 +194,12 @@ fs_copy_prop_dataflow::run()
/* Update liveout for all blocks. */
for (int b = 0; b < cfg->num_blocks; b++) {
for (int i = 0; i < bitset_words; i++) {
- BITSET_WORD new_liveout = (bd[b].livein[i] &
- ~bd[b].kill[i] &
- ~bd[b].liveout[i]);
- if (new_liveout) {
- bd[b].liveout[i] |= new_liveout;
+ const BITSET_WORD old_liveout = bd[b].liveout[i];
+
+ bd[b].liveout[i] |= bd[b].livein[i] & ~bd[b].kill[i];
+
+ if (old_liveout != bd[b].liveout[i])
progress = true;
- }
}
}
--
1.8.3.4
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