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i965/fs: Create the COPY() set for use in copy propagation dataflow.

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This is the "COPY" set from Muchnick's textbook, which is necessary
to do the dataflow algorithm correctly.

v2: Simplify initialization based on Paul Berry's observation that
    out_acp contains exactly what needs to be in the COPY set.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Paul Berry <stereotype441@gmail.com>
This commit is contained in:
Kenneth Graunke
2013-08-08 23:29:56 -07:00
parent 669d4d7f77
commit 597efd2b67
1 changed files with 15 additions and 0 deletions
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src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+15
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@@ -60,6 +60,13 @@ struct block_data {
*/
BITSET_WORD *liveout;
/**
* Which entries in the fs_copy_prop_dataflow acp table are generated by
* instructions in this block which reach the end of the block without
* being killed.
*/
BITSET_WORD *copy;
/**
* Which entries in the fs_copy_prop_dataflow acp table are killed over the
* course of this block.
@@ -110,6 +117,7 @@ fs_copy_prop_dataflow::fs_copy_prop_dataflow(void *mem_ctx, cfg_t *cfg,
for (int b = 0; b < cfg->num_blocks; b++) {
bd[b].livein = rzalloc_array(bd, BITSET_WORD, bitset_words);
bd[b].liveout = rzalloc_array(bd, BITSET_WORD, bitset_words);
bd[b].copy = rzalloc_array(bd, BITSET_WORD, bitset_words);
bd[b].kill = rzalloc_array(bd, BITSET_WORD, bitset_words);
for (int i = 0; i < ACP_HASH_SIZE; i++) {
@@ -117,6 +125,13 @@ fs_copy_prop_dataflow::fs_copy_prop_dataflow(void *mem_ctx, cfg_t *cfg,
acp_entry *entry = (acp_entry *)entry_node;
acp[next_acp] = entry;
/* opt_copy_propagate_local populates out_acp with copies created
* in a block which are still live at the end of the block. This
* is exactly what we want in the COPY set.
*/
BITSET_SET(bd[b].copy, next_acp);
BITSET_SET(bd[b].liveout, next_acp);
next_acp++;
}