[Mesa-dev] [PATCH 10/15] i965/fs: Properly initialize the livein/liveout sets.

[Kenneth Graunke]

Previously, livein was initialized to 0 for all blocks.  According to
the textbook, it should be the universal set (~0) for all blocks except
the one representing the start of the program (which should be 0).

liveout also needs to be initialized to COPY for the initial block.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 .../drivers/dri/i965/brw_fs_copy_propagation.cpp    | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

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 fd726e0..3344f89 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -147,6 +147,7 @@ fs_copy_prop_dataflow::fs_copy_prop_dataflow(void *mem_ctx, cfg_t *cfg,
 void
 fs_copy_prop_dataflow::setup_initial_values()
 {
+   /* Initialize the COPY and KILL sets. */
    for (int b = 0; b < cfg->num_blocks; b++) {
       bblock_t *block = cfg->blocks[b];
 
@@ -177,6 +178,26 @@ fs_copy_prop_dataflow::setup_initial_values()
          bd[b].copy[i] &= ~bd[b].kill[i];
       }
    }
+
+   /* Populate the initial values for the livein and liveout sets.  For the
+    * block at the start of the program, livein = 0 and liveout = copy.
+    * For the others, set liveout to 0 (the empty set) and livein to ~0
+    * (the universal set).
+    */
+   for (int b = 0; b < cfg->num_blocks; b++) {
+      bblock_t *block = cfg->blocks[b];
+      if (block->parents.is_empty()) {
+         for (int i = 0; i < bitset_words; i++) {
+            bd[b].livein[i] = 0u;
+            bd[b].liveout[i] = bd[b].copy[i];
+         }
+      } else {
+         for (int i = 0; i < bitset_words; i++) {
+            bd[b].liveout[i] = 0u;
+            bd[b].livein[i] = ~0u;
+         }
+      }
+   }
 }
 
 /**
-- 
1.8.3.4