i965/fs: Properly initialize the livein/liveout sets.

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@whitecape.org>
Reviewed-by: Paul Berry <stereotype441@gmail.com>

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 9ffb64deb85a8670dc8a8c4ab3c2f131ea8c2ab8..81e3693286a8702bb2a4ddeaead44e9c54c27086 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -151,6 +151,7 @@ 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];
 
@@ -169,6 +170,26 @@ fs_copy_prop_dataflow::setup_initial_values()
          }
       }
    }
+
+   /* 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;
+         }
+      }
+   }
 }
 
 /**