[Mesa-dev] [PATCH] i965/fs: Ignore type in cmod prop if scan_inst is CMP.

[Matt Turner]

total instructions in shared programs: 6263270 -> 6203091 (-0.96%)
instructions in affected programs:     2606529 -> 2546350 (-2.31%)
helped:                                14301
GAINED:                                5
LOST:                                  3

Revewed-by: Jason Ekstrand <jason.ekstrand at intel.com> [v1]
---
 .../drivers/dri/i965/brw_fs_cmod_propagation.cpp   | 25 +++++++++++-----------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp
index 1935f06..798fef3 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp
@@ -94,21 +94,22 @@ opt_cmod_propagation_local(bblock_t *block)
                 scan_inst->dst.reg_offset != inst->src[0].reg_offset)
                break;
 
-            /* This must be done before the dst.type check because the result
-             * type of the AND will always be D, but the result of the CMP
-             * could be anything.  The assumption is that the AND is just
-             * figuring out what the result of the previous comparison was
-             * instead of doing a new comparison with a different type.
-             */
-            if (inst->opcode == BRW_OPCODE_AND) {
-               if (scan_inst->opcode == BRW_OPCODE_CMP) {
-                  inst->remove(block);
-                  progress = true;
-               }
-
+            /* CMP's result is the same regardless of dest type. */
+            if (inst->conditional_mod == BRW_CONDITIONAL_NZ &&
+                scan_inst->opcode == BRW_OPCODE_CMP &&
+                (inst->dst.type == BRW_REGISTER_TYPE_D ||
+                 inst->dst.type == BRW_REGISTER_TYPE_UD)) {
+               inst->remove(block);
+               progress = true;
                break;
             }
 
+            /* If the AND wasn't handled by the previous case, it isn't safe
+             * to remove it.
+             */
+            if (inst->opcode == BRW_OPCODE_AND)
+               break;
+
             /* Comparisons operate differently for ints and floats */
             if (scan_inst->dst.type != inst->dst.type)
                break;
-- 
2.0.5