i965/fs: Allow constant propagation into MACH.

This happens quite a bit with varying-index uniform loads.  We could also
do better by avoiding the MACH entirely, but there's no reason not to at
least take this step.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

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 ec72ede87b9a1d89288ba01f5f19f75d04d8b0cc..96c9b4efc4b0840679e2059dd51bed6fb46b2e93 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -262,6 +262,7 @@ fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry)
          progress = true;
          break;
 
+      case BRW_OPCODE_MACH:
       case BRW_OPCODE_MUL:
       case BRW_OPCODE_ADD:
          if (i == 1) {
@@ -269,10 +270,11 @@ fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry)
             progress = true;
          } else if (i == 0 && inst->src[1].file != IMM) {
             /* Fit this constant in by commuting the operands.
-             * Exception: we can't do this for 32-bit integer MUL
+             * Exception: we can't do this for 32-bit integer MUL/MACH
              * because it's asymmetric.
              */
-            if (inst->opcode == BRW_OPCODE_MUL &&
+            if ((inst->opcode == BRW_OPCODE_MUL ||
+                 inst->opcode == BRW_OPCODE_MACH) &&
                 (inst->src[1].type == BRW_REGISTER_TYPE_D ||
                  inst->src[1].type == BRW_REGISTER_TYPE_UD))
                break;