i965/fs: Allow register coalescing where the source is a uniform.

Removes 0.8% of the fragment shader instructions on Unigine Tropics.

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index a9617c5..e07798c 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1196,7 +1196,8 @@ fs_visitor::register_coalesce()
       if (inst->opcode != BRW_OPCODE_MOV ||
          inst->predicated ||
          inst->saturate ||
-         inst->dst.file != GRF || inst->src[0].file != GRF ||
+         inst->dst.file != GRF || (inst->src[0].file != GRF &&
+                                   inst->src[0].file != UNIFORM)||
          inst->dst.type != inst->src[0].type)
         continue;
 
@@ -1218,7 +1219,8 @@ fs_visitor::register_coalesce()
               interfered = true;
               break;
            }
-           if (scan_inst->dst.reg == inst->src[0].reg &&
+           if (inst->src[0].file == GRF &&
+               scan_inst->dst.reg == inst->src[0].reg &&
                (scan_inst->dst.reg_offset == inst->src[0].reg_offset ||
                 scan_inst->is_tex())) {
               interfered = true;
@@ -1226,10 +1228,13 @@ fs_visitor::register_coalesce()
            }
         }
 
-        /* The gen6 MATH instruction can't handle source modifiers, so avoid
-         * coalescing those for now.  We should do something more specific.
+        /* The gen6 MATH instruction can't handle source modifiers or
+         * unusual register regions, so avoid coalescing those for
+         * now.  We should do something more specific.
          */
-        if (intel->gen >= 6 && scan_inst->is_math() && has_source_modifiers) {
+        if (intel->gen >= 6 &&
+            scan_inst->is_math() &&
+            (has_source_modifiers || inst->src[0].file == UNIFORM)) {
            interfered = true;
            break;
         }
@@ -1248,11 +1253,10 @@ fs_visitor::register_coalesce()
            if (scan_inst->src[i].file == GRF &&
                scan_inst->src[i].reg == inst->dst.reg &&
                scan_inst->src[i].reg_offset == inst->dst.reg_offset) {
-              scan_inst->src[i].reg = inst->src[0].reg;
-              scan_inst->src[i].reg_offset = inst->src[0].reg_offset;
-              scan_inst->src[i].abs |= inst->src[0].abs;
-              scan_inst->src[i].negate ^= inst->src[0].negate;
-              scan_inst->src[i].smear = inst->src[0].smear;
+              fs_reg new_src = inst->src[0];
+              new_src.negate ^= scan_inst->src[i].negate;
+              new_src.abs |= scan_inst->src[i].abs;
+              scan_inst->src[i] = new_src;
            }
         }
       }