intel/compiler: Improve fix_3src_operand()for-rafael

Allow ATTR and IMM sources unconditionally (ATTR are just GRFs, IMM will
be handled by opt_combine_constants(). Both are already allowed by
opt_copy_propagation().

Also allow FIXED_GRF if the regioning is 8,8,1. Could also allow other
stride=1 regions (e.g., 4,4,1) and scalar regions but I don't think
those occur. This is sufficient to allow a pass added in a future commit
(fs_visitor::lower_linterp) to avoid emitting extra MOV instructions.

I removed the 'src.stride > 1' case because it seems wrong: 3-src
instructions on Gen6-9 are align16-only and can only do stride=1 or
stride=0. A run through Jenkins with an assert(src.stride <= 1) never
triggers, so it seems that it was dead code.

1 files changed, 18 insertions, 5 deletions

diff --git a/src/intel/compiler/brw_fs_builder.h b/src/intel/compiler/brw_fs_builder.h
index 3fc6e5f2c25..a69e3c6ae80 100644
--- a/src/intel/compiler/brw_fs_builder.h
+++ b/src/intel/compiler/brw_fs_builder.h
@@ -733,13 +733,26 @@ namespace brw {
       src_reg
       fix_3src_operand(const src_reg &src) const
       {
-         if (src.file == VGRF || src.file == UNIFORM || src.stride > 1) {
+         switch (src.file) {
+         case FIXED_GRF:
+            /* FINISHME: Could handle scalar region, other stride=1 regions */
+            if (src.vstride != BRW_VERTICAL_STRIDE_8 ||
+                src.width != BRW_WIDTH_8 ||
+                src.hstride != BRW_HORIZONTAL_STRIDE_1)
+               break;
+            /* fallthrough */
+         case ATTR:
+         case VGRF:
+         case UNIFORM:
+         case IMM:
             return src;
-         } else {
-            dst_reg expanded = vgrf(src.type);
-            MOV(expanded, src);
-            return expanded;
+         default:
+            break;
          }
+
+         dst_reg expanded = vgrf(src.type);
+         MOV(expanded, src);
+         return expanded;
       }
 
       /**