i965/fs: Pass a BAD_FILE register to the logical FB write when oMask is unused.

This will let the optimizer know that the sample mask value is unused
so its definition can be DCE'ed.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index f5add6ec676b1081c4db7301ba341b48cc9cbd0b..0b350d5ff76e87be1d197f55d4bf3aecc7cec469 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3797,7 +3797,7 @@ lower_fb_write_logical_send(const fs_builder &bld, fs_inst *inst,
       length++;
    }
 
-   if (prog_data->uses_omask) {
+   if (sample_mask.file != BAD_FILE) {
       sources[length] = fs_reg(VGRF, bld.shader->alloc.allocate(1),
                                BRW_REGISTER_TYPE_UD);
 

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 25e1a445136ed01ddb40685de84894b1b33c2410..3a49794c9cf57aa6c314dda3641f2fdff115a9b3 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -394,7 +394,8 @@ fs_visitor::emit_single_fb_write(const fs_builder &bld,
 
    const fs_reg sources[] = {
       color0, color1, src0_alpha, src_depth, dst_depth, src_stencil,
-      sample_mask, brw_imm_ud(components)
+      (prog_data->uses_omask ? sample_mask : fs_reg()),
+      brw_imm_ud(components)
    };
    assert(ARRAY_SIZE(sources) - 1 == FB_WRITE_LOGICAL_SRC_COMPONENTS);
    fs_inst *write = bld.emit(FS_OPCODE_FB_WRITE_LOGICAL, fs_reg(),