i965/fs: Enumerate logical fb writes arguments

Gen9 adds the ability to write out a stencil value, so we need to expand the
virtual payload by one. Abstracting this now makes that change easier to read.

I was admittedly confused early on about some of the hardcoding. If people
believe the resulting code is inferior, I am not super attached to the patch.

v2:
Remove explicit numbering from the enumeration (Matt).
Use a real naming scheme, and reference it in the opcode definition (Curro)
Add a missed hardcoded logical position in get_lowered_simd_width (Ben)
Add an assertion to make sure the component numbering is correct (Ben)

Cc: Matt Turner <[email protected]>
Cc: Francisco Jerez <[email protected]>
Signed-off-by: Ben Widawsky <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 7cc4f3c927a..9e2b221265c 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -710,6 +710,7 @@ fs_visitor::emit_single_fb_write(const fs_builder &bld,
       color0, color1, src0_alpha, src_depth, dst_depth, sample_mask,
       fs_reg(components)
    };
+   assert(ARRAY_SIZE(sources) - 1 == FB_WRITE_LOGICAL_SRC_COMPONENTS);
    fs_inst *write = bld.emit(FS_OPCODE_FB_WRITE_LOGICAL, fs_reg(),
                              sources, ARRAY_SIZE(sources));