[Mesa-dev] [PATCH 2/2] i965/fs: Set force_uncompressed and force_sechalf on samplepos setup.

[Kenneth Graunke]

gen8_fs_generator uses these to decide whether to set the execution size
to 8 or 16, so we incorrectly made both of these MOVs the full width in
SIMD16 shaders.  (It happened to work out on Gen4-7.)

Setting them should also help inform optimization passes what's really
going on, which could help avoid bugs.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/drivers/dri/i965/brw_fs.cpp | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index a3ad375..ceea32a 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1248,19 +1248,21 @@ fs_visitor::emit_samplepos_setup(ir_variable *ir)
       stride(retype(brw_vec1_grf(payload.sample_pos_reg, 0),
                     BRW_REGISTER_TYPE_B), 16, 8, 2);
 
-   emit(MOV(int_sample_x, fs_reg(sample_pos_reg)));
+   fs_inst *inst = emit(MOV(int_sample_x, fs_reg(sample_pos_reg)));
    if (dispatch_width == 16) {
-      fs_inst *inst = emit(MOV(half(int_sample_x, 1),
-                               fs_reg(suboffset(sample_pos_reg, 16))));
+      inst->force_uncompressed = true;
+      inst = emit(MOV(half(int_sample_x, 1),
+                      fs_reg(suboffset(sample_pos_reg, 16))));
       inst->force_sechalf = true;
    }
    /* Compute gl_SamplePosition.x */
    compute_sample_position(pos, int_sample_x);
    pos.reg_offset++;
-   emit(MOV(int_sample_y, fs_reg(suboffset(sample_pos_reg, 1))));
+   inst = emit(MOV(int_sample_y, fs_reg(suboffset(sample_pos_reg, 1))));
    if (dispatch_width == 16) {
-      fs_inst *inst = emit(MOV(half(int_sample_y, 1),
-                               fs_reg(suboffset(sample_pos_reg, 17))));
+      inst->force_uncompressed = true;
+      inst = emit(MOV(half(int_sample_y, 1),
+                      fs_reg(suboffset(sample_pos_reg, 17))));
       inst->force_sechalf = true;
    }
    /* Compute gl_SamplePosition.y */
-- 
2.0.0