[Mesa-dev] [PATCH] i965/fs: Don't set flag_subreg_nr = 1 on predicated FB write setup.

[Kenneth Graunke]

On Haswell, we implement "discard" via predicated SEND messages, using
f0.1 instead of f0.0.  To accomplish this, we set inst->flag_subreg to 1
on the FS_OPCODE_FB_WRITE.

Most instructions using fs_inst::flag_subreg expand to a single assembly
instruction.  However, FS_OPCODE_FB_WRITE can generate several MOVs for
setting up header information.  We don't want to set flag_subreg on
those, so override the default state back to 0.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_fs_generator.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
index cec2e82..710406c 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
@@ -152,6 +152,7 @@ fs_generator::generate_fb_write(fs_inst *inst)
       brw_set_default_mask_control(p, BRW_MASK_DISABLE);
       brw_set_default_predicate_control(p, BRW_PREDICATE_NONE);
       brw_set_default_compression_control(p, BRW_COMPRESSION_NONE);
+      brw_set_default_flag_reg(p, 0, 0);
 
       /* On HSW, the GPU will use the predicate on SENDC, unless the header is
        * present.
-- 
2.0.2