[Mesa-dev] [PATCH 1/2] i965: Fix Haswell discard regressions since Gen4-5 line AA fix.

Kenneth Graunke kenneth at whitecape.org
Tue Jun 10 20:12:47 PDT 2014

In commit dc2d3a7f5c217a7cee92380fbf503924a9591bea, Iago accidentally
moved fire_fb_write() above the brw_pop_insn_state(), which caused the
SEND to lose its predication and change from WE_normal to WE_all.
Haswell uses predicated SENDs for discards, so this broke Piglit's
tests for discards.

We want the Gen4-5 MOV to be uncompressed, unpredicated, and unmasked,
but the actual FB write itself should respect those.  So, pop state
first, and force it again around the single MOV.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: Iago Toral Quiroga <itoral at igalia.com>
 src/mesa/drivers/dri/i965/brw_fs_generator.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

I originally Piglit those patches on Crestline, but neglected to test
Haswell, and missed this.  Whoops.  But easily fixed!

I tested these two patches on both Crestline and Haswell this time,
and also tested Iago's line_aa demo to make sure it still worked too.

diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
index 3787d24..d21b4e2 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
@@ -106,9 +106,14 @@ fs_generator::fire_fb_write(fs_inst *inst,
    uint32_t msg_control;
    if (brw->gen < 6) {
+      brw_push_insn_state(p);
+      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_message_reg(base_reg + 1),
               brw_vec8_grf(1, 0));
+      brw_pop_insn_state(p);
    if (this->dual_source_output)
@@ -196,6 +201,8 @@ fs_generator::generate_fb_write(fs_inst *inst)
       implied_header = brw_null_reg();
+   brw_pop_insn_state(p);
    if (!runtime_check_aads_emit) {
       fire_fb_write(inst, inst->base_mrf, implied_header, inst->mlen);
    } else {
@@ -221,8 +228,6 @@ fs_generator::generate_fb_write(fs_inst *inst)
       brw_land_fwd_jump(p, jmp);
       fire_fb_write(inst, inst->base_mrf, implied_header, inst->mlen);
-   brw_pop_insn_state(p);

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