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

[Iago Toral]

Urgh, sorry about that :-(
I'll be more careful when manipulating the state flags next time.

Iago

On Tue, 2014-06-10 at 20:12 -0700, Kenneth Graunke wrote:
> 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_MOV(p,
>                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);
>  }
>  
>  void