[Mesa-dev] [PATCH 2/2] Implement WaClearTDRRegBeforeEOTForNonPS.

[Kenneth Graunke]

On Thursday, November 30, 2017 4:42:48 PM PST Rafael Antognolli wrote:
> The bspec describes:
> 
>    "WA: Clear tdr register before send EOT in all non-PS shader kernels
> 
>    mov(8) tdr0:ud 0x0:ud {NoMask}"
> 
> Signed-off-by: Rafael Antognolli <rafael.antognolli at intel.com>
> ---
>  src/intel/compiler/brw_fs_generator.cpp | 7 +++++++
>  src/intel/compiler/brw_reg.h            | 6 ++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/src/intel/compiler/brw_fs_generator.cpp b/src/intel/compiler/brw_fs_generator.cpp
> index 28790c86a64..78aa764fe73 100644
> --- a/src/intel/compiler/brw_fs_generator.cpp
> +++ b/src/intel/compiler/brw_fs_generator.cpp
> @@ -573,6 +573,13 @@ fs_generator::generate_urb_write(fs_inst *inst, struct brw_reg payload)
>  {
>     brw_inst *insn;
>  
> +   if (inst->eot) {
> +      brw_push_insn_state(p);
> +      brw_set_default_mask_control(p, BRW_MASK_DISABLE);
> +      brw_MOV(p, brw_tdr_reg(), brw_imm_uw(0));
> +      brw_pop_insn_state(p);
> +   }
> +
>     insn = brw_next_insn(p, BRW_OPCODE_SEND);
>  
>     brw_set_dest(p, insn, brw_null_reg());
> diff --git a/src/intel/compiler/brw_reg.h b/src/intel/compiler/brw_reg.h
> index ec1045b612a..a039c6f676c 100644
> --- a/src/intel/compiler/brw_reg.h
> +++ b/src/intel/compiler/brw_reg.h
> @@ -774,6 +774,12 @@ brw_address_reg(unsigned subnr)
>     return brw_uw1_reg(BRW_ARCHITECTURE_REGISTER_FILE, BRW_ARF_ADDRESS, subnr);
>  }
>  
> +static inline struct brw_reg
> +brw_tdr_reg(void)
> +{
> +   return brw_uw1_reg(BRW_ARCHITECTURE_REGISTER_FILE, BRW_ARF_TDR, 0);
> +}
> +
>  /* If/else instructions break in align16 mode if writemask & swizzle
>   * aren't xyzw.  This goes against the convention for other scalar
>   * regs:
> 

Still not clear whether this is needed for compute shaders or not.

Looks good for the other stages.

My gut feeling is that this only matters if you're doing preemption
(possibly mid-draw preemption), but I have no data to back that up.
We may as well do it...

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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