[Mesa-dev] [PATCH 4/4] radeonsi: postponed KILL isn't postponed anymore, but maintains WQM

[Nicolai Hähnle]

I found my peace with the new intrinsic for now. This series is

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

On 14.10.2017 02:58, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
> 
> This restores performance for the drirc workaround, i.e.
> KILL_IF does:
>     visible = src0 >= 0;
>     kill_flag &= visible; // accumulate kills
>     amdgcn_kill(wqm_vote(visible)); // kill fully dead quads only
> 
> And all helper pixels are killed at the end of the shader:
>     amdgcn_kill(kill_flag);
> ---
>   src/amd/common/ac_llvm_build.c                    | 7 +++++++
>   src/amd/common/ac_llvm_build.h                    | 1 +
>   src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c | 6 ++++++
>   3 files changed, 14 insertions(+)
> 
> diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
> index 0550f80..2f8f59f 100644
> --- a/src/amd/common/ac_llvm_build.c
> +++ b/src/amd/common/ac_llvm_build.c
> @@ -1398,20 +1398,27 @@ LLVMValueRef ac_build_cvt_pkrtz_f16(struct ac_llvm_context *ctx,
>   					   v2f16, args, 2,
>   					   AC_FUNC_ATTR_READNONE);
>   		return LLVMBuildBitCast(ctx->builder, res, ctx->i32, "");
>   	}
>   
>   	return ac_build_intrinsic(ctx, "llvm.SI.packf16", ctx->i32, args, 2,
>   				  AC_FUNC_ATTR_READNONE |
>   				  AC_FUNC_ATTR_LEGACY);
>   }
>   
> +LLVMValueRef ac_build_wqm_vote(struct ac_llvm_context *ctx, LLVMValueRef i1)
> +{
> +	assert(HAVE_LLVM >= 0x0600);
> +	return ac_build_intrinsic(ctx, "llvm.amdgcn.wqm.vote", ctx->i1,
> +				  &i1, 1, AC_FUNC_ATTR_READNONE);
> +}
> +
>   void ac_build_kill_if_false(struct ac_llvm_context *ctx, LLVMValueRef i1)
>   {
>   	if (HAVE_LLVM >= 0x0600) {
>   		ac_build_intrinsic(ctx, "llvm.amdgcn.kill", ctx->voidt,
>   				   &i1, 1, 0);
>   		return;
>   	}
>   
>   	LLVMValueRef value = LLVMBuildSelect(ctx->builder, i1,
>   					     LLVMConstReal(ctx->f32, 1),
> diff --git a/src/amd/common/ac_llvm_build.h b/src/amd/common/ac_llvm_build.h
> index b721782..088a986 100644
> --- a/src/amd/common/ac_llvm_build.h
> +++ b/src/amd/common/ac_llvm_build.h
> @@ -258,20 +258,21 @@ struct ac_image_args {
>   	LLVMValueRef addr;
>   	unsigned dmask;
>   	bool unorm;
>   	bool da;
>   };
>   
>   LLVMValueRef ac_build_image_opcode(struct ac_llvm_context *ctx,
>   				   struct ac_image_args *a);
>   LLVMValueRef ac_build_cvt_pkrtz_f16(struct ac_llvm_context *ctx,
>   				    LLVMValueRef args[2]);
> +LLVMValueRef ac_build_wqm_vote(struct ac_llvm_context *ctx, LLVMValueRef i1);
>   void ac_build_kill_if_false(struct ac_llvm_context *ctx, LLVMValueRef i1);
>   LLVMValueRef ac_build_bfe(struct ac_llvm_context *ctx, LLVMValueRef input,
>   			  LLVMValueRef offset, LLVMValueRef width,
>   			  bool is_signed);
>   
>   void ac_get_image_intr_name(const char *base_name,
>   			    LLVMTypeRef data_type,
>   			    LLVMTypeRef coords_type,
>   			    LLVMTypeRef rsrc_type,
>   			    char *out_name, unsigned out_len);
> diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
> index 283a889..913b6c3 100644
> --- a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
> +++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
> @@ -62,20 +62,26 @@ static void kil_emit(const struct lp_build_tgsi_action *action,
>   	LLVMValueRef visible;
>   
>   	if (emit_data->inst->Instruction.Opcode == TGSI_OPCODE_KILL_IF) {
>   		visible = emit_data->args[0];
>   	} else {
>   		assert(emit_data->inst->Instruction.Opcode == TGSI_OPCODE_KILL);
>   		visible = LLVMConstInt(ctx->i1, false, 0);
>   	}
>   
>   	if (ctx->shader->selector->force_correct_derivs_after_kill) {
> +		/* LLVM 6.0 can kill immediately while maintaining WQM. */
> +		if (HAVE_LLVM >= 0x0600) {
> +			ac_build_kill_if_false(&ctx->ac,
> +					       ac_build_wqm_vote(&ctx->ac, visible));
> +		}
> +
>   		LLVMValueRef mask = LLVMBuildLoad(builder, ctx->postponed_kill, "");
>   		mask = LLVMBuildAnd(builder, mask, visible, "");
>   		LLVMBuildStore(builder, mask, ctx->postponed_kill);
>   		return;
>   	}
>   
>   	ac_build_kill_if_false(&ctx->ac, visible);
>   }
>   
>   static void emit_icmp(const struct lp_build_tgsi_action *action,
> 


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.