[Mesa-dev] [RFC 3/6] i915: Add support for xfb overflow on query buffer objects.

[Ian Romanick]

Minor nit: i965 in the subject. :)

On 12/05/2016 10:16 AM, Rafael Antognolli wrote:
> Enable getting the results of a transform feedback overflow query with a
> buffer object.
> 
> Signed-off-by: Rafael Antognolli <rafael.antognolli at intel.com>
> ---
>  src/mesa/drivers/dri/i965/hsw_queryobj.c | 108 +++++++++++++++++++++++++++++++
>  1 file changed, 108 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/hsw_queryobj.c b/src/mesa/drivers/dri/i965/hsw_queryobj.c
> index 0da2c3d..0c9dbdc 100644
> --- a/src/mesa/drivers/dri/i965/hsw_queryobj.c
> +++ b/src/mesa/drivers/dri/i965/hsw_queryobj.c
> @@ -187,6 +187,103 @@ gpr0_to_bool(struct brw_context *brw)
>  }
>  
>  static void
> +load_gen_written_data_to_regs(struct brw_context *brw,
> +                              struct brw_query_object *query,
> +                              int idx)
> +{
> +   int offset = idx * sizeof(uint64_t) * 4;
> +
> +   brw_load_register_mem64(brw,
> +                           HSW_CS_GPR(1),
> +                           query->bo,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           offset);
> +
> +   offset += sizeof(uint64_t);
> +   brw_load_register_mem64(brw,
> +                           HSW_CS_GPR(2),
> +                           query->bo,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           offset);
> +
> +   offset += sizeof(uint64_t);
> +   brw_load_register_mem64(brw,
> +                           HSW_CS_GPR(3),
> +                           query->bo,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           offset);
> +
> +   offset += sizeof(uint64_t);
> +   brw_load_register_mem64(brw,
> +                           HSW_CS_GPR(4),
> +                           query->bo,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           I915_GEM_DOMAIN_INSTRUCTION,
> +                           offset);
> +}
> +
> +/*
> + * R3 = R4 - R3;
> + * R1 = R2 - R1;
> + * R1 = R3 - R1;
> + * R0 = R0 | R1;
> + */
> +static void
> +calc_overflow_for_stream(struct brw_context *brw)
> +{
> +   static const uint32_t maths[] = {
> +      MI_MATH_ALU2(LOAD, SRCA, R4),
> +      MI_MATH_ALU2(LOAD, SRCB, R3),
> +      MI_MATH_ALU0(SUB),
> +      MI_MATH_ALU2(STORE, R3, ACCU),
> +      MI_MATH_ALU2(LOAD, SRCA, R2),
> +      MI_MATH_ALU2(LOAD, SRCB, R1),
> +      MI_MATH_ALU0(SUB),
> +      MI_MATH_ALU2(STORE, R1, ACCU),
> +      MI_MATH_ALU2(LOAD, SRCA, R3),
> +      MI_MATH_ALU2(LOAD, SRCB, R1),
> +      MI_MATH_ALU0(SUB),
> +      MI_MATH_ALU2(STORE, R1, ACCU),
> +      MI_MATH_ALU2(LOAD, SRCA, R1),
> +      MI_MATH_ALU2(LOAD, SRCB, R0),
> +      MI_MATH_ALU0(OR),
> +      MI_MATH_ALU2(STORE, R0, ACCU),
> +   };
> +
> +   BEGIN_BATCH(1 + ARRAY_SIZE(maths));
> +   OUT_BATCH(HSW_MI_MATH | (1 + ARRAY_SIZE(maths) - 2));
> +
> +   for (int m = 0; m < ARRAY_SIZE(maths); m++)
> +      OUT_BATCH(maths[m]);
> +
> +   ADVANCE_BATCH();
> +}
> +
> +static void
> +calc_overflow_to_gpr0(struct brw_context *brw, struct brw_query_object *query,
> +                       int count)
> +{
> +   brw_load_register_imm64(brw, HSW_CS_GPR(0), 0ull);
> +
> +   for (int i = 0; i < count; i++) {
> +      load_gen_written_data_to_regs(brw, query, i);
> +      calc_overflow_for_stream(brw);
> +   }
> +}
> +
> +static void
> +overflow_result_to_grp0(struct brw_context *brw,
> +                        struct brw_query_object *query,
> +                        int count)
> +{
> +   calc_overflow_to_gpr0(brw, query, count);
> +   gpr0_to_bool(brw);
> +}
> +
> +static void
>  hsw_result_to_gpr0(struct gl_context *ctx, struct brw_query_object *query,
>                     struct gl_buffer_object *buf, intptr_t offset,
>                     GLenum pname, GLenum ptype)
> @@ -223,6 +320,11 @@ hsw_result_to_gpr0(struct gl_context *ctx, struct brw_query_object *query,
>                                I915_GEM_DOMAIN_INSTRUCTION,
>                                I915_GEM_DOMAIN_INSTRUCTION,
>                                0 * sizeof(uint64_t));
> +   } else if (query->Base.Target == GL_TRANSFORM_FEEDBACK_STREAM_OVERFLOW_ARB
> +              || query->Base.Target == GL_TRANSFORM_FEEDBACK_OVERFLOW_ARB) {
> +      /* Don't do anything in advance here, since the math for this is a little
> +       * more complex.
> +       */
>     } else {
>        brw_load_register_mem64(brw,
>                                HSW_CS_GPR(1),
> @@ -274,6 +376,12 @@ hsw_result_to_gpr0(struct gl_context *ctx, struct brw_query_object *query,
>     case GL_ANY_SAMPLES_PASSED_CONSERVATIVE:
>        gpr0_to_bool(brw);
>        break;
> +   case GL_TRANSFORM_FEEDBACK_STREAM_OVERFLOW_ARB:
> +      overflow_result_to_grp0(brw, query, 1);
> +      break;
> +   case GL_TRANSFORM_FEEDBACK_OVERFLOW_ARB:
> +      overflow_result_to_grp0(brw, query, MAX_VERTEX_STREAMS);
> +      break;
>     }
>  }
>  
>