On Mon, 2015-10-19 at 21:08 -0700, Matt Turner wrote:
> Otherwise we'd emit a MOV from the null register (which isn't allowed).
>
> Helps 24 programs in shader-db (the geometry shaders in GSCloth):
>
> instructions in affected programs: 302 -> 262 (-13.25%)
Makes sense to me,
Reviewed-by: Iago Toral Quiroga <ito...@igalia.com>
Out of curiosity, does moving from the null register have any actual
consequences?
Iago
> ---
> src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp | 18 +++++++++++++-----
> src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp | 2 +-
> 2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> index f891910..c39f97e 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> @@ -1221,6 +1221,9 @@ vec4_visitor::emit_untyped_surface_read(unsigned
> surf_index, dst_reg dst,
> void
> vec4_visitor::emit_ndc_computation()
> {
> + if (output_reg[VARYING_SLOT_POS].file == BAD_FILE)
> + return;
> +
> /* Get the position */
> src_reg pos = src_reg(output_reg[VARYING_SLOT_POS]);
>
> @@ -1286,7 +1289,8 @@ vec4_visitor::emit_psiz_and_flags(dst_reg reg)
> * Later, clipping will detect ucp[6] and ensure the primitive is
> * clipped against all fixed planes.
> */
> - if (devinfo->has_negative_rhw_bug) {
> + if (devinfo->has_negative_rhw_bug &&
> + output_reg[BRW_VARYING_SLOT_NDC].file != BAD_FILE) {
> src_reg ndc_w = src_reg(output_reg[BRW_VARYING_SLOT_NDC]);
> ndc_w.swizzle = BRW_SWIZZLE_WWWW;
> emit(CMP(dst_null_f(), ndc_w, src_reg(0.0f), BRW_CONDITIONAL_L));
> @@ -1334,8 +1338,10 @@ vec4_visitor::emit_generic_urb_slot(dst_reg reg, int
> varying)
> assert(varying < VARYING_SLOT_MAX);
> assert(output_reg[varying].type == reg.type);
> current_annotation = output_reg_annotation[varying];
> - /* Copy the register, saturating if necessary */
> - return emit(MOV(reg, src_reg(output_reg[varying])));
> + if (output_reg[varying].file != BAD_FILE)
> + return emit(MOV(reg, src_reg(output_reg[varying])));
> + else
> + return NULL;
> }
>
> void
> @@ -1354,11 +1360,13 @@ vec4_visitor::emit_urb_slot(dst_reg reg, int varying)
> }
> case BRW_VARYING_SLOT_NDC:
> current_annotation = "NDC";
> - emit(MOV(reg, src_reg(output_reg[BRW_VARYING_SLOT_NDC])));
> + if (output_reg[BRW_VARYING_SLOT_NDC].file != BAD_FILE)
> + emit(MOV(reg, src_reg(output_reg[BRW_VARYING_SLOT_NDC])));
> break;
> case VARYING_SLOT_POS:
> current_annotation = "gl_Position";
> - emit(MOV(reg, src_reg(output_reg[VARYING_SLOT_POS])));
> + if (output_reg[VARYING_SLOT_POS].file != BAD_FILE)
> + emit(MOV(reg, src_reg(output_reg[VARYING_SLOT_POS])));
> break;
> case VARYING_SLOT_EDGE:
> /* This is present when doing unfilled polygons. We're supposed to
> copy
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
> index 485a80e..5dd4f98 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
> @@ -217,7 +217,7 @@ vec4_vs_visitor::emit_urb_slot(dst_reg reg, int varying)
> * shader.
> */
> vec4_instruction *inst = emit_generic_urb_slot(reg, varying);
> - if (key->clamp_vertex_color)
> + if (inst && key->clamp_vertex_color)
> inst->saturate = true;
> break;
> }
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