[Mesa-dev] [RFCv3 05/11] nir: add lowering pass for y-transform
Connor Abbott
cwabbott0 at gmail.com
Mon Feb 1 16:00:29 UTC 2016
On Sun, Jan 31, 2016 at 3:16 PM, Rob Clark <robdclark at gmail.com> wrote:
> From: Rob Clark <robclark at freedesktop.org>
>
> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> ---
> src/compiler/Makefile.sources | 1 +
> src/compiler/nir/nir.h | 12 +
> src/compiler/nir/nir_lower_wpos_ytransform.c | 317 +++++++++++++++++++++++++++
> 3 files changed, 330 insertions(+)
> create mode 100644 src/compiler/nir/nir_lower_wpos_ytransform.c
>
> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
> index c9780d6..26c4c65 100644
> --- a/src/compiler/Makefile.sources
> +++ b/src/compiler/Makefile.sources
> @@ -200,6 +200,7 @@ NIR_FILES = \
> nir/nir_lower_vars_to_ssa.c \
> nir/nir_lower_var_copies.c \
> nir/nir_lower_vec_to_movs.c \
> + nir/nir_lower_wpos_ytransform.c \
> nir/nir_metadata.c \
> nir/nir_move_vec_src_uses_to_dest.c \
> nir/nir_normalize_cubemap_coords.c \
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 67fe079..a973a44 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -2119,6 +2119,18 @@ void nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables);
>
> void nir_lower_two_sided_color(nir_shader *shader);
>
> +
> +typedef struct nir_lower_wpos_ytransform_options {
> + int state_tokens[5];
AFAIK the state slot stuff is only used for old assembly shaders. Why
are we using it here?
> + bool fs_coord_origin_upper_left :1;
> + bool fs_coord_origin_lower_left :1;
> + bool fs_coord_pixel_center_integer :1;
> + bool fs_coord_pixel_center_half_integer :1;
> +} nir_lower_wpos_ytransform_options;
> +
> +bool nir_lower_wpos_ytransform(nir_shader *shader,
> + const nir_lower_wpos_ytransform_options *options);
> +
> void nir_lower_atomics(nir_shader *shader,
> const struct gl_shader_program *shader_program);
> void nir_lower_to_source_mods(nir_shader *shader);
> diff --git a/src/compiler/nir/nir_lower_wpos_ytransform.c b/src/compiler/nir/nir_lower_wpos_ytransform.c
> new file mode 100644
> index 0000000..89d160b
> --- /dev/null
> +++ b/src/compiler/nir/nir_lower_wpos_ytransform.c
> @@ -0,0 +1,317 @@
> +/*
> + * Copyright © 2015 Red Hat
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + */
> +
> +#include "nir.h"
> +#include "nir_builder.h"
> +
> +/* Lower gl_FragCoord (and fddy) to account for driver's requested coordinate-
> + * origin and pixel-center vs. shader. If transformation is required, a
> + * gl_FbWposYTransform uniform is inserted (with the specified state-slots)
> + * and additional instructions are inserted to transform gl_FragCoord (and
> + * fddy src arg).
> + *
> + * This is based on the logic in emit_wpos()/emit_wpos_adjustment() in TGSI
> + * compiler.
> + *
> + * Run before nir_lower_io.
> + */
> +
> +typedef struct {
> + const nir_lower_wpos_ytransform_options *options;
> + nir_shader *shader;
> + nir_builder b;
> + nir_variable *transform;
> +} lower_wpos_ytransform_state;
> +
> +static nir_ssa_def *
> +get_transform(lower_wpos_ytransform_state *state)
> +{
> + if (state->transform == NULL) {
> + /* NOTE: name must be prefixed w/ "gl_" to trigger slot based
> + * special handling in uniform setup:
> + */
> + nir_variable *var = nir_variable_create(state->shader,
> + nir_var_uniform,
> + glsl_vec4_type(),
> + "gl_FbWposYTransform");
> +
> + var->num_state_slots = 1;
> + var->state_slots = ralloc_array(var, nir_state_slot, 1);
> + memcpy(var->state_slots[0].tokens, state->options->state_tokens,
> + sizeof(var->state_slots[0].tokens));
> +
> + state->transform = var;
> + }
> + return nir_load_var(&state->b, state->transform);
> +}
> +
> +/* NIR equiv of TGSI CMP instruction: */
> +static nir_ssa_def *
> +nir_cmp(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1, nir_ssa_def *src2)
> +{
> + return nir_bcsel(b, nir_flt(b, src0, nir_imm_float(b, 0.0)), src1, src2);
I'm not that familiar with TGSI, but you're selecting src1 if src0 is
less than zero, which seems... not quite right. Is that really how
TGSI CMP works?
> +}
> +
> +static nir_ssa_def *
> +nir_scalar(nir_builder *b, nir_ssa_def *def, int c)
> +{
> + unsigned swizzle[4] = {c, c, c, c};
> + return nir_swizzle(b, def, swizzle, 4, false);
> +}
> +
> +/* see emit_wpos_adjustment() in st_mesa_to_tgsi.c */
> +static void
> +emit_wpos_adjustment(lower_wpos_ytransform_state *state,
> + nir_intrinsic_instr *intr,
> + bool invert, float adjX, float adjY[2])
> +{
> + nir_builder *b = &state->b;
> + nir_variable *fragcoord = intr->variables[0]->var;
> + nir_ssa_def *wpostrans, *wpos_temp, *wpos_temp_y, *wpos_input;
> +
> + assert(intr->dest.is_ssa);
> +
> + b->cursor = nir_before_instr(&intr->instr);
> +
> + wpostrans = get_transform(state);
> + wpos_input = nir_load_var(b, fragcoord);
> +
> + /* First, apply the coordinate shift: */
> + if (adjX || adjY[0] || adjY[1]) {
> + if (adjY[0] != adjY[1]) {
> + /* Adjust the y coordinate by adjY[1] or adjY[0] respectively
> + * depending on whether inversion is actually going to be applied
> + * or not, which is determined by testing against the inversion
> + * state variable used below, which will be either +1 or -1.
> + */
> + nir_ssa_def *adj_temp;
> +
> + adj_temp = nir_cmp(b,
> + nir_scalar(b, wpostrans, invert ? 2 : 0),
> + nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f),
> + nir_imm_vec4(b, adjX, adjY[1], 0.0f, 0.0f));
First, the nir builder will automatically splat things for you when
the sizes are mismatched so you can just do nir_channel() here and
avoid having to define nir_scalar().
Secondly, why the weird TGSI-style comparison? Why can't you just pass
in a normal boolean? At least, I'd like to see nir_cmp() inlined here
-- for someone who doesn't know about TGSI, it would be easy to skip
over the nir_cmp without realizing that there's some weird
gallium-specific stuff going on inside here.
> +
> + wpos_temp = nir_fadd(b, wpos_input, adj_temp);
> + } else {
> + wpos_temp = nir_fadd(b,
> + wpos_input,
> + nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f));
> + }
> + wpos_input = wpos_temp;
> + } else {
> + /* MOV wpos_temp, input[wpos]
> + */
> + wpos_temp = wpos_input;
> + }
> +
> + /* Now the conditional y flip: STATE_FB_WPOS_Y_TRANSFORM.xy/zw will be
> + * inversion/identity, or the other way around if we're drawing to an FBO.
> + */
> + if (invert) {
> + /* MAD wpos_temp.y, wpos_input, wpostrans.xxxx, wpostrans.yyyy
> + */
> + wpos_temp_y = nir_ffma(b,
> + nir_channel(b, wpos_temp, 1),
> + nir_channel(b, wpostrans, 0),
> + nir_channel(b, wpostrans, 1));
> + } else {
> + /* MAD wpos_temp.y, wpos_input, wpostrans.zzzz, wpostrans.wwww
> + */
> + wpos_temp_y = nir_ffma(b,
> + nir_channel(b, wpos_temp, 1),
> + nir_channel(b, wpostrans, 2),
> + nir_channel(b, wpostrans, 3));
> + }
> +
> + wpos_temp = nir_vec4(b,
> + nir_channel(b, wpos_temp, 0),
> + wpos_temp_y,
> + nir_channel(b, wpos_temp, 2),
> + nir_channel(b, wpos_temp, 3));
> +
> + nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(wpos_temp));
> +}
> +
> +static void
> +lower_fragcoord(lower_wpos_ytransform_state *state, nir_intrinsic_instr *intr)
> +{
> + const nir_lower_wpos_ytransform_options *options = state->options;
> + nir_variable *fragcoord = intr->variables[0]->var;
> + float adjX = 0.0f;
> + float adjY[2] = { 0.0f, 0.0f };
> + bool invert = false;
> +
> + /* Based on logic in emit_wpos():
> + *
> + * Query the pixel center conventions supported by the pipe driver and set
> + * adjX, adjY to help out if it cannot handle the requested one internally.
> + *
> + * The bias of the y-coordinate depends on whether y-inversion takes place
> + * (adjY[1]) or not (adjY[0]), which is in turn dependent on whether we are
> + * drawing to an FBO (causes additional inversion), and whether the the pipe
> + * driver origin and the requested origin differ (the latter condition is
> + * stored in the 'invert' variable).
> + *
> + * For height = 100 (i = integer, h = half-integer, l = lower, u = upper):
> + *
> + * center shift only:
> + * i -> h: +0.5
> + * h -> i: -0.5
> + *
> + * inversion only:
> + * l,i -> u,i: ( 0.0 + 1.0) * -1 + 100 = 99
> + * l,h -> u,h: ( 0.5 + 0.0) * -1 + 100 = 99.5
> + * u,i -> l,i: (99.0 + 1.0) * -1 + 100 = 0
> + * u,h -> l,h: (99.5 + 0.0) * -1 + 100 = 0.5
> + *
> + * inversion and center shift:
> + * l,i -> u,h: ( 0.0 + 0.5) * -1 + 100 = 99.5
> + * l,h -> u,i: ( 0.5 + 0.5) * -1 + 100 = 99
> + * u,i -> l,h: (99.0 + 0.5) * -1 + 100 = 0.5
> + * u,h -> l,i: (99.5 + 0.5) * -1 + 100 = 0
> + */
> +
> + if (fragcoord->data.origin_upper_left) {
> + /* Fragment shader wants origin in upper-left */
> + if (options->fs_coord_origin_upper_left) {
> + /* the driver supports upper-left origin */
> + } else if (options->fs_coord_origin_lower_left) {
> + /* the driver supports lower-left origin, need to invert Y */
> + invert = true;
> + } else {
> + unreachable("invalid options");
> + }
> + } else {
> + /* Fragment shader wants origin in lower-left */
> + if (options->fs_coord_origin_lower_left) {
> + /* the driver supports lower-left origin */
> + } else if (options->fs_coord_origin_upper_left) {
> + /* the driver supports upper-left origin, need to invert Y */
> + invert = true;
> + } else {
> + unreachable("invalid options");
> + }
> + }
> +
> + if (fragcoord->data.pixel_center_integer) {
> + /* Fragment shader wants pixel center integer */
> + if (options->fs_coord_pixel_center_integer) {
> + /* the driver supports pixel center integer */
> + adjY[1] = 1.0f;
> + } else if (options->fs_coord_pixel_center_half_integer) {
> + /* the driver supports pixel center half integer, need to bias X,Y */
> + adjX = -0.5f;
> + adjY[0] = -0.5f;
> + adjY[1] = 0.5f;
> + } else {
> + unreachable("invalid options");
> + }
> + } else {
> + /* Fragment shader wants pixel center half integer */
> + if (options->fs_coord_pixel_center_half_integer) {
> + /* the driver supports pixel center half integer */
> + } else if (options->fs_coord_pixel_center_integer) {
> + /* the driver supports pixel center integer, need to bias X,Y */
> + adjX = adjY[0] = adjY[1] = 0.5f;
> + } else {
> + unreachable("invalid options");
> + }
> + }
> +
> + emit_wpos_adjustment(state, intr, invert, adjX, adjY);
> +}
> +
> +/* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */
> +static void
> +lower_fddy(lower_wpos_ytransform_state *state, nir_alu_instr *fddy)
> +{
> + nir_builder *b = &state->b;
> + nir_ssa_def *p, *pt, *trans;
> +
> + b->cursor = nir_before_instr(&fddy->instr);
> +
> + p = nir_ssa_for_alu_src(b, fddy, 0);
> + trans = get_transform(state);
> + pt = nir_fmul(b, p, nir_channel(b, trans, 0));
> +
> + nir_instr_rewrite_src(&fddy->instr,
> + &fddy->src[0].src,
> + nir_src_for_ssa(pt));
> +}
> +
> +static bool
> +lower_wpos_ytransform_block(nir_block *block, void *_state)
> +{
> + lower_wpos_ytransform_state *state = _state;
> +
> + nir_foreach_instr_safe(block, instr) {
> + if (instr->type == nir_instr_type_intrinsic) {
> + nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
> + if (intr->intrinsic == nir_intrinsic_load_var) {
> + nir_deref_var *dvar = intr->variables[0];
> + nir_variable *var = dvar->var;
> +
> + if (strcmp(var->name, "gl_FragCoord") == 0) {
> + /* gl_FragCoord should not have array/struct deref's: */
> + assert(dvar->deref.child == NULL);
> + lower_fragcoord(state, intr);
> + }
> + }
> + } else if (instr->type == nir_instr_type_alu) {
> + nir_alu_instr *alu = nir_instr_as_alu(instr);
> + if (alu->op == nir_op_fddy)
> + lower_fddy(state, alu);
> + }
> + }
> +
> + return true;
> +}
> +
> +static void
> +lower_wpos_ytransform_impl(lower_wpos_ytransform_state *state, nir_function_impl *impl)
> +{
> + nir_builder_init(&state->b, impl);
> +
> + nir_foreach_block(impl, lower_wpos_ytransform_block, state);
> + nir_metadata_preserve(impl, nir_metadata_block_index |
> + nir_metadata_dominance);
> +}
> +
> +bool
> +nir_lower_wpos_ytransform(nir_shader *shader,
> + const nir_lower_wpos_ytransform_options *options)
> +{
> + lower_wpos_ytransform_state state = {
> + .options = options,
> + .shader = shader,
> + };
> +
> + assert(shader->stage == MESA_SHADER_FRAGMENT);
> +
> + nir_foreach_function(shader, function) {
> + if (function->impl)
> + lower_wpos_ytransform_impl(&state, function->impl);
> + }
> +
> + return state.transform != NULL;
> +}
> --
> 2.5.0
>
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