[Mesa-dev] [RFCv3 05/11] nir: add lowering pass for y-transform
Rob Clark
robdclark at gmail.com
Mon Feb 1 16:48:56 UTC 2016
On Mon, Feb 1, 2016 at 11:00 AM, Connor Abbott <cwabbott0 at gmail.com> wrote:
> 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?
nope, state-slots are alive and well w/ glsl for builtins, etc. Quite
possibly it dates back to old ARB assembly shaders.. but it is still
the way for compiler / lowering to insert builtin params, afaict. We
do the same thing in other places too (like drawpix lowering).
>> + 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?
I'm never sure if TGSI is backwards or my hw is backwards (since they
disagree about src argument order).. but yes, this is how TGSI 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().
ok, I can drop 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.
Hmm, otoh the way it is currently makes it easier for folks familiar
w/ TGSI, and makes it easier to compare side by side the NIR lowering
pass with the original TGSI version. This was intentional.
BR,
-R
>> +
>> + 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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