[Mesa-dev] [PATCH] nir: add lowering pass for glBitmap
Connor Abbott
cwabbott0 at gmail.com
Thu Apr 14 22:33:22 UTC 2016
On Thu, Apr 14, 2016 at 6:10 PM, Rob Clark <robdclark at gmail.com> wrote:
> From: Rob Clark <robclark at freedesktop.org>
>
> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>
> ---
> src/compiler/Makefile.sources | 1 +
> src/compiler/nir/nir.h | 7 ++
> src/compiler/nir/nir_lower_bitmap.c | 167 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 175 insertions(+)
> create mode 100644 src/compiler/nir/nir_lower_bitmap.c
>
> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
> index 290ed35..8d8eca2 100644
> --- a/src/compiler/Makefile.sources
> +++ b/src/compiler/Makefile.sources
> @@ -186,6 +186,7 @@ NIR_FILES = \
> nir/nir_liveness.c \
> nir/nir_lower_alu_to_scalar.c \
> nir/nir_lower_atomics.c \
> + nir/nir_lower_bitmap.c \
> nir/nir_lower_clip.c \
> nir/nir_lower_double_packing.c \
> nir/nir_lower_drawpixels.c \
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index bdc9e8b..c334702 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -2301,6 +2301,13 @@ typedef struct nir_lower_drawpixels_options {
> void nir_lower_drawpixels(nir_shader *shader,
> const nir_lower_drawpixels_options *options);
>
> +typedef struct nir_lower_bitmap_options {
> + unsigned sampler;
> + bool swizzle_xxxx;
> +} nir_lower_bitmap_options;
> +
> +void nir_lower_bitmap(nir_shader *shader, const nir_lower_bitmap_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_bitmap.c b/src/compiler/nir/nir_lower_bitmap.c
> new file mode 100644
> index 0000000..fdca80c
> --- /dev/null
> +++ b/src/compiler/nir/nir_lower_bitmap.c
> @@ -0,0 +1,167 @@
> +/*
> + * 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 glBitmap().
> + *
> + * This is based on the logic in st_get_bitmap_shader() in TGSI compiler.
> + * From st_cb_bitmap.c:
> + *
> + * glBitmaps are drawn as textured quads. The user's bitmap pattern
> + * is stored in a texture image. An alpha8 texture format is used.
> + * The fragment shader samples a bit (texel) from the texture, then
> + * discards the fragment if the bit is off.
> + *
> + * Note that we actually store the inverse image of the bitmap to
> + * simplify the fragment program. An "on" bit gets stored as texel=0x0
> + * and an "off" bit is stored as texel=0xff. Then we kill the
> + * fragment if the negated texel value is less than zero.
> + *
> + * Note that the texture format will be, according to what driver supports,
> + * in order of preference (with swizzle):
> + *
> + * I8_UNORM - .xxxx
> + * A8_UNORM - .000x
> + * L8_UNORM - .xxx1
> + *
> + * If L8_UNORM, options->swizzle_xxxx is true. Otherwise we can just use
> + * the .w comp.
> + *
> + * Run before nir_lower_io.
> + */
> +
> +typedef struct {
> + const nir_lower_bitmap_options *options;
> + nir_shader *shader;
> + nir_builder b;
> + nir_variable *texcoord;
> +} lower_bitmap_state;
> +
> +static nir_ssa_def *
> +get_texcoord(lower_bitmap_state *state)
> +{
> + if (state->texcoord == NULL) {
> + nir_variable *texcoord = NULL;
> +
> + /* find gl_TexCoord, if it exists: */
> + nir_foreach_variable(var, &state->shader->inputs) {
> + if (var->data.location == VARYING_SLOT_TEX0) {
> + texcoord = var;
> + break;
> + }
> + }
> +
> + /* otherwise create it: */
> + if (texcoord == NULL) {
> + texcoord = nir_variable_create(state->shader,
> + nir_var_shader_in,
> + glsl_vec4_type(),
> + "gl_TexCoord");
> + texcoord->data.location = VARYING_SLOT_TEX0;
> + }
> +
> + state->texcoord = texcoord;
> + }
> + return nir_load_var(&state->b, state->texcoord);
> +}
> +
> +static void
> +lower_bitmap(lower_bitmap_state *state, nir_instr *instr)
> +{
> + nir_builder *b = &state->b;
> + nir_ssa_def *texcoord;
> + nir_tex_instr *tex;
> + nir_ssa_def *cond;
> + nir_intrinsic_instr *discard;
> +
> + b->cursor = nir_before_instr(instr);
> +
> + texcoord = get_texcoord(state);
> +
> + tex = nir_tex_instr_create(state->shader, 1);
> + tex->op = nir_texop_tex;
> + tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
> + tex->coord_components = 2;
> + tex->sampler_index = state->options->sampler;
> + tex->texture_index = state->options->sampler;
> + tex->dest_type = nir_type_float;
> + tex->src[0].src = nir_src_for_ssa(texcoord);
> +
> + nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
> + nir_builder_instr_insert(b, &tex->instr);
> +
> + /* kill if tex != 0.0.. take .x or .w channel according to format: */
> + cond = nir_f2b(b, nir_channel(b, &tex->dest.ssa,
> + state->options->swizzle_xxxx ? 0 : 3));
> +
> + discard = nir_intrinsic_instr_create(state->shader,
> + nir_intrinsic_discard_if);
> + discard->src[0] = nir_src_for_ssa(cond);
> + nir_builder_instr_insert(b, &discard->instr);
> +}
> +
> +static bool
> +lower_bitmap_block(nir_block *block, void *_state)
> +{
> + lower_bitmap_state *state = _state;
> +
> + /* TODO is there a better way to prepend instructions to
> + * the shader? If, hypothetically, there were more than
> + * one function, this probably wouldn't be the right way
> + */
So this change happened after these patches were written, but there's
now nir_shader_get_entrypoint() so you should probably use that. Also,
you can use nir_start_block() to get the first block in the impl
rather than needing a separate function (and it won't conflict with my
rewrite series!).
> + nir_foreach_instr_safe(block, instr) {
> + lower_bitmap(state, instr);
> + break;
> + }
> +
> + return false;
> +}
> +
> +static void
> +lower_bitmap_impl(lower_bitmap_state *state, nir_function_impl *impl)
> +{
> + nir_builder_init(&state->b, impl);
> +
> + nir_foreach_block(impl, lower_bitmap_block, state);
> + nir_metadata_preserve(impl, nir_metadata_block_index |
> + nir_metadata_dominance);
> +}
> +
> +void
> +nir_lower_bitmap(nir_shader *shader,
> + const nir_lower_bitmap_options *options)
> +{
> + lower_bitmap_state state = {
> + .options = options,
> + .shader = shader,
> + };
> +
> + assert(shader->stage == MESA_SHADER_FRAGMENT);
> +
> + nir_foreach_function(shader, function) {
> + if (function->impl)
> + lower_bitmap_impl(&state, function->impl);
> + }
> +}
> --
> 2.5.5
>
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