nir: add lowering pass for glDrawPixels

Signed-off-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/compiler/Makefile.sources

@@ -190,6 +190,7 @@ NIR_FILES = \
 	nir/nir_lower_clip.c \
 	nir/nir_lower_double_ops.c \
 	nir/nir_lower_double_packing.c \
+	nir/nir_lower_drawpixels.c \
 	nir/nir_lower_global_vars_to_local.c \
 	nir/nir_lower_gs_intrinsics.c \
 	nir/nir_lower_load_const_to_scalar.c \

src/compiler/nir/nir.h

@@ -2385,6 +2385,19 @@ typedef struct nir_lower_wpos_ytransform_options {
 bool nir_lower_wpos_ytransform(nir_shader *shader,
                                const nir_lower_wpos_ytransform_options *options);
 
+typedef struct nir_lower_drawpixels_options {
+   int texcoord_state_tokens[5];
+   int scale_state_tokens[5];
+   int bias_state_tokens[5];
+   unsigned drawpix_sampler;
+   unsigned pixelmap_sampler;
+   bool pixel_maps :1;
+   bool scale_and_bias :1;
+} nir_lower_drawpixels_options;
+
+void nir_lower_drawpixels(nir_shader *shader,
+                          const nir_lower_drawpixels_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);

src/compiler/nir/nir_lower_drawpixels.c

@@ -0,0 +1,254 @@
+/*
+ * 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 glDrawPixels().
+ *
+ * This is based on the logic in st_get_drawpix_shader() in TGSI compiler.
+ *
+ * Run before nir_lower_io.
+ */
+
+typedef struct {
+   const nir_lower_drawpixels_options *options;
+   nir_shader   *shader;
+   nir_builder   b;
+   nir_variable *texcoord, *scale, *bias;
+} lower_drawpixels_state;
+
+static nir_ssa_def *
+get_texcoord(lower_drawpixels_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 nir_variable *
+create_uniform(nir_shader *shader, const char *name, const int state_tokens[5])
+{
+   nir_variable *var = nir_variable_create(shader,
+                                           nir_var_uniform,
+                                           glsl_vec4_type(),
+                                           name);
+   var->num_state_slots = 1;
+   var->state_slots = ralloc_array(var, nir_state_slot, 1);
+   memcpy(var->state_slots[0].tokens, state_tokens,
+          sizeof(var->state_slots[0].tokens));
+   return var;
+}
+
+static nir_ssa_def *
+get_scale(lower_drawpixels_state *state)
+{
+   if (state->scale == NULL) {
+      state->scale = create_uniform(state->shader, "gl_PTscale",
+                                    state->options->scale_state_tokens);
+   }
+   return nir_load_var(&state->b, state->scale);
+}
+
+static nir_ssa_def *
+get_bias(lower_drawpixels_state *state)
+{
+   if (state->bias == NULL) {
+      state->bias = create_uniform(state->shader, "gl_PTbias",
+                                   state->options->bias_state_tokens);
+   }
+   return nir_load_var(&state->b, state->bias);
+}
+
+static nir_ssa_def *
+get_texcoord_const(lower_drawpixels_state *state)
+{
+   if (state->bias == NULL) {
+      state->bias = create_uniform(state->shader, "gl_MultiTexCoord0",
+                                   state->options->texcoord_state_tokens);
+   }
+   return nir_load_var(&state->b, state->bias);
+}
+
+static void
+lower_color(lower_drawpixels_state *state, nir_intrinsic_instr *intr)
+{
+   nir_builder *b = &state->b;
+   nir_ssa_def *texcoord;
+   nir_tex_instr *tex;
+   nir_ssa_def *def;
+
+   assert(intr->dest.is_ssa);
+
+   b->cursor = nir_before_instr(&intr->instr);
+
+   texcoord = get_texcoord(state);
+
+   /* replace load_var(gl_Color) w/ texture sample:
+    *   TEX def, texcoord, drawpix_sampler, 2D
+    */
+   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->drawpix_sampler;
+   tex->texture_index = state->options->drawpix_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);
+   def = &tex->dest.ssa;
+
+   /* Apply the scale and bias. */
+   if (state->options->scale_and_bias) {
+      /* MAD def, def, scale, bias; */
+      def = nir_ffma(b, def, get_scale(state), get_bias(state));
+   }
+
+   if (state->options->pixel_maps) {
+      static const unsigned swiz_xy[4] = {0,1};
+      static const unsigned swiz_zw[4] = {2,3};
+
+      /* do four pixel map look-ups with two TEX instructions: */
+      nir_ssa_def *def_xy, *def_zw;
+
+      /* TEX def.xy, def.xyyy, pixelmap_sampler, 2D; */
+      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->pixelmap_sampler;
+      tex->texture_index = state->options->pixelmap_sampler;
+      tex->dest_type = nir_type_float;
+      tex->src[0].src = nir_src_for_ssa(nir_swizzle(b, def, swiz_xy, 2, true));
+
+      nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
+      nir_builder_instr_insert(b, &tex->instr);
+      def_xy = &tex->dest.ssa;
+
+      /* TEX def.zw, def.zwww, pixelmap_sampler, 2D; */
+      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->pixelmap_sampler;
+      tex->dest_type = nir_type_float;
+      tex->src[0].src = nir_src_for_ssa(nir_swizzle(b, def, swiz_zw, 2, true));
+
+      nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
+      nir_builder_instr_insert(b, &tex->instr);
+      def_zw = &tex->dest.ssa;
+
+      /* def = vec4(def.xy, def.zw); */
+      def = nir_vec4(b,
+                     nir_channel(b, def_xy, 0),
+                     nir_channel(b, def_xy, 1),
+                     nir_channel(b, def_zw, 0),
+                     nir_channel(b, def_zw, 1));
+   }
+
+   nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(def));
+}
+
+static void
+lower_texcoord(lower_drawpixels_state *state, nir_intrinsic_instr *intr)
+{
+   nir_ssa_def *texcoord_const = get_texcoord_const(state);
+   nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(texcoord_const));
+}
+
+static bool
+lower_drawpixels_block(lower_drawpixels_state *state, nir_block *block)
+{
+   nir_foreach_instr_safe(instr, block) {
+      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 (var->data.location == VARYING_SLOT_COL0) {
+               /* gl_FragCoord should not have array/struct deref's: */
+               assert(dvar->deref.child == NULL);
+               lower_color(state, intr);
+            } else if (var->data.location == VARYING_SLOT_TEX0) {
+               /* gl_TexCoord should not have array/struct deref's: */
+               assert(dvar->deref.child == NULL);
+               lower_texcoord(state, intr);
+            }
+         }
+      }
+   }
+
+   return true;
+}
+
+static void
+lower_drawpixels_impl(lower_drawpixels_state *state, nir_function_impl *impl)
+{
+   nir_builder_init(&state->b, impl);
+
+   nir_foreach_block(block, impl) {
+      lower_drawpixels_block(state, block);
+   }
+   nir_metadata_preserve(impl, nir_metadata_block_index |
+                               nir_metadata_dominance);
+}
+
+void
+nir_lower_drawpixels(nir_shader *shader,
+                     const nir_lower_drawpixels_options *options)
+{
+   lower_drawpixels_state state = {
+      .options = options,
+      .shader = shader,
+   };
+
+   assert(shader->stage == MESA_SHADER_FRAGMENT);
+
+   nir_foreach_function(function, shader) {
+      if (function->impl)
+         lower_drawpixels_impl(&state, function->impl);
+   }
+}