[Mesa-dev] [PATCH 3/4] nir: Add a lowering pass for texture projectors.
Eric Anholt
eric at anholt.net
Wed Apr 1 15:11:04 PDT 2015
Not much hardware wants them these days, and it might give us a chance to
do CSE or algebraic at the NIR level.
---
I wrote this originally for vc4, but I'm not sure I'm going to turn it
on -- I'm using a non-Newton-Raphson RCP in my TXP handling right now,
and if I do this pass then I get the N-R step added. If it's not
necessary, I probably shouldn't spend those instructions on it.
src/glsl/Makefile.sources | 1 +
src/glsl/nir/nir.h | 1 +
src/glsl/nir/nir_lower_tex_projector.c | 142 +++++++++++++++++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 src/glsl/nir/nir_lower_tex_projector.c
diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index b56fa26..ffce706 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -37,6 +37,7 @@ NIR_FILES = \
nir/nir_lower_phis_to_scalar.c \
nir/nir_lower_samplers.cpp \
nir/nir_lower_system_values.c \
+ nir/nir_lower_tex_projector.c \
nir/nir_lower_to_source_mods.c \
nir/nir_lower_vars_to_ssa.c \
nir/nir_lower_var_copies.c \
diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 24deb82..6e2aa97 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1601,6 +1601,7 @@ void nir_lower_samplers(nir_shader *shader,
struct gl_program *prog);
void nir_lower_system_values(nir_shader *shader);
+void nir_lower_tex_projector(nir_shader *shader);
void nir_lower_atomics(nir_shader *shader);
void nir_lower_to_source_mods(nir_shader *shader);
diff --git a/src/glsl/nir/nir_lower_tex_projector.c b/src/glsl/nir/nir_lower_tex_projector.c
new file mode 100644
index 0000000..6327b23
--- /dev/null
+++ b/src/glsl/nir/nir_lower_tex_projector.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright © 2015 Broadcom
+ *
+ * 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.
+ */
+
+/*
+ * This lowering pass converts the coordinate division for texture projection
+ * to be done in ALU instructions instead of asking the texture operation to
+ * do so.
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+
+static nir_ssa_def *
+channel(nir_builder *b, nir_ssa_def *def, int c)
+{
+ return nir_swizzle(b, def, (unsigned[4]){c, c, c, c}, 1, false);
+}
+
+static bool
+nir_lower_tex_projector_block(nir_block *block, void *void_state)
+{
+ nir_builder *b = void_state;
+
+ nir_foreach_instr_safe(block, instr) {
+ if (instr->type != nir_instr_type_tex)
+ continue;
+
+ nir_tex_instr *tex = nir_instr_as_tex(instr);
+ nir_builder_insert_before_instr(b, &tex->instr);
+
+ /* Find the projector in the srcs list, if present. */
+ int proj_index;
+ for (proj_index = 0; proj_index < tex->num_srcs; proj_index++) {
+ if (tex->src[proj_index].src_type == nir_tex_src_projector)
+ break;
+ }
+ if (proj_index == tex->num_srcs)
+ continue;
+ nir_ssa_def *inv_proj =
+ nir_frcp(b, nir_ssa_for_src(b, tex->src[proj_index].src, 1));
+
+ /* Walk through the sources projecting the arguments. */
+ for (int i = 0; i < tex->num_srcs; i++) {
+ switch (tex->src[i].src_type) {
+ case nir_tex_src_coord:
+ case nir_tex_src_comparitor:
+ break;
+ default:
+ continue;
+ }
+ nir_ssa_def *unprojected =
+ nir_ssa_for_src(b, tex->src[i].src, nir_tex_instr_src_size(tex, i));
+ nir_ssa_def *projected = nir_fmul(b, unprojected, inv_proj);
+
+ /* Array indices don't get projected, so make an new vector with the
+ * coordinate's array index untouched.
+ */
+ if (tex->is_array && tex->src[i].src_type == nir_tex_src_coord) {
+ switch (tex->coord_components) {
+ case 4:
+ projected = nir_vec4(b,
+ channel(b, projected, 0),
+ channel(b, projected, 1),
+ channel(b, projected, 2),
+ channel(b, unprojected, 3));
+ break;
+ case 3:
+ projected = nir_vec3(b,
+ channel(b, projected, 0),
+ channel(b, projected, 1),
+ channel(b, unprojected, 2));
+ break;
+ case 2:
+ projected = nir_vec2(b,
+ channel(b, projected, 0),
+ channel(b, unprojected, 1));
+ break;
+ default:
+ unreachable("bad texture coord count for array");
+ break;
+ }
+ }
+
+ nir_instr_rewrite_src(&tex->instr,
+ &tex->src[i].src,
+ nir_src_for_ssa(projected));
+ }
+
+ /* Now move the later tex sources down the array so that the projector
+ * disappears.
+ */
+ nir_src dead = {.is_ssa = false, .ssa = NULL};
+ nir_instr_rewrite_src(&tex->instr, &tex->src[proj_index].src, dead);
+ memmove(&tex->src[proj_index],
+ &tex->src[proj_index + 1],
+ (tex->num_srcs - proj_index) * sizeof(*tex->src));
+ tex->num_srcs--;
+ }
+
+ return true;
+}
+
+static void
+nir_lower_tex_projector_impl(nir_function_impl *impl)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+
+ nir_foreach_block(impl, nir_lower_tex_projector_block, &b);
+
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+}
+
+void
+nir_lower_tex_projector(nir_shader *shader)
+{
+ nir_foreach_overload(shader, overload) {
+ if (overload->impl)
+ nir_lower_tex_projector_impl(overload->impl);
+ }
+}
--
2.1.4
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