--- /dev/null
+/*
+ * 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.
+ */
+
+#include "v3d_compiler.h"
+#include "compiler/nir/nir_builder.h"
+
+/** @file v3d_nir_lower_txf_ms.c
+ *
+ * V3D's MSAA surfaces are laid out in UIF textures where each pixel is a 2x2
+ * quad in the texture. This pass lowers the txf_ms with a ms_index source to
+ * a plain txf with the sample_index pulling out the correct texel from the
+ * 2x2 quad.
+ */
+
+#define V3D_MAX_SAMPLES 4
+
+static void
+vc4_nir_lower_txf_ms_instr(struct v3d_compile *c, nir_builder *b,
+ nir_tex_instr *instr)
+{
+ if (instr->op != nir_texop_txf_ms)
+ return;
+
+ b->cursor = nir_before_instr(&instr->instr);
+
+ int coord_index = nir_tex_instr_src_index(instr, nir_tex_src_coord);
+ int sample_index = nir_tex_instr_src_index(instr, nir_tex_src_ms_index);
+ nir_ssa_def *coord = instr->src[coord_index].src.ssa;
+ nir_ssa_def *sample = instr->src[sample_index].src.ssa;
+
+ nir_ssa_def *one = nir_imm_int(b, 1);
+ coord = nir_ishl(b, coord, nir_imm_int(b, 1));
+ coord = nir_vec2(b,
+ nir_iadd(b,
+ nir_channel(b, coord, 0),
+ nir_iand(b, sample, one)),
+ nir_iadd(b,
+ nir_channel(b, coord, 1),
+ nir_iand(b, nir_ushr(b, sample, one), one)));
+
+ nir_instr_rewrite_src(&instr->instr,
+ &instr->src[nir_tex_src_coord].src,
+ nir_src_for_ssa(coord));
+ nir_tex_instr_remove_src(instr, sample_index);
+ instr->op = nir_texop_txf;
+ instr->sampler_dim = GLSL_SAMPLER_DIM_2D;
+}
+
+void
+v3d_nir_lower_txf_ms(nir_shader *s, struct v3d_compile *c)
+{
+ nir_foreach_function(function, s) {
+ if (!function->impl)
+ continue;
+
+ nir_builder b;
+ nir_builder_init(&b, function->impl);
+
+ nir_foreach_block(block, function->impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_tex)
+ continue;
+
+ vc4_nir_lower_txf_ms_instr(c, &b,
+ nir_instr_as_tex(instr));
+ }
+ }
+
+ nir_metadata_preserve(function->impl,
+ nir_metadata_block_index |
+ nir_metadata_dominance);
+ }
+}