pan/mdg: Move writeout lowering to common panfrost
These will be used in the Bifrost compiler, albeit for a slightly
different purpose.
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7446>
diff --git a/src/panfrost/util/pan_lower_writeout.c b/src/panfrost/util/pan_lower_writeout.c
new file mode 100644
index 0000000..b415540
--- /dev/null
+++ b/src/panfrost/util/pan_lower_writeout.c
@@ -0,0 +1,255 @@
+/*
+ * Copyright (C) 2018-2020 Collabora, Ltd.
+ * Copyright (C) 2019-2020 Icecream95
+ *
+ * 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 "pan_ir.h"
+#include "compiler/nir/nir_builder.h"
+
+/* Midgard can write all of color, depth and stencil in a single writeout
+ * operation, so we merge depth/stencil stores with color stores.
+ * If there are no color stores, we add a write to the "depth RT".
+ *
+ * For Bifrost, we want these combined so we can properly order
+ * +ZS_EMIT with respect to +ATEST and +BLEND, as well as combining
+ * depth/stencil stores into a single +ZS_EMIT op.
+ */
+bool
+pan_nir_lower_zs_store(nir_shader *nir)
+{
+ if (nir->info.stage != MESA_SHADER_FRAGMENT)
+ return false;
+
+ nir_variable *z_var = NULL, *s_var = NULL;
+
+ nir_foreach_shader_out_variable(var, nir) {
+ if (var->data.location == FRAG_RESULT_DEPTH)
+ z_var = var;
+ else if (var->data.location == FRAG_RESULT_STENCIL)
+ s_var = var;
+ }
+
+ if (!z_var && !s_var)
+ return false;
+
+ bool progress = false;
+
+ nir_foreach_function(function, nir) {
+ if (!function->impl) continue;
+
+ nir_intrinsic_instr *z_store = NULL, *s_store = NULL;
+
+ nir_foreach_block(block, function->impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_store_output)
+ continue;
+
+ if (z_var && nir_intrinsic_base(intr) == z_var->data.driver_location) {
+ assert(!z_store);
+ z_store = intr;
+ }
+
+ if (s_var && nir_intrinsic_base(intr) == s_var->data.driver_location) {
+ assert(!s_store);
+ s_store = intr;
+ }
+ }
+ }
+
+ if (!z_store && !s_store) continue;
+
+ bool replaced = false;
+
+ nir_foreach_block(block, function->impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_store_output)
+ continue;
+
+ const nir_variable *var = nir_find_variable_with_driver_location(nir, nir_var_shader_out, nir_intrinsic_base(intr));
+ assert(var);
+
+ if (var->data.location != FRAG_RESULT_COLOR &&
+ var->data.location < FRAG_RESULT_DATA0)
+ continue;
+
+ if (var->data.index)
+ continue;
+
+ assert(nir_src_is_const(intr->src[1]) && "no indirect outputs");
+
+ nir_builder b;
+ nir_builder_init(&b, function->impl);
+
+ assert(!z_store || z_store->instr.block == instr->block);
+ assert(!s_store || s_store->instr.block == instr->block);
+ b.cursor = nir_after_block_before_jump(instr->block);
+
+ nir_intrinsic_instr *combined_store;
+ combined_store = nir_intrinsic_instr_create(b.shader, nir_intrinsic_store_combined_output_pan);
+
+ combined_store->num_components = intr->src[0].ssa->num_components;
+
+ nir_intrinsic_set_base(combined_store, nir_intrinsic_base(intr));
+
+ unsigned writeout = PAN_WRITEOUT_C;
+ if (z_store)
+ writeout |= PAN_WRITEOUT_Z;
+ if (s_store)
+ writeout |= PAN_WRITEOUT_S;
+
+ nir_intrinsic_set_component(combined_store, writeout);
+
+ struct nir_ssa_def *zero = nir_imm_int(&b, 0);
+
+ struct nir_ssa_def *src[4] = {
+ intr->src[0].ssa,
+ intr->src[1].ssa,
+ z_store ? z_store->src[0].ssa : zero,
+ s_store ? s_store->src[0].ssa : zero,
+ };
+
+ for (int i = 0; i < 4; ++i)
+ combined_store->src[i] = nir_src_for_ssa(src[i]);
+
+ nir_builder_instr_insert(&b, &combined_store->instr);
+
+ nir_instr_remove(instr);
+
+ replaced = true;
+ }
+ }
+
+ /* Insert a store to the depth RT (0xff) if needed */
+ if (!replaced) {
+ nir_builder b;
+ nir_builder_init(&b, function->impl);
+
+ nir_block *block = NULL;
+ if (z_store && s_store)
+ assert(z_store->instr.block == s_store->instr.block);
+
+ if (z_store)
+ block = z_store->instr.block;
+ else
+ block = s_store->instr.block;
+
+ b.cursor = nir_after_block_before_jump(block);
+
+ nir_intrinsic_instr *combined_store;
+ combined_store = nir_intrinsic_instr_create(b.shader, nir_intrinsic_store_combined_output_pan);
+
+ combined_store->num_components = 4;
+
+ unsigned base;
+ if (z_store)
+ base = nir_intrinsic_base(z_store);
+ else
+ base = nir_intrinsic_base(s_store);
+ nir_intrinsic_set_base(combined_store, base);
+
+ unsigned writeout = 0;
+ if (z_store)
+ writeout |= PAN_WRITEOUT_Z;
+ if (s_store)
+ writeout |= PAN_WRITEOUT_S;
+
+ nir_intrinsic_set_component(combined_store, writeout);
+
+ struct nir_ssa_def *zero = nir_imm_int(&b, 0);
+
+ struct nir_ssa_def *src[4] = {
+ nir_imm_vec4(&b, 0, 0, 0, 0),
+ zero,
+ z_store ? z_store->src[0].ssa : zero,
+ s_store ? s_store->src[0].ssa : zero,
+ };
+
+ for (int i = 0; i < 4; ++i)
+ combined_store->src[i] = nir_src_for_ssa(src[i]);
+
+ nir_builder_instr_insert(&b, &combined_store->instr);
+ }
+
+ if (z_store)
+ nir_instr_remove(&z_store->instr);
+
+ if (s_store)
+ nir_instr_remove(&s_store->instr);
+
+ nir_metadata_preserve(function->impl, nir_metadata_block_index | nir_metadata_dominance);
+ progress = true;
+ }
+
+ return progress;
+}
+
+/* Real writeout stores, which break execution, need to be moved to after
+ * dual-source stores, which are just standard register writes. */
+bool
+pan_nir_reorder_writeout(nir_shader *nir)
+{
+ bool progress = false;
+
+ nir_foreach_function(function, nir) {
+ if (!function->impl) continue;
+
+ nir_foreach_block(block, function->impl) {
+ nir_instr *last_writeout = NULL;
+
+ nir_foreach_instr_reverse_safe(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_store_output)
+ continue;
+
+ const nir_variable *var = nir_find_variable_with_driver_location(nir, nir_var_shader_out, nir_intrinsic_base(intr));
+
+ if (var->data.index) {
+ if (!last_writeout)
+ last_writeout = instr;
+ continue;
+ }
+
+ if (!last_writeout)
+ continue;
+
+ /* This is a real store, so move it to after dual-source stores */
+ exec_node_remove(&instr->node);
+ exec_node_insert_after(&last_writeout->node, &instr->node);
+
+ progress = true;
+ }
+ }
+ }
+
+ return progress;
+}