1 files changed, 113 insertions, 0 deletions
diff --git a/src/kosmickrisp/vulkan/kk_nir_lower_multiview.c b/src/kosmickrisp/vulkan/kk_nir_lower_multiview.c
new file mode 100644
index 00000000000..f90e50339f2
--- /dev/null
+++ b/src/kosmickrisp/vulkan/kk_nir_lower_multiview.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2025 LunarG, Inc.
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "kk_shader.h"
+
+#include "nir.h"
+#include "nir_builder.h"
+
+/* View index maps to layer id in Metal */
+static bool
+replace_view_index_with_zero(nir_builder *b, nir_intrinsic_instr *instr,
+                             void *data)
+{
+   if (instr->intrinsic != nir_intrinsic_load_view_index)
+      return false;
+
+   b->cursor = nir_before_instr(&instr->instr);
+   nir_def *layer_id = nir_load_layer_id(b);
+   nir_def_replace(&instr->def, layer_id);
+   return true;
+}
+
+/* View index maps to layer id in Metal */
+static bool
+replace_view_index_with_layer_id(nir_builder *b, nir_intrinsic_instr *instr,
+                                 void *data)
+{
+   if (instr->intrinsic != nir_intrinsic_load_view_index)
+      return false;
+
+   b->cursor = nir_before_instr(&instr->instr);
+   nir_def *layer_id = nir_load_layer_id(b);
+   nir_def_replace(&instr->def, layer_id);
+   return true;
+}
+
+static bool
+replace_view_id_with_value(nir_builder *b, nir_intrinsic_instr *instr,
+                           void *data)
+{
+   if (instr->intrinsic != nir_intrinsic_load_view_index)
+      return false;
+
+   b->cursor = nir_before_instr(&instr->instr);
+   nir_def *view_index = (nir_def *)data;
+   nir_def_replace(&instr->def, view_index);
+   return true;
+}
+
+bool
+kk_nir_lower_vs_multiview(nir_shader *nir, uint32_t view_mask)
+{
+   assert(nir->info.stage == MESA_SHADER_VERTEX);
+
+   /* Embed view indices and return */
+   uint32_t view_count = util_bitcount(view_mask);
+   nir_function_impl *entrypoint = nir_shader_get_entrypoint(nir);
+   nir_builder b = nir_builder_at(nir_before_impl(entrypoint));
+
+   /* Create array and initialize */
+   nir_variable *view_indices = nir_local_variable_create(
+      entrypoint, glsl_array_type(glsl_uint_type(), view_count, 0),
+      "view_indices");
+   nir_deref_instr *view_indices_deref = nir_build_deref_var(&b, view_indices);
+   uint32_t count = 0u;
+   u_foreach_bit(index, view_mask) {
+      nir_store_deref(
+         &b, nir_build_deref_array_imm(&b, view_indices_deref, count++),
+         nir_imm_int(&b, index), 1);
+   }
+
+   /* Access array based on the amplification id */
+   nir_def *amplification_id = nir_load_amplification_id_kk(&b);
+   nir_def *view_index = nir_load_deref(
+      &b, nir_build_deref_array(&b, view_indices_deref, amplification_id));
+
+   bool progress = nir_shader_intrinsics_pass(
+      nir, replace_view_id_with_value, nir_metadata_control_flow, view_index);
+
+   if (progress) {
+      BITSET_SET(nir->info.system_values_read,
+                 SYSTEM_VALUE_AMPLIFICATION_ID_KK);
+   }
+
+   /* With a single view index, Metal's vertex amplification will disregard the
+    * render target offset. We need to apply it ourselves in shader */
+   if (view_count == 1u) {
+      nir_variable *layer_id = nir_create_variable_with_location(
+         nir, nir_var_shader_out, VARYING_SLOT_LAYER, glsl_uint_type());
+      nir_deref_instr *layer_id_deref = nir_build_deref_var(&b, layer_id);
+      nir_def *view_index = nir_imm_int(&b, util_last_bit(view_mask) - 1u);
+      nir_store_deref(&b, layer_id_deref, view_index, 0xFFFFFFFF);
+
+      nir->info.outputs_written |= BITFIELD64_BIT(VARYING_SLOT_LAYER);
+      progress = true;
+   }
+
+   return progress;
+}
+
+bool
+kk_nir_lower_fs_multiview(nir_shader *nir, uint32_t view_mask)
+{
+   if (view_mask == 0u)
+      return nir_shader_intrinsics_pass(nir, replace_view_index_with_zero,
+                                        nir_metadata_control_flow, NULL);
+
+   return nir_shader_intrinsics_pass(nir, replace_view_index_with_layer_id,
+                                     nir_metadata_control_flow, NULL);
+}