radv: Add RADV_DEBUG=nort

This makes vkCmdTraceRaysKHR and ray queries no-ops and is useful
for triaging GPU hangs with raytracing.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23603>

docs/envvars.rst

@@ -1160,6 +1160,9 @@ RADV driver environment variables
       disable NGG for GFX10 and GFX10.3
    ``nonggc``
       disable NGG culling on GPUs where it's enabled by default (GFX10.3+ only).
+   ``nort``
+      skip executing vkCmdTraceRays and ray queries (RT extensions will still be
+      advertised)
    ``notccompatcmask``
       disable TC-compat CMASK for MSAA surfaces
    ``noumr``

src/amd/vulkan/nir/radv_nir_lower_ray_queries.c

@@ -27,6 +27,7 @@
 #include "util/hash_table.h"
 
 #include "bvh/bvh.h"
+#include "radv_debug.h"
 #include "radv_nir.h"
 #include "radv_private.h"
 #include "radv_rt_common.h"
@@ -372,7 +373,7 @@ enum rq_intersection_type {
 
 static void
 lower_rq_initialize(nir_builder *b, nir_ssa_def *index, nir_intrinsic_instr *instr,
-                    struct ray_query_vars *vars)
+                    struct ray_query_vars *vars, struct radv_instance *instance)
 {
    rq_store_var(b, index, vars->flags, instr->src[2].ssa, 0x1);
    rq_store_var(b, index, vars->cull_mask, nir_ishl_imm(b, instr->src[3].ssa, 24), 0x1);
@@ -420,7 +421,8 @@ lower_rq_initialize(nir_builder *b, nir_ssa_def *index, nir_intrinsic_instr *ins
 
    rq_store_var(b, index, vars->trav.top_stack, nir_imm_int(b, -1), 1);
 
-   rq_store_var(b, index, vars->incomplete, nir_imm_bool(b, true), 0x1);
+   rq_store_var(b, index, vars->incomplete,
+                nir_imm_bool(b, !(instance->debug_flags & RADV_DEBUG_NO_RT)), 0x1);
 }
 
 static nir_ssa_def *
@@ -741,7 +743,7 @@ radv_nir_lower_ray_queries(struct nir_shader *shader, struct radv_device *device
                lower_rq_generate_intersection(&builder, index, intrinsic, vars);
                break;
             case nir_intrinsic_rq_initialize:
-               lower_rq_initialize(&builder, index, intrinsic, vars);
+               lower_rq_initialize(&builder, index, intrinsic, vars, device->instance);
                break;
             case nir_intrinsic_rq_load:
                new_dest = lower_rq_load(&builder, index, intrinsic, vars);

src/amd/vulkan/radv_cmd_buffer.c

@@ -10037,6 +10037,9 @@ static void
 radv_trace_rays(struct radv_cmd_buffer *cmd_buffer, const VkTraceRaysIndirectCommand2KHR *tables,
                 uint64_t indirect_va, enum radv_rt_mode mode)
 {
+   if (cmd_buffer->device->instance->debug_flags & RADV_DEBUG_NO_RT)
+      return;
+
    struct radv_compute_pipeline *pipeline = &cmd_buffer->state.rt_pipeline->base;
    struct radv_shader *rt_prolog = cmd_buffer->state.rt_prolog;
    uint32_t base_reg = rt_prolog->info.user_data_0;

src/amd/vulkan/radv_debug.h

@@ -71,6 +71,7 @@ enum {
    RADV_DEBUG_EXTRA_MD = 1ull << 40,
    RADV_DEBUG_NO_GPL = 1ull << 41,
    RADV_DEBUG_VIDEO_ARRAY_PATH = 1ull << 42,
+   RADV_DEBUG_NO_RT = 1ull << 43,
 };
 
 enum {

src/amd/vulkan/radv_instance.c

@@ -77,6 +77,7 @@ static const struct debug_control radv_debug_options[] = {
    {"extra_md", RADV_DEBUG_EXTRA_MD},
    {"nogpl", RADV_DEBUG_NO_GPL},
    {"videoarraypath", RADV_DEBUG_VIDEO_ARRAY_PATH},
+   {"nort", RADV_DEBUG_NO_RT},
    {NULL, 0}};
 
 const char *

src/amd/vulkan/radv_pipeline.c

@@ -204,6 +204,8 @@ radv_get_hash_flags(const struct radv_device *device, bool stats)
       hash_flags |= RADV_HASH_SHADER_NO_FMASK;
    if (device->physical_device->use_ngg_streamout)
       hash_flags |= RADV_HASH_SHADER_NGG_STREAMOUT;
+   if (device->instance->debug_flags & RADV_DEBUG_NO_RT)
+      hash_flags |= RADV_HASH_SHADER_NO_RT;
    return hash_flags;
 }
 

src/amd/vulkan/radv_private.h

@@ -2162,6 +2162,7 @@ struct radv_event {
 #define RADV_HASH_SHADER_RT_WAVE64             (1 << 18)
 #define RADV_HASH_SHADER_NO_FMASK              (1 << 19)
 #define RADV_HASH_SHADER_NGG_STREAMOUT         (1 << 20)
+#define RADV_HASH_SHADER_NO_RT                 (1 << 21)
 
 struct radv_pipeline_key;
 struct radv_ray_tracing_group;