radv: fix crash in shader tracing.

Enabling tracing, and then having a vmfault, can leads to a segfault
before we print out the traces, as if a meta shader is executing
and we don't have the NIR for it.

Just pass the stage and give back a default.

Fixes: 9b9ccee4d6 ("radv: take LDS into account for compute shader occupancy stats")
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/amd/vulkan/radv_nir_to_llvm.c

@@ -4244,9 +4244,10 @@ ac_setup_rings(struct radv_shader_context *ctx)
 
 unsigned
 radv_nir_get_max_workgroup_size(enum chip_class chip_class,
+				gl_shader_stage stage,
 				const struct nir_shader *nir)
 {
-	switch (nir->info.stage) {
+	switch (stage) {
 	case MESA_SHADER_TESS_CTRL:
 		return chip_class >= GFX7 ? 128 : 64;
 	case MESA_SHADER_GEOMETRY:
@@ -4257,6 +4258,8 @@ radv_nir_get_max_workgroup_size(enum chip_class chip_class,
 		return 0;
 	}
 
+	if (!nir)
+		return chip_class >= GFX9 ? 128 : 64;
 	unsigned max_workgroup_size = nir->info.cs.local_size[0] *
 		nir->info.cs.local_size[1] *
 		nir->info.cs.local_size[2];
@@ -4340,6 +4343,7 @@ LLVMModuleRef ac_translate_nir_to_llvm(struct ac_llvm_compiler *ac_llvm,
 	for (int i = 0; i < shader_count; ++i) {
 		ctx.max_workgroup_size = MAX2(ctx.max_workgroup_size,
 		                              radv_nir_get_max_workgroup_size(ctx.options->chip_class,
+									      shaders[i]->info.stage,
 									      shaders[i]));
 	}
 

src/amd/vulkan/radv_private.h

@@ -2138,6 +2138,7 @@ void radv_compile_nir_shader(struct ac_llvm_compiler *ac_llvm,
 			     const struct radv_nir_compiler_options *options);
 
 unsigned radv_nir_get_max_workgroup_size(enum chip_class chip_class,
+					 gl_shader_stage stage,
 					 const struct nir_shader *nir);
 
 /* radv_shader_info.h */

src/amd/vulkan/radv_shader.c

@@ -1234,7 +1234,7 @@ generate_shader_stats(struct radv_device *device,
 				     lds_increment);
 	} else if (stage == MESA_SHADER_COMPUTE) {
 		unsigned max_workgroup_size =
-				radv_nir_get_max_workgroup_size(chip_class, variant->nir);
+			radv_nir_get_max_workgroup_size(chip_class, stage, variant->nir);
 		lds_per_wave = (conf->lds_size * lds_increment) /
 			       DIV_ROUND_UP(max_workgroup_size, 64);
 	}