iris: always include an extra constbuf0 if using UBOs

In st_nir_lower_uniforms_to_ubo() all UBO access in the shader have
its index incremented to open room for uniforms in constbuf0.  So if
we use UBOs, we always need to include the extra binding entry in the
table.

To avoid doing this checks both when compiling the shader and when
assigning binding tables, store the num_cbufs in iris_compiled_shader.

Fixes a bunch of tests from Piglit and CTS that use UBOs but don't use
uniforms or system values.  Note that some tests fitting this criteria
were passing because the UBOs were moved to be push
constants (avoiding the problem).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/gallium/drivers/iris/iris_context.h

@@ -263,6 +263,9 @@ struct iris_compiled_shader {
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
 
+   /** Number of constbufs expected by the shader. */
+   unsigned num_cbufs;
+
    /**
     * Derived 3DSTATE_STREAMOUT and 3DSTATE_SO_DECL_LIST packets
     * (the VUE-based information for transform feedback outputs).
@@ -642,8 +645,6 @@ void gen11_init_state(struct iris_context *ice);
 /* iris_program.c */
 const struct shader_info *iris_get_shader_info(const struct iris_context *ice,
                                                gl_shader_stage stage);
-unsigned iris_get_shader_num_ubos(const struct iris_context *ice,
-                                  gl_shader_stage stage);
 struct iris_bo *iris_get_scratch_space(struct iris_context *ice,
                                        unsigned per_thread_scratch,
                                        gl_shader_stage stage);
@@ -665,7 +666,8 @@ struct iris_compiled_shader *iris_upload_shader(struct iris_context *ice,
                                                 struct brw_stage_prog_data *,
                                                 uint32_t *streamout,
                                                 enum brw_param_builtin *sysv,
-                                                unsigned num_system_values);
+                                                unsigned num_system_values,
+                                                unsigned num_cbufs);
 const void *iris_find_previous_compile(const struct iris_context *ice,
                                        enum iris_program_cache_id cache_id,
                                        unsigned program_string_id);

src/gallium/drivers/iris/iris_program.c

@@ -515,7 +515,8 @@ assign_common_binding_table_offsets(const struct gen_device_info *devinfo,
                                     const struct nir_shader *nir,
                                     struct brw_stage_prog_data *prog_data,
                                     uint32_t next_binding_table_offset,
-                                    unsigned num_system_values)
+                                    unsigned num_system_values,
+                                    unsigned num_cbufs)
 {
    const struct shader_info *info = &nir->info;
 
@@ -535,13 +536,10 @@ assign_common_binding_table_offsets(const struct gen_device_info *devinfo,
       prog_data->binding_table.image_start = 0xd0d0d0d0;
    }
 
-   int num_ubos = info->num_ubos +
-                  ((nir->num_uniforms || num_system_values) ? 1 : 0);
-
-   if (num_ubos) {
+   if (num_cbufs) {
       //assert(info->num_ubos <= BRW_MAX_UBO);
       prog_data->binding_table.ubo_start = next_binding_table_offset;
-      next_binding_table_offset += num_ubos;
+      next_binding_table_offset += num_cbufs;
    } else {
       prog_data->binding_table.ubo_start = 0xd0d0d0d0;
    }
@@ -595,7 +593,8 @@ iris_setup_uniforms(const struct brw_compiler *compiler,
                     nir_shader *nir,
                     struct brw_stage_prog_data *prog_data,
                     enum brw_param_builtin **out_system_values,
-                    unsigned *out_num_system_values)
+                    unsigned *out_num_system_values,
+                    unsigned *out_num_cbufs)
 {
    const struct gen_device_info *devinfo = compiler->devinfo;
 
@@ -784,8 +783,17 @@ iris_setup_uniforms(const struct brw_compiler *compiler,
    prog_data->nr_params = nir->num_uniforms / 4;
    prog_data->param = rzalloc_array(mem_ctx, uint32_t, prog_data->nr_params);
 
+   /* System values and uniforms are stored in constant buffer 0, the
+    * user-facing UBOs are indexed by one.  So if any constant buffer is
+    * needed, the constant buffer 0 will be needed, so account for it.
+    */
+   unsigned num_cbufs = nir->info.num_ubos;
+   if (num_cbufs || num_system_values || nir->num_uniforms)
+      num_cbufs++;
+
    *out_system_values = system_values;
    *out_num_system_values = num_system_values;
+   *out_num_cbufs = num_cbufs;
 }
 
 /**
@@ -806,6 +814,7 @@ iris_compile_vs(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &vue_prog_data->base;
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
+   unsigned num_cbufs;
 
    nir_shader *nir = nir_shader_clone(mem_ctx, ish->nir);
 
@@ -821,10 +830,10 @@ iris_compile_vs(struct iris_context *ice,
    // XXX: alt mode
 
    iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                       &num_system_values);
+                       &num_system_values, &num_cbufs);
 
    assign_common_binding_table_offsets(devinfo, nir, prog_data, 0,
-                                       num_system_values);
+                                       num_system_values, num_cbufs);
 
    brw_compute_vue_map(devinfo,
                        &vue_prog_data->vue_map, nir->info.outputs_written,
@@ -852,7 +861,8 @@ iris_compile_vs(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_VS, sizeof(*key), key, program,
-                         prog_data, so_decls, system_values, num_system_values);
+                         prog_data, so_decls, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish->compiled_once) {
       perf_debug(&ice->dbg, "Recompiling vertex shader\n");
@@ -909,22 +919,6 @@ iris_get_shader_info(const struct iris_context *ice, gl_shader_stage stage)
    return &nir->info;
 }
 
-// XXX: this function is gross
-unsigned
-iris_get_shader_num_ubos(const struct iris_context *ice, gl_shader_stage stage)
-{
-   const struct iris_uncompiled_shader *ish = ice->shaders.uncompiled[stage];
-   const struct iris_compiled_shader *shader = ice->shaders.prog[stage];
-
-   if (ish) {
-      const nir_shader *nir = ish->nir;
-      /* see assign_common_binding_table_offsets */
-      return nir->info.num_ubos +
-             ((nir->num_uniforms || shader->num_system_values) ? 1 : 0);
-   }
-   return 0;
-}
-
 /**
  * Get the union of TCS output and TES input slots.
  *
@@ -976,6 +970,7 @@ iris_compile_tcs(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &vue_prog_data->base;
    enum brw_param_builtin *system_values = NULL;
    unsigned num_system_values = 0;
+   unsigned num_cbufs;
 
    nir_shader *nir;
 
@@ -983,9 +978,9 @@ iris_compile_tcs(struct iris_context *ice,
       nir = nir_shader_clone(mem_ctx, ish->nir);
 
       iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                          &num_system_values);
+                          &num_system_values, &num_cbufs);
       assign_common_binding_table_offsets(devinfo, nir, prog_data, 0,
-                                          num_system_values);
+                                          num_system_values, num_cbufs);
    } else {
       nir = brw_nir_create_passthrough_tcs(mem_ctx, compiler, options, key);
 
@@ -1007,7 +1002,8 @@ iris_compile_tcs(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_TCS, sizeof(*key), key, program,
-                         prog_data, NULL, system_values, num_system_values);
+                         prog_data, NULL, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish) {
       if (ish->compiled_once) {
@@ -1077,14 +1073,15 @@ iris_compile_tes(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &vue_prog_data->base;
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
+   unsigned num_cbufs;
 
    nir_shader *nir = nir_shader_clone(mem_ctx, ish->nir);
 
    iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                       &num_system_values);
+                       &num_system_values, &num_cbufs);
 
    assign_common_binding_table_offsets(devinfo, nir, prog_data, 0,
-                                       num_system_values);
+                                       num_system_values, num_cbufs);
 
    struct brw_vue_map input_vue_map;
    brw_compute_tess_vue_map(&input_vue_map, key->inputs_read,
@@ -1107,7 +1104,8 @@ iris_compile_tes(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_TES, sizeof(*key), key, program,
-                         prog_data, so_decls, system_values, num_system_values);
+                         prog_data, so_decls, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish->compiled_once) {
       perf_debug(&ice->dbg, "Recompiling tessellation evaluation shader\n");
@@ -1167,14 +1165,15 @@ iris_compile_gs(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &vue_prog_data->base;
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
+   unsigned num_cbufs;
 
    nir_shader *nir = nir_shader_clone(mem_ctx, ish->nir);
 
    iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                       &num_system_values);
+                       &num_system_values, &num_cbufs);
 
    assign_common_binding_table_offsets(devinfo, nir, prog_data, 0,
-                                       num_system_values);
+                                       num_system_values, num_cbufs);
 
    brw_compute_vue_map(devinfo,
                        &vue_prog_data->vue_map, nir->info.outputs_written,
@@ -1196,7 +1195,8 @@ iris_compile_gs(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_GS, sizeof(*key), key, program,
-                         prog_data, so_decls, system_values, num_system_values);
+                         prog_data, so_decls, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish->compiled_once) {
       perf_debug(&ice->dbg, "Recompiling geometry shader\n");
@@ -1258,17 +1258,18 @@ iris_compile_fs(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &fs_prog_data->base;
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
+   unsigned num_cbufs;
 
    nir_shader *nir = nir_shader_clone(mem_ctx, ish->nir);
 
    // XXX: alt mode
 
    iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                       &num_system_values);
+                       &num_system_values, &num_cbufs);
 
    assign_common_binding_table_offsets(devinfo, nir, prog_data,
                                        MAX2(key->nr_color_regions, 1),
-                                       num_system_values);
+                                       num_system_values, num_cbufs);
    char *error_str = NULL;
    const unsigned *program =
       brw_compile_fs(compiler, &ice->dbg, mem_ctx, key, fs_prog_data,
@@ -1281,7 +1282,8 @@ iris_compile_fs(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_FS, sizeof(*key), key, program,
-                         prog_data, NULL, system_values, num_system_values);
+                         prog_data, NULL, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish->compiled_once) {
       perf_debug(&ice->dbg, "Recompiling fragment shader\n");
@@ -1486,6 +1488,7 @@ iris_compile_cs(struct iris_context *ice,
    struct brw_stage_prog_data *prog_data = &cs_prog_data->base;
    enum brw_param_builtin *system_values;
    unsigned num_system_values;
+   unsigned num_cbufs;
 
    nir_shader *nir = nir_shader_clone(mem_ctx, ish->nir);
 
@@ -1494,10 +1497,10 @@ iris_compile_cs(struct iris_context *ice,
    prog_data->total_shared = nir->info.cs.shared_size;
 
    iris_setup_uniforms(compiler, mem_ctx, nir, prog_data, &system_values,
-                       &num_system_values);
+                       &num_system_values, &num_cbufs);
 
    assign_common_binding_table_offsets(devinfo, nir, prog_data, 1,
-                                       num_system_values);
+                                       num_system_values, num_cbufs);
 
    char *error_str = NULL;
    const unsigned *program =
@@ -1511,7 +1514,8 @@ iris_compile_cs(struct iris_context *ice,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_CS, sizeof(*key), key, program,
-                         prog_data, NULL, system_values, num_system_values);
+                         prog_data, NULL, system_values, num_system_values,
+                         num_cbufs);
 
    if (ish->compiled_once) {
       perf_debug(&ice->dbg, "Recompiling compute shader\n");

src/gallium/drivers/iris/iris_program_cache.c

@@ -166,7 +166,8 @@ iris_upload_shader(struct iris_context *ice,
                    struct brw_stage_prog_data *prog_data,
                    uint32_t *streamout,
                    enum brw_param_builtin *system_values,
-                   unsigned num_system_values)
+                   unsigned num_system_values,
+                   unsigned num_cbufs)
 {
    struct hash_table *cache = ice->shaders.cache;
    struct iris_compiled_shader *shader =
@@ -197,6 +198,7 @@ iris_upload_shader(struct iris_context *ice,
    shader->streamout = streamout;
    shader->system_values = system_values;
    shader->num_system_values = num_system_values;
+   shader->num_cbufs = num_cbufs;
 
    ralloc_steal(shader, shader->prog_data);
    ralloc_steal(shader->prog_data, prog_data->param);
@@ -254,7 +256,7 @@ iris_blorp_upload_shader(struct blorp_batch *blorp_batch,
 
    struct iris_compiled_shader *shader =
       iris_upload_shader(ice, IRIS_CACHE_BLORP, key_size, key, kernel,
-                         prog_data, NULL, NULL, 0);
+                         prog_data, NULL, NULL, 0, 0);
 
    struct iris_bo *bo = iris_resource_bo(shader->assembly.res);
    *kernel_out =

src/gallium/drivers/iris/iris_state.c

@@ -3754,11 +3754,9 @@ iris_populate_binding_table(struct iris_context *ice,
       push_bt_entry(addr);
    }
 
-   const int num_ubos = iris_get_shader_num_ubos(ice, stage);
+   bt_assert(ubo_start, shader->num_cbufs > 0);
 
-   bt_assert(ubo_start, num_ubos > 0);
-
-   for (int i = 0; i < num_ubos; i++) {
+   for (int i = 0; i < shader->num_cbufs; i++) {
       uint32_t addr = use_const_buffer(batch, ice, &shs->constbuf[i]);
       push_bt_entry(addr);
    }