v3dv/pipeline: revamp nir lowering/optimizations passes

The main reason is getting nir_lower_io_to_temporaries and
nir_opt_peephole_select to get some switch/ifelse with store outputs
simplified out, as some tests were failing because the v3d compiler
was not able to handle them.

As this needed some extra lowerings to get that working, we are also
revamping the full nir processing.

Heavily based on intel preprocess/optimize nir passes.

As mentioned on some other v3dv commits, some of this work could be
done by adding those passes to the v3d compiler, allowing to avoid
some duplication. But at this point we prefer to keep the v3d compiler
untouched as much as possible. This could be revisited on the future.

We also remove some passes that are unnedeed or we already know are
called by v3d_compiler.  Although we try to not add too many passes,
we are already adding passes in advance that we think that would be
useful in the near-term.

Among others, gets the following tests working:
  dEQP-VK.binding_model.descriptor_copy.graphics.storage*
  dEQP-VK.binding_model.descriptor_copy.graphics.uniform*

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>

diff --git a/src/broadcom/vulkan/v3dv_pipeline.c b/src/broadcom/vulkan/v3dv_pipeline.c
index 662289b..5f12b16 100644 (file)
--- a/src/broadcom/vulkan/v3dv_pipeline.c
+++ b/src/broadcom/vulkan/v3dv_pipeline.c
@@ -163,6 +163,145 @@ const nir_shader_compiler_options v3dv_nir_options = {
                                    * needs to be supported */
 };
 
+#define OPT(pass, ...) ({                                  \
+   bool this_progress = false;                             \
+   NIR_PASS(this_progress, nir, pass, ##__VA_ARGS__);      \
+   if (this_progress)                                      \
+      progress = true;                                     \
+   this_progress;                                          \
+})
+
+static void
+nir_optimize(nir_shader *nir,
+             struct v3dv_pipeline_stage *stage,
+             bool allow_copies)
+{
+   bool progress;
+
+   do {
+      progress = false;
+      OPT(nir_split_array_vars, nir_var_function_temp);
+      OPT(nir_shrink_vec_array_vars, nir_var_function_temp);
+      OPT(nir_opt_deref);
+      OPT(nir_lower_vars_to_ssa);
+      if (allow_copies) {
+         /* Only run this pass in the first call to nir_optimize.  Later calls
+          * assume that we've lowered away any copy_deref instructions and we
+          * don't want to introduce any more.
+          */
+         OPT(nir_opt_find_array_copies);
+      }
+      OPT(nir_opt_copy_prop_vars);
+      OPT(nir_opt_dead_write_vars);
+      OPT(nir_opt_combine_stores, nir_var_all);
+
+      OPT(nir_lower_alu_to_scalar, NULL, NULL);
+
+      OPT(nir_copy_prop);
+      OPT(nir_lower_phis_to_scalar);
+
+      OPT(nir_copy_prop);
+      OPT(nir_opt_dce);
+      OPT(nir_opt_cse);
+      OPT(nir_opt_combine_stores, nir_var_all);
+
+      /* Passing 0 to the peephole select pass causes it to convert
+       * if-statements that contain only move instructions in the branches
+       * regardless of the count.
+       *
+       * Passing 1 to the peephole select pass causes it to convert
+       * if-statements that contain at most a single ALU instruction (total)
+       * in both branches.
+       */
+      OPT(nir_opt_peephole_select, 0, false, false);
+      OPT(nir_opt_peephole_select, 8, false, true);
+
+      OPT(nir_opt_intrinsics);
+      OPT(nir_opt_idiv_const, 32);
+      OPT(nir_opt_algebraic);
+      OPT(nir_opt_constant_folding);
+
+      OPT(nir_opt_dead_cf);
+
+      OPT(nir_opt_if, false);
+      OPT(nir_opt_conditional_discard);
+
+      OPT(nir_opt_remove_phis);
+      OPT(nir_opt_undef);
+      OPT(nir_lower_pack);
+   } while (progress);
+
+   OPT(nir_remove_dead_variables, nir_var_function_temp, NULL);
+}
+
+static void
+preprocess_nir(nir_shader *nir,
+               struct v3dv_pipeline_stage *stage)
+{
+   /* Make sure we lower variable initializers on output variables so that
+    * nir_remove_dead_variables below sees the corresponding stores
+    */
+   NIR_PASS_V(nir, nir_lower_variable_initializers, nir_var_shader_out);
+
+   /* Now that we've deleted all but the main function, we can go ahead and
+    * lower the rest of the variable initializers.
+    */
+   NIR_PASS_V(nir, nir_lower_variable_initializers, ~0);
+
+   /* Split member structs.  We do this before lower_io_to_temporaries so that
+    * it doesn't lower system values to temporaries by accident.
+    */
+   NIR_PASS_V(nir, nir_split_var_copies);
+   NIR_PASS_V(nir, nir_split_per_member_structs);
+
+   if (nir->info.stage == MESA_SHADER_FRAGMENT)
+      NIR_PASS_V(nir, nir_lower_io_to_vector, nir_var_shader_out);
+   if (nir->info.stage == MESA_SHADER_FRAGMENT) {
+      NIR_PASS_V(nir, nir_lower_input_attachments,
+                 &(nir_input_attachment_options) {
+                    .use_fragcoord_sysval = false,
+                       });
+   }
+
+   NIR_PASS_V(nir, nir_remove_dead_variables, nir_var_shader_in |
+              nir_var_shader_out | nir_var_system_value | nir_var_mem_shared,
+              NULL);
+
+   NIR_PASS_V(nir, nir_propagate_invariant);
+   NIR_PASS_V(nir, nir_lower_io_to_temporaries,
+              nir_shader_get_entrypoint(nir), true, false);
+
+   NIR_PASS_V(nir, nir_lower_system_values);
+   NIR_PASS_V(nir, nir_lower_clip_cull_distance_arrays);
+
+   NIR_PASS_V(nir, nir_lower_alu_to_scalar, NULL, NULL);
+
+   NIR_PASS_V(nir, nir_normalize_cubemap_coords);
+
+   NIR_PASS_V(nir, nir_lower_global_vars_to_local);
+
+   NIR_PASS_V(nir, nir_split_var_copies);
+   NIR_PASS_V(nir, nir_split_struct_vars, nir_var_function_temp);
+
+   nir_optimize(nir, stage, true);
+
+   NIR_PASS_V(nir, nir_lower_load_const_to_scalar);
+
+   /* Lower a bunch of stuff */
+   NIR_PASS_V(nir, nir_lower_var_copies);
+
+   NIR_PASS_V(nir, nir_lower_indirect_derefs, nir_var_shader_in |
+              nir_var_shader_out |
+              nir_var_function_temp, UINT32_MAX);
+
+   NIR_PASS_V(nir, nir_lower_array_deref_of_vec,
+              nir_var_mem_ubo | nir_var_mem_ssbo,
+              nir_lower_direct_array_deref_of_vec_load);
+
+   /* Get rid of split copies */
+   nir_optimize(nir, stage, false);
+}
+
 static nir_shader *
 shader_module_compile_to_nir(struct v3dv_device *device,
                              struct v3dv_pipeline_stage *stage)
@@ -216,44 +355,11 @@ shader_module_compile_to_nir(struct v3dv_device *device,
    }
    assert(exec_list_length(&nir->functions) == 1);
 
-   /* Make sure we lower variable initializers on output variables so that
-    * nir_remove_dead_variables below sees the corresponding stores
-    */
-   NIR_PASS_V(nir, nir_lower_variable_initializers, nir_var_shader_out);
-
-   /* Now that we've deleted all but the main function, we can go ahead and
-    * lower the rest of the variable initializers.
-    */
-   NIR_PASS_V(nir, nir_lower_variable_initializers, ~0);
-
-   /* Split member structs.  We do this before lower_io_to_temporaries so that
-    * it doesn't lower system values to temporaries by accident.
-    */
-   NIR_PASS_V(nir, nir_split_var_copies);
-   NIR_PASS_V(nir, nir_split_per_member_structs);
-
-   /* FIXME: needed? */
-   if (nir->info.stage == MESA_SHADER_FRAGMENT)
-      NIR_PASS_V(nir, nir_lower_io_to_vector, nir_var_shader_out);
-   if (nir->info.stage == MESA_SHADER_FRAGMENT) {
-      NIR_PASS_V(nir, nir_lower_input_attachments,
-                 &(nir_input_attachment_options) {
-                    .use_fragcoord_sysval = false,
-                       });                                                                                                                                                                                            }
-
-   NIR_PASS_V(nir, nir_remove_dead_variables,
-              nir_var_shader_in | nir_var_shader_out |
-              nir_var_system_value | nir_var_mem_shared,
-              NULL);
-
-   NIR_PASS_V(nir, nir_propagate_invariant);
-
-   NIR_PASS_V(nir, nir_lower_system_values);
-   NIR_PASS_V(nir, nir_lower_clip_cull_distance_arrays);
-
    /* Vulkan uses the separate-shader linking model */
    nir->info.separate_shader = true;
 
+   preprocess_nir(nir, stage);
+
    return nir;
 }
 
@@ -864,9 +970,6 @@ st_nir_opts(nir_shader *nir)
 
       NIR_PASS(progress, nir, nir_opt_undef);
       NIR_PASS(progress, nir, nir_opt_conditional_discard);
-      if (nir->options->max_unroll_iterations) {
-         NIR_PASS(progress, nir, nir_opt_loop_unroll, (nir_variable_mode)0);
-      }
    } while (progress);
 }