nir: Convert lower_io to deref instructions

This deletes support for _var intrinsics and legacy deref chains in
favor of deref instructions.  The internals are also reworked a bit to
use deref instructions directly.

Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir_lower_io.c

@@ -33,6 +33,7 @@
 
 #include "nir.h"
 #include "nir_builder.h"
+#include "nir_deref.h"
 
 struct lower_io_state {
    void *dead_ctx;
@@ -86,35 +87,35 @@ nir_is_per_vertex_io(const nir_variable *var, gl_shader_stage stage)
 }
 
 static nir_ssa_def *
-get_io_offset(nir_builder *b, nir_deref_var *deref,
+get_io_offset(nir_builder *b, nir_deref_instr *deref,
               nir_ssa_def **vertex_index,
               int (*type_size)(const struct glsl_type *),
               unsigned *component)
 {
-   nir_deref *tail = &deref->deref;
+   nir_deref_path path;
+   nir_deref_path_init(&path, deref, NULL);
+
+   assert(path.path[0]->deref_type == nir_deref_type_var);
+   nir_deref_instr **p = &path.path[1];
 
    /* For per-vertex input arrays (i.e. geometry shader inputs), keep the
     * outermost array index separate.  Process the rest normally.
     */
    if (vertex_index != NULL) {
-      tail = tail->child;
+      assert((*p)->deref_type == nir_deref_type_array);
-      nir_deref_array *deref_array = nir_deref_as_array(tail);
+      *vertex_index = nir_ssa_for_src(b, (*p)->arr.index, 1);
-
+      p++;
-      nir_ssa_def *vtx = nir_imm_int(b, deref_array->base_offset);
-      if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
-         vtx = nir_iadd(b, vtx, nir_ssa_for_src(b, deref_array->indirect, 1));
-      }
-      *vertex_index = vtx;
    }
 
-   if (deref->var->data.compact) {
+   if (path.path[0]->var->data.compact) {
-      assert(tail->child->deref_type == nir_deref_type_array);
+      assert((*p)->deref_type == nir_deref_type_array);
-      assert(glsl_type_is_scalar(glsl_without_array(deref->var->type)));
+      assert(glsl_type_is_scalar((*p)->type));
-      nir_deref_array *deref_array = nir_deref_as_array(tail->child);
-      /* We always lower indirect dereferences for "compact" array vars. */
-      assert(deref_array->deref_array_type == nir_deref_array_type_direct);
 
-      const unsigned total_offset = *component + deref_array->base_offset;
+      /* We always lower indirect dereferences for "compact" array vars. */
+      nir_const_value *const_index = nir_src_as_const_value((*p)->arr.index);
+      assert(const_index);
+
+      const unsigned total_offset = *component + const_index->u32[0];
       const unsigned slot_offset = total_offset / 4;
       *component = total_offset % 4;
       return nir_imm_int(b, type_size(glsl_vec4_type()) * slot_offset);
@@ -123,35 +124,31 @@ get_io_offset(nir_builder *b, nir_deref_var *deref,
    /* Just emit code and let constant-folding go to town */
    nir_ssa_def *offset = nir_imm_int(b, 0);
 
-   while (tail->child != NULL) {
+   for (; *p; p++) {
-      const struct glsl_type *parent_type = tail->type;
+      if ((*p)->deref_type == nir_deref_type_array) {
-      tail = tail->child;
+         unsigned size = type_size((*p)->type);
 
-      if (tail->deref_type == nir_deref_type_array) {
+         nir_ssa_def *mul =
-         nir_deref_array *deref_array = nir_deref_as_array(tail);
+            nir_imul(b, nir_imm_int(b, size),
-         unsigned size = type_size(tail->type);
+                     nir_ssa_for_src(b, (*p)->arr.index, 1));
 
-         offset = nir_iadd(b, offset,
+         offset = nir_iadd(b, offset, mul);
-                           nir_imm_int(b, size * deref_array->base_offset));
+      } else if ((*p)->deref_type == nir_deref_type_struct) {
-
+         /* p starts at path[1], so this is safe */
-         if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
+         nir_deref_instr *parent = *(p - 1);
-            nir_ssa_def *mul =
-               nir_imul(b, nir_imm_int(b, size),
-                        nir_ssa_for_src(b, deref_array->indirect, 1));
-
-            offset = nir_iadd(b, offset, mul);
-         }
-      } else if (tail->deref_type == nir_deref_type_struct) {
-         nir_deref_struct *deref_struct = nir_deref_as_struct(tail);
 
          unsigned field_offset = 0;
-         for (unsigned i = 0; i < deref_struct->index; i++) {
+         for (unsigned i = 0; i < (*p)->strct.index; i++) {
-            field_offset += type_size(glsl_get_struct_field(parent_type, i));
+            field_offset += type_size(glsl_get_struct_field(parent->type, i));
          }
          offset = nir_iadd(b, offset, nir_imm_int(b, field_offset));
+      } else {
+         unreachable("Unsupported deref type");
       }
    }
 
+   nir_deref_path_finish(&path);
+
    return offset;
 }
 
@@ -247,10 +244,7 @@ lower_store(nir_intrinsic_instr *intrin, struct lower_io_state *state,
       nir_intrinsic_instr_create(state->builder.shader, op);
    store->num_components = intrin->num_components;
 
-   if (intrin->intrinsic == nir_intrinsic_store_var)
+   nir_src_copy(&store->src[0], &intrin->src[1], store);
-      nir_src_copy(&store->src[0], &intrin->src[0], store);
-   else
-      nir_src_copy(&store->src[0], &intrin->src[1], store);
 
    nir_intrinsic_set_base(store, var->data.driver_location);
 
@@ -318,17 +312,14 @@ lower_interpolate_at(nir_intrinsic_instr *intrin, struct lower_io_state *state,
 
    nir_intrinsic_op bary_op;
    switch (intrin->intrinsic) {
-   case nir_intrinsic_interp_var_at_centroid:
    case nir_intrinsic_interp_deref_at_centroid:
       bary_op = (state->options & nir_lower_io_force_sample_interpolation) ?
                 nir_intrinsic_load_barycentric_sample :
                 nir_intrinsic_load_barycentric_centroid;
       break;
-   case nir_intrinsic_interp_var_at_sample:
    case nir_intrinsic_interp_deref_at_sample:
       bary_op = nir_intrinsic_load_barycentric_at_sample;
       break;
-   case nir_intrinsic_interp_var_at_offset:
    case nir_intrinsic_interp_deref_at_offset:
       bary_op = nir_intrinsic_load_barycentric_at_offset;
       break;
@@ -342,10 +333,6 @@ lower_interpolate_at(nir_intrinsic_instr *intrin, struct lower_io_state *state,
    nir_ssa_dest_init(&bary_setup->instr, &bary_setup->dest, 2, 32, NULL);
    nir_intrinsic_set_interp_mode(bary_setup, var->data.interpolation);
 
-   if (intrin->intrinsic == nir_intrinsic_interp_var_at_sample ||
-       intrin->intrinsic == nir_intrinsic_interp_var_at_offset)
-      nir_src_copy(&bary_setup->src[0], &intrin->src[0], bary_setup);
-
    if (intrin->intrinsic == nir_intrinsic_interp_deref_at_sample ||
        intrin->intrinsic == nir_intrinsic_interp_deref_at_offset)
       nir_src_copy(&bary_setup->src[0], &intrin->src[1], bary_setup);
@@ -381,9 +368,7 @@ nir_lower_io_block(nir_block *block,
       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 
       switch (intrin->intrinsic) {
-      case nir_intrinsic_load_var:
       case nir_intrinsic_load_deref:
-      case nir_intrinsic_store_var:
       case nir_intrinsic_store_deref:
       case nir_intrinsic_deref_atomic_add:
       case nir_intrinsic_deref_atomic_imin:
@@ -397,9 +382,6 @@ nir_lower_io_block(nir_block *block,
       case nir_intrinsic_deref_atomic_comp_swap:
          /* We can lower the io for this nir instrinsic */
          break;
-      case nir_intrinsic_interp_var_at_centroid:
-      case nir_intrinsic_interp_var_at_sample:
-      case nir_intrinsic_interp_var_at_offset:
       case nir_intrinsic_interp_deref_at_centroid:
       case nir_intrinsic_interp_deref_at_sample:
       case nir_intrinsic_interp_deref_at_offset:
@@ -411,17 +393,9 @@ nir_lower_io_block(nir_block *block,
          continue;
       }
 
-      nir_deref_var *deref;
+      nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
-      nir_deref_instr *deref_instr = NULL;
-      if (nir_intrinsic_infos[intrin->intrinsic].num_variables > 0) {
-         assert(nir_intrinsic_infos[intrin->intrinsic].num_variables == 1);
-         deref = intrin->variables[0];
-      } else {
-         deref_instr = nir_src_as_deref(intrin->src[0]);
-         deref = nir_deref_instr_to_deref(deref_instr, state->dead_ctx);
-      }
 
-      nir_variable *var = deref->var;
+      nir_variable *var = nir_deref_instr_get_variable(deref);
       nir_variable_mode mode = var->data.mode;
 
       if ((state->modes & mode) == 0)
@@ -447,13 +421,11 @@ nir_lower_io_block(nir_block *block,
       nir_intrinsic_instr *replacement;
 
       switch (intrin->intrinsic) {
-      case nir_intrinsic_load_var:
       case nir_intrinsic_load_deref:
          replacement = lower_load(intrin, state, vertex_index, var, offset,
                                   component_offset);
          break;
 
-      case nir_intrinsic_store_var:
       case nir_intrinsic_store_deref:
          replacement = lower_store(intrin, state, vertex_index, var, offset,
                                    component_offset);
@@ -473,9 +445,6 @@ nir_lower_io_block(nir_block *block,
          replacement = lower_atomic(intrin, state, var, offset);
          break;
 
-      case nir_intrinsic_interp_var_at_centroid:
-      case nir_intrinsic_interp_var_at_sample:
-      case nir_intrinsic_interp_var_at_offset:
       case nir_intrinsic_interp_deref_at_centroid:
       case nir_intrinsic_interp_deref_at_sample:
       case nir_intrinsic_interp_deref_at_offset:
@@ -541,7 +510,7 @@ nir_lower_io(nir_shader *shader, nir_variable_mode modes,
 {
    bool progress = false;
 
-   nir_assert_unlowered_derefs(shader, nir_lower_atomic_derefs);
+   nir_assert_unlowered_derefs(shader, nir_lower_load_store_derefs | nir_lower_interp_derefs | nir_lower_atomic_derefs);
 
    nir_foreach_function(function, shader) {
       if (function->impl) {