nir: Add a ptr_as_array deref type

These correspond directly to SPIR-V's OpPtrAccessChain.  As such, they
treat whatever their parent gives them as if it's the first element in
some array and dereferences that array.  If the parent is, itself, an
array deref, then the two indices can just be added together to get the
final array deref.  However, it can also be used in cases where what you
have is a dereference to some random vec2 value somewhere.  In this
case, we require a cast before the ptr_as_array and use the ptr_stride
field in the cast to provide a stride for the ptr_as_array derefs.

Reviewed-by: Alejandro Piñeiro <[email protected]>
Reviewed-by: Caio Marcelo de Oliveira Filho <[email protected]>

12 files changed, 106 insertions, 13 deletions

diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c
index b0b031cde61..07bb96dc3b0 100644
--- a/src/compiler/nir/nir.c
+++ b/src/compiler/nir/nir.c
@@ -460,7 +460,8 @@ nir_deref_instr_create(nir_shader *shader, nir_deref_type deref_type)
    if (deref_type != nir_deref_type_var)
       src_init(&instr->parent);
 
-   if (deref_type == nir_deref_type_array)
+   if (deref_type == nir_deref_type_array ||
+       deref_type == nir_deref_type_ptr_as_array)
       src_init(&instr->arr.index);
 
    dest_init(&instr->dest);
@@ -1067,7 +1068,8 @@ visit_deref_instr_src(nir_deref_instr *instr,
          return false;
    }
 
-   if (instr->deref_type == nir_deref_type_array) {
+   if (instr->deref_type == nir_deref_type_array ||
+       instr->deref_type == nir_deref_type_ptr_as_array) {
       if (!visit_src(&instr->arr.index, cb, state))
          return false;
    }
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index e991c625536..971d8c4979f 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -998,6 +998,7 @@ typedef enum {
    nir_deref_type_var,
    nir_deref_type_array,
    nir_deref_type_array_wildcard,
+   nir_deref_type_ptr_as_array,
    nir_deref_type_struct,
    nir_deref_type_cast,
 } nir_deref_type;
@@ -1031,6 +1032,10 @@ typedef struct {
       struct {
          unsigned index;
       } strct;
+
+      struct {
+         unsigned ptr_stride;
+      } cast;
    };
 
    /** Destination to store the resulting "pointer" */
@@ -1078,6 +1083,8 @@ bool nir_deref_instr_has_indirect(nir_deref_instr *instr);
 
 bool nir_deref_instr_remove_if_unused(nir_deref_instr *instr);
 
+unsigned nir_deref_instr_ptr_as_array_stride(nir_deref_instr *instr);
+
 typedef struct {
    nir_instr instr;
 
diff --git a/src/compiler/nir/nir_builder.h b/src/compiler/nir/nir_builder.h
index 2076f419ae2..7dbdd5724c2 100644
--- a/src/compiler/nir/nir_builder.h
+++ b/src/compiler/nir/nir_builder.h
@@ -812,6 +812,31 @@ nir_build_deref_array(nir_builder *build, nir_deref_instr *parent,
 }
 
 static inline nir_deref_instr *
+nir_build_deref_ptr_as_array(nir_builder *build, nir_deref_instr *parent,
+                             nir_ssa_def *index)
+{
+   assert(parent->deref_type == nir_deref_type_array ||
+          parent->deref_type == nir_deref_type_ptr_as_array ||
+          parent->deref_type == nir_deref_type_cast);
+
+   nir_deref_instr *deref =
+      nir_deref_instr_create(build->shader, nir_deref_type_ptr_as_array);
+
+   deref->mode = parent->mode;
+   deref->type = parent->type;
+   deref->parent = nir_src_for_ssa(&parent->dest.ssa);
+   deref->arr.index = nir_src_for_ssa(index);
+
+   nir_ssa_dest_init(&deref->instr, &deref->dest,
+                     parent->dest.ssa.num_components,
+                     parent->dest.ssa.bit_size, NULL);
+
+   nir_builder_instr_insert(build, &deref->instr);
+
+   return deref;
+}
+
+static inline nir_deref_instr *
 nir_build_deref_array_wildcard(nir_builder *build, nir_deref_instr *parent)
 {
    assert(glsl_type_is_array(parent->type) ||
@@ -858,7 +883,8 @@ nir_build_deref_struct(nir_builder *build, nir_deref_instr *parent,
 
 static inline nir_deref_instr *
 nir_build_deref_cast(nir_builder *build, nir_ssa_def *parent,
-                     nir_variable_mode mode, const struct glsl_type *type)
+                     nir_variable_mode mode, const struct glsl_type *type,
+                     unsigned ptr_stride)
 {
    nir_deref_instr *deref =
       nir_deref_instr_create(build->shader, nir_deref_type_cast);
@@ -866,6 +892,7 @@ nir_build_deref_cast(nir_builder *build, nir_ssa_def *parent,
    deref->mode = mode;
    deref->type = type;
    deref->parent = nir_src_for_ssa(parent);
+   deref->cast.ptr_stride = ptr_stride;
 
    nir_ssa_dest_init(&deref->instr, &deref->dest,
                      parent->num_components, parent->bit_size, NULL);
diff --git a/src/compiler/nir/nir_clone.c b/src/compiler/nir/nir_clone.c
index 989c5051a54..e690b9165c9 100644
--- a/src/compiler/nir/nir_clone.c
+++ b/src/compiler/nir/nir_clone.c
@@ -311,15 +311,19 @@ clone_deref_instr(clone_state *state, const nir_deref_instr *deref)
       break;
 
    case nir_deref_type_array:
+   case nir_deref_type_ptr_as_array:
       __clone_src(state, &nderef->instr,
                   &nderef->arr.index, &deref->arr.index);
       break;
 
    case nir_deref_type_array_wildcard:
-   case nir_deref_type_cast:
       /* Nothing to do */
       break;
 
+   case nir_deref_type_cast:
+      nderef->cast.ptr_stride = deref->cast.ptr_stride;
+      break;
+
    default:
       unreachable("Invalid instruction deref type");
    }
diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c
index 1dffa285037..76bad2dd9db 100644
--- a/src/compiler/nir/nir_deref.c
+++ b/src/compiler/nir/nir_deref.c
@@ -111,7 +111,8 @@ nir_deref_instr_has_indirect(nir_deref_instr *instr)
       if (instr->deref_type == nir_deref_type_cast)
          return true;
 
-      if (instr->deref_type == nir_deref_type_array &&
+      if ((instr->deref_type == nir_deref_type_array ||
+           instr->deref_type == nir_deref_type_ptr_as_array) &&
           !nir_src_is_const(instr->arr.index))
          return true;
 
@@ -121,6 +122,23 @@ nir_deref_instr_has_indirect(nir_deref_instr *instr)
    return false;
 }
 
+unsigned
+nir_deref_instr_ptr_as_array_stride(nir_deref_instr *deref)
+{
+   assert(deref->deref_type == nir_deref_type_ptr_as_array);
+   nir_deref_instr *parent = nir_deref_instr_parent(deref);
+   switch (parent->deref_type) {
+   case nir_deref_type_array:
+      return glsl_get_explicit_stride(nir_deref_instr_parent(parent)->type);
+   case nir_deref_type_ptr_as_array:
+      return nir_deref_instr_ptr_as_array_stride(parent);
+   case nir_deref_type_cast:
+      return parent->cast.ptr_stride;
+   default:
+      unreachable("Invalid parent for ptr_as_array deref");
+   }
+}
+
 static unsigned
 type_get_array_stride(const struct glsl_type *elem_type,
                       glsl_type_size_align_func size_align)
diff --git a/src/compiler/nir/nir_instr_set.c b/src/compiler/nir/nir_instr_set.c
index 2a9e3396985..060bd9eee0b 100644
--- a/src/compiler/nir/nir_instr_set.c
+++ b/src/compiler/nir/nir_instr_set.c
@@ -96,12 +96,16 @@ hash_deref(uint32_t hash, const nir_deref_instr *instr)
       break;
 
    case nir_deref_type_array:
+   case nir_deref_type_ptr_as_array:
       hash = hash_src(hash, &instr->arr.index);
       break;
 
+   case nir_deref_type_cast:
+      hash = HASH(hash, instr->cast.ptr_stride);
+      break;
+
    case nir_deref_type_var:
    case nir_deref_type_array_wildcard:
-   case nir_deref_type_cast:
       /* Nothing to do */
       break;
 
@@ -351,13 +355,18 @@ nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
          break;
 
       case nir_deref_type_array:
+      case nir_deref_type_ptr_as_array:
          if (!nir_srcs_equal(deref1->arr.index, deref2->arr.index))
             return false;
          break;
 
+      case nir_deref_type_cast:
+         if (deref1->cast.ptr_stride != deref2->cast.ptr_stride)
+            return false;
+         break;
+
       case nir_deref_type_var:
       case nir_deref_type_array_wildcard:
-      case nir_deref_type_cast:
          /* Nothing to do */
          break;
 
diff --git a/src/compiler/nir/nir_opt_copy_propagate.c b/src/compiler/nir/nir_opt_copy_propagate.c
index 7673e9b62dd..fcb85d15535 100644
--- a/src/compiler/nir/nir_opt_copy_propagate.c
+++ b/src/compiler/nir/nir_opt_copy_propagate.c
@@ -224,7 +224,8 @@ copy_prop_instr(nir_instr *instr)
             progress = true;
       }
 
-      if (deref->deref_type == nir_deref_type_array) {
+      if (deref->deref_type == nir_deref_type_array ||
+          deref->deref_type == nir_deref_type_ptr_as_array) {
          while (copy_prop_src(&deref->arr.index, instr, NULL, 1))
             progress = true;
       }
diff --git a/src/compiler/nir/nir_print.c b/src/compiler/nir/nir_print.c
index 95d9bc85656..a73b9d37ae5 100644
--- a/src/compiler/nir/nir_print.c
+++ b/src/compiler/nir/nir_print.c
@@ -636,7 +636,8 @@ print_deref_link(const nir_deref_instr *instr, bool whole_chain, print_state *st
               glsl_get_struct_elem_name(parent->type, instr->strct.index));
       break;
 
-   case nir_deref_type_array: {
+   case nir_deref_type_array:
+   case nir_deref_type_ptr_as_array: {
       nir_const_value *const_index = nir_src_as_const_value(instr->arr.index);
       if (const_index) {
          fprintf(fp, "[%u]", const_index->u32[0]);
@@ -678,6 +679,9 @@ print_deref_instr(nir_deref_instr *instr, print_state *state)
    case nir_deref_type_cast:
       fprintf(fp, " = deref_cast ");
       break;
+   case nir_deref_type_ptr_as_array:
+      fprintf(fp, " = deref_ptr_as_array ");
+      break;
    default:
       unreachable("Invalid deref instruction type");
    }
diff --git a/src/compiler/nir/nir_serialize.c b/src/compiler/nir/nir_serialize.c
index 43016310048..b4187213716 100644
--- a/src/compiler/nir/nir_serialize.c
+++ b/src/compiler/nir/nir_serialize.c
@@ -438,11 +438,15 @@ write_deref(write_ctx *ctx, const nir_deref_instr *deref)
       break;
 
    case nir_deref_type_array:
+   case nir_deref_type_ptr_as_array:
       write_src(ctx, &deref->arr.index);
       break;
 
-   case nir_deref_type_array_wildcard:
    case nir_deref_type_cast:
+      blob_write_uint32(ctx->blob, deref->cast.ptr_stride);
+      break;
+
+   case nir_deref_type_array_wildcard:
       /* Nothing to do */
       break;
 
@@ -475,11 +479,15 @@ read_deref(read_ctx *ctx)
       break;
 
    case nir_deref_type_array:
+   case nir_deref_type_ptr_as_array:
       read_src(ctx, &deref->arr.index, &deref->instr);
       break;
 
-   case nir_deref_type_array_wildcard:
    case nir_deref_type_cast:
+      deref->cast.ptr_stride = blob_read_uint32(ctx->blob);
+      break;
+
+   case nir_deref_type_array_wildcard:
       /* Nothing to do */
       break;
 
diff --git a/src/compiler/nir/nir_validate.c b/src/compiler/nir/nir_validate.c
index ccd0cf782fe..9f8455d21cc 100644
--- a/src/compiler/nir/nir_validate.c
+++ b/src/compiler/nir/nir_validate.c
@@ -470,6 +470,19 @@ validate_deref_instr(nir_deref_instr *instr, validate_state *state)
          }
          break;
 
+      case nir_deref_type_ptr_as_array:
+         /* ptr_as_array derefs must have a parent that is either an array,
+          * ptr_as_array, or cast.  If the parent is a cast, we get the stride
+          * information (if any) from the cast deref.
+          */
+         validate_assert(state,
+                         parent->deref_type == nir_deref_type_array ||
+                         parent->deref_type == nir_deref_type_ptr_as_array ||
+                         parent->deref_type == nir_deref_type_cast);
+         validate_src(&instr->arr.index, state,
+                      nir_dest_bit_size(instr->dest), 1);
+         break;
+
       default:
          unreachable("Invalid deref instruction type");
       }
diff --git a/src/compiler/spirv/vtn_cfg.c b/src/compiler/spirv/vtn_cfg.c
index ab0d42942f2..9cec036d462 100644
--- a/src/compiler/spirv/vtn_cfg.c
+++ b/src/compiler/spirv/vtn_cfg.c
@@ -884,7 +884,7 @@ vtn_emit_cf_list(struct vtn_builder *b, struct list_head *cf_list,
                glsl_get_bare_type(b->func->type->return_type->type);
             nir_deref_instr *ret_deref =
                nir_build_deref_cast(&b->nb, nir_load_param(&b->nb, 0),
-                                    nir_var_local, ret_type);
+                                    nir_var_local, ret_type, 0);
             vtn_local_store(b, src, ret_deref);
          }
 
diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index 6e96cb606b4..3041fa47ec1 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -1627,7 +1627,7 @@ vtn_pointer_from_ssa(struct vtn_builder *b, nir_ssa_def *ssa,
       assert(!vtn_pointer_is_external_block(b, ptr));
       const struct glsl_type *deref_type = ptr_type->deref->type;
       ptr->deref = nir_build_deref_cast(&b->nb, ssa, nir_mode,
-                                        glsl_get_bare_type(deref_type));
+                                        glsl_get_bare_type(deref_type), 0);
    }
 
    return ptr;