glsl: handle implicit sized arrays in ssbo

The current code disallows unsized arrays except at the end of
an SSBO but it is a bit overzealous in doing so.

struct a {
	int b[];
	int f[4];
};

is valid as long as b is implicitly sized within the shader,
i.e. it is accessed only by integer indices.

I've submitted some piglit tests to test for this.

This also has no regressions on piglit on my Haswell.
This fixes:
GL45-CTS.shader_storage_buffer_object.basic-syntax
GL45-CTS.shader_storage_buffer_object.basic-syntaxSSO

This patch moves a chunk of the linker code down, so
that we don't link the uniform blocks until after we've
merged all the variables. The logic went something like:

Removing the checks for last ssbo member unsized from
the compiler and into the linker, meant doing the check
in the link_uniform_blocks code. However to do that the
array sizing had to happen first, so we knew that the
only unsized arrays were in the last block. But array
sizing required the variable to be merged, otherwise
you'd get two different array sizes in different
version of two variables, and one would get lost
when merged. So the solution was to move array sizing
up, after variable merging, but before uniform block
visiting.

Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

6 files changed, 66 insertions, 89 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index b818de6fe1..22bc008332 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -7484,31 +7484,6 @@ ast_interface_block::hir(exec_list *instructions,
          handle_tess_ctrl_shader_output_decl(state, loc, var);
 
       for (unsigned i = 0; i < num_variables; i++) {
-         if (fields[i].type->is_unsized_array()) {
-            if (var_mode == ir_var_shader_storage) {
-               if (i != (num_variables - 1)) {
-                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
-                                   "only last member of a shader storage block "
-                                   "can be defined as unsized array",
-                                   fields[i].name);
-               }
-            } else {
-               /* From GLSL ES 3.10 spec, section 4.1.9 "Arrays":
-               *
-               * "If an array is declared as the last member of a shader storage
-               * block and the size is not specified at compile-time, it is
-               * sized at run-time. In all other cases, arrays are sized only
-               * at compile-time."
-               */
-               if (state->es_shader) {
-                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
-                                 "only last member of a shader storage block "
-                                 "can be defined as unsized array",
-                                 fields[i].name);
-               }
-            }
-         }
-
          if (var->data.mode == ir_var_shader_storage)
             apply_memory_qualifiers(var, fields[i]);
       }
@@ -7624,26 +7599,8 @@ ast_interface_block::hir(exec_list *instructions,
 
          if (var->type->is_unsized_array()) {
             if (var->is_in_shader_storage_block()) {
-               if (!is_unsized_array_last_element(var)) {
-                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
-                                   "only last member of a shader storage block "
-                                   "can be defined as unsized array",
-                                   var->name);
-               }
-               var->data.from_ssbo_unsized_array = true;
-            } else {
-               /* From GLSL ES 3.10 spec, section 4.1.9 "Arrays":
-               *
-               * "If an array is declared as the last member of a shader storage
-               * block and the size is not specified at compile-time, it is
-               * sized at run-time. In all other cases, arrays are sized only
-               * at compile-time."
-               */
-               if (state->es_shader) {
-                  _mesa_glsl_error(&loc, state, "unsized array `%s' definition: "
-                                 "only last member of a shader storage block "
-                                 "can be defined as unsized array",
-                                 var->name);
+               if (is_unsized_array_last_element(var)) {
+                  var->data.from_ssbo_unsized_array = true;
                }
             }
          }
diff --git a/src/compiler/glsl/ir.h b/src/compiler/glsl/ir.h
index d52dbf8a38..e8efd27112 100644
--- a/src/compiler/glsl/ir.h
+++ b/src/compiler/glsl/ir.h
@@ -819,6 +819,7 @@ public:
        */
       unsigned from_ssbo_unsized_array:1; /**< unsized array buffer variable. */
 
+      unsigned implicit_sized_array:1;
       /**
        * Emit a warning if this variable is accessed.
        */
diff --git a/src/compiler/glsl/ir_validate.cpp b/src/compiler/glsl/ir_validate.cpp
index 9d05e7e00a..757f17cbf3 100644
--- a/src/compiler/glsl/ir_validate.cpp
+++ b/src/compiler/glsl/ir_validate.cpp
@@ -743,7 +743,8 @@ ir_validate::visit(ir_variable *ir)
       const glsl_struct_field *fields =
          ir->get_interface_type()->fields.structure;
       for (unsigned i = 0; i < ir->get_interface_type()->length; i++) {
-         if (fields[i].type->array_size() > 0) {
+         if (fields[i].type->array_size() > 0 &&
+             !fields[i].implicit_sized_array) {
             const int *const max_ifc_array_access =
                ir->get_max_ifc_array_access();
 
diff --git a/src/compiler/glsl/link_uniform_blocks.cpp b/src/compiler/glsl/link_uniform_blocks.cpp
index ac415b54f0..3c2d13c99c 100644
--- a/src/compiler/glsl/link_uniform_blocks.cpp
+++ b/src/compiler/glsl/link_uniform_blocks.cpp
@@ -34,9 +34,10 @@ namespace {
 class ubo_visitor : public program_resource_visitor {
 public:
    ubo_visitor(void *mem_ctx, gl_uniform_buffer_variable *variables,
-               unsigned num_variables)
+               unsigned num_variables, struct gl_shader_program *prog)
       : index(0), offset(0), buffer_size(0), variables(variables),
-        num_variables(num_variables), mem_ctx(mem_ctx), is_array_instance(false)
+        num_variables(num_variables), mem_ctx(mem_ctx), is_array_instance(false),
+        prog(prog)
    {
       /* empty */
    }
@@ -56,6 +57,7 @@ public:
    unsigned num_variables;
    void *mem_ctx;
    bool is_array_instance;
+   struct gl_shader_program *prog;
 
 private:
    virtual void visit_field(const glsl_type *type, const char *name,
@@ -148,7 +150,13 @@ private:
        */
       const glsl_type *type_for_size = type;
       if (type->is_unsized_array()) {
-         assert(last_field);
+         if (!last_field) {
+            linker_error(prog, "unsized array `%s' definition: "
+                         "only last member of a shader storage block "
+                         "can be defined as unsized array",
+                         name);
+         }
+
          type_for_size = type->without_array();
       }
 
@@ -314,7 +322,7 @@ create_buffer_blocks(void *mem_ctx, struct gl_context *ctx,
    /* Add each variable from each uniform block to the API tracking
     * structures.
     */
-   ubo_visitor parcel(blocks, variables, num_variables);
+   ubo_visitor parcel(blocks, variables, num_variables, prog);
 
    STATIC_ASSERT(unsigned(GLSL_INTERFACE_PACKING_STD140)
                  == unsigned(ubo_packing_std140));
diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
index 5c0e4b67ff..8e6455310b 100644
--- a/src/compiler/glsl/linker.cpp
+++ b/src/compiler/glsl/linker.cpp
@@ -205,7 +205,8 @@ public:
       /* Generate a link error if the shader has declared this array with an
        * incorrect size.
        */
-      if (size && size != this->num_vertices) {
+      if (!var->data.implicit_sized_array &&
+          size && size != this->num_vertices) {
          linker_error(this->prog, "size of array %s declared as %u, "
                       "but number of input vertices is %u\n",
                       var->name, size, this->num_vertices);
@@ -1494,8 +1495,11 @@ public:
    virtual ir_visitor_status visit(ir_variable *var)
    {
       const glsl_type *type_without_array;
+      bool implicit_sized_array = var->data.implicit_sized_array;
       fixup_type(&var->type, var->data.max_array_access,
-                 var->data.from_ssbo_unsized_array);
+                 var->data.from_ssbo_unsized_array,
+                 &implicit_sized_array);
+      var->data.implicit_sized_array = implicit_sized_array;
       type_without_array = var->type->without_array();
       if (var->type->is_interface()) {
          if (interface_contains_unsized_arrays(var->type)) {
@@ -1553,11 +1557,12 @@ private:
     * it with a sized array whose size is determined by max_array_access.
     */
    static void fixup_type(const glsl_type **type, unsigned max_array_access,
-                          bool from_ssbo_unsized_array)
+                          bool from_ssbo_unsized_array, bool *implicit_sized)
    {
       if (!from_ssbo_unsized_array && (*type)->is_unsized_array()) {
          *type = glsl_type::get_array_instance((*type)->fields.array,
                                                max_array_access + 1);
+         *implicit_sized = true;
          assert(*type != NULL);
       }
    }
@@ -1606,15 +1611,17 @@ private:
       memcpy(fields, type->fields.structure,
              num_fields * sizeof(*fields));
       for (unsigned i = 0; i < num_fields; i++) {
+         bool implicit_sized_array = fields[i].implicit_sized_array;
          /* If SSBO last member is unsized array, we don't replace it by a sized
           * array.
           */
          if (is_ssbo && i == (num_fields - 1))
             fixup_type(&fields[i].type, max_ifc_array_access[i],
-                       true);
+                       true, &implicit_sized_array);
          else
             fixup_type(&fields[i].type, max_ifc_array_access[i],
-                       false);
+                       false, &implicit_sized_array);
+         fields[i].implicit_sized_array = implicit_sized_array;
       }
       glsl_interface_packing packing =
          (glsl_interface_packing) type->interface_packing;
@@ -2168,14 +2175,6 @@ link_intrastage_shaders(void *mem_ctx,
    if (!prog->LinkStatus)
       return NULL;
 
-   /* Link up uniform blocks defined within this stage. */
-   link_uniform_blocks(mem_ctx, ctx, prog, shader_list, num_shaders,
-                       &ubo_blocks, &num_ubo_blocks, &ssbo_blocks,
-                       &num_ssbo_blocks);
-
-   if (!prog->LinkStatus)
-      return NULL;
-
    /* Check that there is only a single definition of each function signature
     * across all shaders.
     */
@@ -2239,24 +2238,6 @@ link_intrastage_shaders(void *mem_ctx,
    linked->ir = new(linked) exec_list;
    clone_ir_list(mem_ctx, linked->ir, main->ir);
 
-   /* Copy ubo blocks to linked shader list */
-   linked->UniformBlocks =
-      ralloc_array(linked, gl_uniform_block *, num_ubo_blocks);
-   ralloc_steal(linked, ubo_blocks);
-   for (unsigned i = 0; i < num_ubo_blocks; i++) {
-      linked->UniformBlocks[i] = &ubo_blocks[i];
-   }
-   linked->NumUniformBlocks = num_ubo_blocks;
-
-   /* Copy ssbo blocks to linked shader list */
-   linked->ShaderStorageBlocks =
-      ralloc_array(linked, gl_uniform_block *, num_ssbo_blocks);
-   ralloc_steal(linked, ssbo_blocks);
-   for (unsigned i = 0; i < num_ssbo_blocks; i++) {
-      linked->ShaderStorageBlocks[i] = &ssbo_blocks[i];
-   }
-   linked->NumShaderStorageBlocks = num_ssbo_blocks;
-
    link_fs_input_layout_qualifiers(prog, linked, shader_list, num_shaders);
    link_tcs_out_layout_qualifiers(prog, linked, shader_list, num_shaders);
    link_tes_in_layout_qualifiers(prog, linked, shader_list, num_shaders);
@@ -2328,6 +2309,42 @@ link_intrastage_shaders(void *mem_ctx,
       return NULL;
    }
 
+   /* Make a pass over all variable declarations to ensure that arrays with
+    * unspecified sizes have a size specified.  The size is inferred from the
+    * max_array_access field.
+    */
+   array_sizing_visitor v;
+   v.run(linked->ir);
+   v.fixup_unnamed_interface_types();
+
+   /* Link up uniform blocks defined within this stage. */
+   link_uniform_blocks(mem_ctx, ctx, prog, shader_list, num_shaders,
+                       &ubo_blocks, &num_ubo_blocks, &ssbo_blocks,
+                       &num_ssbo_blocks);
+
+   if (!prog->LinkStatus) {
+      _mesa_delete_shader(ctx, linked);
+      return NULL;
+   }
+
+   /* Copy ubo blocks to linked shader list */
+   linked->UniformBlocks =
+      ralloc_array(linked, gl_uniform_block *, num_ubo_blocks);
+   ralloc_steal(linked, ubo_blocks);
+   for (unsigned i = 0; i < num_ubo_blocks; i++) {
+      linked->UniformBlocks[i] = &ubo_blocks[i];
+   }
+   linked->NumUniformBlocks = num_ubo_blocks;
+
+   /* Copy ssbo blocks to linked shader list */
+   linked->ShaderStorageBlocks =
+      ralloc_array(linked, gl_uniform_block *, num_ssbo_blocks);
+   ralloc_steal(linked, ssbo_blocks);
+   for (unsigned i = 0; i < num_ssbo_blocks; i++) {
+      linked->ShaderStorageBlocks[i] = &ssbo_blocks[i];
+   }
+   linked->NumShaderStorageBlocks = num_ssbo_blocks;
+
    /* At this point linked should contain all of the linked IR, so
     * validate it to make sure nothing went wrong.
     */
@@ -2353,14 +2370,6 @@ link_intrastage_shaders(void *mem_ctx,
       }
    }
 
-   /* Make a pass over all variable declarations to ensure that arrays with
-    * unspecified sizes have a size specified.  The size is inferred from the
-    * max_array_access field.
-    */
-   array_sizing_visitor v;
-   v.run(linked->ir);
-   v.fixup_unnamed_interface_types();
-
    return linked;
 }
 
diff --git a/src/compiler/glsl_types.h b/src/compiler/glsl_types.h
index 7f9e3184ca..f9a377d764 100644
--- a/src/compiler/glsl_types.h
+++ b/src/compiler/glsl_types.h
@@ -916,6 +916,7 @@ struct glsl_struct_field {
     */
    unsigned explicit_xfb_buffer:1;
 
+   unsigned implicit_sized_array:1;
 #ifdef __cplusplus
    glsl_struct_field(const struct glsl_type *_type, const char *_name)
       : type(_type), name(_name), location(-1), interpolation(0), centroid(0),