glsl: Add precision information to ir_variable

We will need this later on when we implement proper support for
precision qualifiers in the drivers and also to do link time checks for
uniforms as indicated by the spec.

This patch also adds compile-time checks for variables without precision
information (currently, Mesa only checks that a default precision is set
for floats in fragment shaders).

As indicated by Ian, the addition of the precision information to
ir_variable has been done using a bitfield and pahole to identify an
available hole so that memory requirements for ir_variable stay the
same.

v2 (Ian):
  - Avoid if-ladders by defining arrays of supported sampler names and
    indexing
    into them with type->sampler_array + 2 * type->sampler_shadow
  - Make the code that selects the precision qualifier to use an utility
    function
  - Fix a typo

v3 (Tapani):
  - rebased
  - squashed in "Precision qualifiers are not allowed on structs"
  - fixed select_gles_precision for sampler arrays
  - fixed precision_qualifier_allowed for arrays of structs

v4 (Tapani):
  - add atomic_uint handling
  - do not allow precision qualifier on images
  (issues reported by Marta)

v5 (Tapani):
  - support precision qualifier on image types

v6 (Tapani):
  - set precision qualifier on interface block members

Reviewed-by: Samuel Iglesias Gonsálvez <[email protected]>

4 files changed, 303 insertions, 24 deletions

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 7206f1bd913..51ea183147d 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -2146,10 +2146,10 @@ precision_qualifier_allowed(const glsl_type *type)
     * From this, we infer that GLSL 1.30 (and later) should allow precision
     * qualifiers on sampler types just like float and integer types.
     */
-   return type->is_float()
+   return (type->is_float()
        || type->is_integer()
-       || type->is_record()
-       || type->contains_opaque();
+       || type->contains_opaque())
+       && !type->without_array()->is_record();
 }
 
 const glsl_type *
@@ -2167,31 +2167,268 @@ ast_type_specifier::glsl_type(const char **name,
    return type;
 }
 
-const glsl_type *
-ast_fully_specified_type::glsl_type(const char **name,
-                                    struct _mesa_glsl_parse_state *state) const
+/**
+ * From the OpenGL ES 3.0 spec, 4.5.4 Default Precision Qualifiers:
+ *
+ * "The precision statement
+ *
+ *    precision precision-qualifier type;
+ *
+ *  can be used to establish a default precision qualifier. The type field can
+ *  be either int or float or any of the sampler types, (...) If type is float,
+ *  the directive applies to non-precision-qualified floating point type
+ *  (scalar, vector, and matrix) declarations. If type is int, the directive
+ *  applies to all non-precision-qualified integer type (scalar, vector, signed,
+ *  and unsigned) declarations."
+ *
+ * We use the symbol table to keep the values of the default precisions for
+ * each 'type' in each scope and we use the 'type' string from the precision
+ * statement as key in the symbol table. When we want to retrieve the default
+ * precision associated with a given glsl_type we need to know the type string
+ * associated with it. This is what this function returns.
+ */
+static const char *
+get_type_name_for_precision_qualifier(const glsl_type *type)
 {
-   const struct glsl_type *type = this->specifier->glsl_type(name, state);
-
-   if (type == NULL)
-      return NULL;
+   switch (type->base_type) {
+   case GLSL_TYPE_FLOAT:
+      return "float";
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+      return "int";
+   case GLSL_TYPE_ATOMIC_UINT:
+      return "atomic_uint";
+   case GLSL_TYPE_IMAGE:
+   /* fallthrough */
+   case GLSL_TYPE_SAMPLER: {
+      const unsigned type_idx =
+         type->sampler_array + 2 * type->sampler_shadow;
+      const unsigned offset = type->base_type == GLSL_TYPE_SAMPLER ? 0 : 4;
+      assert(type_idx < 4);
+      switch (type->sampler_type) {
+      case GLSL_TYPE_FLOAT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "sampler1D", "sampler1DArray",
+              "sampler1DShadow", "sampler1DArrayShadow"
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "sampler2D", "sampler2DArray",
+              "sampler2DShadow", "sampler2DArrayShadow",
+              "image2D", "image2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "sampler3D", NULL, NULL, NULL,
+              "image3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "samplerCube", "samplerCubeArray",
+              "samplerCubeShadow", "samplerCubeArrayShadow",
+              "imageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "sampler2DMS", "sampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerRect", NULL, "samplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_EXTERNAL: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "samplerExternalOES", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported sampler/image dimensionality");
+         } /* sampler/image float dimensionality */
+         break;
+      case GLSL_TYPE_INT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isampler1D", "isampler1DArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "isampler2D", "isampler2DArray", NULL, NULL,
+              "iimage2D", "iimage2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "isampler3D", NULL, NULL, NULL,
+              "iimage3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "isamplerCube", "isamplerCubeArray", NULL, NULL,
+              "iimageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isampler2DMS", "isampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isamplerRect", NULL, "isamplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "isamplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported isampler/iimage dimensionality");
+         } /* sampler/image int dimensionality */
+         break;
+      case GLSL_TYPE_UINT:
+         switch (type->sampler_dimensionality) {
+         case GLSL_SAMPLER_DIM_1D: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usampler1D", "usampler1DArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_2D: {
+            static const char *const names[8] = {
+              "usampler2D", "usampler2DArray", NULL, NULL,
+              "uimage2D", "uimage2DArray", NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_3D: {
+            static const char *const names[8] = {
+              "usampler3D", NULL, NULL, NULL,
+              "uimage3D", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_CUBE: {
+            static const char *const names[8] = {
+              "usamplerCube", "usamplerCubeArray", NULL, NULL,
+              "uimageCube", NULL, NULL, NULL
+            };
+            return names[offset + type_idx];
+         }
+         case GLSL_SAMPLER_DIM_MS: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usampler2DMS", "usampler2DMSArray", NULL, NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_RECT: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usamplerRect", NULL, "usamplerRectShadow", NULL
+            };
+            return names[type_idx];
+         }
+         case GLSL_SAMPLER_DIM_BUF: {
+            assert(type->base_type == GLSL_TYPE_SAMPLER);
+            static const char *const names[4] = {
+              "usamplerBuffer", NULL, NULL, NULL
+            };
+            return names[type_idx];
+         }
+         default:
+            unreachable("Unsupported usampler/uimage dimensionality");
+         } /* sampler/image uint dimensionality */
+         break;
+      default:
+         unreachable("Unsupported sampler/image type");
+      } /* sampler/image type */
+      break;
+   } /* GLSL_TYPE_SAMPLER/GLSL_TYPE_IMAGE */
+   break;
+   default:
+      unreachable("Unsupported type");
+   } /* base type */
+}
 
-   /* The fragment language does not define a default precision value
-    * for float types, so check that one is defined if the type declaration
-    * isn't providing one explictly.
+static unsigned
+select_gles_precision(unsigned qual_precision,
+                      const glsl_type *type,
+                      struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
+{
+   /* Precision qualifiers do not have any meaning in Desktop GLSL.
+    * In GLES we take the precision from the type qualifier if present,
+    * otherwise, if the type of the variable allows precision qualifiers at
+    * all, we look for the default precision qualifier for that type in the
+    * current scope.
     */
-   if (type->base_type == GLSL_TYPE_FLOAT
-       && state->es_shader
-       && state->stage == MESA_SHADER_FRAGMENT
-       && this->qualifier.precision == ast_precision_none
-       && state->symbols->get_default_precision_qualifier("float") == ast_precision_none) {
-      YYLTYPE loc = this->get_location();
-      _mesa_glsl_error(&loc, state,
-                       "no precision specified this scope for type `%s'",
-                       type->name);
+   assert(state->es_shader);
+
+   unsigned precision = GLSL_PRECISION_NONE;
+   if (qual_precision) {
+      precision = qual_precision;
+   } else if (precision_qualifier_allowed(type)) {
+      const char *type_name =
+         get_type_name_for_precision_qualifier(type->without_array());
+      assert(type_name != NULL);
+
+      precision =
+         state->symbols->get_default_precision_qualifier(type_name);
+      if (precision == ast_precision_none) {
+         _mesa_glsl_error(loc, state,
+                          "No precision specified in this scope for type `%s'",
+                          type->name);
+      }
    }
+   return precision;
+}
 
-   return type;
+const glsl_type *
+ast_fully_specified_type::glsl_type(const char **name,
+                                    struct _mesa_glsl_parse_state *state) const
+{
+   return this->specifier->glsl_type(name, state);
 }
 
 /**
@@ -2729,6 +2966,12 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
    if (qual->flags.q.sample)
       var->data.sample = 1;
 
+   /* Precision qualifiers do not hold any meaning in Desktop GLSL */
+   if (state->es_shader) {
+      var->data.precision =
+         select_gles_precision(qual->precision, var->type, state, loc);
+   }
+
    if (state->stage == MESA_SHADER_GEOMETRY &&
        qual->flags.q.out && qual->flags.q.stream) {
       var->data.stream = qual->stream;
@@ -5918,6 +6161,7 @@ ast_process_structure_or_interface_block(exec_list *instructions,
          fields[i].centroid = qual->flags.q.centroid ? 1 : 0;
          fields[i].sample = qual->flags.q.sample ? 1 : 0;
          fields[i].patch = qual->flags.q.patch ? 1 : 0;
+         fields[i].precision = qual->precision;
 
          /* From Section 4.4.2.3 (Geometry Outputs) of the GLSL 4.50 spec:
           *
@@ -6599,6 +6843,13 @@ ast_interface_block::hir(exec_list *instructions,
          if (var_mode == ir_var_shader_in || var_mode == ir_var_uniform)
             var->data.read_only = true;
 
+         /* Precision qualifiers do not have any meaning in Desktop GLSL */
+         if (state->es_shader) {
+            var->data.precision =
+               select_gles_precision(fields[i].precision, fields[i].type,
+                                     state, &loc);
+         }
+
          if (fields[i].matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED) {
             var->data.matrix_layout = matrix_layout == GLSL_MATRIX_LAYOUT_INHERITED
                ? GLSL_MATRIX_LAYOUT_COLUMN_MAJOR : matrix_layout;
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 32a766ef0f0..d59dee1e369 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -771,6 +771,19 @@ public:
       unsigned index:1;
 
       /**
+       * Precision qualifier.
+       *
+       * In desktop GLSL we do not care about precision qualifiers at all, in
+       * fact, the spec says that precision qualifiers are ignored.
+       *
+       * To make things easy, we make it so that this field is always
+       * GLSL_PRECISION_NONE on desktop shaders. This way all the variables
+       * have the same precision value and the checks we add in the compiler
+       * for this field will never break a desktop shader compile.
+       */
+      unsigned precision:2;
+
+      /**
        * \brief Layout qualifier for gl_FragDepth.
        *
        * This is not equal to \c ir_depth_layout_none if and only if this
diff --git a/src/glsl/nir/glsl_types.cpp b/src/glsl/nir/glsl_types.cpp
index 1c66dce85c4..975b815b0cc 100644
--- a/src/glsl/nir/glsl_types.cpp
+++ b/src/glsl/nir/glsl_types.cpp
@@ -162,6 +162,7 @@ glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
       this->fields.structure[i].sample = fields[i].sample;
       this->fields.structure[i].matrix_layout = fields[i].matrix_layout;
       this->fields.structure[i].patch = fields[i].patch;
+      this->fields.structure[i].precision = fields[i].precision;
    }
 
    mtx_unlock(&glsl_type::mutex);
@@ -779,6 +780,9 @@ glsl_type::record_compare(const glsl_type *b) const
       if (this->fields.structure[i].image_restrict
           != b->fields.structure[i].image_restrict)
          return false;
+      if (this->fields.structure[i].precision
+          != b->fields.structure[i].precision)
+         return false;
    }
 
    return true;
diff --git a/src/glsl/nir/glsl_types.h b/src/glsl/nir/glsl_types.h
index 1f17ad5c5b0..d841a3277db 100644
--- a/src/glsl/nir/glsl_types.h
+++ b/src/glsl/nir/glsl_types.h
@@ -102,6 +102,13 @@ enum glsl_matrix_layout {
    GLSL_MATRIX_LAYOUT_ROW_MAJOR
 };
 
+enum {
+   GLSL_PRECISION_NONE = 0,
+   GLSL_PRECISION_HIGH,
+   GLSL_PRECISION_MEDIUM,
+   GLSL_PRECISION_LOW
+};
+
 #ifdef __cplusplus
 #include "GL/gl.h"
 #include "util/ralloc.h"
@@ -320,7 +327,6 @@ struct glsl_type {
     */
    unsigned count_attribute_slots() const;
 
-
    /**
     * Alignment in bytes of the start of this type in a std140 uniform
     * block.
@@ -829,6 +835,11 @@ struct glsl_struct_field {
    unsigned patch:1;
 
    /**
+    * Precision qualifier
+    */
+   unsigned precision;
+
+   /**
     * Image qualifiers, applicable to buffer variables defined in shader
     * storage buffer objects (SSBOs)
     */