glsl: add support for the imageSize builtin

The code is heavily inspired from Francisco Jerez's code supporting the
image_load_store extension.

Backends willing to support this builtin should handle
__intrinsic_image_size.

v2: Based on the review of Ilia Mirkin
- Enable the extension for GLES 3.1
- Fix indentation
- Fix the return type (float to int, number of components for CubeImages)
- Add a warning related to GLES 3.1

v3: Based on the review of Francisco Jerez
- Refactor the code to share both add_image_function and _image with the other
  image-related functions

v4: Based on Topi Pohjolainen's comments
- Do not add parenthesis for the return value

v5: based on Francisco Jerez's comments:
- Fix a few indent issues
- Reduce the size of a condition by testing the dimension and array properties
  instead of enumerating all the formats.

Signed-off-by: Martin Peres <martin.peres@linux.intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>

src/glsl/builtin_functions.cpp

@@ -412,6 +412,13 @@ shader_image_atomic(const _mesa_glsl_parse_state *state)
            state->ARB_shader_image_load_store_enable);
 }
 
+static bool
+shader_image_size(const _mesa_glsl_parse_state *state)
+{
+   return state->is_version(430, 310) ||
+           state->ARB_shader_image_size_enable;
+}
+
 static bool
 gs_streams(const _mesa_glsl_parse_state *state)
 {
@@ -506,6 +513,11 @@ private:
    /** Create a new function and add the given signatures. */
    void add_function(const char *name, ...);
 
+   typedef ir_function_signature *(builtin_builder::*image_prototype_ctr)(const glsl_type *image_type,
+                                                                          const char *intrinsic_name,
+                                                                          unsigned num_arguments,
+                                                                          unsigned flags);
+
    enum image_function_flags {
       IMAGE_FUNCTION_EMIT_STUB = (1 << 0),
       IMAGE_FUNCTION_RETURNS_VOID = (1 << 1),
@@ -522,6 +534,7 @@ private:
     */
    void add_image_function(const char *name,
                            const char *intrinsic_name,
+                           image_prototype_ctr prototype,
                            unsigned num_arguments,
                            unsigned flags);
 
@@ -723,7 +736,12 @@ private:
                                            const char *intrinsic_name,
                                            unsigned num_arguments,
                                            unsigned flags);
-   ir_function_signature *_image(const glsl_type *image_type,
+   ir_function_signature *_image_size_prototype(const glsl_type *image_type,
+                                                const char *intrinsic_name,
+                                                unsigned num_arguments,
+                                                unsigned flags);
+   ir_function_signature *_image(image_prototype_ctr prototype,
+                                 const glsl_type *image_type,
                                  const char *intrinsic_name,
                                  unsigned num_arguments,
                                  unsigned flags);
@@ -2567,6 +2585,7 @@ builtin_builder::add_function(const char *name, ...)
 void
 builtin_builder::add_image_function(const char *name,
                                     const char *intrinsic_name,
+                                    image_prototype_ctr prototype,
                                     unsigned num_arguments,
                                     unsigned flags)
 {
@@ -2605,12 +2624,13 @@ builtin_builder::add_image_function(const char *name,
       glsl_type::uimage2DMS_type,
       glsl_type::uimage2DMSArray_type
    };
+
    ir_function *f = new(mem_ctx) ir_function(name);
 
    for (unsigned i = 0; i < ARRAY_SIZE(types); ++i) {
       if (types[i]->sampler_type != GLSL_TYPE_FLOAT ||
           (flags & IMAGE_FUNCTION_SUPPORTS_FLOAT_DATA_TYPE))
-         f->add_signature(_image(types[i], intrinsic_name,
+         f->add_signature(_image(prototype, types[i], intrinsic_name,
                                  num_arguments, flags));
    }
 
@@ -2623,13 +2643,15 @@ builtin_builder::add_image_functions(bool glsl)
    const unsigned flags = (glsl ? IMAGE_FUNCTION_EMIT_STUB : 0);
 
    add_image_function(glsl ? "imageLoad" : "__intrinsic_image_load",
-                      "__intrinsic_image_load", 0,
+                       "__intrinsic_image_load",
+                       &builtin_builder::_image_prototype, 0,
                        (flags | IMAGE_FUNCTION_HAS_VECTOR_DATA_TYPE |
                        IMAGE_FUNCTION_SUPPORTS_FLOAT_DATA_TYPE |
                        IMAGE_FUNCTION_READ_ONLY));
 
    add_image_function(glsl ? "imageStore" : "__intrinsic_image_store",
-                      "__intrinsic_image_store", 1,
+                      "__intrinsic_image_store",
+                      &builtin_builder::_image_prototype, 1,
                       (flags | IMAGE_FUNCTION_RETURNS_VOID |
                        IMAGE_FUNCTION_HAS_VECTOR_DATA_TYPE |
                        IMAGE_FUNCTION_SUPPORTS_FLOAT_DATA_TYPE |
@@ -2638,30 +2660,42 @@ builtin_builder::add_image_functions(bool glsl)
    const unsigned atom_flags = flags | IMAGE_FUNCTION_AVAIL_ATOMIC;
 
    add_image_function(glsl ? "imageAtomicAdd" : "__intrinsic_image_atomic_add",
-                      "__intrinsic_image_atomic_add", 1, atom_flags);
+                      "__intrinsic_image_atomic_add",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function(glsl ? "imageAtomicMin" : "__intrinsic_image_atomic_min",
-                      "__intrinsic_image_atomic_min", 1, atom_flags);
+                      "__intrinsic_image_atomic_min",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function(glsl ? "imageAtomicMax" : "__intrinsic_image_atomic_max",
-                      "__intrinsic_image_atomic_max", 1, atom_flags);
+                      "__intrinsic_image_atomic_max",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function(glsl ? "imageAtomicAnd" : "__intrinsic_image_atomic_and",
-                      "__intrinsic_image_atomic_and", 1, atom_flags);
+                      "__intrinsic_image_atomic_and",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function(glsl ? "imageAtomicOr" : "__intrinsic_image_atomic_or",
-                      "__intrinsic_image_atomic_or", 1, atom_flags);
+                      "__intrinsic_image_atomic_or",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function(glsl ? "imageAtomicXor" : "__intrinsic_image_atomic_xor",
-                      "__intrinsic_image_atomic_xor", 1, atom_flags);
+                      "__intrinsic_image_atomic_xor",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function((glsl ? "imageAtomicExchange" :
                        "__intrinsic_image_atomic_exchange"),
-                      "__intrinsic_image_atomic_exchange", 1, atom_flags);
+                      "__intrinsic_image_atomic_exchange",
+                      &builtin_builder::_image_prototype, 1, atom_flags);
 
    add_image_function((glsl ? "imageAtomicCompSwap" :
                        "__intrinsic_image_atomic_comp_swap"),
-                      "__intrinsic_image_atomic_comp_swap", 2, atom_flags);
+                      "__intrinsic_image_atomic_comp_swap",
+                      &builtin_builder::_image_prototype, 2, atom_flags);
+
+   add_image_function(glsl ? "imageSize" : "__intrinsic_image_size",
+                      "__intrinsic_image_size",
+                      &builtin_builder::_image_size_prototype, 1, atom_flags);
 }
 
 ir_variable *
@@ -4837,12 +4871,54 @@ builtin_builder::_image_prototype(const glsl_type *image_type,
 }
 
 ir_function_signature *
-builtin_builder::_image(const glsl_type *image_type,
+builtin_builder::_image_size_prototype(const glsl_type *image_type,
                                        const char *intrinsic_name,
                                        unsigned num_arguments,
                                        unsigned flags)
 {
-   ir_function_signature *sig = _image_prototype(image_type, intrinsic_name,
+   const glsl_type *ret_type;
+   unsigned num_components = image_type->coordinate_components();
+
+   /* From the ARB_shader_image_size extension:
+    * "Cube images return the dimensions of one face."
+    */
+   if (image_type->sampler_dimensionality == GLSL_SAMPLER_DIM_CUBE &&
+       !image_type->sampler_array) {
+      num_components = 2;
+   }
+
+   /* FIXME: Add the highp precision qualifier for GLES 3.10 when it is
+    * supported by mesa.
+    */
+   ret_type = glsl_type::get_instance(GLSL_TYPE_INT, num_components, 1);
+
+   ir_variable *image = in_var(image_type, "image");
+   ir_function_signature *sig = new_sig(ret_type, shader_image_size, 1, image);
+
+   /* Set the maximal set of qualifiers allowed for this image
+    * built-in.  Function calls with arguments having fewer
+    * qualifiers than present in the prototype are allowed by the
+    * spec, but not with more, i.e. this will make the compiler
+    * accept everything that needs to be accepted, and reject cases
+    * like loads from write-only or stores to read-only images.
+    */
+   image->data.image_read_only = true;
+   image->data.image_write_only = true;
+   image->data.image_coherent = true;
+   image->data.image_volatile = true;
+   image->data.image_restrict = true;
+
+   return sig;
+}
+
+ir_function_signature *
+builtin_builder::_image(image_prototype_ctr prototype,
+                        const glsl_type *image_type,
+                        const char *intrinsic_name,
+                        unsigned num_arguments,
+                        unsigned flags)
+{
+   ir_function_signature *sig = (this->*prototype)(image_type, intrinsic_name,
                                                    num_arguments, flags);
 
    if (flags & IMAGE_FUNCTION_EMIT_STUB) {