[Mesa-dev] [PATCH] glsl: buffer variables can be readonly and writeonly

[Samuel Pitoiset]

On 09/15/2017 04:56 PM, Juan A. Suarez Romero wrote:
> On Fri, 2017-09-15 at 13:04 +0200, Juan A. Suarez Romero wrote:
>> On Fri, 2017-09-15 at 12:47 +0200, Samuel Pitoiset wrote:
>>> I guess this will break some piglits.
>>>
>>
>>
>> Right. I'll check them and provide fixes
> 
> 
> After running piglit with and without this patch, I didn't find any
> regression. So it seems no piglit test is affected.

That's quite bad. You might want to add some piglit tests for this.

Also, you probably have to update some code around write_only/read_only 
to reflect that change, for example in 
ast_process_struct_or_iface_block_members.

> 
> 	J.A.
> 
>>
>> Thanks.
>>
>> 	J.A.
>>
>>
>>
>>> On 09/15/2017 10:49 AM, Juan A. Suarez Romero wrote:
>>>> In GLSL ES 3.10 session 4.9 [Memory Access Qualifiers], it has the following description:
>>>>
>>>> "A variable could be qualified as both readonly and writeonly, disallowing both read and write, but still be passed to
>>>> imageSize() to have the size queried.".
>>>>
>>>> This is for image variable, but not for buffer variables.
>>>>
>>>> According to https://github.com/KhronosGroup/OpenGL-API/issues/7 Khronos
>>>> intent is to allow both readonly and writeonly in buffer variables, and
>>>> as such it will update the GLSL specification.
>>>>
>>>> This commit address this issue, and fixes:
>>>>
>>>> KHR-GL{43,44,45}.shader_storage_buffer_object.basic-readonly-writeonly
>>>> KHR-GLES31.core.shader_storage_buffer_object.basic-readonly-writeonly
>>>> ---
>>>>    src/compiler/glsl/ast_to_hir.cpp | 5 -----
>>>>    1 file changed, 5 deletions(-)
>>>>
>>>> diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
>>>> index 45c8ca2a5d..1a94c274b6 100644
>>>> --- a/src/compiler/glsl/ast_to_hir.cpp
>>>> +++ b/src/compiler/glsl/ast_to_hir.cpp
>>>> @@ -7254,11 +7254,6 @@ ast_process_struct_or_iface_block_members(exec_list *instructions,
>>>>                validate_matrix_layout_for_type(state, &loc, decl_type, NULL);
>>>>          }
>>>>    
>>>> -      if (qual->flags.q.read_only && qual->flags.q.write_only) {
>>>> -         _mesa_glsl_error(&loc, state, "buffer variable can't be both "
>>>> -                          "readonly and writeonly.");
>>>> -      }
>>>> -
>>>>          foreach_list_typed (ast_declaration, decl, link,
>>>>                              &decl_list->declarations) {
>>>>             YYLTYPE loc = decl->get_location();
>>>>
>>>
>>>
>>
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