[Mesa-dev] [v2 6/6] mesa: OES_get_program_binary functionality

[Tapani Pälli]

On 11/01/2013 12:38 PM, Erik Faye-Lund wrote:
> On Fri, Nov 1, 2013 at 11:35 AM, Tapani Pälli <tapani.palli at intel.com> wrote:
>> On 11/01/2013 12:21 PM, Erik Faye-Lund wrote:
>>> On Fri, Nov 1, 2013 at 10:16 AM, Tapani Pälli <tapani.palli at intel.com>
>>> wrote:
>>>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
>>>> ---
>>>>    src/mesa/main/shaderapi.c | 46
>>>> +++++++++++++++++++++++++++++++++++++++-------
>>>>    1 file changed, 39 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
>>>> index 7da860d..67aee6b 100644
>>>> --- a/src/mesa/main/shaderapi.c
>>>> +++ b/src/mesa/main/shaderapi.c
>>>> @@ -57,6 +57,8 @@
>>>>    #include "../glsl/ir.h"
>>>>    #include "../glsl/ir_uniform.h"
>>>>    #include "../glsl/program.h"
>>>> +#include "../glsl/ir_cache.h"
>>>> +#include "git_sha1.h"
>>>>
>>>>    /** Define this to enable shader substitution (see below) */
>>>>    #define SHADER_SUBST 0
>>>> @@ -212,7 +214,6 @@ attach_shader(struct gl_context *ctx, GLuint program,
>>>> GLuint shader)
>>>>       struct gl_shader_program *shProg;
>>>>       struct gl_shader *sh;
>>>>       GLuint i, n;
>>>> -
>>>>       const bool same_type_disallowed = _mesa_is_gles(ctx);
>>>>
>>>>       shProg = _mesa_lookup_shader_program_err(ctx, program,
>>>> "glAttachShader");
>>>> @@ -1630,8 +1631,26 @@ _mesa_GetProgramBinary(GLuint program, GLsizei
>>>> bufSize, GLsizei *length,
>>>>       if (length != NULL)
>>>>          *length = 0;
>>>>
>>>> -   (void) binaryFormat;
>>>> -   (void) binary;
>>>> +   size_t size = 0;
>>>> +   char *data = _mesa_program_serialize(shProg, &size, MESA_GIT_SHA1);
>>>> +
>>>> +   /* we have more data that can fit to user given buffer */
>>>> +   if (size > bufSize) {
>>>> +      _mesa_error(ctx, GL_INVALID_OPERATION, __FUNCTION__);
>>>> +      if (data)
>>>> +         free(data);
>>>> +      return;
>>>> +   }
>>>> +
>>>> +   if (data) {
>>>> +      memcpy(binary, data, size);
>>>> +      free(data);
>>>> +   }
>>>> +
>>>> +   if (length != NULL)
>>>> +      *length = size;
>>>> +
>>>> +   *binaryFormat = 0;
>>>>    }
>>>>
>>>>    void GLAPIENTRY
>>>> @@ -1645,10 +1664,23 @@ _mesa_ProgramBinary(GLuint program, GLenum
>>>> binaryFormat,
>>>>       if (!shProg)
>>>>          return;
>>>>
>>>> -   (void) binaryFormat;
>>>> -   (void) binary;
>>>> -   (void) length;
>>>> -   _mesa_error(ctx, GL_INVALID_OPERATION, __FUNCTION__);
>>>> +   if (length <= 0)
>>>> +      return;
>>>> +
>>>> +   /* free possible existing data and initialize structure */
>>>> +   _mesa_free_shader_program_data(ctx, shProg);
>>>> +   _mesa_init_shader_program(ctx, shProg);
>>>> +
>>>> +   /* fill structure from a binary blob */
>>>> +   if (_mesa_program_deserialize(shProg, binary, length, MESA_GIT_SHA1))
>>>> {
>>>
>>> Won't using the git-sha1 as a compatibility-criteria cause issues for
>>> developers with local changes? I'm not so worried about this for
>>> OES_get_program_binary itself, but once the shader-cache is in place
>>> it sounds like a potential source of difficult to track down
>>> misbehavior...
>>
>> I agree it might be too aggressive criteria but it is hard to come up with
>> better and as simple.
> That's not my objection. My objection is that this might give
> headaches for people with local modifications to the glsl-compiler.
> Local modifications does not affect the git-sha1.

For the automatic shader cache this headache could be helped a bit with 
a environment variable or drirc setting that can be used during 
development. On the other hand an automatic cache must work in a 
transparent way so it should be always able to recover when it fails, so 
one should only see it as 'slower than usual' (since 
recompilation/relink required) sort of behaviour. The WIP of the 
automatic cache I sent some time earlier also marked (renamed) these 
'problematic' cached shaders so that they can be detected on further 
runs and cache can ignore those.

I agree that it might become problematic, on the other hand it is also 
easy to just wipe ~/.cache/mesa and disable cache. Not sure if Nvidia or 
Imagination try to handles these cases with their cache implementations.

// Tapani