[Mesa-dev] [PATCH 3/3] mesa: return initial value for VALIDATE_STATUS if pipe not bound

[gregory hainaut]

On Sun, 22 Nov 2015 14:25:31 +1100
Timothy Arceri <t_arceri at yahoo.com.au> wrote:

> On Tue, 2015-09-01 at 13:53 +0300, Tapani Pälli wrote:
> > From OpenGL 4.5 Core spec (7.13):
> > 
> >     "If pipeline is a name that has been generated (without
> > subsequent
> >     deletion) by GenProgramPipelines, but refers to a program
> > pipeline
> >     object that has not been previously bound, the GL first creates
> > a new state vector in the same manner as when BindProgramPipeline
> >     creates a new program pipeline object."
> > 
> > I interpret this as "If GetProgramPipelineiv gets called without a
> > bound (but valid) pipeline object, the state should reflect initial
> > state of a new pipeline object." This is also expected behaviour by
> > ES31-CTS.sepshaderobjs.PipelineApi conformance test.
> > 
> > Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> > ---
> >  src/mesa/main/pipelineobj.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/src/mesa/main/pipelineobj.c
> > b/src/mesa/main/pipelineobj.c
> > index 07acbf1..c2e1d29 100644
> > --- a/src/mesa/main/pipelineobj.c
> > +++ b/src/mesa/main/pipelineobj.c
> > @@ -614,7 +614,8 @@ _mesa_GetProgramPipelineiv(GLuint pipeline,
> > GLenum pname, GLint *params)
> >        *params = pipe->InfoLog ? strlen(pipe->InfoLog) + 1 : 0;
> >        return;
> >     case GL_VALIDATE_STATUS:
> > -      *params = pipe->Validated;
> > +      /* If pipeline is not bound, return initial value 0. */
> > +      *params = (ctx->_Shader->Name != pipe->Name)
> > ? 0 : pipe->Validated;
> 
> Hi Tapani,
> 
> As Gregory has pointed out this change causes a large number of the
> SSO deqp tests to fail.
> 
> I'm not sure what the solution is yet but one thing I have noticed is
> that with this change we will always return a value of 0 as nothing
> ever sets the value of ctx->_Shader->Name.
> 
> I did try setting it when the bind is done but the deqp tests still
> fail as the bind is done after the validate in those tests. Are you
> sure that this must return 0 if the pipe is not bound?
> 
> Tim
> 
> >        return;
> >     case GL_VERTEX_SHADER:
> >        *params = pipe->CurrentProgram[MESA_SHADER_VERTEX]

Hello,

Here my understanding of the specification (with my point of view of GL
users).

On various objects, gen* cmds reserve a key in a hash table but objects
aren't created. Generally the object are created when they're bound (often call bind to
create). However SSO API is (closer of the/a) direct state access API. It is really 
awkward to bind the object to modify it. Besides there is now full DSA. 

So for me, the following pipeline command must created the object if it
wasn't created (read if it wasn't bound)

1/ BindProgramPipeline
2/ UseProgramStages
3/ CreateProgramPipelines (???: not sure, but likely)
4/ ActiveShaderProgram
5/ GetProgramPipelineiv
6/ ValidateProgramPipeline

Note: can be read as all pipeline commands, so it is nearly equivalent to
create the object in GenProgramPipelines. The only exception is IsProgramPipeline.


So GetProgramPipelineiv (and others gl cmd) must start with:
if (! pipe->IsCreated ) {
    pipe->Init();
    pipe->IsCreated = true;
}


For example:
GenProgramPipelines(1, &pipe);
GetProgramPipelineiv(pipe, X, X); // Must create the object and therefore will return the initial value (0)

GenProgramPipelines(1, &pipe2);
ValidateProgramPipeline(pipe2); // Will create the object
GetProgramPipelineiv(pipe2, X, X); // object was created by ValidateProgramPipeline, we can return the property

As a side note, if Mesa is updated. Piglit test will need some updates too.

Best regards,
Gregory