[Mesa-dev] RFC: Increase gallium PIPE_MAX_SHADER_INPUTS/OUTPUTS

[Zack Rusin]

On Thursday 08 July 2010 11:40:56 Keith Whitwell wrote:
> On Thu, 2010-07-08 at 08:36 -0700, Brian Paul wrote:
> > PIPE_MAX_SHADER_INPUTS/OUTPUTS are currently set to 16 in p_state.h
> > 
> > That's actually not enough to accomodate OpenGL's needs.  For example,
> > a Mesa vertex shader has these inputs:
> > 
> > typedef enum
> > {
> > 
> >     VERT_ATTRIB_POS = 0,
> >     VERT_ATTRIB_WEIGHT = 1,
> >     VERT_ATTRIB_NORMAL = 2,
> >     VERT_ATTRIB_COLOR0 = 3,
> >     VERT_ATTRIB_COLOR1 = 4,
> >     VERT_ATTRIB_FOG = 5,
> >     VERT_ATTRIB_COLOR_INDEX = 6,
> >     VERT_ATTRIB_POINT_SIZE = 6,  /*alias*/
> >     VERT_ATTRIB_EDGEFLAG = 7,
> >     VERT_ATTRIB_TEX0 = 8,
> >     VERT_ATTRIB_TEX1 = 9,
> >     VERT_ATTRIB_TEX2 = 10,
> >     VERT_ATTRIB_TEX3 = 11,
> >     VERT_ATTRIB_TEX4 = 12,
> >     VERT_ATTRIB_TEX5 = 13,
> >     VERT_ATTRIB_TEX6 = 14,
> >     VERT_ATTRIB_TEX7 = 15,
> >     VERT_ATTRIB_GENERIC0 = 16,
> >     VERT_ATTRIB_GENERIC1 = 17,
> >     VERT_ATTRIB_GENERIC2 = 18,
> >     VERT_ATTRIB_GENERIC3 = 19,
> >     VERT_ATTRIB_GENERIC4 = 20,
> >     VERT_ATTRIB_GENERIC5 = 21,
> >     VERT_ATTRIB_GENERIC6 = 22,
> >     VERT_ATTRIB_GENERIC7 = 23,
> >     VERT_ATTRIB_GENERIC8 = 24,
> >     VERT_ATTRIB_GENERIC9 = 25,
> >     VERT_ATTRIB_GENERIC10 = 26,
> >     VERT_ATTRIB_GENERIC11 = 27,
> >     VERT_ATTRIB_GENERIC12 = 28,
> >     VERT_ATTRIB_GENERIC13 = 29,
> >     VERT_ATTRIB_GENERIC14 = 30,
> >     VERT_ATTRIB_GENERIC15 = 31,
> >     VERT_ATTRIB_MAX = 32
> > 
> > } gl_vert_attrib;
> > 
> > With PIPE_MAX_SHADER_INPUTS=16 there's potentially little or no space
> > left for any user-defined inputs if most of the conventional
> > attributes are used.
> > 
> > I propose bumping these limits to 32 each.  Any concerns?
> 
> Sounds good.  There's also the confusingly almost related value
> "PIPE_MAX_ATTRIBS" which is already 32.

I think the first actually responds to GL_MAX_VARYING_FLOATS * 4, the other to 
GL_MAX_VERTEX_ATTRIBS. They're both actually safe minimums, GL says that the 
first one needs to be at least 8, the other needs to be at least 16. So our 
values just double the minimum. We probably should have hardware queries for 
both. Also increasing PIPE_MAX_SHADER_INPUTS to 32 sounds good. 

z