glsl/i965: move lower_offset_array up to GLSL compiler level.

This lowering pass will be useful for gallium drivers as well, in order to support
the GL TG4 oddity that is textureGatherOffsets.

Signed-off-by: Dave Airlie <airlied@redhat.com>
gallium: add texture gather support to gallium (v3)

This adds support to gallium for a TG4 instruction,
and two CAPs. The first CAP is required for GL_ARB_texture_gather.

The second CAP is required to expose GL_ARB_gpu_shader5.

However so far we haven't found any hardware that natively
exposes the textureGatherOffsets feature from GL, so just
lower it for now. If hardware appears for this we can add
another CAP to allow TG4 to take 4 offsets.

v2: add component selection src and a cap to say
hw can do it. (st can use to help control
GL_ARB_gpu_shader5/GLSL 4.00). Add docs.

v3: rename to SM5, add docs.

Signed-off-by: Dave Airlie <airlied@redhat.com>
st/mesa: add texture gather support. (v2)

This adds support for GL_ARB_texture_gather, and one step of
support for GL_ARB_gpu_shader5.

This adds support for passing the TG4 instruction, along
with non-constant texture offsets, and tracking them for the
optimisation passes.

This doesn't support native textureGatherOffsets hw, to do that
you'd need to add a CAP and if set disable the lowering pass,
and bump the MAX offsets to 4, then do the i0,j0 sampling using
those.

Signed-off-by: Dave Airlie <airlied@redhat.com>
r600g: limit texture offset application

Only apply texture offsets values for the correct type of texture
targets.

Signed-off-by: Dave Airlie <airlied@redhat.com>
r600g: start of TG4 implementation
nv50: txg support