i965/fs: Expose "urb_setup" as part of brw_wm_prog_data.

At the moment, for Gen6+, the FS assumes that all varying inputs are
delivered to it in the order in which they appear in the
gl_program::InputsRead bitfield, and the SF/SBE setup code ensures
that they are delivered in this order.

When we add support for more than 64 varying components, this will no
longer always be possible, because the Gen6+ SF/SBE stage is only
capable of performing arbitrary reorderings of 16 varying slots.

To allow extra flexibility in the ordering of FS varyings, this patch
causes the FS to advertise exactly what ordering it expects.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Change brw_wm_prog_data::urb_read_length to num_varying_inputs.

On gen4-5, the FS stage reads varying inputs from URB entries that
were output by the SF thread, where each register stores the
interpolation setup for two components of a vec4, therefore the FS
urb_read_length is twice the number of FS input varyings.  On gen6+,
varying inputs are directly deposited in the FS payload by the SF/SBE
fixed function logic, so urb_read_length is irrelevant.

However, in future patches, it will be nice to be able to consult
brw_wm_prog_data to determine how many varying inputs the FS expects
(rather than inferring it from gl_program::InputsRead).  So instead of
storing urb_read_length, we simply store num_varying_inputs in
brw_wm_prog_data.  On gen4-5, we multiply this by 2 to recover the URB
read length.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Consult brw_wm_prog_data::num_varying_inputs when setting up WM state.

Previously, we assumed that the number of varying inputs consumed by
the fragment shader was equal to the number of bits set in
gl_program::InputsRead.  However, we'll soon be making two changes
that will cause that not to be true:

- We'll stop wasting varying input space for gl_FragCoord and
  gl_FrontFacing, which aren't varyings.

- For fragment shaders that have more than 16 varying inputs, we'll
  adjust the layout of the inputs to account for the fact that the
  SF/SBE pipeline stage can't reorder inputs beyond the first 16; if
  there are GS outputs that the FS doens't use (or vice versa) this
  may cause the number of FS varying inputs to change.

So, instead of trying to guess the number of FS inputs from
gl_program::InputsRead, simply read it from
brw_wm_prog_data:num_varying_inputs, which is guaranteed to be correct
since it's populated by fs_visitor::calculate_urb_setup().

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/sf: Use BRW_SF_URB_ENTRY_READ_OFFSET rather than hardcoded values.

We always program the SF unit to start reading the vertex URB entry at
offset 1.  In upcoming patches, we'll be adding FS code that relies on
this.  So consistently use the constant BRW_SF_URB_ENTRY_READ_OFFSET
rather than hardcoding a 1.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/sf: Consolidate common code for setting up gen6-7 attribute overrides.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/sf: Consult brw_wm_prog_data when setting up SF/SBE state.

Previously, the SF/SBE setup code delivered varying inputs to the FS
in the order in which they appear in the gl_program::InputsRead
bitfield, since that's what the FS expects.

When we add support for more than 64 varying components, this will no
longer always be the case, because the Gen6+ SF/SBE stage is only
capable of performing arbitrary reorderings of 16 varying slots.  So,
when there are more than 16 vec4's worth of varying inputs, the FS
will have to adjust the order its input varyings in order to partially
match the order of outputs from the geometry or vertex shader.

To allow extra flexibility in the ordering of FS varyings, this patch
causes the SF/SBE to deliver varying inputs to the FS in exactly the
order that the FS requests, by consulting brw_wm_prog_data::urb_setup
and brw_wm_prog_data::num_varying_inputs.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Stop wasting input attribute space on gl_FragCoord and gl_FrontFacing.

Previously, if a fragment shader accessed gl_FragCoord or
gl_FrontFacing, we would assign them their own slots in the fragment
shader input attribute array, using up space that could be made
available to real varyings.  This was not strictly necessary (since
these values are not true varyings, and are instead computed from
other data available in the FS payload).  But we had to do it anyway
because the SF/SBE setup code assumed that every 1 bit in the
gl_program::InputsRead bitfield corresponded to a genuine varying
variable.

Now that the SF/SBE code consults brw_wm_prog_data and only sets up
the attributes that the fragment shader actually needs, we don't have
to do this anymore.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6+: Remove VUE map dependency on userclip_active.

Previously, on Gen6+, we laid out the vertex (or geometry) shader VUE
map differently depending whether user clipping was active.  If it was
active, we put the clip distances in slots 2 and 3 (where the clipper
expects them); if it was inactive, we assigned them in the order of
the gl_varying_slot enum.

This made for unnecessary recompiles, since turning clipping on/off
for a shader that used gl_ClipDistance might rearrange the varyings.
It also required extra bookkeeping, since it required the user
clipping flag to be provided to brw_compute_vue_map() as a parameter.

With this patch, we always put clip distances at in slots 2 and 3 if
they are written to.  do_vs_prog() and do_gs_prog() are responsible
for ensuring that clip distances are written to when user clipping is
enabled (as do_vs_prog() previously did for gen4-5).

This makes the only input to brw_compute_vue_map() a bitfield of which
varyings the shader writes to, a fact that we'll take advantage of in
forthcoming patches.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gs: Stop storing an input VUE map in the GS program key.

Now that the vertex shader output VUE map is determined solely by a
64-bit bitfield, we don't have to store it in its entirety in the
geometry shader program key; instead, we can just store the bitfield,
and let the geometry shader infer the VUE map at compile time.

This dramatically reduces the size of the geometry shader program key,
which we want to keep small since it gets recomputed whenever the
active program changes.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Simplify computation of key.input_slots_valid during precompile.

The for loop was rather silly.  In addition to checking brw->gen < 6
on each loop iteration, it took pains to exclude bits from
fp->Base.InputsRead that don't correspond to fragment shader inputs.
But those bits would never have been set in the first place, since the
only bits that are ever set in fp->Base.InputsRead are fragment shader
inputs.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: When >64 input components, order them to match prev pipeline stage.

Since the SF/SBE stage is only capable of performing arbitrary
reorderings of 16 varying slots, we can't arrange the fragment shader
inputs in an arbitrary order if there are more than 16 input varying
slots in use.  We need to make sure that slots 16-31 match the
corresponding outputs of the previous pipeline stage.

The easiest way to accomplish this is to just make all varying slots
match up with the previous pipeline stage.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/vec4: Generate URB writes using a loop.

Previously we only ever did 1 or 2 URB writes, since the maximum
number of varyings we support is small enough to fit in 2 URB writes.
But GL 3.2 requires the geometry shader to support 128 output varying
components, and this could require up to 3 URB writes.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6: Fix assertions on VS/GS URB size.

The "{VS,GS} URB Entry Allocation Size" fields of 3DSTATE_URB allow
values in the range 0-4, but they are U8-1 fields, so the range of
possible allocation sizes is 1-5.  We were erroneously prohibiting a
size of 5.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/ff_gs: Generate URB writes using a loop.

Previously we only ever did 1 URB write, since the maximum number of
varyings we support is small enough to fit in 1 URB write (when using
BRW_URB_SWIZZLE_NONE, which is what the pre-Gen7 GS always uses).  But
we're about to increase the number of varying components we support
from 64 to 128.

With 128 varyings, the most URB writes we'll have to do is 2, but it's
just as easy to write a general-purpose loop.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6+: Support 128 varying components.

GL 3.2 requires us to support 128 varying components for geometry
shader outputs and fragment shader inputs, and 64 varying components
otherwise.  But there's no hardware limitation that restricts us to 64
varying components, and core Mesa doesn't currently allow different
stages to have different maximum values, so just go ahead and enable
128 varying components for all stages.  This gets us better test
coverage anyway.

Even though we are only working on GL 3.2 support for gen7 right now,
gen6 also supports 128 varying components, so go ahead and switch it
on there too.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gs: Add new primitive types.

As part of its support for geometry shaders, GL 3.2 introduces four
new primitive types: GL_LINES_ADJACENCY, GL_LINE_STRIP_ADJACENCY,
GL_TRIANGLES_ADJACENCY, and GL_TRIANGLE_STRIP_ADJACENCY.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gs: New gs primitive types are supported by HW primitive restart.

When we previously implemented primitive restart, we didn't add cases
to brw_primitive_restart.c's can_cut_index_handle_prims() for the
primitive types that are introduced with geometry shaders.  It turns
out that all of the new primitive types are supported by hardware
primitive restart.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
glsl: Keep track of location for interface block fields.

This patch adds a "location" element to struct glsl_struct_field, so
that we can keep track of the gl_varying_slot associated with each
built-in geometry shader input.

In lower_named_interface_blocks, we use this value to populate the
"location" field in the ir_variable that stores each geometry shader
input.
glsl/gs: add gl_in support to builtin_variables.cpp.

Previously, builtin_variables.cpp was written assuming that we
supported ARB_geometry_shader4 style geometry shader inputs, meaning
that each built-in varying input to a geometry was supplied via an
array variable whose name ended in "In", e.g. gl_PositionIn or
gl_PointSizeIn.

However, in GLSL 1.50 style geometry shaders, things work
differently--built-in inputs are supplied to geometry shaders via a
built-in interface block called gl_in, which contains all the built-in
inputs using their usual names (e.g. the gl_Position input is supplied
to the geometry shader as gl_in[i].gl_Position).

This patch adds the necessary logic to builtin_variables.cpp to create
the gl_in interface block and populate it accordingly for geometry
shader inputs.  The old ARB_geometry_shader4 style varyings are
removed, though they can easily be added back in the future if we
decide to support ARB_geometry_shader4.
glsl/gs: handle gl_ClipDistance geometry input in lower_clip_distance.

This corresponds to the lowering of gl_ClipDistance to
gl_ClipDistanceMESA for vertex and geometry shader outputs.  Since
this lowering pass occurs after lower_named_interface blocks, it deals
with 2D arrays (gl_ClipDistance[vertex][clip_plane]) rather than 1D
arrays in an interface block
(gl_in[vertex].gl_ClipDistance[clip_plane]).

v2 (Paul Berry <stereotype441@gmail.com>): Fix indexing order for
gl_ClipDistance input lowering.  Properly lower bulk assignment of
gl_ClipDistance inputs.  Rework for GLSL 1.50 style geometry shaders.