i965/fs: Only unroll high-accuracy dFdy() from SIMD16 to SIMD8 on gen4 and IVB.

In commit 800610f (i965/fs: Improve accuracy of dFdy() to match
dFdx()) I unrolled the high-accuracy dFdy() computation from a single
SIMD16 instruction to two SIMD8 instructions because of text I found
in the i965 (gen4) PRM saying that instruction compression could not
be used in align16 mode.  I couldn't find similar text in later
hardware docs, and I observed problems trying to use instruction
compression on align16 mode on Ivy Bridge, so I assumed that the
restriction still applied and the associated documentation had simply
been lost.

After consultation with the hardware engineers, it turns out this is
not the case.  In point of fact, the restriction was dropped in gen5,
re-introduced in Ivy Bridge, and dropped again in Haswell.  The reason
I didn't notice this is that in the Ivy Bridge documentation, the
restriction was in a different section, and described using different
language.

Now that we know that the restriction only applies to Gen4 and Ivy
Bridge, we can limit the unrolling to those platforms.

Tested on gen5, gen6, and gen7 (both Ivy Bridge and Haswell).
glsl: mark variables produced by lower_named_interface_blocks.

These variables will need to be treated specially by
program_resource_visitor, so that they can be addressed through the
API using their interface block name (and array index, for interface
block arrays).
glsl: Account for interface block lowering in program_resource_visitor.

When program_resource_visitor visits variables that were created by
lower_named_interface_blocks, it needs to do extra work to un-do the
effects of lower_named_interface_blocks and construct the proper API
names.

Fixes piglit test
spec/glsl-1.50/execution/interface-blocks-api-access-members.
vbo: Make vbo_sw_primitive_restart optionally count primitives.

This will be necessary in order to get the i965 back-end to produce
the correct value of gl_PrimitiveIDIn when using software primitive
restart.
i965/gs: Fix gl_PrimitiveIDIn when using SW primitive restart.

Ivy Bridge hardware doesn't support primitve restart under all
circumstances--when it doesn't, we emulate it in software by splitting
up each logical draw operation into multiple 3DPRIMITIVE commands.
This causes the hardware's primitive ID counter to be reset to 0,
producing incorrect values for gl_PrimitiveIDIn.

To work around that problem, we create a hidden uniform which is added
to the hardware's primitive ID counter at the top of the geometry
shader; the software primitive restart mechanism ensures that this
uniform always contains the number of primitives that were sent down
the pipeline by previous 3DPRIMITIVE commands within the same logical
draw operation.

To reduce the performance impact of the workaround, we only compile it
into the shader when the hardware is Ivy Bridge and the shader
accesses gl_PrimitiveIDIn.  To reduce unnecessary state updates, we
only flag _NEW_PROGRAM_CONSTANTS when when the workaround is compiled
in *and* software primitive restart is active.

On Ivy Bridge, fixes all variants of
"glsl-1.50-geometry-primitive-id-restart" except the GL_LINE_LOOP
variants, which are broken due to an unrelated hardware limitation.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70604
i965/vec4: Add the ability for attributes to be interleaved.

When geometry shaders are operated in "single" or "dual instanced"
mode, a single set of geometry shader inputs is interleaved into the
thread payload (with each payload register containing a pair of
inputs) in order to save register space.

This patch modifies vec4_visitor::lower_attributes_to_hw_regs so that
it can handle the interleaved format.

Reviewed-by: Eric Anholt <eric@anholt.net>
i965/vec4: if register allocation fails, don't try to schedule.

Otherwise the scheduler would be invoked with prog_data->total_grf ==
0, causing havoc.

In a future patch, this will allow us to try compiling a geometry
shader in DUAL_OBJECT mode with spilling disabled, and then fall back
to DUAL_INSTANCED mode if that failed.

Reviewed-by: Eric Anholt <eric@anholt.net>
i965/vec4: Add the ability to suppress register spilling.

In future patches, this will allow us to first try compiling a
geometry shader in DUAL_OBJECT mode (which is more efficient but uses
more registers) and then if spilling is required, fall back on
DUAL_INSTANCED mode.

Reviewed-by: Eric Anholt <eric@anholt.net>
i965/gs: Add the ability to compile a DUAL_INSTANCED geometry shader.

Not yet enabled.

Reviewed-by: Eric Anholt <eric@anholt.net>
i965/gs: Fix up gl_PointSize input swizzling for DUAL_INSTANCED gs.

Geometry shaders that run in "DUAL_INSTANCED" mode store their inputs
in vec4's.  This means that when compiling gl_PointSize input
swizzling (a MOV instruction which uses a geometry shader input as
both source and destination), we need to do two things:

- Set force_writemask_all to ensure that the MOV happens regardless of
  which channels are enabled.

- Set the source register region to <4;4,1> (instead of <0;4,1> to
  satisfy register region restrictions.
i965/gs: fix up primitive ID workaround for DUAL_INSTANCE dispatch.

Parallel change to "i965/gs: Fix up gl_PointSize input swizzling for
DUAL_INSTANCED gs.", except applied to the gl_PrimitiveID fixup
instead of the gl_PointSize fixup.
i965/gs: If a DUAL_OBJECT gs would spill, fall back to DUAL_INSTANCED.

This is similar to what we do for 16-wide vs 8-wide fragment shaders.
First we try compiling the geometry shader in DUAL_OBJECT mode.  If we
can't do that without spilling, we fall back on DUAL_INSTANCED mode,
which should require less spilling (since it uses an interleaved
layout of payload registers).

In an ideal world we'd fall back to SINGLE mode, which would allow us
to interleave general-purpose registers too (resulting in even less
likelihood of spilling).  But at the moment, the vec4 generator and
visitor classes don't have the infrastructure to interleave general
purpose registers, so DUAL_INSTANCED is the best we can do.

As a side benefit this paves the way for implementing instanced
geometry shaders (which are incompatible with DUAL_OBJECT mode).

Since most geometry shaders used in piglit testing are small,
DUAL_INSTANCED mode won't get exercised very much in a normal piglit
run.  To force DUAL_INSTANCED mode to be used for all geometry
shaders, set INTEL_DEBUG=nodualobj.

Reviewed-by: Eric Anholt <eric@anholt.net>
i965: Reduce gl_MaxGeometryInputComponents to 64.

Although in principle there is no hardware limitation that prevents
gl_MaxGeometryInputComponents from being set to 128 on Gen7, we have
the following limitations in the vec4 compiler back end:

- Registers assigned to geometry shader inputs can't be spilled or
  later re-used for any other purpose.

- The last 16 registers are set aside for the "MRF hack", meaning they
  can only be used to send messages, and not for general purpose
  computation.

- Up to 32 registers may be reserved for push constants, even if there
  is sufficient register pressure to make this impractical.

A shader using 128 geometry input components, and having an input type
of triangles_adjacency, would use up:

- 1 register for r0 (which holds URB handles and various pieces of
  control information).

- 1 register for gl_PrimitiveID.

- 102 registers for geometry shader inputs (17 registers per input
  vertex, assuming DUAL_INSTANCED dispatch mode and allowing for one
  register of overhead for gl_Position and gl_PointSize, which are
  present in the URB map even if they are not used).

- Up to 32 registers for push constants.

- 16 registers for the "MRF hack".

That's a total of 152 registers, which is well over the 128 registers
the hardware supports.

Fortunately, the GLSL 1.50 spec allows us to reduce
gl_MaxGeometryInputComponents to 64.  Doing that frees up 48
registers, brining the total down to 104 registers, leaving 24
registers available to do computation.

Fixes piglit test
spec/glsl-1.50/execution/geometry/max-input-components.

Reviewed-by: Eric Anholt <eric@anholt.net>
mesa: Fix geometry shader program queries.

The queries GEOMETRY_VERTICES_OUT, GEOMETRY_INPUT_TYPE, and
GEOMETRY_OUTPUT_TYPE (defined by GL 3.2) differ from the corresponding
queries in ARB_geometry_shader4 in the following ways:

- They use different enum values

- They can only be queried; they cannot be set.

- Attempting to query them yields INVALID_OPERATION if the program is
  not linked, or lacks a geometry shader.

This patch switches us over from the ARB_geometry_shader4 behaviour to
the GL 3.2 behaviour.

Fixes piglit test query-gs-prim-types.

v2: Improve comment above has_core_gs.
glsl: Call check_builtin_array_max_size when redeclaring gl_in.

Normally when a built-in array (such as gl_ClipDistance) is
redeclared, we call get_variable_being_redeclared() to do the
redeclaration, and it in turn calls check_builtin_array_max_size() to
make sure that the redeclared array size isn't too large.

However when a built-in array is redeclared as part of redeclaring
gl_in, we don't call get_variable_being_redeclared() (since the
individual built-ins aren't each represented by their own ir_variable
anymore).  So we need to add an explicit call to
check_builtin_array_max_size() to make sure the new array size isn't
too large.

Note: at the moment this is redundant with a test that's done at link
time, so there's no change to piglit results.  But the patch that
follows will prevent link errors from being reported if gl_PerVertex
isn't used, so in order to prevent that patch from causing
regressions, we need to add the compile check now.  Besides, it's
nicer to report this error at compile time anyhow.
glsl: Remove unused gl_PerVertex interface blocks.

The GLSL 4.10 rules for redeclaration of built-in interface blocks
(which we've chosen to regard as clarifications of GLSL 1.50) only
require gl_PerVertex blocks to match in shaders that actually use
those blocks.  The easiest way to implement this is to detect
situations where a compiled shader doesn't refer to any elements of
gl_PerVertex, and remove all the associated ir_variables from the
shader at the end of ast-to-ir conversion.

Fixes piglit tests
linker/interstage-{pervertex,pervertex-in,pervertex-out}-redeclaration-unneeded.
glsl: When disabling gl_PerVertex variables, check that mode matches.

In commit 1b4a737 (glsl: Support redeclaration of VS and GS
gl_PerVertex output), I added code to ensure that when an unnamed
gl_PerVertex interface block is redeclared, any ir_variables that
weren't included in the redeclaration are removed from the IR (and the
symbol table).  This ensures that only those variables that were
explicitly redeclared may be used.

However, when I wrote this code, I neglected to match the variable
mode when finding variables to remove.  This meant that redeclaring a
built-in output block might cause the built-in input gl_in to be
accidentally removed.

Fixes piglit test gs-redeclares-pervertex-out-only.
!UPSTREAM: i965/gs: Generalize some error messages for GS.

TODO: find more places to generalize.
TODO: Don't use "VS/GS" terminology.  Use "vec4" terminology, since that will endure longer.
!UPSTREAM: glsl/linker: Fail if linking geometry shader with 0 GEOMETRY_VERTICES_OUT.

ARB_geometry_shader4 spec 2.15.2:
"Linking will also fail [...] if the program object contains objects to form a
geometry shader, and the value of GEOMETRY_VERTICES_OUT_ARB is zero."

Reviewed-by: Paul Berry <stereotype441@gmail.com>

TODO: May not be necessary for GLSL 1.50 style geometry shaders.  Make a test to validate.
!UPSTREAM: Debug optimization passes.