glsl: Add an ir_variable::reinit_interface_type() function.

This will be used by future patches to change an ir_variable's
interface type when the gl_PerVertex built-in interface block is
redeclared.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Make it possible to disable a variable in the symbol table.

In later patches, we'll use this in order to implement the required
behaviour that after the gl_PerVertex interface block has been
redeclared, only members of the redeclared interface block may be
used.

v2: Update the function name and comment to clarify that we aren't
actually removing the variable from the symbol table, just disabling
it.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Error check redeclarations of gl_PerVertex.

This patch verifies that:

- The gl_PerVertex input interface block may only be redeclared in a
  geometry shader, and that it may only be redeclared as gl_in[].

- The gl_PerVertex output interface block may only be redeclared in a
  vertex or geometry shader, and that it may only be redeclared as a
  non-array without an interface name.

- gl_PerVertex may not be redeclared as any other type of interface
  block (i.e. as a uniform interface block).

As a side-effect, the code now keeps track of what the previous
declaration of gl_PerVertex was--this will be needed in future
patches.

Fixes piglit tests:
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-in-with-incorrect-name.geom
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-out-as-array.geom
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-out-with-instance-name.geom

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Support redeclaration of VS and GS gl_PerVertex output.

Fixes piglit tests:
- spec/glsl-1.50/execution/redeclare-pervertex-out-subset-gs
- spec/glsl-1.50/execution/redeclare-pervertex-subset-vs

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Catch redeclaration of interface block instance names at compile time.

From section 4.1.9 (Arrays) of the GLSL 4.40 spec (as of revision 7):

    However, unless noted otherwise, blocks cannot be redeclared;
    an unsized array in a user-declared block cannot be sized
    through redeclaration.

The only place where the spec notes that interface blocks can be
redeclared is to allow for redeclaration of built-in interface blocks
such as gl_PerVertex.  Therefore, user-defined interface blocks can
never be redeclared.  This is a clarification of previous intent (see
Khronos bug 10659).

We were already preventing interface block redeclaration using the
same block name at compile time, but we weren't preventing interface
block redeclaration using the same instance name (and different block
names) at compile time.  And we weren't preventing an instance name
from conflicting with a previously-declared ordinary variable.

In practice the problem would be caught at link time, but only because
of a coincidence: since ast_interface_block::hir() wasn't doing any
checking to see if the instance name already existed in the shader, it
was creating a second ir_variable in the shader having the same name
but a different type.  Coincidentally, when the linker checked for
intrastage consistency of global variable declarations, it treated the
two declarations from the same shader as a conflict, so it reported a
link error.

But it seems dangerous to rely on that linker behaviour to catch
illegal redeclarations that really ought to be detected at compile
time.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Support redeclaration of GS gl_PerVertex input.

Fixes piglit test
spec/glsl-1.50/execution/redeclare-pervertex-subset-vs-to-gs.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
glsl: Don't allow gl_PerVertex to be redeclared after it's been used.

Fixes piglit tests:
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-in-after-other-usage.geom
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-out-after-other-usage.geom
- spec/glsl-1.50/compiler/gs-redeclares-pervertex-out-after-usage.geom
- spec/glsl-1.50/compiler/vs-redeclares-pervertex-out-after-other-usage.vert
- spec/glsl-1.50/compiler/vs-redeclares-pervertex-out-after-usage.vert

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
i965/fs: Short-circuit a loop in live variable analysis.

This has no functional effect, but should make subsequent changes a
little simpler.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
i965/fs: Rename num_vars to num_vgrfs in live interval analysis.

num_vars was shorthand for the number of virtual GRFs.  num_vgrfs is a
bit clearer.  Plus, the next patch will introduce "vars" which are
distinct from vgrfs.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
i965/fs: Do live variables dataflow analysis on a per-channel level.

This significantly improves our handling of VGRFs of size > 1.

Previously, we only marked VGRFs as def'd if the whole register was
written by a single instruction.  Large VGRFs which were written
piecemeal would not be considered def'd at all, even if they were
ultimately completely written.

Without being def'd, these were then marked "live in" to the basic
block, often extending the range to preceding blocks and sometimes
even the start of the program.

The new per-component tracking gives more accurate live intervals,
which makes register coalescing more effective.

In the future, this should help with texturing from GRFs on Gen7+.
A sampler message might be represented by a 2-register VGRF which
holds the texture coordinates.  If those are incoming varyings,
they'll be produced by two PLN instructions, which are piecemeal writes.

No reduction in shader-db instruction counts.  However, code which
prints the live interval ranges does show that some VGRFs now have
smaller (and more correct) live intervals.

v2: Rebase on current send-from-GRF code requiring adding extra use[]s.
v3: Rebase on live intervals fix to include defs in the end of the
    interval.
v4 (Kenneth Graunke): Rebase; split off a few preparatory patches;
    add lots of comments; minor style changes; rewrite commit message.
v5 (Eric Anholt): whitespace nit.

Written-by: Eric Anholt <eric@anholt.net> [v1-3]
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org> [v4]
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net> (v4)
i965/fs: Create a helper function for invalidating live intervals.

For now, this simply sets live_intervals_valid = false, but in the
future it will do something more sophisticated.

Based on a patch by Eric Anholt.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
i965/fs: Factor def[]/use[] setup out to a separate function.

These blocks are about to grow some more code, and the indentation was
getting out of hand.

v2 (Kenneth Graunke): Rebase, minor typo fixes and style changes.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Track live variable ranges on a per-channel level.

This is the information we'll actually use to replace the
virtual_grf_start[]/end[] arrays.

No change in shader-db.

v2 (Kenneth Graunke): Rebase; minor comment updates.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Remove start/end aliases in compute_live_intervals().

In compute_live_intervals(), start and end are shorter names for
the virtual_grf_start and virtual_grf_end class members.

Now that the fs_live_intervals class has arrays named start and end
which are indexed by var, rather than VGRF, reusing the name is
confusing.  Plus, most of the code has been factored out, so using the
long names isn't as inconvenient.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
i965/fs: Invalidate live intervals when compacting; don't fix them.

When compacting the list of VGRFs, we patch up the live interval ranges
(which are indexed by VGRF number).  Unfortunately, once we make
per-component data available, this will become too complicated to
maintain.  Instead, simply invalidate them.

This was pulled out of a patch by Eric Anholt.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
i965/fs: Keep a copy of the live variables class around.

Now optimization passes will be able to look at the per-channel ranges.

v2: Rebase on various optimization pass changes.
v3 (Kenneth Graunke): Rename live_variables to live_intervals; split
   introduction of invalidate_live_intervals() into a separate patch.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Use the new per-channel live ranges for dead code elimination.

v2 (Kenneth Graunke): Rebase on s/live_variables/live_intervals/g.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Use per-channel interference for register_coalesce_2().

This will let us coalesce into texture-from-GRF arguments, which would
otherwise be prevented due to the live interval for the whole vgrf
extending across all the MOVs setting up the channels of the message

v2 (Kenneth Graunke): Rebase for renames.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965/fs: Allocate more register classes on gen7.

For texturing from GRFs, we now have payloads of arbitrary sizes up to the
message length limit.

v2 (Kenneth Graunke): Rebase on intel_context -> brw_context change.
v3: Add some comment text.
v4: Change some magic 16s to BRW_MAX_MRF (noted by Ken).  Leave the 11,
    which is the magic "max sampler message length".  BRW_MAX_MRF sizing
    on the little int arrays is retained because I could see us needing to
    extend in the future if we move to GRFs for FB writes (those go to at
    least 12 long in a quick scan of the specs)

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> (v2)
Acked-by: Matt Turner <mattst88@gmail.com>
i965/fs: Convert gen7 to using GRFs for texture messages.

Looking at Lightsmark's shaders, the way we used MRFs (or in gen7's
case, GRFs) was bad in a couple of ways.  One was that it prevented
compute-to-MRF for the common case of a texcoord that gets used
exactly once, but where the texcoord setup all gets emitted before the
texture calls (such as when it's a bare fragment shader input, which
gets interpolated before processing main()).  Another was that it
introduced a bunch of dependencies that constrained scheduling, and
forced waits for texture operations to be done before they are
required.  For example, we can now move the compute-to-MRF
interpolation for the second texture send down after the first send.

The downside is that this generally prevents
remove_duplicate_mrf_writes() from doing anything, whereas previously
it avoided work for the case of sampling from the same texcoord twice.
However, I suspect that most of the win that originally justified that
code was in avoiding the WAR stall on the first send, which this patch
also avoids, rather than the small cost of the extra instruction.  We
see instruction count regressions in shaders in unigine, yofrankie,
savage2, hon, and gstreamer.

Improves GLB2.7 performance by 0.633628% +/- 0.491809% (n=121/125, avg of
~66fps, outliers below 61 dropped).

Improves openarena performance by 1.01092% +/- 0.66897% (n=425).

No significant difference on Lightsmark (n=44).

v2: Squash in the fix for register unspilling for send-from-GRF, fixing a
    segfault in lightsmark.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Matt Turner <mattst88@gmail.com>