Previously, we were doing a lazy creation of the parallel copy
instructions.  This is confusing, hard to get right, and involves some
extra state tracking of the copies.  This commit adds an extra walk over
the basic blocks to add the block-end parallel copies up front.  This
should be much less confusing and, consequently, easier to get right.  This
commit also adds more comments about parallel copies to help explain what
all is going on.

As a consequence of these changes, we can now remove the at_end parameter
from nir_parallel_copy_instr.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

The new name is a little longer but less confusing.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Before, we were emitting the full pile of setup instructions for sample_id
and sample_pos every time they were used.  With this commit, we emit them
in their own pass once at the beginning of the shader and simply emit uses
later on.  When it comes time for setting up VS, we can put setup for its
special values in the same pass.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Originally, this field was intended for determining if the given
instruction acted per-component or if it had mismatching source and
destination sizes that would have to be interpreted specially.  However, we
can easily derive this from output_size == 0, so it's not really that
useful.  Also, the values we were setting in nir_opcodes.h for this field
were completely bogus and it was never used.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Prior to this commit, we had a big switch statement for this.  Now it's
baked into the opcode metadata so we can just use that.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This commit adds some algebraic properties to the metadata of each opcode
in NIR.  In particular, you now know, just from the metadata, if a given
opcode is commutative or associative.  This will be useful for algebraic
transformation passes that want to be able to match a + b as well as b + a
in one go.

v2: Make algebraic properties all caps.  This was more consistent with the
    intrinsics flags and seems better for flags in general.

    Also, the enums are now declared with (1 << n) rather then hex values.

v3: fmin and fmax technically aren't commutative or associative.  Things
    get funny when one of the arguments is a NaN.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

As it was, we weren't ever using load_const in a non-SSA way.  This allows
us to substantially simplify the load_const instruction.  If we ever need a
non-SSA constant load, we can do a load_const and an imov.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Previously, lower_atomics was non-SSA only.  We assert-failed if the
destination of an atomic operation intrinsic was an SSA def and we used
temporary registers for computing offsets.  This commit changes both of
these behaviors.  We now use SSA values for computing offsets (so we can
optimize them) and we handle SSA destinations.  We also move the pass to
run before we go out of SSA on i965 as it now generates SSA values.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Before, we were using foreach_dest and switching on whether the destination
was an SSA value.  This works, except not all destinations are SSA values
so we have to special-case ssa_undef instructions.  Now that we have a
foreach_ssa_def function, we can iterate over all of the register
destinations in one pass and iterate over the SSA destinations in a second.
This way, if we add other ssa-only instructions, we won't have to worry
about adding them to the special case we have for ssa_undef.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

There are some functions whose destinations are SSA-only and so aren't a
nir_dest.  This provides a function that is capable of iterating over the
SSA definitions defined by those functions.  If you want registers, you
should use the old iterator.

v2: Kenneth Graunke <kenneth@whitecape.org>:
 - Fix nir_foreach_ssa_def's return value.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Previously, we were just iterating over the program "in order" which
kind-of approximates a DFS, but not really.  In particular, we got the
following case wrong:

loop {
   a = 3;
   if (foo) {
      a = 5;
   } else {
      break;
   }
   use(a);
}

where use(a) would get 3 instead of 5 because of premature popping of the
SSA def stack.  Now, since we do an actaul DFS, we should evaluate use(a)
immediately after a = 5 and we should be ok.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

We stopped generating predicates in glsl_to_nir some time ago.  Right now,
it's all dead untested code that I'm not convinced always worked in the
first place.  If we decide we want them back, we can revert this patch.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Previously, the condition was a scalar that applied to all components
simultaneously.  As of this commit, the condition is a vector and each
component is switched seperately.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

nir_metadata_dirty was a terrible name because the parameter it takes is
the metadata to be preserved.  This is really confusing because it looks
like it's doing the opposite of what it is actually doing.  Now it's named
sensibly.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

v2 Jason Ekstrand <jason.ekstrand@intel.com>:
 - Use the nir_tex_src_sampler_offset source type instead of the
   sampler_indirect thing that I cooked up before.

Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>

v2 Jason Ekstrand <jason.ekstrand@intel.com>:
 - Use the nir_tex_src_sampler_offset source type instead of the
   sampler_indirect thing that I cooked up before.

Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>

This helps a lot with things like lowering passes that may need to add
sources.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

In particular, we rename nir_tex_src_sampler_index to _sampler_offset and
add a sampler_array_size field to nir_tex_instr.  This way we can pass the
size of sampler arrays through to backends even after removing the variable
information and, with it, the type.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

In GLSL-to-NIR we were just setting the base index to 0 whenever there was
an indirect so having it expressed as a sum makes no sense.  Also, while a
base offset may make sense for the memory location (first element in the
array, etc.) it makes less sense for the actual uniform buffer index.  This
may change later, but it seems to make more sense for now.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This commit renames nir_instr_as_texture to nir_instr_as_tex and renames
nir_instr_type_texture to nir_instr_type_tex to be consistent with
nir_tex_instr.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This is no longer needed because it's now part of the algebraic
optimization pass

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This pass uses the previously built algebraic transformations framework and
should act as an example for anyone else wanting to make an algebraic
transformation pass for NIR.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This commit builds on the nir_search.h infastructure by adding a bit of
python code that makes it stupid easy to write an algebraic transformation
pass.  The nir_algebraic.py file contains four python classes that
correspond directly to the datastructures in nir_search.c and allow you to
easily generate the C code to represent them.  Given a list of
search-and-replace operations, it can then generate a function that applies
those transformations to a shader.

The transformations can be specified manually, or they can be specified
using nested tuples.  The nested tuples make a neat little language for
specifying expression trees and search-and-replace operations in a very
readable and easy-to-edit fasion.

The generated code is also fairly efficient.  Insteady of blindly calling
nir_replace_instr with every single transformation and on every single
instruction, it uses a switch statement on the instruction opcode to do a
first-order culling and only calls nir_replace_instr if the opcode is known
to match the first opcode in the search expression.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

This framework provides a simple way to do simple search-and-replace
operations on NIR code.  The nir_search.h header provides four simple data
structures for representing expressions:  nir_value and four subtypes:
nir_variable, nir_constant, and nir_expression.  An expression tree can
then be represented by nesting these data structures as needed.  The
nir_replace_instr function takes an instruction, an expression, and a
value; if the instruction matches the expression, it is replaced with a new
chain of instructions to generate the given replacement value.  The
framework keeps track of swizzles on sources and automatically generates
the currect swizzles for the replacement value.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Previously, the casting operations were macros.  While this is usually
fine, the casting macro used the input parameter twice leading to strange
behavior when you passed the result of another function into it.  Since we
know the source and destination types explicitly, we don't loose anything
by making it a function.

Also, this gives us a nice little macro for creating cast function that
will hopefully prevent mistyping.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>