[Mesa-dev] [PATCH 000/123] Reintroducing NIR, a new IR for mesa

Jason Ekstrand jason at jlekstrand.net
Tue Jan 6 13:34:51 PST 2015


On Mon, Jan 5, 2015 at 11:28 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:

> Patches 100, 102-104, 106-109, 114-117, 121-146 are:
>
> Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>
>

Noted.  I'm working on dealing with comments now.
--Jason


>
> Whew! I think I've looked through everything.
>
> On Tue, Dec 16, 2014 at 1:04 AM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
>
>> NIR (pronounced "ner") is a new IR (internal representation) for the Mesa
>> shader compiler that will sit between the old IR (GLSL IR) and back-end
>> compilers.  The primary purpose of NIR is to be more efficient for doing
>> optimizations and generate better code for the back-ends.  We have a lot
>> of
>> optimizations implemented in GLSL IR right now.  However, they still
>> generate fairly bad code primarily because its tree-based structure makes
>> writing good optimizations difficult.  For this reason, we have
>> implemented
>> a lot of optimizations in the i965 back-end compilers just to fix up the
>> code we get from GLSL IR.  The "proper fix" to this is to implement a
>> better high-level IR; enter NIR.
>>
>> Most of the initial work on NIR including setting up common data
>> structures, helper methods, and a few basic passes was by Connor Abbot who
>> interned with us over the summer.  Connor did a fantastic job, but there
>> is
>> still a lot left to be done.  I've spent the last two months trying to
>> fill
>> in the pieces that we need in order to get NIR off the ground.  At this
>> point, we now have compitent in and out of SSA passes, are at zero piglit
>> regressions for i965 SIMD8 fragment shaders, and the shader-db numbers
>> aren't terrible.
>>
>> This is still a bit experimental.  I have been testing only on HSW but it
>> should work ok on SNB and later.  Eventually, once we get booleans fixed
>> up, it should work fine on older chips as well.  It also doesn't yet
>> support SIMD16, so performance won't be that great.  That said, I think we
>> are at the point now where we should try and land this and I can stop
>> developing in my masive private branch.  Since this isn't quite ready for
>> prime-time yet, using it requires setting the INTEL_USE_NIR environment
>> variable.
>>
>> A few key points about NIR:
>>
>>  1. It is primarily an SSA-based IR.
>>  2. It supports source/destination-modifiers and swizzles/*write-masks.
>>  3. Standard GPU operations such as sin() and fmad() are first-class ALU
>>     operations, not intrinsics.
>>  4. GLSL concepts like inputs, outputs, uniforms, etc. are built into the
>>     IR so we can do proper analysis on them.
>>  5. Even though it's SSA, it still has a concept of registers and
>>     write-masks in the core IR data structures.  This means we can
>> generate
>>     code that is much closer to what backends want.
>>  6. Control flow is structured explicitly in the IR.
>>
>> (*write-masks are not available for SSA values)
>>
>> While source/destination modifiers and writemasks/swizzles are not
>> particularly useful for optimizations, having them represented in the IR
>> gives us the ability to generate more useful code for backends.
>>
>> A few notes about review:
>>
>>  1. For those of you who aren't interested in the general compiler, I'm
>>     sorry for the patch-bomb.  However, several people have requsted that
>>     we maintain the history of the NIR development since connor's original
>>     drop at the end of the summer.  Therefore, while I've squashed several
>>     things, I've tried to leave the diff of what I've done more-or-less
>>     preserved.
>>
>>  2. No, this is not LLVM.  There was a long-winded discussion about that
>>     when Connor dropped his patches that went a whole lot of nowhere as
>>     usual.  I would really prefer if we left that debate alone.  If there
>>     must be bikeshedding on the topic, please do so on the cover-letter
>>     e-mail.
>>
>>  3. Please keep all bikeshedding about C++, typedefs, etc.  on the core
>>     datastructures e-mail.  If we need, we can split that off in its own
>>     thread.
>>
>>  4. While I welcome review, I don't plan to make non-trivial changes to
>>     specific patches or squash anything beyond what has already been
>>     squashed.  I've tried thus far to more-or-less keep the history and
>> I'd
>>     like to continue this if we can.
>>
>>  5. Eric Anholt has also written NIR -> TGSI -> NIR passes which will
>>     hopefully get landed soon after NIR initially lands.  Exactly how that
>>     all gets hooked up for other gallium drivers beyond vc4 is outside the
>>     scope of this series.
>>
>> I have pushed a branch to my personal freedesktop.org account.  For
>> certain
>> types of review, it may be easier to look at the end result rather than
>> the
>> patches.  The branch can be found via freedesktop cgit here:
>>
>> http://cgit.freedesktop.org/~jekstrand/mesa/log/?h=review/nir-v1
>>
>> Last week, I did a presentation for some of the other Intel people to try
>> and help bring them up to speed on NIR concepts quickly.  As part of this,
>> I typed up a bunch of notes that provide a decent overview of a lot of NIR
>> concepts.  Those notes can be found here:
>>
>> http://www.jlekstrand.net/jason/projects/mesa/nir-notes/
>>
>> Happy reviewing!
>>
>> P.S. Connor, Don't do too much reviewing before your finals are done. :-P
>>
>> Connor Abbott (22):
>>   exec_list: add a list_foreach_typed_reverse() macro
>>   nir: add initial README
>>   nir: add a simple C wrapper around glsl_types.h
>>   nir: add the core datastructures
>>   nir: add core helper functions
>>   nir: add a printer
>>   nir: add a validation pass
>>   nir: add a glsl-to-nir pass
>>   nir: add a pass to lower variables for scalar backends
>>   nir: keep track of the number of input, output, and uniform slots
>>   nir: add a pass to remove unused variables
>>   nir: add a pass to lower sampler instructions
>>   nir: add a pass to lower system value reads
>>   nir: add a pass to lower atomics
>>   nir: add an optimization to turn global registers into local registers
>>   nir: calculate dominance information
>>   nir: add a pass to convert to SSA
>>   nir: add an SSA-based copy propagation pass
>>   nir: add an SSA-based dead code elimination pass
>>   i965/fs: make emit_fragcoord_interpolation() more general
>>   i965/fs: Don't pass through the coordinate type
>>   i965/fs: add a NIR frontend
>>
>> Jason Ekstrand (101):
>>   i965/fs: Only use nir for 8-wide non-fast-clear shaders.
>>   i965/fs_nir: Make the sampler register always unsigned
>>   i965/fs_nir: Use the correct types for texture inputs
>>   i965/fs_nir: Use the correct texture offset immediate
>>   Fix what I think are a few NIR typos
>>   Fix up varying pull constants
>>   i965/fs_nir: Add support for sample_pos and sample_id
>>   nir/glsl: Add support for saturate
>>   nir: Add fine and coarse derivative opcodes
>>   nir/glsl: Add support for coarse and fine derivatives
>>   i965/fs_nir: Handle coarse/fine derivatives
>>   nir/lower_atomics: Multiply array offsets by ATOMIC_COUNTER_SIZE
>>   i965/fs_nir: Add atomic counters support
>>   i965/fs: Allow reinterpretation in constant propagation
>>   nir: Add NIR_TRUE and NIR_FALSE constants and use them for boolean
>>     immediates
>>   nir: Add intrinsics to do alternate interpolation on inputs
>>   i965/fs: Don't take an ir_variable for emit_general_interpolation
>>   i965/fs_nir: Don't duplicate emit_general_interpolation
>>   nir: Add a naieve from-SSA pass
>>   nir: Add a lower_vec_to_movs pass
>>   i965/fs_nir: Convert the shader to/from SSA
>>   nir/lower_variables_scalar: Silence a compiler warning
>>   nir: Add a basic metadata management system
>>   nir: Add an assert
>>   nir/foreach_block: Return false if the callback on the last block
>>     fails
>>   nir: Add a foreach_block_reverse function
>>   nir: Add a function to detect if a block is immediately followed by an
>>     if
>>   nir: Make the nir_index_* functions return the nuber of items
>>   nir: Add an SSA-based liveness analysis pass.
>>   nir: Add an initialization function for SSA definitions
>>   nir: Automatically handle SSA uses when an instruction is inserted
>>   nir: Add a function for rewriting all the uses of a SSA def
>>   nir: Add a parallel copy instruction type
>>   nir: Add a function for comparing two sources
>>   nir: Add a better out-of-SSA pass
>>   i965/fs_nir: Do retyping for ALU srouces in get_nir_alu_src
>>   glsl/list: Fix the exec_list_validate function
>>   nir: Validate all lists in the validator
>>   nir/print: Don't reindex things
>>   nir: Differentiate between signed and unsigned versions of find_msb
>>   i965/fs_nir: Validate optimization passes
>>   nir/nir: Fix a bug in move_successors
>>   glsl/list: Add a foreach_list_typed_safe_reverse macro
>>   nir/nir: Use safe iterators when iterating over the CFG
>>   nir/nir: Patch up phi predecessors in move_successors
>>   nir: Add a peephole select optimization
>>   i965/fs_nir: Turn on the peephole select optimization
>>   nir: Validate that the SSA def and register indices are unique
>>   nir: Add a fused multiply-add peephole
>>   nir: Add a basic CSE pass
>>   i965/fs_nir: Add the CSE pass and actually run in a loop
>>   i965/fs_nir: Use an array rather than a hash table for register lookup
>>   i965/fs_nir: Handle SSA constants
>>   i965/fs_nir: Properly saturate multiplies
>>   nir: Add a helper for rewriting an instruction source
>>   nir/lower_samplers: Use the nir_instr_rewrite_src function
>>   nir: Clean up nir_deref helper functions
>>   nir: Make array deref direct vs. indirect an enum
>>   nir: Add a concept of a wildcard array dereference
>>   nir: Use an integer index for specifying structure fields
>>   nir: Don't require a function in ssa_def_init
>>   nir/copy_propagate: Don't cause size mismatches on phi node sources
>>   nir: Validate that the sources of a phi have the same size as the
>>     destination
>>   nir/glsl: Don't allocate a state_slots array for 0 state slots
>>   i965/fs_nir: Don't dump the shader.
>>   nir: Use the enum for the variable mode
>>   nir: Automatically update SSA if uses
>>   nir: Add a copy splitting pass
>>   nir: Add a pass to lower local variable accesses to SSA values
>>   nir: Add a pass to lower local variables to registers
>>   nir: Add a pass for lowering input/output loads/stores
>>   nir: Add a pass to lower global variables to local variables
>>   nir/glsl: Generate SSA NIR
>>   i965/fs_nir: Use the new variable lowering code
>>   nir/validate: Ensure that outputs are write-only and inputs are
>>     read-only
>>   nir: Remove the old variable lowering code
>>   nir: Vectorize intrinsics
>>   nir/validate: Validate intrinsic source/destination sizes
>>   nir: Add gpu_shader5 interpolation intrinsics
>>   nir/glsl: Add support for gpu_shader5 interpolation instrinsics
>>   nir: Add a helper for getting a constant value from an SSA source
>>   i965/fs_nir: Add a has_indirect flag and clean up some of the
>>     input/output code
>>   i965/fs_nir: Implement the ARB_gpu_shader5 interpolation intrinsics
>>   nir: Add neg, abs, and sat opcodes
>>   nir: Add a lowering pass for adding source modifiers where possible
>>   nir: Make the type casting operations static inline functions
>>   nir/glsl: Emit abs, neg, and sat operations instead of source
>>     modifiers
>>   nir: Add an expression matching framework
>>   nir: Add infastructure for generating algebraic transformation passes
>>   nir: Add an algebraic optimization pass
>>   nir: Add a basic constant folding pass
>>   nir: Remove the ffma peephole
>>   nir: Make texture instruction names more consistent
>>   nir: Constant fold array indirects
>>   nir: Use a source for uniform buffer indices instead of an index
>>   nir: Add a sampler index indirect to nir_tex_instr
>>   nir: Rework the way samplers are lowered
>>   i965/fs_nir: Add support for indirect texture arrays
>>   nir/metadata: Rename metadata_dirty to metadata_preserve
>>   nir: Call nir_metadata_preserve more places
>>   nir: Make bcsel a fully vector operation
>>
>>  src/glsl/Makefile.am                               |   10 +-
>>  src/glsl/Makefile.sources                          |   39 +-
>>  src/glsl/list.h                                    |   19 +-
>>  src/glsl/nir/README                                |  118 ++
>>  src/glsl/nir/glsl_to_nir.cpp                       | 1825
>> +++++++++++++++++
>>  src/glsl/nir/glsl_to_nir.h                         |   40 +
>>  src/glsl/nir/nir.c                                 | 2042
>> ++++++++++++++++++++
>>  src/glsl/nir/nir.h                                 | 1433 ++++++++++++++
>>  src/glsl/nir/nir_algebraic.py                      |  249 +++
>>  src/glsl/nir/nir_dominance.c                       |  298 +++
>>  src/glsl/nir/nir_from_ssa.c                        |  859 ++++++++
>>  src/glsl/nir/nir_intrinsics.c                      |   49 +
>>  src/glsl/nir/nir_intrinsics.h                      |  140 ++
>>  src/glsl/nir/nir_live_variables.c                  |  282 +++
>>  src/glsl/nir/nir_lower_atomics.c                   |  146 ++
>>  src/glsl/nir/nir_lower_global_vars_to_local.c      |  107 +
>>  src/glsl/nir/nir_lower_io.c                        |  324 ++++
>>  src/glsl/nir/nir_lower_locals_to_regs.c            |  308 +++
>>  src/glsl/nir/nir_lower_samplers.cpp                |  181 ++
>>  src/glsl/nir/nir_lower_system_values.c             |  107 +
>>  src/glsl/nir/nir_lower_to_source_mods.c            |  181 ++
>>  src/glsl/nir/nir_lower_variables.c                 | 1046 ++++++++++
>>  src/glsl/nir/nir_lower_vec_to_movs.c               |   96 +
>>  src/glsl/nir/nir_metadata.c                        |   54 +
>>  src/glsl/nir/nir_opcodes.c                         |   46 +
>>  src/glsl/nir/nir_opcodes.h                         |  356 ++++
>>  src/glsl/nir/nir_opt_algebraic.py                  |   67 +
>>  src/glsl/nir/nir_opt_constant_folding.c            |  355 ++++
>>  src/glsl/nir/nir_opt_copy_propagate.c              |  325 ++++
>>  src/glsl/nir/nir_opt_cse.c                         |  269 +++
>>  src/glsl/nir/nir_opt_dce.c                         |  186 ++
>>  src/glsl/nir/nir_opt_global_to_local.c             |  103 +
>>  src/glsl/nir/nir_opt_peephole_select.c             |  214 ++
>>  src/glsl/nir/nir_print.c                           |  948 +++++++++
>>  src/glsl/nir/nir_remove_dead_variables.c           |  138 ++
>>  src/glsl/nir/nir_search.c                          |  337 ++++
>>  src/glsl/nir/nir_search.h                          |   80 +
>>  src/glsl/nir/nir_split_var_copies.c                |  225 +++
>>  src/glsl/nir/nir_to_ssa.c                          |  660 +++++++
>>  src/glsl/nir/nir_types.cpp                         |  143 ++
>>  src/glsl/nir/nir_types.h                           |   75 +
>>  src/glsl/nir/nir_validate.c                        |  912 +++++++++
>>  src/mesa/drivers/dri/i965/Makefile.sources         |    1 +
>>  src/mesa/drivers/dri/i965/brw_fs.cpp               |   74 +-
>>  src/mesa/drivers/dri/i965/brw_fs.h                 |   57 +-
>>  .../drivers/dri/i965/brw_fs_copy_propagation.cpp   |    4 +-
>>  src/mesa/drivers/dri/i965/brw_fs_fp.cpp            |   32 +-
>>  src/mesa/drivers/dri/i965/brw_fs_nir.cpp           | 1778
>> +++++++++++++++++
>>  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp       |   39 +-
>>  src/mesa/main/bitset.h                             |    1 +
>>  50 files changed, 17301 insertions(+), 77 deletions(-)
>>  create mode 100644 src/glsl/nir/README
>>  create mode 100644 src/glsl/nir/glsl_to_nir.cpp
>>  create mode 100644 src/glsl/nir/glsl_to_nir.h
>>  create mode 100644 src/glsl/nir/nir.c
>>  create mode 100644 src/glsl/nir/nir.h
>>  create mode 100644 src/glsl/nir/nir_algebraic.py
>>  create mode 100644 src/glsl/nir/nir_dominance.c
>>  create mode 100644 src/glsl/nir/nir_from_ssa.c
>>  create mode 100644 src/glsl/nir/nir_intrinsics.c
>>  create mode 100644 src/glsl/nir/nir_intrinsics.h
>>  create mode 100644 src/glsl/nir/nir_live_variables.c
>>  create mode 100644 src/glsl/nir/nir_lower_atomics.c
>>  create mode 100644 src/glsl/nir/nir_lower_global_vars_to_local.c
>>  create mode 100644 src/glsl/nir/nir_lower_io.c
>>  create mode 100644 src/glsl/nir/nir_lower_locals_to_regs.c
>>  create mode 100644 src/glsl/nir/nir_lower_samplers.cpp
>>  create mode 100644 src/glsl/nir/nir_lower_system_values.c
>>  create mode 100644 src/glsl/nir/nir_lower_to_source_mods.c
>>  create mode 100644 src/glsl/nir/nir_lower_variables.c
>>  create mode 100644 src/glsl/nir/nir_lower_vec_to_movs.c
>>  create mode 100644 src/glsl/nir/nir_metadata.c
>>  create mode 100644 src/glsl/nir/nir_opcodes.c
>>  create mode 100644 src/glsl/nir/nir_opcodes.h
>>  create mode 100644 src/glsl/nir/nir_opt_algebraic.py
>>  create mode 100644 src/glsl/nir/nir_opt_constant_folding.c
>>  create mode 100644 src/glsl/nir/nir_opt_copy_propagate.c
>>  create mode 100644 src/glsl/nir/nir_opt_cse.c
>>  create mode 100644 src/glsl/nir/nir_opt_dce.c
>>  create mode 100644 src/glsl/nir/nir_opt_global_to_local.c
>>  create mode 100644 src/glsl/nir/nir_opt_peephole_select.c
>>  create mode 100644 src/glsl/nir/nir_print.c
>>  create mode 100644 src/glsl/nir/nir_remove_dead_variables.c
>>  create mode 100644 src/glsl/nir/nir_search.c
>>  create mode 100644 src/glsl/nir/nir_search.h
>>  create mode 100644 src/glsl/nir/nir_split_var_copies.c
>>  create mode 100644 src/glsl/nir/nir_to_ssa.c
>>  create mode 100644 src/glsl/nir/nir_types.cpp
>>  create mode 100644 src/glsl/nir/nir_types.h
>>  create mode 100644 src/glsl/nir/nir_validate.c
>>  create mode 100644 src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>>
>> --
>> 2.2.0
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>>
>
>
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