[Mesa-dev] [PATCH 000/123] Reintroducing NIR, a new IR for mesa
Connor Abbott
cwabbott0 at gmail.com
Tue Dec 16 14:52:29 PST 2014
Hi,
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.
I know you've said this, but I think there might still be some benefit
from re-arranging a few things. In particular, I think patches 21, 36,
39, 59, and 65 should probably get put first so that we can push them
+ patch 1 right away (with appropriate review), since they're not
NIR-specific. I've reviewed the ones I feel qualified to review (and
that I didn't write!) to help with this. I know I got feedback on a
few of those prep patches that we should wait to commit them until the
things they introduce have users, but I think that since there are now
patches in the list and we want to land them soon-ish it might be a
good idea to commit them earlier in order to reduce the size of this
patch-bomb :) Feel free to disagree, though...
Connor
>
> 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
>
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