Commit Graph

320 Commits

Author SHA1 Message Date
Lei Zhang 56f60a1ce7 [mlir][spirv] Use SingleBlock + NoTerminator for spv.module
This allows us to remove the `spv.mlir.endmodule` op and
all the code associated with it.

Along the way, tightened the APIs for `spv.module` a bit
by removing some aliases. Now we use `getRegion` to get
the only region, and `getBody` to get the region's only
block.

Reviewed By: mravishankar, hanchung

Differential Revision: https://reviews.llvm.org/D103265
2021-06-09 14:00:06 -04:00
Valentin Clement cf84670579 [mlir][openacc][NFC] move index in processDataOperands
Move the index variable used to track variables inside of the specific
processDataOperands functions.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D103924
2021-06-09 10:28:30 -04:00
Valentin Clement 1005ef445d [mlir][openacc] Translate UpdateOp to LLVM IR
Add translation to LLVM IR for the UpdateOp with host and device operands.
Translation is done with call using the runtime. This is done in a similar way as
D101504 and D102381.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D102382
2021-05-26 11:42:15 -04:00
Valentin Clement ab5ff154ab [mlir][openacc] Translate ExitDataop to LLVM IR
Translate ExitDataOp with delete and copyout operands to runtime call.
This is done in a similar way as D101504.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D102381
2021-05-17 11:11:59 -04:00
Adrian Kuegel 5ef21506b9 Add support for complex constants to MLIR core.
BEGIN_PUBLIC
Add support for complex constants to MLIR core.
END_PUBLIC

Differential Revision: https://reviews.llvm.org/D101908
2021-05-17 09:12:39 +02:00
Valentin Clement 113b807017 [mlir][openacc] Add OpenACC translation to LLVM IR (enter_data op create/copyin)
This patch begins to translate acc.enter_data operation to call to tgt runtime call.
It currently only translate create/copyin operands of memref type. This acts as a basis to add support
for FIR types in the Flang/OpenACC support. It follows more or less a similar path than clang
with `omp target enter data map` directives.
This patch is taking a different approach than D100678 and perform a translation to LLVM IR
and make use of the OpenMPIRBuilder instead of doing a conversion to the LLVMIR dialect.

OpenACC support in Flang will rely on the current OpenMP runtime where 1:1 lowering can be
applied. Some extension will be added where features are not available yet.

Big part of this code will be shared for other standalone data operations in the OpenACC
dialect such as acc.exit_data and acc.update.

It is likely that parts of the lowering can also be shared later with the ops for
standalone data directives in the OpenMP dialect when they are introduced.

This is an initial translation and it probably needs more work.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D101504
2021-05-12 13:41:14 -04:00
Dumitru Potop 9a0ea5994b [mlir] Support alignment in LLVM dialect GlobalOp
First step in adding alignment as an attribute to MLIR global definitions. Alignment can be specified for global objects in LLVM IR. It can also be specified as a named attribute in the LLVMIR dialect of MLIR. However, this attribute has no standing and is discarded during translation from MLIR to LLVM IR. This patch does two things: First, it adds the attribute to the syntax of the llvm.mlir.global operation, and by doing this it also adds accessors and verifications. The syntax is "align=XX" (with XX being an integer), placed right after the value of the operation. Second, it allows transforming this operation to and from LLVM IR. It is checked whether the value is an integer power of 2.

Reviewed By: ftynse, mehdi_amini

Differential Revision: https://reviews.llvm.org/D101492
2021-05-12 09:07:20 +02:00
Uday Bondhugula 1c777ab459 [MLIR] Switch llvm.noalias to a unit attribute
Switch llvm.noalias attribute from a boolean attribute to a unit
attribute.

Differential Revision: https://reviews.llvm.org/D102225
2021-05-11 15:41:09 +05:30
Mats Petersson 7280f4b279 [OpenMP][MLIR]Add support for guided, auto and runtime scheduling
When using parallel loop construct, the OpenMP specification allows for
guided, auto and runtime as scheduling variants (as well as static and
dynamic which are already supported).

This adds the translation from MLIR to LLVM-IR for these scheduling
variants.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D101435
2021-05-10 09:18:52 +00:00
Alex Zinenko 72d013dd73 [mlir] OpenMP-to-LLVM: properly set outer alloca insertion point
Previously, the OpenMP to LLVM IR conversion was setting the alloca insertion
point to the same position as the main compuation when converting OpenMP
`parallel` operations. This is problematic if, for example, the `parallel`
operation is placed inside a loop and would keep allocating on stack on each
iteration leading to stack overflow.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D101307
2021-05-10 10:04:52 +02:00
KareemErgawy-TomTom e4dee7e730 [MLIR][SPIRV] Properly (de-)serialize BranchConditionalOp.
Implements proper (de-)serialization logic for BranchConditionalOp when
such ops have true/false target operands.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D101602
2021-05-07 09:00:50 +02:00
Lei Zhang 41bc54cc56 [mlir][spirv] NFC: Replace OwningSPIRVModuleRef with OwningOpRef
Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D102009
2021-05-06 17:17:44 -04:00
Navdeep Kumar 875eb523c1 [MLIR][GPU][NVVM] Add warp synchronous matrix-multiply accumulate ops
Add warp synchronous matrix-multiply accumulate ops in GPU and NVVM
dialect. Add following three ops to GPU dialect :-
  1.) subgroup_mma_load_matrix
  2.) subgroup_mma_store_matrix
  3.) subgroup_mma_compute
Add following three ops to NVVM dialect :-
  1.) wmma.m16n16k16.load.[a,b,c].[f16,f32].row.stride
  2.) wmma.m16n16k16.store.d.[f16,f32].row.stride
  3.) wmma.m16n16k16.mma.row.row.[f16,f32].[f16,f32]

Reviewed By: bondhugula, ftynse, ThomasRaoux

Differential Revision: https://reviews.llvm.org/D95330
2021-05-06 12:06:25 +05:30
Ranjith Kumar H b65472d66d [MLIR] Add and propagate section attribute for LLVM_GlobalOp
Add a section attribute to LLVM_GlobalOp, during module translation attribute value is propagated to llvm

Reviewed By: sgrechanik, ftynse, mehdi_amini

Differential Revision: https://reviews.llvm.org/D100947
2021-04-28 04:15:49 +00:00
clementval c46a88625d [mlir][llvm] Add UnnamedAddr attribute to GlobalOp
This patch add the UnnamedAddr attribute for the GlobalOp in the LLVM
dialect. The attribute is also handled to and from LLVM IR.

This is meant to be used in a follow up patch to lower OpenACC/OpenMP ops to
call to kmp and tgt runtime calls (D100678).

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D100677
2021-04-19 21:45:14 -04:00
Mats Petersson 517c3aee4d [OpenMP IRBuilder, MLIR] Add support for OpenMP do schedule dynamic
The implementation supports static schedule for Fortran do loops. This
implements the dynamic variant of the same concept.

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D97393
2021-04-16 16:09:49 +01:00
Javier Setoain b739bada9d [mlir][ArmSVE] Cleanup dialect registration
ArmSVE dialect is behind the recent changes in how the Vector dialect
interacts with backend vector dialects and the MLIR -> LLVM IR
translation module. This patch cleans up ArmSVE initialization within
Vector and removes the need for an LLVMArmSVE dialect.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D100171
2021-04-16 15:56:51 +02:00
River Riddle 4efb7754e0 [mlir][NFC] Add a using directive for llvm::SetVector
Differential Revision: https://reviews.llvm.org/D100436
2021-04-15 16:09:34 -07:00
Emilio Cota 8508a63b88 [mlir] Rename AVX512 dialect to X86Vector
We will soon be adding non-AVX512 operations to MLIR, such as AVX's rsqrt. In https://reviews.llvm.org/D99818 several possibilities were discussed, namely to (1) add non-AVX512 ops to the AVX512 dialect, (2) add more dialects (e.g. AVX dialect for AVX rsqrt), and (3) expand the scope of the AVX512 to include these SIMD x86 ops, thereby renaming the dialect to something more accurate such as X86Vector.

Consensus was reached on option (3), which this patch implements.

Reviewed By: aartbik, ftynse, nicolasvasilache

Differential Revision: https://reviews.llvm.org/D100119
2021-04-12 19:20:04 +02:00
Mehdi Amini 38b106f681 Improve error message when tring to export to LLVM IR with a dialect missing the interface
Dialects can be translated to LLVM IR when they have the
LLVMTranslationDialectInterface interface registered. In case the
interface isn't explicitly registered, even the LLVM dialect can't be
exported to LLVM IR. This make the error message more explicit on this.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D96729
2021-04-08 23:21:27 +00:00
Jean Perier ffa455d4d4 [mlir] Translate global initializers after creating all LLVM IR globals
In case an operation in a global initializer region refers to another
global variable defined afterwards in the module of itself, translation
to LLVM IR was currently crashing because it could not find the LLVM IR global
when going through the initializer block.

To solve this problem, split global conversion to LLVM IR into two passes. A
first pass that creates LLVM IR global variables, and a second one that converts
the initializer, if any, and adds it to the llvm global.

Differential Revision: https://reviews.llvm.org/D99246
2021-03-25 09:53:58 +01:00
Mehdi Amini 973ddb7d6e Define a `NoTerminator` traits that allows operations with a single block region to not provide a terminator
In particular for Graph Regions, the terminator needs is just a
historical artifact of the generalization of MLIR from CFG region.
Operations like Module don't need a terminator, and before Module
migrated to be an operation with region there wasn't any needed.

To validate the feature, the ModuleOp is migrated to use this trait and
the ModuleTerminator operation is deleted.

This patch is likely to break clients, if you're in this case:

- you may iterate on a ModuleOp with `getBody()->without_terminator()`,
  the solution is simple: just remove the ->without_terminator!
- you created a builder with `Builder::atBlockTerminator(module_body)`,
  just use `Builder::atBlockEnd(module_body)` instead.
- you were handling ModuleTerminator: it isn't needed anymore.
- for generic code, a `Block::mayNotHaveTerminator()` may be used.

Differential Revision: https://reviews.llvm.org/D98468
2021-03-25 03:59:03 +00:00
Vladislav Vinogradov fee9054232 [mlir][ODS] Support specialized Attribute class for Enums
Add a feature to `EnumAttr` definition to generate
specialized Attribute class for the particular enumeration.

This class will inherit `StringAttr` or `IntegerAttr` and
will override `classof` and `getValue` methods.

With this class the enumeration predicate can be checked with simple
RTTI calls (`isa`, `dyn_cast`) and it will return the typed enumeration
directly instead of raw string/integer.

Based on the following discussion:
https://llvm.discourse.group/t/rfc-add-enum-attribute-decorator-class/2252

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D97836
2021-03-17 16:44:24 +03:00
Aart Bik 6ad7b97e20 [mlir][amx] Add Intel AMX dialect (architectural-specific vector dialect)
The Intel Advanced Matrix Extensions (AMX) provides a tile matrix
multiply unit (TMUL), a tile control register (TILECFG), and eight
tile registers TMM0 through TMM7 (TILEDATA). This new MLIR dialect
provides a bridge between MLIR concepts like vectors and memrefs
and the lower level LLVM IR details of AMX.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D98470
2021-03-15 17:59:05 -07:00
Arpith C. Jacob b4a516cc43 [mlir] Add LLVM loop codegen options to control software pipelining
Support specifying the II and disabling pipelining.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D98420
2021-03-11 16:46:44 +01:00
Alex Zinenko 78f3fb4f46 [mlir] Update comments in ArmNeon dialect. NFC
These were not updated when squashing LLVMArmNeon and ArmNeon dialects.
2021-03-10 13:35:57 +01:00
Alex Zinenko a776942ba1 [mlir] squash LLVM_AVX512 dialect into AVX512
The dialect separation was introduced to demarkate ops operating in different
type systems. This is no longer the case after the LLVM dialect has migrated to
using built-in vector types, so the original reason for separation is no longer
valid. Squash the two dialects into one.

The code size decrease isn't quite large: the ops originally in LLVM_AVX512 are
preserved because they match LLVM IR intrinsics specialized for vector element
bitwidth. However, it is still conceptually beneficial to have only one
dialect. I originally considered to use Tablegen multiclasses to define both
the type-polymorphic op and its two intrinsic-related instantiations, but
decided against it given both the complexity of the required Tablegen input and
its dissimilarity with the rest of ODS-defined ops, both potentially resulting
in very poor maintainability.

Depends On D98327

Reviewed By: nicolasvasilache, springerm

Differential Revision: https://reviews.llvm.org/D98328
2021-03-10 13:07:26 +01:00
Mehdi Amini 8205c1a90a Rework LLVM Dialect LoopOptions attribute
Instead of storing an array of LoopOpt attributes, which were just
wrapping std::pair<enum, int> anyway, we can have an attribute storing
a sorted ArrayRef<std::pair<enum, int>> as a single unit. This improves
here the textual format and the general API. Note that we're limiting
the options to fit into an int64_t by design, but this isn't a new
constraint.

Building the LoopOptions attribute is likely worth a specific builder
for efficient reason, that'll be the subject of a future patch.

Differential Revision: https://reviews.llvm.org/D98105
2021-03-09 19:43:45 +00:00
Alex Zinenko 8184247f0b [mlir] move LLVM target import header and tests
Move Target/LLVMIR.h to target/LLVMIR/Import.h to better reflect the purpose of
this file. Also move all LLVM IR target tests under the LLVMIR directory.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D98178
2021-03-09 09:22:14 +01:00
River Riddle a4bb667d83 [mlir][IR][NFC] Define the Location classes in ODS instead of C++
This also removes the need for LocationDetail.h.

Differential Revision: https://reviews.llvm.org/D98092
2021-03-08 14:32:40 -08:00
KareemErgawy-TomTom 3fb384d50e [MLIR][SPIRV] Rename `spv.selection` to `spv.mlir.selection`.
To unify the naming scheme across all ops in the SPIR-V dialect, we are
moving from spv.camelCase to spv.CamelCase everywhere. For ops that
don't have a SPIR-V spec counterpart, we use spv.mlir.snake_case.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D98014
2021-03-06 16:05:31 +01:00
Alex Zinenko 6410ee0d09 [mlir] Squash LLVM_ArmNeon dialect into ArmNeon
The two dialects are largely redundant. The former was introduced as a mirror
of the latter operating on LLVM dialect types. This is no longer necessary
since the LLVM dialect operates on built-in types. Combine the two dialects.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D98060
2021-03-05 23:33:32 +01:00
KareemErgawy-TomTom 29812a6195 [MLIR][SPIRV] Rename `spv.loop` to `spv.mlir.loop`.
To unify the naming scheme across all ops in the SPIR-V dialect,
we are moving from spv.camelCase to spv.CamelCase everywhere.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D97918
2021-03-05 15:44:30 -05:00
KareemErgawy-TomTom c74eb466d2 [MLIR][SPIRV] Rename `spv.globalVariable` to `spv.GlobalVariable`.
To unify the naming scheme across all ops in the SPIR-V dialect, we are
moving from spv.camelCase to spv.CamelCase everywhere.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D97919
2021-03-04 16:24:59 -05:00
KareemErgawy-TomTom 5abdca47b3 [MLIR][SPIRV] Rename `spv.constant` to `spv.Constant`.
To unify the naming scheme across all ops in the SPIR-V dialect, we are
moving from `spv.camelCase` to `spv.CamelCase` everywhere.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D97917
2021-03-04 16:15:56 -05:00
Arpith C. Jacob 4e393350c5 [mlir] Add an AccessGroup attribute to load/store LLVM dialect ops and generate the access_group LLVM metadata.
This also includes LLVM dialect ops created from intrinsics.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D97944
2021-03-04 18:17:23 +01:00
Alex Zinenko 19db802e7b [mlir] make implementations of translation to LLVM IR interfaces private
There is no need for the interface implementations to be exposed, opaque
registration functions are sufficient for all users, similarly to passes.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D97852
2021-03-04 09:16:32 +01:00
Arpith C. Jacob 4a2930f495 [mlir] Add loop codegen options to some LLVM dialect ops.
Add a Loop Option attribute and generate llvm metadata attached to
branch instructions to control code generation.

Reviewed By: ftynse, mehdi_amini

Differential Revision: https://reviews.llvm.org/D96820
2021-03-04 09:01:57 +01:00
River Riddle e6260ad043 [mlir] Simplify various pieces of code now that Identifier has access to the Context/Dialect
This also exposed a bug in Dialect loading where it was not correctly identifying identifiers that had the dialect namespace as a prefix.

Differential Revision: https://reviews.llvm.org/D97431
2021-02-26 18:00:05 -08:00
Alex Zinenko 12875ed976 [mlir] generate enum translation functions with unused attribute
The functions translating enums to LLVM IR are generated in a single
file included in many places, not all of which use all translations.
Generate functions with "unused" attribute to silence compiler warnings.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D96880
2021-02-18 09:44:40 +01:00
Alex Zinenko 4a3473ff3b [mlir] silence unused-function warnings in table-generated code
Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D96695
2021-02-17 19:28:31 +01:00
Alex Zinenko ce8f10d6cb [mlir] Simplify ModuleTranslation for LLVM IR
A series of preceding patches changed the mechanism for translating MLIR to
LLVM IR to use dialect interface with delayed registration. It is no longer
necessary for specific dialects to derive from ModuleTranslation. Remove all
virtual methods from ModuleTranslation and factor out the entry point to be a
free function.

Also perform some cleanups in ModuleTranslation internals.

Depends On D96774

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D96775
2021-02-16 18:42:52 +01:00
Alex Zinenko 9cd47a26d5 [mlir] add verifiers for NVVM and ROCDL kernel attributes
Make sure they can only be attached to LLVM functions as a result of converting
GPU functions to the LLVM Dialect.
2021-02-16 18:06:54 +01:00
Alex Zinenko 176379e0c8 [mlir] Use the interface-based translation for LLVM "intrinsic" dialects
Port the translation of five dialects that define LLVM IR intrinsics
(LLVMAVX512, LLVMArmNeon, LLVMArmSVE, NVVM, ROCDL) to the new dialect
interface-based mechanism. This allows us to remove individual translations
that were created for each of these dialects and just use one common
MLIR-to-LLVM-IR translation that potentially supports all dialects instead,
based on what is registered and including any combination of translatable
dialects. This removal was one of the main goals of the refactoring.

To support the addition of GPU-related metadata, the translation interface is
extended with the `amendOperation` function that allows the interface
implementation to post-process any translated operation with dialect attributes
from the dialect for which the interface is implemented regardless of the
operation's dialect. This is currently applied to "kernel" functions, but can
be used to construct other metadata in dialect-specific ways without
necessarily affecting operations.

Depends On D96591, D96504

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D96592
2021-02-15 14:43:07 +01:00
Alex Zinenko 66900b3eae [mlir] Use dialect interfaces to translate OpenMP dialect to LLVM IR
Migrate the translation of the OpenMP dialect operations to LLVM IR to the new
dialect-based mechanism.

Depends On D96503

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D96504
2021-02-12 18:37:47 +01:00
Alex Zinenko b77bac0572 [mlir] Introduce dialect interfaces for translation to LLVM IR
The existing approach to translation to the LLVM IR relies on a single
translation supporting the base LLVM dialect, extensible through inheritance to
support intrinsic-based dialects also derived from LLVM IR such as NVVM and
AVX512. This approach does not scale well as it requires additional
translations to be created for each new intrinsic-based dialect and does not
allow them to mix in the same module, contrary to the rest of the MLIR
infrastructure. Furthermore, OpenMP translation ingrained itself into the main
translation mechanism.

Start refactoring the translation to LLVM IR to operate using dialect
interfaces. Each dialect that contains ops translatable to LLVM IR can
implement the interface for translating them, and the top-level translation
driver can operate on interfaces without knowing about specific dialects.
Furthermore, the delayed dialect registration mechanism allows one to avoid a
dependency on LLVM IR in the dialect that is translated to it by implementing
the translation as a separate library and only registering it at the client
level.

This change introduces the new mechanism and factors out the translation of the
"main" LLVM dialect. The remaining dialects will follow suit.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D96503
2021-02-12 17:49:44 +01:00
Alex Zinenko 4c4876c314 [mlir] Use target-specific GPU kernel attributes in lowering pipelines
Until now, the GPU translation to NVVM or ROCDL intrinsics relied on the
presence of the generic `gpu.kernel` attribute to attach additional LLVM IR
metadata to the relevant functions. This would be problematic if each dialect
were to handle the conversion of its own options, which is the intended
direction for the translation infrastructure. Introduce `nvvm.kernel` and
`rocdl.kernel` in addition to `gpu.kernel` and base translation on these new
attributes instead.

Reviewed By: herhut

Differential Revision: https://reviews.llvm.org/D96591
2021-02-12 14:09:24 +01:00
Alex Zinenko 0881a4f1bf [mlir] make ModuleTranslation mapping fields private
ModuleTranslation contains multiple fields that keep track of the mappings
between various MLIR and LLVM IR components. The original ModuleTranslation
extension model was based on inheritance, with these fields being protected and
thus accessible in the ModuleTranslation and derived classes. The
inheritance-based model doesn't scale to translation of more than one derived
dialect and will be progressively replaced with a more flexible one based on
dialect interfaces and a translation state that is separate from
ModuleTranslation. This change prepares the replacement by making the mappings
private and providing public methods to access them.

Depends On D96436

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D96437
2021-02-11 14:50:49 +01:00
Alex Zinenko 2996a8d675 [mlir] avoid exposing mutable DialectRegistry from MLIRContext
MLIRContext allows its users to access directly to the DialectRegistry it
contains. While sometimes useful for registering additional dialects on an
already existing context, this breaks the encapsulation by essentially giving
raw accesses to a part of the context's internal state. Remove this mutable
access and instead provide a method to append a given DialectRegistry to the
one already contained in the context. Also provide a shortcut mechanism to
construct a context from an already existing registry, which seems to be a
common use case in the wild. Keep read-only access to the registry contained in
the context in case it needs to be copied or used for constructing another
context.

With this change, DialectRegistry is no longer concerned with loading the
dialects and deciding whether to invoke delayed interface registration. Loading
is concentrated in the MLIRContext, and the functionality of the registry
better reflects its name.

Depends On D96137

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D96331
2021-02-10 12:07:34 +01:00
River Riddle fe7c0d90b2 [mlir][IR] Remove the concept of `OperationProperties`
These properties were useful for a few things before traits had a better integration story, but don't really carry their weight well these days. Most of these properties are already checked via traits in most of the code. It is better to align the system around traits, and improve the performance/cost of traits in general.

Differential Revision: https://reviews.llvm.org/D96088
2021-02-09 12:00:15 -08:00