This CL changes various predicates and rewrite rules to use $-placeholders and
`tgfmt` as the driver for substitution. This will make the predicates and rewrite
rules more consistent regarding their arguments and more readable.
--
PiperOrigin-RevId: 243250739
This CL adds EnumAttr as a general mechanism for modelling enum attributes. Right now
it is using StringAttr under the hood since MLIR does not have native support for enum
attributes.
--
PiperOrigin-RevId: 241334043
Before this CL, the result type of the pattern match results need to be as same
as the first operand type, operand broadcast type or a generic tensor type.
This CL adds a new trait to set the result type by attribute. For example, the
TFL_ConstOp can use this to set the output type to its value attribute.
PiperOrigin-RevId: 240441249
Previously we have multiple mechanisms to specify op definition and match constraints:
TypeConstraint, AttributeConstraint, Type, Attr, mAttr, mAttrAnyOf, mPat. These variants
are not added because there are so many distinct cases we need to model; essentially,
they are all carrying a predicate. It's just an artifact of implementation.
It's quite confusing for users to grasp these variants and choose among them. Instead,
as the OpBase TableGen file, we need to strike to provide an unified mechanism. Each
dialect has the flexibility to define its own aliases if wanted.
This CL removes mAttr, mAttrAnyOf, mPat. A new base class, Constraint, is added. Now
TypeConstraint and AttrConstraint derive from Constraint. Type and Attr further derive
from TypeConstraint and AttrConstraint, respectively.
Comments are revised and examples are added to make it clear how to use constraints.
PiperOrigin-RevId: 240125076
The only reason in starting with a fixedpoint add is that it is the absolute simplest variant and illustrates the level of abstraction I'm aiming for.
The overall flow would be:
1. Determine quantization parameters (out of scope of this cl).
2. Source dialect rules to lower supported math ops to the quantization dialect (out of scope of this cl).
3. Quantization passes: [-quant-convert-const, -quant-lower-uniform-real-math, -quant-lower-unsupported-to-float] (the last one not implemented yet)
4. Target specific lowering of the integral arithmetic ops (roughly at the level of gemmlowp) to more fundamental operations (i.e. calls to gemmlowp, simd instructions, DSP instructions, etc).
How I'm doing this should facilitate implementation of just about any kind of backend except TFLite, which has a very course, adhoc surface area for its quantized kernels. Options there include (I'm not taking an opinion on this - just trying to provide options):
a) Not using any of this: just match q/dbarrier + tf math ops to the supported TFLite quantized op set.
b) Implement the more fundamental integer math ops on TFLite and convert to those instead of the current op set.
Note that I've hand-waved over the process of choosing appropriate quantization parameters. Getting to that next. As you can see, different implementations will likely have different magic combinations of specific math support, and we will need the target system that has been discussed for some of the esoteric cases (i.e. many DSPs only support POT fixedpoint).
Two unrelated changes to the overall goal of this CL and can be broken out of desired:
- Adding optional attribute support to TabelGen
- Allowing TableGen native rewrite hooks to return nullptr, signalling that no rewrite has been done.
PiperOrigin-RevId: 235267229
This CL added a tblgen::DagLeaf wrapper class with several helper methods for handling
DAG arguments. It helps to refactor the rewriter generation logic to be more higher
level.
This CL also added a tblgen::ConstantAttr wrapper class for constant attributes.
PiperOrigin-RevId: 232050683
* Matching an attribute and specifying a attribute constraint is the same thing executionally, so represent it such.
* Extract AttrConstraint helper to match TypeConstraint and use that where mAttr was previously used in RewriterGen.
PiperOrigin-RevId: 231213580
Add default values to attributes, to allow attribute being left unspecified. The attr getter will always return an attribute so callers need not check for it, if the attribute is not set then the default will be returned (at present the default will be constructed upon query but this will be changed).
Add op definition for tf.AvgPool in ops.td, rewrite matcher using pattern using attribute matching & transforms. Adding some helper functions to make it simpler.
Handle attributes with dialect prefix and map them to getter without dialect prefix.
Note: VerifyAvgPoolOp could probably be autogenerated by know given the predicate specification on attributes, but deferring that to a follow up.
PiperOrigin-RevId: 230364857
Change MinMaxAttr to match hasValidMinMaxAttribute behavior. Post rewriting the other users of that function it could be removed too. The currently generated error message is:
error: 'tfl.fake_quant' op attribute 'minmax' failed to satisfy constraint of MinMaxAttr
PiperOrigin-RevId: 229775631
Start simple with single predicate match & transform rules for attributes.
* Its unclear whether modelling Attr predicates will be needed so start with allowing matching attributes with a single predicate.
* The input and output attr type often differs and so add ability to specify a transform between the input and output format.
PiperOrigin-RevId: 229580879
In TableGen definitions, the "Type" class has been used for types of things
that can be stored in Attributes, but not necessarily present in the MLIR type
system. As a consequence, records like "String" or "DerviedAttrBody" were of
class "Type", which can be confusing. Furthermore, the "builderCall" field of
the "Type" class serves only for attribute construction. Some TableGen "Type"
subclasses that correspond to MLIR kinds of types do not have a canonical way
of construction only from the data available in TableGen, e.g. MemRefType would
require the list of affine maps. This leads to a conclusion that the entities
that describe types of objects appearing in Attributes should be independent of
"Type": they have some properties "Type"s don't and vice versa.
Do not parameterize Tablegen "Attr" class by an instance of "Type". Instead,
provide a "constBuilderCall" field that can be used to build an attribute from
a constant value stored in TableGen instead of indirectly going through
Attribute.Type.builderCall. Some attributes still don't have a
"constBuilderCall" because they used to depend on types without a
"builderCall".
Drop definitions of class "Type" that don't correspond to MLIR Types. Provide
infrastructure to define type-dependent attributes and string-backed attributes
for convenience.
PiperOrigin-RevId: 229570087
This CL added a tblgen::Attribute class to wrap around raw TableGen
Record getValue*() calls on Attr defs, which will provide a nicer
API for handling TableGen Record.
PiperOrigin-RevId: 228581107
Lei Zhang