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
