Store the last token parsed in the parser state so that the range parsed
can utilize its end rather than the start of the token after parsed.
This results in a tighter range (especially true in the case of
comments, see
```mlir
|%c4 = arith.constant 4 : index
// Foo
|
```
vs
```mlir
|%c4 = arith.constant 4 : index|
```
).
Discovered while working on a little textual post processing tool.
Printing cyclic attributes and types currently has no first-class
support within the AsmPrinter and AsmParser. The workaround for this
issue used in all mutable attributes and types upstream has been to
create a `thread_local static SetVector` keeping track of currently
parsed and printed attributes.
This solution is not ideal readability wise due to the use of globals
and keeping track of state. Worst of all, this pattern had to be
reimplemented for every mutable attribute and type.
This patch therefore adds support for this pattern in `AsmPrinter` and
`AsmParser` replacing the use of this pattern. By calling
`tryStartCyclingPrint/Parse`, the mutable attribute or type are
registered in an internal stack. All subsequent calls to the function
with the same attribute or type will lead to returning failure. This way
the nesting can be detected and a short form printed or parsed instead.
Through the resetter returned by the call, the cyclic printing or
parsing region automatically ends on return.
A distinct attribute associates a referenced attribute with a unique
identifier. Every call to its create function allocates a new
distinct attribute instance. The address of the attribute instance
temporarily serves as its unique identifier. Similar to the names
of SSA values, the final unique identifiers are generated during
pretty printing.
Examples:
#distinct = distinct[0]<42.0 : f32>
#distinct1 = distinct[1]<42.0 : f32>
#distinct2 = distinct[2]<array<i32: 10, 42>>
This mechanism is meant to generate attributes with a unique
identifier, which can be used to mark groups of operations
that share a common properties such as if they are aliasing.
The design of the distinct attribute ensures minimal memory
footprint per distinct attribute since it only contains a reference
to another attribute. All distinct attributes are stored outside of
the storage uniquer in a thread local store that is part of the
context. It uses one bump pointer allocator per thread to ensure
distinct attributes can be created in-parallel.
Reviewed By: rriddle, Dinistro, zero9178
Differential Revision: https://reviews.llvm.org/D153360
The current Parser library is solely focused on providing API for
the textual MLIR format, but MLIR will soon also provide a binary
format. This commit renames the current Parser library to AsmParser to
better correspond to what the library is actually intended for. A new
Parser library is added which will act as a unified parser interface
between both text and binary formats. Most parser clients are
unaffected, given that the unified interface is essentially the same as
the current interface. Only clients that rely on utilizing the
AsmParserState, or those that want to parse Attributes/Types need to be
updated to point to the AsmParser library.
Differential Revision: https://reviews.llvm.org/D129605
