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Version 0.5 of the new "TableGen Backend Developer's Guide."

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MLIR documentation updated for new TableGen documentation files.
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llvm/docs/TableGen/BackEnds.rst
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@ -8,22 +8,30 @@ TableGen BackEnds
Introduction
============
TableGen backends are at the core of TableGen's functionality. The source files
provide the semantics to a generated (in memory) structure, but it's up to the
backend to print this out in a way that is meaningful to the user (normally a
C program including a file or a textual list of warnings, options and error
messages).
TableGen backends are at the core of TableGen's functionality. The source
files provide the classes and records that are parsed and end up as a
collection of record instances, but it's up to the backend to interpret and
print the records in a way that is meaningful to the user (normally a C++
include file or a textual list of warnings, options, and error messages).
TableGen is used by both LLVM and Clang with very different goals. LLVM uses it
as a way to automate the generation of massive amounts of information regarding
instructions, schedules, cores and architecture features. Some backends generate
output that is consumed by more than one source file, so they need to be created
in a way that is easy to use pre-processor tricks. Some backends can also print
C code structures, so that they can be directly included as-is.
TableGen is used by both LLVM, Clang, and MLIR with very different goals.
LLVM uses it as a way to automate the generation of massive amounts of
information regarding instructions, schedules, cores, and architecture
features. Some backends generate output that is consumed by more than one
source file, so they need to be created in a way that makes it is easy for
preprocessor tricks to be used. Some backends can also print C++ code
structures, so that they can be directly included as-is.
Clang, on the other hand, uses it mainly for diagnostic messages (errors,
warnings, tips) and attributes, so more on the textual end of the scale.
MLIR uses TableGen to define operations, operation dialects, and operation
traits.
See the :doc:`TableGen Programmer's Reference <./ProgRef>` for an in-depth
description of TableGen, and :doc:`TableGen Backend Developer's Guide
<./BackGuide>` for a guide to writing a new backend.
LLVM BackEnds
=============
@ -928,17 +936,3 @@ in ``-print-records``.
These values are not expected to be needed by backends. The standard
``printable`` field can be used to extract a representation of them
in TableGen source syntax if necessary.
How to write a back-end
=======================
TODO.
Until we get a step-by-step HowTo for writing TableGen backends, you can at
least grab the boilerplate (build system, new files, etc.) from Clang's
r173931.
TODO: How they work, how to write one. This section should not contain details
about any particular backend, except maybe ``-print-enums`` as an example. This
should highlight the APIs in ``TableGen/Record.h``.

787
llvm/docs/TableGen/BackGuide.rst Normal file
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@ -0,0 +1,787 @@
===================================
TableGen Backend Developer's Guide
===================================
.. sectnum::
.. contents::
:local:
Introduction
============
The purpose of TableGen is to generate complex output files based on
information from source files that are significantly easier to code than the
output files would be, and also easier to maintain and modify over time. The
information is coded in a declarative style involving classes and records,
which are then processed by TableGen. The internalized records are passed on
to various backends, which extract information from a subset of the records
and generate an output file. These output files are typically ``.inc`` files
for C++, but may be any type of file that the backend developer needs.
This document is a guide to writing a backend for TableGen. It is not a
complete reference manual, but rather a guide to using the facilities
provided by TableGen for the backends. For a complete reference to the
various data structures and functions involved, see the Doxygen
documentation.
This document assumes that you have read the :doc:`TableGen Programmer's
Reference <./ProgRef>`, which provides a detailed reference for coding
TableGen source files. This document and the relevant Doxygen pages will be
improved over time.
Data Structures
===============
The following sections describe the data structures that contain the classes
and records that are collected from the TableGen source files by the
TableGen parser. Note that the term *class* refers to an abstract record
class, while the term *record* refers to a concrete record.
Unless otherwise noted, functions associated with classes are instance
functions.
``RecordKeeper``
----------------
An instance of the ``RecordKeeper`` class acts as the container for all the
classes and records parsed and collected by TableGen. The ``RecordKeeper``
instance is passed to the backend when it is invoked by TableGen. This class
is usually abbreviated ``RK``.
There are two maps in the recordkeeper, one for classes and one for records
(the latter often referred to as *defs*). Each map maps the class or record
name to an instance of the ``Record`` class (see `Record`_), which contains
all the information about that class or record. The ``RecordKeeper`` class
defines a type that must be used to declare these maps if they are requested
directly.
.. code-block:: text
using RecordMap = std::map<std::string, std::unique_ptr<Record>,
std::less<>>;
In addition to the two maps, the ``RecordKeeper`` instance contains:
* A map that maps the names of global variables to their values.
Global variables are defined in TableGen files with outer
``defvar`` statements.
* A counter for naming anonymous records.
The ``RecordKeeper`` class provides a few useful functions.
* Functions to get the complete class and record maps.
* Functions to get a subset of the records based on their parent classes.
* Functions to get individual classes, records, and globals.
A ``RecordKeeper`` instance can be printed to an output stream with the ``<<``
operator.
``Record``
----------
Each class or record built by TableGen is represented by an instance of
the ``Record`` class. The ``RecordKeeper`` instance contains one map for the
classes and one for the records. The primary data members of a record are
the record name, the vector of field names and their values, and the vector of
superclasses of the record.
The record name is stored as a pointer to an ``Init`` (see `Init`_), which
is a class whose instances hold TableGen values (sometimes refered to as
*initializers*). The field names and values are stored in a vector of
``RecordVal`` instances (see `RecordVal`_), each of which contains both the
field name and its value. The superclass vector contains a sequence of
pairs, with each pair including the superclass record and its source
file location.
In addition to those members, a ``Record`` instance contains:
* A vector of source file locations that includes the record definition
itself, plus the locations of any multiclasses involved in its definition.
* For a class record, a vector of the class's template arguments.
* An instance of ``DefInit`` (see `DefInit`_) corresponding to this record.
* A unique record ID.
* A boolean that specifies whether this is a class definition.
* A boolean that specifies whether this is an anonymous record.
The ``Record`` class provides many useful functions.
* Functions to get the record name, fields, source file locations,
template arguments, and unique ID.
* Functions to get all the record's superclasses or just its direct
superclasses.
* Functions to get a particular field value by specifying its name in various
forms, and returning its value in various forms
(see `Getting Record Names and Fields`_).
* Boolean functions to check the various attributes of the record.
A ``Record`` instance can be printed to an output stream with the ``<<``
operator.
``RecordVal``
-------------
Each field of a record is stored in an instance of the ``RecordVal`` class.
The ``Record`` instance includes a vector of these value instances. A
``RecordVal`` instance contains the name of the field, stored in an ``Init``
instance. It also contains the value of the field, likewise stored in an
``Init``. (A better name for this class might be ``RecordField``.)
In addition to those primary members, the ``RecordVal`` has other data members.
* The source file location of the field definition.
* The type of the field, stored as an instance
of the ``RecTy`` class (see `RecTy`_).
The ``RecordVal`` class provides some useful functions.
* Functions to get the name of the field in various forms.
* A function to get the type of the field.
* A function to get the value of the field.
* A function to get the source file location.
Note that field values are more easily obtained directly from the ``Record``
instance (see `Record`_).
A ``RecordVal`` instance can be printed to an output stream with the ``<<``
operator.
``RecTy``
---------
The ``RecTy`` class is used to represent the types of field values. It is
the base class for a series of subclasses, one for each of the
available field types. The ``RecTy`` class has one data member that is an
enumerated type specifying the specific type of field value. (A better
name for this class might be ``FieldTy``.)
The ``RecTy`` class provides a few useful functions.
* A virtual function to get the type name as a string.
* A virtual function to check whether all the values of this type can
be converted to another given type.
* A virtual function to check whether this type is a subtype of
another given type.
* A function to get the corresponding ``list``
type for lists with elements of this type. For example, the function
returns the ``list<int>`` type when called with the ``int`` type.
The subclasses that inherit from ``RecTy`` are
``BitRecTy``,
``BitsRecTy``,
``CodeRecTy``,
``DagRecTy``,
``IntRecTy``,
``ListRecTy``,
``RecordRecTy``, and
``StringRecTy``.
Some of these classes have additional members that
are described in the following subsections.
*All* of the classes derived from ``RecTy`` provide the ``get()`` function.
It returns an instance of ``Recty`` corresponding to the derived class.
Some of the ``get()`` functions require an argument to
specify which particular variant of the type is desired. These arguments are
described in the following subsections.
A ``RecTy`` instance can be printed to an output stream with the ``<<``
operator.
.. warning::
It is not specified whether there is a single ``RecTy`` instance of a
particular type or multiple instances.
``BitsRecTy``
~~~~~~~~~~~~~
This class includes a data member with the size of the ``bits`` value and a
function to get that size.
The ``get()`` function takes the length of the sequence, *n*, and returns the
``BitsRecTy`` type corresponding to ``bits<``\ *n*\ ``>``.
``ListRecTy``
~~~~~~~~~~~~~
This class includes a data member that specifies the type of the list's
elements and a function to get that type.
The ``get()`` function takes the ``RecTy`` *type* of the list members and
returns the ``ListRecTy`` type corresponding to ``list<``\ *type*\ ``>``.
``RecordRecTy``
~~~~~~~~~~~~~~~
This class includes data members that contain the list of parent classes of
this record. It also provides a function to obtain the array of classes and
two functions to get the iterator ``begin()`` and ``end()`` values. The
class defines a type for the return values of the latter two functions.
.. code-block:: text
using const_record_iterator = Record * const *;
The ``get()`` function takes an ``ArrayRef`` of pointers to the ``Record``
instances of the *direct* superclasses of the record and returns the ``RecordRecTy``
corresponding to the record inheriting from those superclasses.
``Init``
--------
The ``Init`` class is used to represent TableGen values. The name derives
from *initialization value*. This class should not be confused with the
``RecordVal`` class, which represents record fields, both their names and
values. The ``Init`` class is the base class for a series of
subclasses, one for each of the available value types.
The primary data member
of ``Init`` is an enumerated type that represents the specific type of the
value.
The ``Init`` class provides a few useful functions.
* A boolean virtual function to determine whether a value is completely
specified; that is, has no uninitialized subvalues.
* Virtual functions to get the value as a string.
* Virtual functions to cast the value to other types, implement the bit
range feature of TableGen, and implement the list slice feature.
The subclasses that inherit directly from ``Init`` are
``UnsetInit`` and ``TypedInit``.
An ``Init`` instance can be printed to an output stream with the ``<<``
operator.
.. warning::
It is not specified whether two separate initialization values with
the same underlying type and value (e.g., two strings with the value
"Hello") are represented by two ``Init``\ s or share the same ``Init``.
``UnsetInit``
~~~~~~~~~~~~~
This class, a subclass of ``Init``, represents the unset (uninitialized)
value. The static function ``get()`` can be used to obtain the singleton
``Init`` of this type.
``TypedInit``
~~~~~~~~~~~~~
This class, a subclass of ``Init``, acts as the parent class of the classes
that represent specific value types (except for the unset value). These
classes include ``BitInit``, ``BitsInit``, ``CodeInit``, ``DagInit``,
``DefInit``, ``IntInit``, ``ListInit``, and ``StringInit``. (There are
additional derived types used by the TableGen parser.)
This class includes a data member that specifies the ``RecTy`` type of the
value. It provides a function to get that ``RecTy`` type.
``BitInit``
~~~~~~~~~~~
The ``BitInit`` class is a subclass of ``TypedInit``. Its instances
represent the possible values of a bit: 0 or 1. It includes a data member
that contains the bit.
*All* of the classes derived from ``TypedInit`` provide the following functions.
* A static function named ``get()`` that returns an ``Init`` representing
the specified value(s). In the case of ``BitInit``, ``get(true)`` returns
an instance of ``BitInit`` representing true, while ``get(false)`` returns
an instance
representing false. As noted above, it is not specified whether there
is exactly one or more than one ``BitInit`` representing true (or false).
* A function named ``GetValue()`` that returns the value of the instance
in a more direct form, in this case as a ``bool``.
``BitsInit``
~~~~~~~~~~~~
The ``BitsInit`` class is a subclass of ``TypedInit``. Its instances
represent sequences of bits, from high-order to low-order. It includes a
data member with the length of the sequence and a vector of pointers to
``Init`` instances, one per bit.
The class provides the usual ``get()`` function. It does not provide the
``getValue()`` function.
The class provides the following additional functions.
* A function to get the number of bits in the sequence.
* A function that gets a bit specified by an integer index.
``CodeInit``
~~~~~~~~~~~~
The ``CodeInit`` class is a subclass of ``TypedInit``. Its instances
represent arbitrary-length strings produced from ``code`` literals in the
TableGen files. It includes a data member that contains a ``StringRef`` of
the value. It also includes a data member specifying the source code
location of the code stirng.
The class provides the usual ``get()`` and ``getValue()`` functions. The
latter function returns the ``StringRef``.
The ``getLoc()`` function returns the source code location.
``DagInit``
~~~~~~~~~~~
The ``DagInit`` class is a subclass of ``TypedInit``. Its instances
represent the possible direct acyclic graphs (``dag``).
The class includes a pointer to an ``Init`` for the DAG operator and a
pointer to a ``StringInit`` for the operator name. It includes the count of
DAG operands and the count of operand names. Finally, it includes a vector of
pointers to ``Init`` instances for the operands and another to
``StringInit`` instances for the operand names.
(The DAG operands are also referred to as *arguments*.)
The class provides two forms of the usual ``get()`` function. It does not
provide the usual ``getValue()`` function.
The class provides many additional functions:
* Functions to get the operator in various forms and to get the
operator name in various forms.
* Functions to determine whether there are any operands and to get the
number of operands.
* Functions to the get the operands, both individually and together.
* Functions to determine whether there are any names and to
get the number of names
* Functions to the get the names, both individually and together.
* Functions to get the operand iterator ``begin()`` and ``end()`` values.
* Functions to get the name iterator ``begin()`` and ``end()`` values.
The class defines two types for the return values of the operand and name
iterators.
.. code-block:: text
using const_arg_iterator = SmallVectorImpl<Init*>::const_iterator;
using const_name_iterator = SmallVectorImpl<StringInit*>::const_iterator;
``DefInit``
~~~~~~~~~~~
The ``DefInit`` class is a subclass of ``TypedInit``. Its instances
represent the records that were collected by TableGen. It includes a data
member that is a pointer to the record's ``Record`` instance.
The class provides the usual ``get()`` function. It does not provide
``getValue()``. Instead, it provides ``getDef()``, which returns the
``Record`` instance.
``IntInit``
~~~~~~~~~~~
The ``IntInit`` class is a subclass of ``TypedInit``. Its instances
represent the possible values of a 64-bit integer. It includes a data member
that contains the integer.
The class provides the usual ``get()`` and ``getValue()`` functions. The
latter function returns the integer as an ``int64_t``.
The class also provides a function, ``getBit()``, to obtain a specified bit
of the integer value.
``ListInit``
~~~~~~~~~~~~
The ``ListInit`` class is a subclass of ``TypedInit``. Its instances
represent lists of elements of some type. It includes a data member with the
length of the list and a vector of pointers to ``Init`` instances, one per
element.
The class provides the usual ``get()`` and ``getValues()`` functions. The
latter function returns an ``ArrayRef`` of the vector of pointers to ``Init``
instances.
The class provides these additional functions.
* A function to get the element type.
* Functions to get the length of the vector and to determine whether
it is empty.
* Functions to get an element specified by an integer index and return
it in various forms.
* Functions to get the iterator ``begin()`` and ``end()`` values. The
class defines a type for the return type of these two functions.
.. code-block:: text
using const_iterator = Init *const *;
``StringInit``
~~~~~~~~~~~~~~
The ``StringInit`` class is a subclass of ``TypedInit``. Its instances
represent arbitrary-length strings. It includes a data member
that contains a ``StringRef`` of the value.
The class provides the usual ``get()`` and ``getValue()`` functions. The
latter function returns the ``StringRef``.
Creating a New Backend
======================
The following steps are required to create a new backend for TableGen.
#. Invent a name for your backend C++ file, say ``GenAddressModes``.
#. Write the new backend, using the file ``TableGenBackendSkeleton.cpp``
as a starting point.
#. Determine which instance of TableGen requires the new backend. There is
one instance for Clang and another for LLVM. Or you may be building
your own instance.
#. Modify the selected ``tablegen.cpp`` to include your new backend.
a. Add the name to the enumerated type ``ActionType``.
#. Add a keyword to the ``ActionType`` command option using the
``clEnumValN()`` function.
#. Add a case to the ``switch`` statement in the *xxx*\ ``TableGenMain()``
function. It should invoke the "main function" of your backend, which
in this case, according to convention, is named ``EmitAddressModes``.
5. Add a declaration of your "main function" to the corresponding
``TableGenBackends.h`` header file.
#. Add your backend C++ file to the appropriate ``CMakeLists.txt`` file so
that it will be built.
#. Add your C++ file to the system.
The Backend Skeleton
====================
The file ``TableGenBackendSkeleton.cpp`` provides a skeleton C++ translation
unit for writing a new TableGen backend. Here are a few notes on the file.
* The list of includes is the minimal list required by most backends.
* As with all LLVM C++ files, it has a ``using namespace llvm;`` statement.
It also has an anonymous namespace that contains all the file-specific
data structure definitions, along with the class embodying the emitter
data members and functions. Continuing with the ``GenAddressModes`` example,
this class is named ``AddressModesEmitter``.
* The constructor for the emitter class accepts a ``RecordKeeper`` reference,
typically named ``RK``. The ``RecordKeeper`` reference is saved in a data
member so that records can be obtained from it. This data member is usually
named ``Records``.
* One function is named ``run``. It is invoked by the backend's "main
function" to collect records and emit the output file. It accepts an instance
of the ``raw_ostream`` class, typically named ``OS``. The output file is
emitted by writing to this stream.
* The ``run`` function should use the ``emitSourceFileHeader`` helper function
to include a standard header in the emitted file.
* The only function in the ``llvm`` namespace is the backend "main function."
In this example, it is named ``EmitAddressModes``. It creates an instance
of the ``AddressModesEmitter`` class, passing the ``RecordKeeper``
instance, then invokes the ``run`` function, passing the ``raw_ostream``
instance.
All the examples in the remainder of this document will assume the naming
conventions used in the skeleton file.
Getting Classes
===============
The ``RecordKeeper`` class provides two functions for getting the
``Record`` instances for classes defined in the TableGen files.
* ``getClasses()`` returns a ``RecordMap`` reference for all the classes.
* ``getClass(``\ *name*\ ``)`` returns a ``Record`` reference for the named
class.
If you need to iterate over all the class records:
.. code-block:: text
for (auto ClassPair : Records.getClasses()) {
Record *ClassRec = ClassPair.second.get();
...
}
``ClassPair.second`` gets the class's ``unique_ptr``, then ``.get()`` gets the
class ``Record`` itself.
Getting Records
===============
The ``RecordKeeper`` class provides four functions for getting the
``Record`` instances for concrete records defined in the TableGen files.
* ``getDefs()`` returns a ``RecordMap`` reference for all the concrete
records.
* ``getDef(``\ *name*\ ``)`` return a ``Record`` reference for the named
concrete record.
* ``getAllDerivedDefinitions(``\ *classname*\ ``)`` returns a vector of
``Record`` references for the concrete records that derive from the
given class.
* ``getAllDerivedDefinitionsTwo(``\ *classname1*\ ``,`` *classname2*\ ``)`` returns
a vector of ``Record`` references for the concrete records that derive from
*both* of the given classes. [function to come]
This statement obtains all the records that derive from the ``Attribute``
class and iterates over them.
.. code-block:: text
auto AttrRecords = Records.getAllDerivedDefinitions("Attribute");
for (Record *AttrRec : AttrRecords) {
...
}
Getting Record Names and Fields
===============================
As described above (see `Record`_), there are multiple functions that
return the name of a record. One particularly useful one is
``getNameInitAsString()``, which returns the name as a ``std::string``.
There are also multiple functions that return the fields of a record. To
obtain and iterate over all the fields:
.. code-block:: text
for (const RecordVal &Field : SomeRec->getValues()) {
...
}
You will recall that ``RecordVal`` is the class whose instances contain
information about the fields in records.
The ``getValue()`` function returns the ``RecordVal`` instance for a field
specified by name. There are multiple overloaded functions, some taking a
``StringRef`` and others taking a ``const Init *``. Some functions return a
``RecordVal *`` and others return a ``const RecordVal *``. If the field does
not exist, a fatal error message is printed.
More often than not, you are interested in the value of the field, not all
the information in the ``RecordVal``. There is a large set of functions that
take a field name in some form and return its value. One function,
``getValueInit``, returns the value as an ``Init *``. Another function,
``isValueUnset``, returns a boolean specifying whether the value is unset
(uninitialized).
Most of the functions return the value in some more useful form. For
example:
.. code-block:: text
std::vector<int64_t> RegCosts =
SomeRec->getValueAsListOfInts("RegCosts");
The field ``RegCosts`` is assumed to be a list of integers. That list is
returned as a ``std::vector`` of 64-bit integers. If the field is not a list
of integers, a fatal error message is printed.
Here is a function that returns a field value as a ``Record``, but returns
null if the field does not exist.
.. code-block:: text
if (Record *BaseRec = SomeRec->getValueAsOptionalDef(BaseFieldName)) {
...
}
The field is assumed to have another record as its value. That record is returned
as a pointer to a ``Record``. If the field does not exist or is unset, the
functions returns null.
Getting Record Superclasses
===========================
The ``Record`` class provides a function to obtain the superclasses of a
record. It is named ``getSuperClasses`` and returns an ``ArrayRef`` of an
array of ``std::pair`` pairs. The superclasses are in post-order: the order
in which the superclasses were visited while copying their fields into the
record. Each pair consists of a pointer to the ``Record`` instance for a
superclass record and an instance of the ``SMRange`` class. The range
indicates the source file locations of the beginning and end of the class
definition.
This example obtains the superclasses of the ``Prototype`` record and then
iterates over the pairs in the returned array.
.. code-block:: text
ArrayRef<std::pair<Record *, SMRange>>
Superclasses = Prototype->getSuperClasses();
for (const auto &SuperPair : Superclasses) {
...
}
The ``Record`` class also provides a function, ``getDirectSuperClasses``, to
append the *direct* superclasses of a record to a given vector of type
``SmallVectorImpl<Record *>``.
Emitting Text to the Output Stream
==================================
The ``run`` function is passed a ``raw_ostream`` to which it prints the
output file. By convention, this stream is saved in the emitter class member
named ``OS``, although some ``run`` functions are simple and just use the
stream without saving it. The output can be produced by writing values
directly to the output stream, or by using the ``std::format()`` or
``llvm::formatv()`` functions.
.. code-block:: text
OS << "#ifndef " << NodeName << "\n";
OS << format("0x%0*x, ", Digits, Value);
Instances of the following classes can be printed using the ``<<`` operator:
``RecordKeeper``,
``Record``,
``RecTy``,
``RecordVal``, and
``Init``.
A constant and two helper functions are provided for producing the output
file. The constant ``MAX_LINE_LEN`` specifies the maximum length of output
lines. The helper function ``printLine`` prints a horizontal line comment.
The helper function ``emitSourceFileHeader`` prints the header comment that
should be included at the top of every output file.
Printing Error Messages
=======================
TableGen records are often derived from multiple classes and also often
defined through a sequence of multiclasses. Because of this, it can be
difficult for backends to report clear error messages with accurate source
file locations. To make error reporting easier, five error reporting
functions are provided, each with four overloads. [all combinations to come]
* ``PrintWarning`` prints a message tagged as a warning.
* ``PrintError`` prints a message tagged as an error.
* ``PrintFatalError`` prints a message tagged as an error and then terminates.
* ``PrintNote`` prints a note. It is often used after one of the previous
functions to provide more information.
* ``PrintFatalNote`` prints a note and then terminates.
Each of these five functions is overloaded four times.
* ``PrintError(const Twine &Msg)``:
Prints the message with no source file location.
* ``PrintError(ArrayRef<SMLoc> ErrorLoc, const Twine &Msg)``:
Prints the message followed by the specified source line,
along with a pointer to the item in error. The array of
source file locations is typically taken from a ``Record`` instance.
* ``PrintError(const Record *Rec, const Twine &Msg)``:
Prints the message followed by the source line associated with the
specified record (see `Record`_).
* ``PrintError(const RecordVal *RecVal, const Twine &Msg)``:
Prints the message followed by the source line associated with the
specified record field (see `RecordVal`_).
Using these functions, the goal is to produce the most specific error report
possible.
Debugging Tools
===============
TableGen provides some tools to aid in debugging backends.
The ``PrintRecords`` Backend
----------------------------
The TableGen command option ``--print-records`` invokes a simple backend
that prints all the classes and records defined in the source files. This is
the default backend option. The output looks like this:
.. code-block:: text
------------- Classes -----------------
...
class XEntry<string XEntry:str = ?, int XEntry:val1 = ?> { // XBase
string Str = XEntry:str;
bits<8> Val1 = { !cast<bits<8>>(XEntry:val1){7}, ... };
bit Val3 = 1;
}
...
------------- Defs -----------------
def ATable { // GenericTable
string FilterClass = "AEntry";
string CppTypeName = "AEntry";
list<string> Fields = ["Str", "Val1", "Val2"];
list<string> PrimaryKey = ["Val1", "Val2"];
string PrimaryKeyName = "lookupATableByValues";
bit PrimaryKeyEarlyOut = 0;
}
...
def anonymous_0 { // AEntry
string Str = "Bob";
bits<8> Val1 = { 0, 0, 0, 0, 0, 1, 0, 1 };
bits<10> Val2 = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1 };
}
Classes are shown with their template arguments, parent classes (following
``//``), and fields. Records are shown with their parent classes and
fields. Note that anonymous records are named ``anonymous_0``,
``anonymous_1``, etc.
The ``PrintDetailedRecords`` Backend
------------------------------------
[to come]

9
llvm/docs/TableGen/ProgRef.rst
View File

@ -26,9 +26,12 @@ you are looking for a simple overview, check out :doc:`TableGen Overview <./inde
An example of a backend is ``RegisterInfo``, which generates the register
file information for a particular target machine, for use by the LLVM
target-independent code generator. See :doc:`TableGen Backends <./BackEnds>` for
a description of the LLVM TableGen backends. Here are a few of the things
backends can do.
target-independent code generator. See :doc:`TableGen Backends <./BackEnds>`
for a description of the LLVM TableGen backends, and :doc:`TableGen
Backend Developer's Guide <./BackGuide>` for a guide to writing a new
backend.
Here are a few of the things backends can do.
* Generate the register file information for a particular target machine.

1
llvm/lib/TableGen/CMakeLists.txt
View File

@ -6,6 +6,7 @@ add_llvm_component_library(LLVMTableGen
SetTheory.cpp
StringMatcher.cpp
TableGenBackend.cpp
TableGenBackendSkeleton.cpp
TGLexer.cpp
TGParser.cpp

62
llvm/lib/TableGen/TableGenBackendSkeleton.cpp Normal file
View File

@ -0,0 +1,62 @@
//===- SkeletonEmitter.cpp - Skeleton TableGen backend -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This Tablegen backend emits ...
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <algorithm>
#include <set>
#include <string>
#include <vector>
#define DEBUG_TYPE "skeleton-emitter"
using namespace llvm;
namespace {
// Any helper data structures can be defined here. Some backends use
// structs to collect information from the records.
class SkeletonEmitter {
private:
RecordKeeper &Records;
public:
SkeletonEmitter(RecordKeeper &RK) : Records(RK) {}
void run(raw_ostream &OS);
}; // End emitter class.
} // End anonymous namespace.
void SkeletonEmitter::run(raw_ostream &OS) {
emitSourceFileHeader("Skeleton data structures", OS);
}
namespace llvm {
// The only thing that should be in the llvm namespace is the
// emitter entry point function.
void EmitSkeleton(RecordKeeper &RK, raw_ostream &OS) {
// Instantiate the emitter class and invoke run().
SkeletonEmitter(RK).run(OS);
}
} // End llvm namespace.

8
mlir/docs/OpDefinitions.md
View File

@ -57,8 +57,7 @@ including but not limited to:
We use TableGen as the language for specifying operation information. TableGen
itself just provides syntax for writing records; the syntax and constructs
allowed in a TableGen file (typically with filename suffix `.td`) can be found
[here][TableGenIntro]. The formal language specification can be found
[here][TableGenRef]. _Roughly_ speaking,
[here][TableGenProgRef].
* TableGen `class` is similar to C++ class; it can be templated and
subclassed.
@ -72,7 +71,7 @@ allowed in a TableGen file (typically with filename suffix `.td`) can be found
be anything, including `dag` itself. We can have names attached to both the
operator and the arguments like `(MyOp:$op_name MyArg:$arg_name)`.
Please see the [language introduction][TableGenIntro] to learn about all the
Please see the [language reference][TableGenProgRef] to learn about all the
types and expressions supported by TableGen.
## Operation Definition
@ -1508,8 +1507,7 @@ requirements that were desirable:
TODO: document expectation if the dependent op's definition changes.
[TableGen]: https://llvm.org/docs/TableGen/index.html
[TableGenIntro]: https://llvm.org/docs/TableGen/LangIntro.html
[TableGenRef]: https://llvm.org/docs/TableGen/LangRef.html
[TableGenProgRef]: https://llvm.org/docs/TableGen/ProgRef.html
[TableGenBackend]: https://llvm.org/docs/TableGen/BackEnds.html#introduction
[OpBase]: https://github.com/llvm/llvm-project/blob/master/mlir/include/mlir/IR/OpBase.td
[OpDefinitionsGen]: https://github.com/llvm/llvm-project/blob/master/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp

2
mlir/docs/Tutorials/QuickstartRewrites.md
View File

@ -16,7 +16,7 @@ table-driven manner.
## Adding operation
An operation in MLIR is specified using a definition in
[TableGen](https://llvm.org/docs/TableGen/LangIntro.html) file. TableGen is a
[TableGen](https://llvm.org/docs/TableGen/index.html) file. TableGen is a
modeling tool to specify the ops and the C++ code to interact with these
operations are generated from. To define an operation one needs to specify: