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1===================================2TableGen Backend Developer's Guide3===================================4 5.. sectnum::6 7.. contents::8 :local:9 10Introduction11============12 13The purpose of TableGen is to generate complex output files based on14information from source files that are significantly easier to code than the15output files would be, and also easier to maintain and modify over time. The16information is coded in a declarative style involving classes and records,17which are then processed by TableGen. The internalized records are passed on18to various backends, which extract information from a subset of the records19and generate an output file. These output files are typically ``.inc`` files20for C++, but they may be any type of file that the backend developer needs.21 22This document is a guide to writing a backend for TableGen. It is not a23complete reference manual, but rather a guide to using the facilities24provided by TableGen for the backends. For a complete reference to the25various data structures and functions involved, see the primary TableGen26header file (``record.h``) and/or the Doxygen documentation.27 28This document assumes that you have read the :doc:`TableGen Programmer's29Reference <./ProgRef>`, which provides a detailed reference for coding30TableGen source files. For a description of the existing backends, see31:doc:`TableGen BackEnds <./BackEnds>`.32 33Data Structures34===============35 36The following sections describe the data structures that contain the classes37and records that are collected from the TableGen source files by the38TableGen parser. Note that the term *class* refers to an abstract record39class, while the term *record* refers to a concrete record.40 41Unless otherwise noted, functions associated with classes are instance42functions.43 44``RecordKeeper``45----------------46 47An instance of the ``RecordKeeper`` class acts as the container for all the48classes and records parsed and collected by TableGen. The ``RecordKeeper``49instance is passed to the backend when it is invoked by TableGen. This class50is usually abbreviated ``RK``.51 52There are two maps in the recordkeeper, one for classes and one for records53(the latter often referred to as *defs*). Each map maps the class or record54name to an instance of the ``Record`` class (see `Record`_), which contains55all the information about that class or record.56 57In addition to the two maps, the ``RecordKeeper`` instance contains:58 59* A map that maps the names of global variables to their values.60 Global variables are defined in TableGen files with outer61 ``defvar`` statements.62 63* A counter for naming anonymous records.64 65The ``RecordKeeper`` class provides a few useful functions.66 67* Functions to get the complete class and record maps.68 69* Functions to get a subset of the records based on their parent classes.70 71* Functions to get individual classes, records, and globals, by name.72 73A ``RecordKeeper`` instance can be printed to an output stream with the ``<<``74operator.75 76``Record``77----------78 79Each class or record built by TableGen is represented by an instance of80the ``Record`` class. The ``RecordKeeper`` instance contains one map for the81classes and one for the records. The primary data members of a record are82the record name, the vector of field names and their values, and the vector of83superclasses of the record.84 85The record name is stored as a pointer to an ``Init`` (see `Init`_), which86is a class whose instances hold TableGen values (sometimes referred to as87*initializers*). The field names and values are stored in a vector of88``RecordVal`` instances (see `RecordVal`_), each of which contains both the89field name and its value. The superclass vector contains a sequence of90pairs, with each pair including the superclass record and its source91file location.92 93In addition to those members, a ``Record`` instance contains:94 95* A vector of source file locations that includes the record definition96 itself, plus the locations of any multiclasses involved in its definition.97 98* For a class record, a vector of the class's template arguments.99 100* An instance of ``DefInit`` (see `DefInit`_) corresponding to this record.101 102* A unique record ID.103 104* A boolean that specifies whether this is a class definition.105 106* A boolean that specifies whether this is an anonymous record.107 108The ``Record`` class provides many useful functions.109 110* Functions to get the record name, fields, source file locations,111 template arguments, and unique ID.112 113* Functions to get all the record's superclasses or just its direct114 superclasses.115 116* Functions to get a particular field value by specifying its name in various117 forms and returning its value in various forms118 (see `Getting Record Names and Fields`_).119 120* Boolean functions to check the various attributes of the record.121 122A ``Record`` instance can be printed to an output stream with the ``<<``123operator.124 125 126``RecordVal``127-------------128 129Each field of a record is stored in an instance of the ``RecordVal`` class.130The ``Record`` instance includes a vector of these value instances. A131``RecordVal`` instance contains the name of the field, stored in an ``Init``132instance. It also contains the value of the field, likewise stored in an133``Init``. (A better name for this class might be ``RecordField``.)134 135In addition to those primary members, the ``RecordVal`` has other data members.136 137* The source file location of the field definition.138 139* The type of the field, stored as an instance140 of the ``RecTy`` class (see `RecTy`_).141 142The ``RecordVal`` class provides some useful functions.143 144* Functions to get the name of the field in various forms.145 146* A function to get the type of the field.147 148* A function to get the value of the field.149 150* A function to get the source file location.151 152Note that field values are more easily obtained directly from the ``Record``153instance (see `Record`_).154 155A ``RecordVal`` instance can be printed to an output stream with the ``<<``156operator.157 158``RecTy``159---------160 161The ``RecTy`` class is used to represent the types of field values. It is162the base class for a series of subclasses, one for each of the163available field types. The ``RecTy`` class has one data member that is an164enumerated type specifying the specific type of field value. (A better165name for this class might be ``FieldTy``.)166 167The ``RecTy`` class provides a few useful functions.168 169* A virtual function to get the type name as a string.170 171* A virtual function to check whether all the values of this type can172 be converted to another given type.173 174* A virtual function to check whether this type is a subtype of175 another given type.176 177* A function to get the corresponding ``list``178 type for lists with elements of this type. For example, the function179 returns the ``list<int>`` type when called with the ``int`` type.180 181The subclasses that inherit from ``RecTy`` are182``BitRecTy``,183``BitsRecTy``,184``CodeRecTy``,185``DagRecTy``,186``IntRecTy``,187``ListRecTy``,188``RecordRecTy``, and189``StringRecTy``.190Some of these classes have additional members that191are described in the following subsections.192 193*All* of the classes derived from ``RecTy`` provide the ``get()`` function.194It returns an instance of ``RecTy`` corresponding to the derived class.195Some of the ``get()`` functions require an argument to196specify which particular variant of the type is desired. These arguments are197described in the following subsections.198 199A ``RecTy`` instance can be printed to an output stream with the ``<<``200operator.201 202.. warning::203 It is not specified whether there is a single ``RecTy`` instance of a204 particular type or multiple instances.205 206 207``BitsRecTy``208~~~~~~~~~~~~~209 210This class includes a data member with the size of the ``bits`` value and a211function to get that size.212 213The ``get()`` function takes the length of the sequence, *n*, and returns the214``BitsRecTy`` type corresponding to ``bits<``\ *n*\ ``>``.215 216``ListRecTy``217~~~~~~~~~~~~~218 219This class includes a data member that specifies the type of the list's220elements and a function to get that type.221 222The ``get()`` function takes the ``RecTy`` *type* of the list members and223returns the ``ListRecTy`` type corresponding to ``list<``\ *type*\ ``>``.224 225 226``RecordRecTy``227~~~~~~~~~~~~~~~228 229This class includes data members that contain the list of parent classes of230this record. It also provides a function to obtain the array of classes and231two functions to get the iterator ``begin()`` and ``end()`` values. The232class defines a type for the return values of the latter two functions.233 234.. code-block:: text235 236 using const_record_iterator = Record * const *;237 238The ``get()`` function takes an ``ArrayRef`` of pointers to the ``Record``239instances of the *direct* superclasses of the record and returns the ``RecordRecTy``240corresponding to the record inheriting from those superclasses.241 242``Init``243--------244 245The ``Init`` class is used to represent TableGen values. The name derives246from *initialization value*. This class should not be confused with the247``RecordVal`` class, which represents record fields, both their names and248values. The ``Init`` class is the base class for a series of subclasses, one249for each of the available value types. The primary data member of ``Init``250is an enumerated type that represents the specific type of the value.251 252The ``Init`` class provides a few useful functions.253 254* A function to get the type enumerator.255 256* A boolean virtual function to determine whether a value is completely257 specified; that is, has no uninitialized subvalues.258 259* Virtual functions to get the value as a string.260 261* Virtual functions to cast the value to other types, implement the bit262 range feature of TableGen, and implement the list slice feature.263 264* A virtual function to get a particular bit of the value.265 266The subclasses that inherit directly from ``Init`` are267``UnsetInit`` and ``TypedInit``.268 269An ``Init`` instance can be printed to an output stream with the ``<<``270operator.271 272.. warning::273 It is not specified whether two separate initialization values with274 the same underlying type and value (e.g., two strings with the value275 "Hello") are represented by two ``Init``\ s or share the same ``Init``.276 277``UnsetInit``278~~~~~~~~~~~~~279 280This class, a subclass of ``Init``, represents the unset (uninitialized)281value. The static function ``get()`` can be used to obtain the singleton282``Init`` of this type.283 284 285``TypedInit``286~~~~~~~~~~~~~287 288This class, a subclass of ``Init``, acts as the parent class of the classes289that represent specific value types (except for the unset value). These290classes include ``BitInit``, ``BitsInit``, ``DagInit``, ``DefInit``,291``IntInit``, ``ListInit``, and ``StringInit``. (There are additional derived292types used by the TableGen parser.)293 294This class includes a data member that specifies the ``RecTy`` type of the295value. It provides a function to get that ``RecTy`` type.296 297``BitInit``298~~~~~~~~~~~299 300The ``BitInit`` class is a subclass of ``TypedInit``. Its instances301represent the possible values of a bit: 0 or 1. It includes a data member302that contains the bit.303 304*All* of the classes derived from ``TypedInit`` provide the following functions:305 306* A static function named ``get()`` that returns an ``Init`` representing307 the specified value(s). In the case of ``BitInit``, ``get(true)`` returns308 an instance of ``BitInit`` representing true, while ``get(false)`` returns309 an instance310 representing false. As noted above, it is not specified whether there311 is exactly one or more than one ``BitInit`` representing true (or false).312 313* A function named ``GetValue()`` that returns the value of the instance314 in a more direct form, in this case as a ``bool``.315 316``BitsInit``317~~~~~~~~~~~~318 319The ``BitsInit`` class is a subclass of ``TypedInit``. Its instances320represent sequences of bits, from high-order to low-order. It includes a321data member with the length of the sequence and a vector of pointers to322``Init`` instances, one per bit.323 324The class provides the usual ``get()`` function. It does not provide the325``getValue()`` function.326 327The class provides the following additional functions.328 329* A function to get the number of bits in the sequence.330 331* A function that gets a bit specified by an integer index.332 333``DagInit``334~~~~~~~~~~~335 336The ``DagInit`` class is a subclass of ``TypedInit``. Its instances337represent the possible directed acyclic graphs (``dag``).338 339The class includes a pointer to an ``Init`` for the DAG operator and a340pointer to a ``StringInit`` for the operator name. It includes the count of341DAG operands and the count of operand names. Finally, it includes a vector of342pointers to ``Init`` instances for the operands and another to343``StringInit`` instances for the operand names.344(The DAG operands are also referred to as *arguments*.)345 346The class provides two forms of the usual ``get()`` function. It does not347provide the usual ``getValue()`` function.348 349The class provides many additional functions:350 351* Functions to get the operator in various forms and to get the352 operator name in various forms.353 354* Functions to determine whether there are any operands and to get the355 number of operands.356 357* Functions to get the operands, both individually and together.358 359* Functions to determine whether there are any names and to360 get the number of names.361 362* Functions to get the names, both individually and together.363 364* Functions to get the operand iterator ``begin()`` and ``end()`` values.365 366* Functions to get the name iterator ``begin()`` and ``end()`` values.367 368The class defines two types for the return values of the operand and name369iterators.370 371.. code-block:: text372 373 using const_arg_iterator = SmallVectorImpl<Init*>::const_iterator;374 using const_name_iterator = SmallVectorImpl<StringInit*>::const_iterator;375 376 377``DefInit``378~~~~~~~~~~~379 380The ``DefInit`` class is a subclass of ``TypedInit``. Its instances381represent the records that were collected by TableGen. It includes a data382member that is a pointer to the record's ``Record`` instance.383 384The class provides the usual ``get()`` function. It does not provide385``getValue()``. Instead, it provides ``getDef()``, which returns the386``Record`` instance.387 388``IntInit``389~~~~~~~~~~~390 391The ``IntInit`` class is a subclass of ``TypedInit``. Its instances392represent the possible values of a 64-bit integer. It includes a data member393that contains the integer.394 395The class provides the usual ``get()`` and ``getValue()`` functions. The396latter function returns the integer as an ``int64_t``.397 398The class also provides a function, ``getBit()``, to obtain a specified bit399of the integer value.400 401``ListInit``402~~~~~~~~~~~~403 404The ``ListInit`` class is a subclass of ``TypedInit``. Its instances405represent lists of elements of some type. It includes a data member with the406length of the list and a vector of pointers to ``Init`` instances, one per407element.408 409The class provides the usual ``get()`` and ``getValues()`` functions. The410latter function returns an ``ArrayRef`` of the vector of pointers to ``Init``411instances.412 413The class provides these additional functions:414 415* A function to get the element type.416 417* Functions to get the length of the vector and to determine whether418 it is empty.419 420* Functions to get an element specified by an integer index and return421 it in various forms.422 423* Functions to get the iterator ``begin()`` and ``end()`` values. The424 class defines a type for the return type of these two functions.425 426.. code-block:: text427 428 using const_iterator = Init *const *;429 430 431``StringInit``432~~~~~~~~~~~~~~433 434The ``StringInit`` class is a subclass of ``TypedInit``. Its instances435represent arbitrary-length strings. It includes a data member436that contains a ``StringRef`` of the value.437 438The class provides the usual ``get()`` and ``getValue()`` functions. The439latter function returns the ``StringRef``.440 441Creating a New Backend442======================443 444The following steps are required to create a new backend for TableGen.445 446#. Invent a name for your backend C++ file, say ``GenAddressModes``.447 448#. Write the new backend, using the file ``TableGenBackendSkeleton.cpp``449 as a starting point.450 451#. Determine which instance of TableGen requires the new backend. There is452 one instance for Clang and another for LLVM. Or you may be building453 your own instance.454 455#. Add your backend C++ file to the appropriate ``CMakeLists.txt`` file so456 that it will be built.457 458#. Add your C++ file to the system.459 460The Backend Skeleton461====================462 463The file ``TableGenBackendSkeleton.cpp`` provides a skeleton C++ translation464unit for writing a new TableGen backend. Here are a few notes on the file:465 466* The list of includes is the minimal list required by most backends.467 468* As with all LLVM C++ files, it has a ``using namespace llvm;`` statement.469 It also has an anonymous namespace that contains all the file-specific470 data structure definitions, along with the class embodying the emitter471 data members and functions. Continuing with the ``GenAddressModes`` example,472 this class is named ``AddressModesEmitter``.473 474* The constructor for the emitter class accepts a ``RecordKeeper`` reference,475 typically named ``RK``. The ``RecordKeeper`` reference is saved in a data476 member so that records can be obtained from it. This data member is usually477 named ``Records``.478 479* One function is named ``run``. It is invoked by the backend's "main480 function" to collect records and emit the output file. It accepts an instance481 of the ``raw_ostream`` class, typically named ``OS``. The output file is482 emitted by writing to this stream.483 484* The ``run`` function should use the ``emitSourceFileHeader`` helper function485 to include a standard header in the emitted file.486 487* Register the class or the function as the command-line option488 with ``llvm/TableGen/TableGenBackend.h``.489 490 * Use ``llvm::TableGen::Emitter::OptClass<AddressModesEmitter>``491 if the class has the constructor ``(RK)`` and492 the method ``run(OS)``.493 494 * Otherwise, use ``llvm::TableGen::Emitter::Opt``.495 496All the examples in the remainder of this document will assume the naming497conventions used in the skeleton file.498 499Getting Classes500===============501 502The ``RecordKeeper`` class provides two functions for getting the503``Record`` instances for classes defined in the TableGen files.504 505* ``getClasses()`` returns a ``RecordMap`` reference for all the classes.506 507* ``getClass(``\ *name*\ ``)`` returns a ``Record`` reference for the named508 class.509 510If you need to iterate over all the class records:511 512.. code-block:: text513 514 for (auto ClassPair : Records.getClasses()) {515 Record *ClassRec = ClassPair.second.get();516 ...517 }518 519``ClassPair.second`` gets the class's ``unique_ptr``, and then ``.get()`` gets the520class ``Record`` itself.521 522 523Getting Records524===============525 526The ``RecordKeeper`` class provides four functions for getting the527``Record`` instances for concrete records defined in the TableGen files.528 529* ``getDefs()`` returns a ``RecordMap`` reference for all the concrete530 records.531 532* ``getDef(``\ *name*\ ``)`` returns a ``Record`` reference for the named533 concrete record.534 535* ``getAllDerivedDefinitions(``\ *classname*\ ``)`` returns a vector of536 ``Record`` references for the concrete records that derive from the537 given class.538 539* ``getAllDerivedDefinitions(``\ *classnames*\ ``)`` returns540 a vector of ``Record`` references for the concrete records that derive from541 *all* of the given classes.542 543This statement obtains all the records that derive from the ``Attribute``544class and iterates over them.545 546.. code-block:: text547 548 auto AttrRecords = Records.getAllDerivedDefinitions("Attribute");549 for (Record *AttrRec : AttrRecords) {550 ...551 }552 553Getting Record Names and Fields554===============================555 556As described above (see `Record`_), there are multiple functions that557return the name of a record. One particularly useful one is558``getNameInitAsString()``, which returns the name as a ``std::string``.559 560There are also multiple functions that return the fields of a record. To561obtain and iterate over all the fields:562 563.. code-block:: text564 565 for (const RecordVal &Field : SomeRec->getValues()) {566 ...567 }568 569You will recall that ``RecordVal`` is the class whose instances contain570information about the fields in records.571 572The ``getValue()`` function returns the ``RecordVal`` instance for a field573specified by name. There are multiple overloaded functions, some taking a574``StringRef`` and others taking a ``const Init *``. Some functions return a575``RecordVal *`` and others return a ``const RecordVal *``. If the field does576not exist, a fatal error message is printed.577 578More often than not, you are interested in the value of the field, not all579the information in the ``RecordVal``. There is a large set of functions that580take a field name in some form and return its value. One function,581``getValueInit``, returns the value as an ``Init *``. Another function,582``isValueUnset``, returns a boolean specifying whether the value is unset583(uninitialized).584 585Most of the functions return the value in some more useful form. For586example:587 588.. code-block:: text589 590 std::vector<int64_t> RegCosts =591 SomeRec->getValueAsListOfInts("RegCosts");592 593The field ``RegCosts`` is assumed to be a list of integers. That list is594returned as a ``std::vector`` of 64-bit integers. If the field is not a list595of integers, a fatal error message is printed.596 597Here is a function that returns a field value as a ``Record``, but returns598null if the field does not exist.599 600.. code-block:: text601 602 if (Record *BaseRec = SomeRec->getValueAsOptionalDef(BaseFieldName)) {603 ...604 }605 606The field is assumed to have another record as its value. That record is returned607as a pointer to a ``Record``. If the field does not exist or is unset, the608function returns null.609 610Getting Record Superclasses611===========================612 613The ``Record`` class provides a function to obtain the direct superclasses614of a record. It is named ``getDirectSuperClasses`` and returns an615``ArrayRef`` of an array of ``std::pair`` instances. Each pair consists of a616pointer to the ``Record`` instance for a superclass record and an instance617of the ``SMRange`` class. The range indicates the source file locations of618the beginning and end of the class definition.619 620This example obtains the direct superclasses of the ``Prototype`` record and621then iterates over the pairs in the returned array.622 623.. code-block:: text624 625 ArrayRef<std::pair<const Record *, SMRange>>626 Superclasses = Prototype->getDirectSuperClasses();627 for (const auto &[Super, Range] : Superclasses) {628 ...629 }630 631The ``Record`` class also provides a function, ``getSuperClasses``, to632return a vector of *all* superclasses of a record. The superclasses are in633postorder: the order in which the superclasses were visited while copying634their fields into the record.635 636Emitting Text to the Output Stream637==================================638 639The ``run`` function is passed a ``raw_ostream`` to which it prints the640output file. By convention, this stream is saved in the emitter class member641named ``OS``, although some ``run`` functions are simple and just use the642stream without saving it. The output can be produced by writing values643directly to the output stream, or by using the ``std::format()`` or644``llvm::formatv()`` functions.645 646.. code-block:: text647 648 OS << "#ifndef " << NodeName << "\n";649 650 OS << format("0x%0*x, ", Digits, Value);651 652Instances of the following classes can be printed using the ``<<`` operator:653``RecordKeeper``,654``Record``,655``RecTy``,656``RecordVal``, and657``Init``.658 659The helper function ``emitSourceFileHeader()`` prints the header comment660that should be included at the top of every output file. A call to it is661included in the skeleton backend file ``TableGenBackendSkeleton.cpp``.662 663Printing Error Messages664=======================665 666TableGen records are often derived from multiple classes and also often667defined through a sequence of multiclasses. Because of this, it can be668difficult for backends to report clear error messages with accurate source669file locations. To make error reporting easier, five error reporting670functions are provided, each with four overloads.671 672* ``PrintWarning`` prints a message tagged as a warning.673 674* ``PrintError`` prints a message tagged as an error.675 676* ``PrintFatalError`` prints a message tagged as an error and then terminates.677 678* ``PrintNote`` prints a note. It is often used after one of the previous679 functions to provide more information.680 681* ``PrintFatalNote`` prints a note and then terminates.682 683Each of these five functions is overloaded four times.684 685* ``PrintError(const Twine &Msg)``:686 Prints the message with no source file location.687 688* ``PrintError(ArrayRef<SMLoc> ErrorLoc, const Twine &Msg)``:689 Prints the message followed by the specified source line,690 along with a pointer to the item in error. The array of691 source file locations is typically taken from a ``Record`` instance.692 693* ``PrintError(const Record *Rec, const Twine &Msg)``:694 Prints the message followed by the source line associated with the695 specified record (see `Record`_).696 697* ``PrintError(const RecordVal *RecVal, const Twine &Msg)``:698 Prints the message followed by the source line associated with the699 specified record field (see `RecordVal`_).700 701Using these functions, the goal is to produce the most specific error report702possible.703 704Debugging Tools705===============706 707TableGen provides some tools to aid in debugging backends.708 709The ``PrintRecords`` Backend710----------------------------711 712The TableGen command option ``--print-records`` invokes a simple backend713that prints all the classes and records defined in the source files. This is714the default backend option. The format of the output is guaranteed to be715constant over time, so that the output can be compared in tests. The output716looks like this:717 718.. code-block:: text719 720 ------------- Classes -----------------721 ...722 class XEntry<string XEntry:str = ?, int XEntry:val1 = ?> { // XBase723 string Str = XEntry:str;724 bits<8> Val1 = { !cast<bits<8>>(XEntry:val1){7}, ... };725 bit Val3 = 1;726 }727 ...728 ------------- Defs -----------------729 def ATable { // GenericTable730 string FilterClass = "AEntry";731 string CppTypeName = "AEntry";732 list<string> Fields = ["Str", "Val1", "Val2"];733 list<string> PrimaryKey = ["Val1", "Val2"];734 string PrimaryKeyName = "lookupATableByValues";735 bit PrimaryKeyEarlyOut = 0;736 }737 ...738 def anonymous_0 { // AEntry739 string Str = "Bob";740 bits<8> Val1 = { 0, 0, 0, 0, 0, 1, 0, 1 };741 bits<10> Val2 = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1 };742 }743 744Classes are shown with their template arguments, parent classes (following745``//``), and fields. Records are shown with their parent classes and746fields. Note that anonymous records are named ``anonymous_0``,747``anonymous_1``, etc.748 749The ``PrintDetailedRecords`` Backend750------------------------------------751 752The TableGen command option ``--print-detailed-records`` invokes a backend753that prints all the global variables, classes, and records defined in the754source files. The format of the output is *not* guaranteed to be constant755over time. The output looks like this:756 757.. code-block:: text758 759 DETAILED RECORDS for file llvm-project\llvm\lib\target\arc\arc.td760 761 -------------------- Global Variables (5) --------------------762 763 AMDGPUBufferIntrinsics = [int_amdgcn_s_buffer_load, ...764 AMDGPUImageDimAtomicIntrinsics = [int_amdgcn_image_atomic_swap_1d, ...765 ...766 -------------------- Classes (758) --------------------767 768 AMDGPUBufferLoad |IntrinsicsAMDGPU.td:879|769 Template args:770 LLVMType AMDGPUBufferLoad:data_ty = llvm_any_ty |IntrinsicsAMDGPU.td:879|771 Superclasses: (SDPatternOperator) Intrinsic AMDGPURsrcIntrinsic772 Fields:773 list<SDNodeProperty> Properties = [SDNPMemOperand] |Intrinsics.td:348|774 string LLVMName = "" |Intrinsics.td:343|775 ...776 -------------------- Records (12303) --------------------777 778 AMDGPUSample_lz_o |IntrinsicsAMDGPU.td:560|779 Defm sequence: |IntrinsicsAMDGPU.td:584| |IntrinsicsAMDGPU.td:566|780 Superclasses: AMDGPUSampleVariant781 Fields:782 string UpperCaseMod = "_LZ_O" |IntrinsicsAMDGPU.td:542|783 string LowerCaseMod = "_lz_o" |IntrinsicsAMDGPU.td:543|784 ...785 786* Global variables defined with outer ``defvar`` statements are shown with787 their values.788 789* The classes are shown with their source location, template arguments,790 superclasses, and fields.791 792* The records are shown with their source location, ``defm`` sequence,793 superclasses, and fields.794 795Superclasses are shown in the order processed, with indirect superclasses in796parentheses. Each field is shown with its value and the source location at797which it was set.798The ``defm`` sequence gives the locations of the ``defm`` statements that799were involved in generating the record, in the order they were invoked.800 801Timing TableGen Phases802----------------------803 804TableGen provides a phase timing feature that produces a report of the time805used by the various phases of parsing the source files and running the806selected backend. This feature is enabled with the ``--time-phases`` option807of the TableGen command.808 809If the backend is *not* instrumented for timing, then a report such as the810following is produced. This is the timing for the811``--print-detailed-records`` backend run on the AMDGPU target.812 813.. code-block:: text814 815 ===-------------------------------------------------------------------------===816 TableGen Phase Timing817 ===-------------------------------------------------------------------------===818 Total Execution Time: 101.0106 seconds (102.4819 wall clock)819 820 ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---821 85.5197 ( 84.9%) 0.1560 ( 50.0%) 85.6757 ( 84.8%) 85.7009 ( 83.6%) Backend overall822 15.1789 ( 15.1%) 0.0000 ( 0.0%) 15.1789 ( 15.0%) 15.1829 ( 14.8%) Parse, build records823 0.0000 ( 0.0%) 0.1560 ( 50.0%) 0.1560 ( 0.2%) 1.5981 ( 1.6%) Write output824 100.6986 (100.0%) 0.3120 (100.0%) 101.0106 (100.0%) 102.4819 (100.0%) Total825 826Note that all the time for the backend is lumped under "Backend overall".827 828If the backend is instrumented for timing, then its processing is829divided into phases and each one timed separately. This is the timing for830the ``--emit-dag-isel`` backend run on the AMDGPU target.831 832.. code-block:: text833 834 ===-------------------------------------------------------------------------===835 TableGen Phase Timing836 ===-------------------------------------------------------------------------===837 Total Execution Time: 746.3868 seconds (747.1447 wall clock)838 839 ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---840 657.7938 ( 88.1%) 0.1404 ( 90.0%) 657.9342 ( 88.1%) 658.6497 ( 88.2%) Emit matcher table841 70.2317 ( 9.4%) 0.0000 ( 0.0%) 70.2317 ( 9.4%) 70.2700 ( 9.4%) Convert to matchers842 14.8825 ( 2.0%) 0.0156 ( 10.0%) 14.8981 ( 2.0%) 14.9009 ( 2.0%) Parse, build records843 2.1840 ( 0.3%) 0.0000 ( 0.0%) 2.1840 ( 0.3%) 2.1791 ( 0.3%) Sort patterns844 1.1388 ( 0.2%) 0.0000 ( 0.0%) 1.1388 ( 0.2%) 1.1401 ( 0.2%) Optimize matchers845 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0050 ( 0.0%) Write output846 746.2308 (100.0%) 0.1560 (100.0%) 746.3868 (100.0%) 747.1447 (100.0%) Total847 848The backend has been divided into four phases and timed separately.849 850If you want to instrument a backend, refer to the backend ``DAGISelEmitter.cpp``851and search for ``Records.startTimer``.852