-.. _extending_llvm:
-
============================================================
Extending LLVM: Adding instructions, intrinsics, types, etc.
============================================================
LLVM? Is it a new fundamental capability that LLVM does not support at its
current incarnation or can it be synthesized from already pre-existing LLVM
elements? If you are not sure, ask on the `LLVM-dev
-<http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev>`_ list. The reason is that
+<http://lists.llvm.org/mailman/listinfo/llvm-dev>`_ list. The reason is that
extending LLVM will get involved as you need to update all the different passes
that you intend to use with your extension, and there are ``many`` LLVM analyses
and transformations, so it may be quite a bit of work.
what the restrictions are. Talk to other people about it so that you are
sure it's a good idea.
-#. ``llvm/include/llvm/Intrinsics*.td``:
+#. ``llvm/include/llvm/IR/Intrinsics*.td``:
Add an entry for your intrinsic. Describe its memory access characteristics
for optimization (this controls whether it will be DCE'd, CSE'd, etc). Note
- that any intrinsic using the ``llvm_int_ty`` type for an argument will
- be deemed by ``tblgen`` as overloaded and the corresponding suffix will
- be required on the intrinsic's name.
+ that any intrinsic using one of the ``llvm_any*_ty`` types for an argument or
+ return type will be deemed by ``tblgen`` as overloaded and the corresponding
+ suffix will be required on the intrinsic's name.
#. ``llvm/lib/Analysis/ConstantFolding.cpp``:
If it is possible to constant fold your intrinsic, add support to it in the
``canConstantFoldCallTo`` and ``ConstantFoldCall`` functions.
-#. ``llvm/test/Regression/*``:
+#. ``llvm/test/*``:
Add test cases for your test cases to the test suite
#. TODO: document complex patterns.
-#. ``llvm/test/Regression/CodeGen/*``:
+#. ``llvm/test/CodeGen/*``:
Add test cases for your new node to the test suite.
- ``llvm/test/Regression/CodeGen/X86/bswap.ll`` is a good example.
+ ``llvm/test/CodeGen/X86/bswap.ll`` is a good example.
Adding a new instruction
========================
to maintain compatibility with the previous version. Only add an instruction
if it is absolutely necessary.
-#. ``llvm/include/llvm/Instruction.def``:
+#. ``llvm/include/llvm/IR/Instruction.def``:
add a number for your instruction and an enum name
-#. ``llvm/include/llvm/Instructions.h``:
+#. ``llvm/include/llvm/IR/Instructions.h``:
add a definition for the class that will represent your instruction
-#. ``llvm/include/llvm/Support/InstVisitor.h``:
+#. ``llvm/include/llvm/IR/InstVisitor.h``:
add a prototype for a visitor to your new instruction type
-#. ``llvm/lib/AsmParser/Lexer.l``:
+#. ``llvm/lib/AsmParser/LLLexer.cpp``:
add a new token to parse your instruction from assembly text file
-#. ``llvm/lib/AsmParser/llvmAsmParser.y``:
+#. ``llvm/lib/AsmParser/LLParser.cpp``:
add the grammar on how your instruction can be read and what it will
construct as a result
-#. ``llvm/lib/Bitcode/Reader/Reader.cpp``:
+#. ``llvm/lib/Bitcode/Reader/BitcodeReader.cpp``:
+
+ add a case for your instruction and how it will be parsed from bitcode
+
+#. ``llvm/lib/Bitcode/Writer/BitcodeWriter.cpp``:
add a case for your instruction and how it will be parsed from bitcode
-#. ``llvm/lib/VMCore/Instruction.cpp``:
+#. ``llvm/lib/IR/Instruction.cpp``:
add a case for how your instruction will be printed out to assembly
-#. ``llvm/lib/VMCore/Instructions.cpp``:
+#. ``llvm/lib/IR/Instructions.cpp``:
implement the class you defined in ``llvm/include/llvm/Instructions.h``
#. Test your instruction
-#. ``llvm/lib/Target/*``:
+#. ``llvm/lib/Target/*``:
add support for your instruction to code generators, or add a lowering pass.
-#. ``llvm/test/Regression/*``:
+#. ``llvm/test/*``:
add your test cases to the test suite.
Adding a fundamental type
-------------------------
-#. ``llvm/include/llvm/Type.h``:
+#. ``llvm/include/llvm/IR/Type.h``:
add enum for the new type; add static ``Type*`` for this type
-#. ``llvm/lib/VMCore/Type.cpp``:
+#. ``llvm/lib/IR/Type.cpp`` and ``llvm/lib/IR/ValueTypes.cpp``:
add mapping from ``TypeID`` => ``Type*``; initialize the static ``Type*``
-#. ``llvm/lib/AsmReader/Lexer.l``:
+#. ``llvm/llvm/llvm-c/Core.cpp``:
+
+ add enum ``LLVMTypeKind`` and modify
+ ``LLVMTypeKind LLVMGetTypeKind(LLVMTypeRef Ty)`` for the new type
+
+#. ``llvm/include/llvm/IR/TypeBuilder.h``:
+
+ add new class to represent new type in the hierarchy
+
+#. ``llvm/lib/AsmParser/LLLexer.cpp``:
add ability to parse in the type from text assembly
-#. ``llvm/lib/AsmReader/llvmAsmParser.y``:
+#. ``llvm/lib/AsmParser/LLParser.cpp``:
add a token for that type
+#. ``llvm/lib/Bitcode/Writer/BitcodeWriter.cpp``:
+
+ modify ``static void WriteTypeTable(const ValueEnumerator &VE,
+ BitstreamWriter &Stream)`` to serialize your type
+
+#. ``llvm/lib/Bitcode/Reader/BitcodeReader.cpp``:
+
+ modify ``bool BitcodeReader::ParseTypeType()`` to read your data type
+
+#. ``include/llvm/Bitcode/LLVMBitCodes.h``:
+
+ add enum ``TypeCodes`` for the new type
+
Adding a derived type
---------------------
-#. ``llvm/include/llvm/Type.h``:
+#. ``llvm/include/llvm/IR/Type.h``:
add enum for the new type; add a forward declaration of the type also
-#. ``llvm/include/llvm/DerivedTypes.h``:
+#. ``llvm/include/llvm/IR/DerivedTypes.h``:
add new class to represent new class in the hierarchy; add forward
declaration to the TypeMap value type
-#. ``llvm/lib/VMCore/Type.cpp``:
+#. ``llvm/lib/IR/Type.cpp`` and ``llvm/lib/IR/ValueTypes.cpp``:
- add support for derived type to:
+ add support for derived type, notably `enum TypeID` and `is`, `get` methods.
- .. code-block:: c++
+#. ``llvm/llvm/llvm-c/Core.cpp``:
- std::string getTypeDescription(const Type &Ty,
- std::vector<const Type*> &TypeStack)
- bool TypesEqual(const Type *Ty, const Type *Ty2,
- std::map<const Type*, const Type*> &EqTypes)
+ add enum ``LLVMTypeKind`` and modify
+ `LLVMTypeKind LLVMGetTypeKind(LLVMTypeRef Ty)` for the new type
- add necessary member functions for type, and factory methods
+#. ``llvm/include/llvm/IR/TypeBuilder.h``:
-#. ``llvm/lib/AsmReader/Lexer.l``:
+ add new class to represent new class in the hierarchy
- add ability to parse in the type from text assembly
+#. ``llvm/lib/AsmParser/LLLexer.cpp``:
-#. ``llvm/lib/BitCode/Writer/Writer.cpp``:
+ modify ``lltok::Kind LLLexer::LexIdentifier()`` to add ability to
+ parse in the type from text assembly
- modify ``void BitcodeWriter::outputType(const Type *T)`` to serialize your
- type
+#. ``llvm/lib/Bitcode/Writer/BitcodeWriter.cpp``:
-#. ``llvm/lib/BitCode/Reader/Reader.cpp``:
+ modify ``static void WriteTypeTable(const ValueEnumerator &VE,
+ BitstreamWriter &Stream)`` to serialize your type
- modify ``const Type *BitcodeReader::ParseType()`` to read your data type
+#. ``llvm/lib/Bitcode/Reader/BitcodeReader.cpp``:
-#. ``llvm/lib/VMCore/AsmWriter.cpp``:
+ modify ``bool BitcodeReader::ParseTypeType()`` to read your data type
- modify
+#. ``include/llvm/Bitcode/LLVMBitCodes.h``:
- .. code-block:: c++
+ add enum ``TypeCodes`` for the new type
- void calcTypeName(const Type *Ty,
- std::vector<const Type*> &TypeStack,
- std::map<const Type*,std::string> &TypeNames,
- std::string &Result)
+#. ``llvm/lib/IR/AsmWriter.cpp``:
+ modify ``void TypePrinting::print(Type *Ty, raw_ostream &OS)``
to output the new derived type
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