Formation, SSA-based Optimization, Register Allocation, Prolog/Epilog Code
Insertion, Late Machine Code Optimizations, and Code Emission.
-* :doc:`TableGenFundamentals` --- a document that describes the TableGen
+* :doc:`TableGen/index` --- a document that describes the TableGen
(``tblgen``) application that manages domain-specific information to support
LLVM code generation. TableGen processes input from a target description
file (``.td`` suffix) and generates C++ code that can be used for code
know about your target when parsing the ``--enable-targets`` option. Search
the configure script for ``TARGETS_TO_BUILD``, add your target to the lists
there (some creativity required), and then reconfigure. Alternatively, you can
-change ``autotools/configure.ac`` and regenerate configure by running
+change ``autoconf/configure.ac`` and regenerate configure by running
``./autoconf/AutoRegen.sh``.
Target Machine
* ``getTargetLowering()``
* ``getJITInfo()``
+Some architectures, such as GPUs, do not support jumping to an arbitrary
+program location and implement branching using masked execution and loop using
+special instructions around the loop body. In order to avoid CFG modifications
+that introduce irreducible control flow not handled by such hardware, a target
+must call `setRequiresStructuredCFG(true)` when being initialized.
+
In addition, the ``XXXTargetMachine`` constructor should specify a
``TargetDescription`` string that determines the data layout for the target
machine, including characteristics such as pointer size, alignment, and
int16_t getNamedOperandIdx(uint16_t Opcode, uint16_t NamedIndex);
} // End namespace XXX
+Instruction Operand Types
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+TableGen will also generate an enumeration consisting of all named Operand
+types defined in the backend, in the llvm::XXX::OpTypes namespace.
+Some common immediate Operand types (for instance i8, i32, i64, f32, f64)
+are defined for all targets in ``include/llvm/Target/Target.td``, and are
+available in each Target's OpTypes enum. Also, only named Operand types appear
+in the enumeration: anonymous types are ignored.
+For example, the X86 backend defines ``brtarget`` and ``brtarget8``, both
+instances of the TableGen ``Operand`` class, which represent branch target
+operands:
+
+.. code-block:: llvm
+
+ def brtarget : Operand<OtherVT>;
+ def brtarget8 : Operand<OtherVT>;
+
+This results in:
+
+.. code-block:: c++
+
+ namespace X86 {
+ namespace OpTypes {
+ enum OperandType {
+ ...
+ brtarget,
+ brtarget8,
+ ...
+ i32imm,
+ i64imm,
+ ...
+ OPERAND_TYPE_LIST_END
+ } // End namespace OpTypes
+ } // End namespace X86
+
+In typical TableGen fashion, to use the enum, you will need to define a
+preprocessor macro:
+
+.. code-block:: c++
+
+ #define GET_INSTRINFO_OPERAND_TYPES_ENUM // For OpTypes enum
+ #include "XXXGenInstrInfo.inc"
+
+
Instruction Scheduling
----------------------