information (e.g., an ``add`` instruction is almost identical to a ``sub``
instruction). In order to allow the maximum amount of commonality to be
factored out, the LLVM code generator uses the
-`TableGen <TableGenFundamentals.html>`_ tool to describe big chunks of the
+:doc:`TableGen <TableGenFundamentals>` tool to describe big chunks of the
target machine, which allows the use of domain-specific and target-specific
abstractions to reduce the amount of repetition.
------------------------
The ``DataLayout`` class is the only required target description class, and it
-is the only class that is not extensible (you cannot derived a new class from
+is the only class that is not extensible (you cannot derive a new class from
it). ``DataLayout`` specifies information about how the target lays out memory
for structures, the alignment requirements for various data types, the size of
pointers in the target, and whether the target is little-endian or
big-endian.
-.. _targetlowering:
+.. _TargetLowering:
The ``TargetLowering`` class
----------------------------
* the type to use for shift amounts, and
* various high-level characteristics, like whether it is profitable to turn
- division by a constant into a multiplication sequence
+ division by a constant into a multiplication sequence.
+
+.. _TargetRegisterInfo:
The ``TargetRegisterInfo`` class
--------------------------------
The ``TargetRegisterInfo`` class is used to describe the register file of the
target and any interactions between the registers.
-Registers in the code generator are represented in the code generator by
-unsigned integers. Physical registers (those that actually exist in the target
-description) are unique small numbers, and virtual registers are generally
-large. Note that register ``#0`` is reserved as a flag value.
+Registers are represented in the code generator by unsigned integers. Physical
+registers (those that actually exist in the target description) are unique
+small numbers, and virtual registers are generally large. Note that
+register ``#0`` is reserved as a flag value.
Each register in the processor description has an associated
``TargetRegisterDesc`` entry, which provides a textual name for the register
SREM or UREM operation. The `legalize types`_ and `legalize operations`_ phases
are responsible for turning an illegal DAG into a legal DAG.
+.. _SelectionDAG-Process:
+
SelectionDAG Instruction Selection Process
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The initial SelectionDAG is na\ :raw-html:`ï`\ vely peephole expanded from
-the LLVM input by the ``SelectionDAGLowering`` class in the
-``lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp`` file. The intent of this pass
+the LLVM input by the ``SelectionDAGBuilder`` class. The intent of this pass
is to expose as much low-level, target-specific details to the SelectionDAG as
possible. This pass is mostly hard-coded (e.g. an LLVM ``add`` turns into an
``SDNode add`` while a ``getelementptr`` is expanded into the obvious
A target implementation tells the legalizer which types are supported (and which
register class to use for them) by calling the ``addRegisterClass`` method in
-its TargetLowering constructor.
+its ``TargetLowering`` constructor.
.. _legalize operations:
.. _Legalizer:
To perform this pattern match, the PowerPC backend includes the following
instruction definitions:
-::
+.. code-block:: text
+ :emphasize-lines: 4-5,9
def FMADDS : AForm_1<59, 29,
(ops F4RC:$FRT, F4RC:$FRA, F4RC:$FRC, F4RC:$FRB),
"fadds $FRT, $FRA, $FRB",
[(set F4RC:$FRT, (fadd F4RC:$FRA, F4RC:$FRB))]>;
-The portion of the instruction definition in bold indicates the pattern used to
-match the instruction. The DAG operators (like ``fmul``/``fadd``) are defined
-in the ``include/llvm/Target/TargetSelectionDAG.td`` file. " ``F4RC``" is the
-register class of the input and result values.
+The highlighted portion of the instruction definitions indicates the pattern
+used to match the instructions. The DAG operators (like ``fmul``/``fadd``)
+are defined in the ``include/llvm/Target/TargetSelectionDAG.td`` file.
+"``F4RC``" is the register class of the input and result values.
The TableGen DAG instruction selector generator reads the instruction patterns
in the ``.td`` file and automatically builds parts of the pattern matching code
specific to the code generator for a particular target. First we start with a
table that summarizes what features are supported by each target.
+.. _target-feature-matrix:
+
Target Feature Matrix
---------------------
:raw-html:`<tr>`
:raw-html:`<th>Feature</th>`
:raw-html:`<th>ARM</th>`
-:raw-html:`<th>CellSPU</th>`
:raw-html:`<th>Hexagon</th>`
:raw-html:`<th>MBlaze</th>`
:raw-html:`<th>MSP430</th>`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_reliable">is generally reliable</a></td>`
:raw-html:`<td class="yes"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MBlaze -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_asmparser">assembly parser</a></td>`
:raw-html:`<td class="no"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="yes"></td> <!-- MBlaze -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_disassembler">disassembler</a></td>`
:raw-html:`<td class="yes"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="yes"></td> <!-- MBlaze -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_inlineasm">inline asm</a></td>`
:raw-html:`<td class="yes"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="yes"></td> <!-- MBlaze -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_jit">jit</a></td>`
:raw-html:`<td class="partial"><a href="#feat_jit_arm">*</a></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MBlaze -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_objectwrite">.o file writing</a></td>`
:raw-html:`<td class="no"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="yes"></td> <!-- MBlaze -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a hr:raw-html:`ef="#feat_tailcall">tail calls</a></td>`
:raw-html:`<td class="yes"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MBlaze -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_segstacks">segmented stacks</a></td>`
:raw-html:`<td class="no"></td> <!-- ARM -->`
-:raw-html:`<td class="no"></td> <!-- CellSPU -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MBlaze -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
Tail call optimization, callee reusing the stack of the caller, is currently
supported on x86/x86-64 and PowerPC. It is performed if:
-* Caller and callee have the calling convention ``fastcc`` or ``cc 10`` (GHC
- call convention).
+* Caller and callee have the calling convention ``fastcc``, ``cc 10`` (GHC
+ calling convention) or ``cc 11`` (HiPE calling convention).
* The call is a tail call - in tail position (ret immediately follows call and
ret uses value of call or is void).
projects / oota-llvm.git / blobdiff