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Differential D129996

[docs] Remove unmaintained target feature matrix
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Authored by asb on Jul 18 2022, 3:52 AM.

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tstellar
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rG86c4242976f7: [docs] Remove unmaintained target feature matrix
Summary

Back in 2017, a table was added to the codegen documentation listing which features various backends support. It received a few updates since then, but not since the end of 2019. Having such a table is a nice idea, but it hasn't been kept up to date, it isn't easy to ensure that it is up to date, and the table probably isn't very discoverable for most users who would be interested in this information anyway (it would be better suited to some kind of "what can LLVM do for me?" page).

For all of the above reasons, I propose removing it.

Diff Detail

Event Timeline

asb created this revision.Jul 18 2022, 3:52 AM
Herald added a project: Restricted Project. · View Herald TranscriptJul 18 2022, 3:52 AM
Herald added subscribers: wingo, pmatos, StephenFan and 2 others. · View Herald Transcript
asb requested review of this revision.Jul 18 2022, 3:52 AM
Herald added a project: Restricted Project. · View Herald TranscriptJul 18 2022, 3:52 AM
Harbormaster completed remote builds in B175992: Diff 445445.Jul 18 2022, 5:05 AM
tstellar accepted this revision.Jul 18 2022, 7:53 AM
This revision is now accepted and ready to land.Jul 18 2022, 7:53 AM
This revision was landed with ongoing or failed builds.Jul 18 2022, 10:38 AM
Closed by commit rG86c4242976f7: [docs] Remove unmaintained target feature matrix (authored by asb). · Explain Why
This revision was automatically updated to reflect the committed changes.
asb added a commit: rG86c4242976f7: [docs] Remove unmaintained target feature matrix.

Revision Contents

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llvm/
docs/
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Diff 445563

llvm/docs/CodeGenerator.rst

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.. _Implementations of the abstract target description interfaces: .. _Implementations of the abstract target description interfaces:
.. _implement the target description: .. _implement the target description:
Target-specific Implementation Notes Target-specific Implementation Notes
==================================== ====================================
This section of the document explains features or design decisions that are This section of the document explains features or design decisions that are
specific to the code generator for a particular target. First we start with a specific to the code generator for a particular target.
table that summarizes what features are supported by each target.
.. _target-feature-matrix:
Target Feature Matrix
---------------------
Note that this table does not list features that are not supported fully by any
target yet. It considers a feature to be supported if at least one subtarget
supports it. A feature being supported means that it is useful and works for
most cases, it does not indicate that there are zero known bugs in the
implementation. Here is the key:
:raw-html:`<table border="1" cellspacing="0">`
:raw-html:`<tr>`
:raw-html:`<th>Unknown</th>`
:raw-html:`<th>Not Applicable</th>`
:raw-html:`<th>No support</th>`
:raw-html:`<th>Partial Support</th>`
:raw-html:`<th>Complete Support</th>`
:raw-html:`</tr>`
:raw-html:`<tr>`
:raw-html:`<td class="unknown"></td>`
:raw-html:`<td class="na"></td>`
:raw-html:`<td class="no"></td>`
:raw-html:`<td class="partial"></td>`
:raw-html:`<td class="yes"></td>`
:raw-html:`</tr>`
:raw-html:`</table>`
Here is the table:
:raw-html:`<table width="689" border="1" cellspacing="0">`
:raw-html:`<tr><td></td>`
:raw-html:`<td colspan="13" align="center" style="background-color:#ffc">Target</td>`
:raw-html:`</tr>`
:raw-html:`<tr>`
:raw-html:`<th>Feature</th>`
:raw-html:`<th>ARM</th>`
:raw-html:`<th>Hexagon</th>`
:raw-html:`<th>MSP430</th>`
:raw-html:`<th>Mips</th>`
:raw-html:`<th>NVPTX</th>`
:raw-html:`<th>PowerPC</th>`
:raw-html:`<th>Sparc</th>`
:raw-html:`<th>SystemZ</th>`
:raw-html:`<th>X86</th>`
:raw-html:`<th>XCore</th>`
:raw-html:`<th>eBPF</th>`
:raw-html:`</tr>`
: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="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="yes"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="yes"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="yes"></td> <!-- XCore -->`
:raw-html:`<td class="yes"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="no"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="no"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="no"></td> <!-- XCore -->`
:raw-html:`<td class="no"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="na"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="yes"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="yes"></td> <!-- XCore -->`
:raw-html:`<td class="yes"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="yes"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="unknown"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="yes"></td> <!-- XCore -->`
:raw-html:`<td class="no"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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> <!-- Hexagon -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="na"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="unknown"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="no"></td> <!-- XCore -->`
:raw-html:`<td class="yes"></td> <!-- eBPF -->`
:raw-html:`</tr>`
:raw-html:`<tr>`
:raw-html:`<td><a href="#feat_objectwrite">.o&nbsp;file writing</a></td>`
:raw-html:`<td class="no"></td> <!-- ARM -->`
:raw-html:`<td class="no"></td> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="na"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="no"></td> <!-- Sparc -->`
:raw-html:`<td class="yes"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="no"></td> <!-- XCore -->`
:raw-html:`<td class="yes"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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="yes"></td> <!-- Hexagon -->`
:raw-html:`<td class="unknown"></td> <!-- MSP430 -->`
:raw-html:`<td class="yes"></td> <!-- Mips -->`
:raw-html:`<td class="no"></td> <!-- NVPTX -->`
:raw-html:`<td class="yes"></td> <!-- PowerPC -->`
:raw-html:`<td class="unknown"></td> <!-- Sparc -->`
:raw-html:`<td class="no"></td> <!-- SystemZ -->`
:raw-html:`<td class="yes"></td> <!-- X86 -->`
:raw-html:`<td class="no"></td> <!-- XCore -->`
:raw-html:`<td class="no"></td> <!-- eBPF -->`
:raw-html:`</tr>`
: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> <!-- Hexagon -->`
:raw-html:`<td class="no"></td> <!-- MSP430 -->`
:raw-html:`<td class="no"></td> <!-- Mips -->`
:raw-html:`<td class="no"></td> <!-- NVPTX -->`
:raw-html:`<td class="no"></td> <!-- PowerPC -->`
:raw-html:`<td class="no"></td> <!-- Sparc -->`
:raw-html:`<td class="no"></td> <!-- SystemZ -->`
:raw-html:`<td class="partial"><a href="#feat_segstacks_x86">*</a></td> <!-- X86 -->`
:raw-html:`<td class="no"></td> <!-- XCore -->`
:raw-html:`<td class="no"></td> <!-- eBPF -->`
:raw-html:`</tr>`
:raw-html:`</table>`
.. _feat_reliable:
Is Generally Reliable
^^^^^^^^^^^^^^^^^^^^^
This box indicates whether the target is considered to be production quality.
This indicates that the target has been used as a static compiler to compile
large amounts of code by a variety of different people and is in continuous use.
.. _feat_asmparser:
Assembly Parser
^^^^^^^^^^^^^^^
This box indicates whether the target supports parsing target specific .s files
by implementing the MCAsmParser interface. This is required for llvm-mc to be
able to act as a native assembler and is required for inline assembly support in
the native .o file writer.
.. _feat_disassembler:
Disassembler
^^^^^^^^^^^^
This box indicates whether the target supports the MCDisassembler API for
disassembling machine opcode bytes into MCInst's.
.. _feat_inlineasm:
Inline Asm
^^^^^^^^^^
This box indicates whether the target supports most popular inline assembly
constraints and modifiers.
.. _feat_jit:
JIT Support
^^^^^^^^^^^
This box indicates whether the target supports the JIT compiler through the
ExecutionEngine interface.
.. _feat_jit_arm:
The ARM backend has basic support for integer code in ARM codegen mode, but
lacks NEON and full Thumb support.
.. _feat_objectwrite:
.o File Writing
^^^^^^^^^^^^^^^
This box indicates whether the target supports writing .o files (e.g. MachO,
ELF, and/or COFF) files directly from the target. Note that the target also
must include an assembly parser and general inline assembly support for full
inline assembly support in the .o writer.
Targets that don't support this feature can obviously still write out .o files,
they just rely on having an external assembler to translate from a .s file to a
.o file (as is the case for many C compilers).
.. _feat_tailcall:
Tail Calls
^^^^^^^^^^
This box indicates whether the target supports guaranteed tail calls. These are
calls marked "`tail <LangRef.html#i_call>`_" and use the fastcc calling
convention. Please see the `tail call section`_ for more details.
.. _feat_segstacks:
Segmented Stacks
^^^^^^^^^^^^^^^^
This box indicates whether the target supports segmented stacks. This replaces
the traditional large C stack with many linked segments. It is compatible with
the `gcc implementation <http://gcc.gnu.org/wiki/SplitStacks>`_ used by the Go
front end.
.. _feat_segstacks_x86:
Basic support exists on the X86 backend. Currently vararg doesn't work and the
object files are not marked the way the gold linker expects, but simple Go
programs can be built by dragonegg.
.. _tail call section: .. _tail call section:
Tail call optimization Tail call optimization
---------------------- ----------------------
Tail call optimization, callee reusing the stack of the caller, is currently Tail call optimization, callee reusing the stack of the caller, is currently
supported on x86/x86-64, PowerPC, AArch64, and WebAssembly. It is performed on supported on x86/x86-64, PowerPC, AArch64, and WebAssembly. It is performed on
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