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LLVM {{env.config.release}} Release Notes
=========================================

```{contents}
```

````{only} PreRelease
```{warning} These are in-progress notes for the upcoming LLVM {{env.config.release}}
             release. Release notes for previous releases can be found on
             [the Download Page](https://releases.llvm.org/download.html).
```
````

Introduction
============

This document contains the release notes for the LLVM Compiler Infrastructure,
release {{env.config.release}}.  Here we describe the status of LLVM, including
major improvements from the previous release, improvements in various subprojects
of LLVM, and some of the current users of the code.  All LLVM releases may be
downloaded from the [LLVM releases web site](https://llvm.org/releases/).

For more information about LLVM, including information about the latest
release, please check out the [main LLVM web site](https://llvm.org/).  If you
have questions or comments, the [Discourse forums](https://discourse.llvm.org)
is a good place to ask them.

Note that if you are reading this file from a Git checkout or the main
LLVM web page, this document applies to the *next* release, not the current
one.  To see the release notes for a specific release, please see the
[releases page](https://llvm.org/releases/).

Non-comprehensive list of changes in this release
=================================================

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* ...

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Special New Feature
-------------------

Makes programs 10x faster by doing Special New Thing.
-->

Changes to the LLVM IR
----------------------

* Removed `llvm.convert.to.fp16` and `llvm.convert.from.fp16`
  intrinsics. These are equivalent to `fptrunc` and `fpext` with half
  with a bitcast.

* "denormal-fp-math" and "denormal-fp-math-f32" string attributes were
  migrated to first-class denormal_fpenv attribute.

* The `"nooutline"` attribute is now writen as `nooutline`. Existing IR and
  bitcode will be automatically updated.

Changes to LLVM infrastructure
------------------------------

* Removed ``Constant::isZeroValue``. It was functionally identical to
  ``Constant::isNullValue`` for all types except floating-point negative
  zero. All callers should use ``isNullValue`` instead. ``isZeroValue``
  will be reintroduced in the future with bitwise-all-zeros semantics
  to support non-zero null pointers.

* Removed TypePromoteFloat legalization from SelectionDAG

* Removed `bugpoint`. Usage has been replaced by `llvm-reduce` and
  `llvm/utils/reduce_pipeline.py`.

Changes to building LLVM
------------------------

Changes to TableGen
-------------------

Changes to Interprocedural Optimizations
----------------------------------------

Changes to Vectorizers
----------------------

Changes to the AArch64 Backend
------------------------------

* The `sysp`, `mrrs`, and `msrr` instructions are now accepted without
  requiring the `+d128` feature gating.

Changes to the AMDGPU Backend
-----------------------------

* Initial support for gfx1310

Changes to the ARM Backend
--------------------------

* The `r14` register can now be used as an alias for the link register `lr`
  in inline assembly. Clang always canonicalizes the name to `lr`, but other
  frontends may not.

Changes to the AVR Backend
--------------------------

Changes to the DirectX Backend
------------------------------

Changes to the Hexagon Backend
------------------------------

Changes to the LoongArch Backend
--------------------------------

* DWARF fission is now compatible with linker relaxations, allowing `-gsplit-dwarf` and `-mrelax`
  to be used together when building for the LoongArch platform.

Changes to the MIPS Backend
---------------------------

Changes to the NVPTX Backend
----------------------------

* The default SM version has been changed from `sm_30` to `sm_75`. `sm_75` is
  the oldest GPU variant compatible with the widest range of recent major CUDA
  Toolkit versions (11/12/13).

Changes to the PowerPC Backend
------------------------------

Changes to the RISC-V Backend
-----------------------------

* `llvm-objdump` now has support for `--symbolize-operands` with RISC-V.
* `-mcpu=spacemit-x100` was added.
* Change P extension version to match the 019 draft specification. Encoded in `-march` as `0p19`.
* Mnemonics for MOP/HINT-based instructions (`lpad`, `pause`, `ntl.*`, `c.ntl.*`,
  `sspush`, `sspopchk`, `ssrdp`, `c.sspush`, `c.sspopchk`) are now always
  available in the assembler and disassembler without requiring their respective
  extensions.
* Adds experimental assembler support for the 'Zvabd` (RISC-V Integer Vector
  Absolute Difference) extension.
* `-mcpu=spacemit-a100` was added.
* The opt-in `-riscv-enable-p-ext-simd-codegen` flag has been removed. P extension SIMD code generation is now enabled automatically if the P extension is supported.
* `-mcpu=xt-c910v2` and `-mcpu=xt-c920v2` were added.

Changes to the WebAssembly Backend
----------------------------------

Changes to the Windows Target
-----------------------------

* The `.seh_startchained` and `.seh_endchained` assembly instructions have been removed and replaced
  with a new `.seh_splitchained` instruction.

Changes to the X86 Backend
--------------------------

* `.att_syntax` directive is now emitted for assembly files when AT&T syntax is
  in use. This matches the behaviour of Intel syntax and aids with
  compatibility when changing the default Clang syntax to the Intel syntax.

Changes to the OCaml bindings
-----------------------------

Changes to the Python bindings
------------------------------

Changes to the C API
--------------------

Changes to the CodeGen infrastructure
-------------------------------------

Changes to the Metadata Info
----------------------------

Changes to the Debug Info
-------------------------

Changes to the LLVM tools
-------------------------

* `llvm-objcopy` no longer corrupts the symbol table when `--update-section` is called for ELF files.
* `FileCheck` option `-check-prefix` now accepts a comma-separated list of
  prefixes, making it an alias of the existing `-check-prefixes` option.

Changes to LLDB
---------------

### Deprecated APIs

* ``SBTarget::GetDataByteSize()``, ``SBTarget::GetCodeByteSize()``, and ``SBSection::GetTargetByteSize()``
  have been deprecated. They always return 1, as before.

### FreeBSD

#### Userspace Debugging

* Support for MIPS64 has been removed.
* The minimum assumed FreeBSD version is now 14. The effect of which is that watchpoints are
  assumed to be supported.

#### Kernel Debugging

* The plugin that analyzes FreeBSD kernel core dump and live core has been renamed from `freebsd-kernel` to
 `freebsd-kernel-core`. Remote kernel debugging is still handled by the `gdb-remote` plugin. 
* Support for libfbsdvmcore has been removed. As a result, FreeBSD kernel dump debugging is now only
  available on FreeBSD hosts. Live kernel debugging through the GDB remote protocol is still available
  from any platform.
* Support for ARM, PPC64le, and RISCV64 has been added.
* The crashed thread is now automatically selected on start.
* Threads are listed in incrmental order by pid then by tid.
* Unread kernel messages saved in msgbufp are now printed when lldb starts. This information is printed only
  when lldb is in the interactive mode (i.e. not in batch mode).
* Writing to the core is now supported. For safety reasons, this feature is off by default. To enable it,
  `plugin.process.freebsd-kernel-core.read-only` must be set to `false`. This setting is available when
  using `/dev/mem` or a kernel dump. However, since `kvm_write()` does not support writing to kernel dumps,
  writes to a kernel dump will still fail when the setting is false.

### Linux

* On Arm Linux, the tpidruro register can now be read. Writing to this register is not supported.
* Thread local variables are now supported on Arm Linux if the program being debugged is using glibc.

Changes to BOLT
---------------

Changes to Sanitizers
---------------------

* Add a random delay into ThreadSanitizer to help find rare thread interleavings.

Other Changes
-------------

External Open Source Projects Using LLVM {{env.config.release}}
===============================================================

Additional Information
======================

A wide variety of additional information is available on the
[LLVM web page](https://llvm.org/), in particular in the
[documentation](https://llvm.org/docs/) section.  The web page also contains
versions of the API documentation which is up-to-date with the Git version of
the source code.  You can access versions of these documents specific to this
release by going into the `llvm/docs/` directory in the LLVM tree.

If you have any questions or comments about LLVM, please feel free to contact
us via the [Discourse forums](https://discourse.llvm.org).