llvm/docs/ReleaseNotes.md - llvm-project - Git at Google

 <!-- This document is written in Markdown and uses extra directives provided by
 MyST (https://myst-parser.readthedocs.io/en/latest/). -->

 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
 =================================================

 <!-- For small 1-3 sentence descriptions, just add an entry at the end of
 this list. If your description won't fit comfortably in one bullet
 point (e.g. maybe you would like to give an example of the
 functionality, or simply have a lot to talk about), see the comment below
 for adding a new subsection. -->

 * ...

 <!-- If you would like to document a larger change, then you can add a
 subsection about it right here. You can copy the following boilerplate:

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

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

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

 * The `x86_mmx` IR type has been removed. It will be translated to
   the standard vector type `<1 x i64>` in bitcode upgrade.
 * Renamed `llvm.experimental.stepvector` intrinsic to `llvm.stepvector`.

 * Added `usub_cond` and `usub_sat` operations to `atomicrmw`.

 * Introduced `noalias.addrspace` metadata.

 * Remove the following intrinsics which can be replaced with a `bitcast`:

   * `llvm.nvvm.bitcast.f2i`
   * `llvm.nvvm.bitcast.i2f`
   * `llvm.nvvm.bitcast.d2ll`
   * `llvm.nvvm.bitcast.ll2d`

 * Remove the following intrinsics which can be replaced with a funnel-shift:

   * `llvm.nvvm.rotate.b32`
   * `llvm.nvvm.rotate.right.b64`
   * `llvm.nvvm.rotate.b64`

 * Remove the following intrinsics which can be replaced with an
   `addrspacecast`:

   * `llvm.nvvm.ptr.gen.to.global`
   * `llvm.nvvm.ptr.gen.to.shared`
   * `llvm.nvvm.ptr.gen.to.constant`
   * `llvm.nvvm.ptr.gen.to.local`
   * `llvm.nvvm.ptr.global.to.gen`
   * `llvm.nvvm.ptr.shared.to.gen`
   * `llvm.nvvm.ptr.constant.to.gen`
   * `llvm.nvvm.ptr.local.to.gen`

 * Remove the following intrinsics which can be relaced with a load from
   addrspace(1) with an !invariant.load metadata

   * `llvm.nvvm.ldg.global.i`
   * `llvm.nvvm.ldg.global.f`
   * `llvm.nvvm.ldg.global.p`

 * Operand bundle values can now be metadata strings.

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

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

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

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

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

 * `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
   the required alignment space with a sequence of `0x0` bytes (the requested
   fill value) rather than NOPs.

 * Assembler/disassembler support has been added for Armv9.6-A (2024)
   architecture extensions.

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

 * Removed `llvm.amdgcn.flat.atomic.fadd` and
   `llvm.amdgcn.global.atomic.fadd` intrinsics. Users should use the
   {ref}`atomicrmw <i_atomicrmw>` instruction with `fadd` and
   addrspace(0) or addrspace(1) instead.

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

 * `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
   the required alignment space with a sequence of `0x0` bytes (the requested
   fill value) rather than NOPs.

 * The default behavior for frame pointers in leaf functions has been updated.
   When the `-fno-omit-frame-pointer` option is specified, `FPKeepKindStr` is
   set to `-mframe-pointer=all`, meaning the frame pointer (FP) is now retained
   in leaf functions by default. To eliminate the frame pointer in leaf functions,
   you must explicitly use the `-momit-leaf-frame-pointer` option.

 * When using the `MOVT` or `MOVW` instructions, the Assembler will now check to
   ensure that any addend that is used is within a 16-bit signed value range. If the
   addend falls outside of this range, the LLVM backend will emit an error like so
   `Relocation Not In Range`.

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

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

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

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

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

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

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

 * `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
   the required alignment space with a sequence of `0x0` bytes (the requested
   fill value) rather than NOPs.
 * Added Syntacore SCR4 and SCR5 CPUs: `-mcpu=syntacore-scr4/5-rv32/64`
 * `-mcpu=sifive-p470` was added.
 * Added Hazard3 CPU as taped out for RP2350: `-mcpu=rp2350-hazard3` (32-bit
   only).
 * Fixed length vector support using RVV instructions now requires VLEN>=64. This
   means Zve32x and Zve32f will also require Zvl64b. The prior support was
   largely untested.
 * The `Zvbc32e` and `Zvkgs` extensions are now supported experimentally.
 * Added `Smctr`, `Ssctr` and `Svvptc` extensions.
 * `-mcpu=syntacore-scr7` was added.
 * The `Zacas` extension is no longer marked as experimental.
 * The `Smmpm`, `Smnpm`, `Ssnpm`, `Supm`, and `Sspm` pointer masking extensions
   are no longer marked as experimental.
 * The `Sha` extension is now supported.
 * The RVA23U64, RVA23S64, RVB23U64, and RVB23S64 profiles are no longer marked
   as experimental.

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

 The default target CPU, "generic", now enables the `-mnontrapping-fptoint`
 and `-mbulk-memory` flags, which correspond to the [Bulk Memory Operations]
 and [Non-trapping float-to-int Conversions] language features, which are
 [widely implemented in engines].

 [Bulk Memory Operations]: https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
 [Non-trapping float-to-int Conversions]: https://github.com/WebAssembly/spec/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md
 [widely implemented in engines]: https://webassembly.org/features/

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

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

 * `.balign N, 0x90`, `.p2align N, 0x90`, and `.align N, 0x90` in code sections
   now fill the required alignment space with repeating `0x90` bytes, rather than
   using optimised NOP filling. Optimised NOP filling fills the space with NOP
   instructions of various widths, not just those that use the `0x90` byte
   encoding. To use optimised NOP filling in a code section, leave off the
   "fillval" argument, i.e. `.balign N`, `.p2align N` or `.align N` respectively.

 * Due to the removal of the `x86_mmx` IR type, functions with
   `x86_mmx` arguments or return values will use a different,
   incompatible, calling convention ABI. Such functions are not
   generally seen in the wild (Clang never generates them!), so this is
   not expected to result in real-world compatibility problems.

 * Support ISA of `AVX10.2-256` and `AVX10.2-512`.

 * Supported instructions of `MOVRS AND AVX10.2`

 * Supported ISA of `SM4(EVEX)`.

 * Supported ISA of `MSR_IMM`.

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

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

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

 * The following symbols are deleted due to the removal of the `x86_mmx` IR type:

   * `LLVMX86_MMXTypeKind`
   * `LLVMX86MMXTypeInContext`
   * `LLVMX86MMXType`

  * The following functions are added to further support non-null-terminated strings:

   * `LLVMGetNamedFunctionWithLength`
   * `LLVMGetNamedGlobalWithLength`

 * The following functions are added to access the `LLVMContextRef` associated
    with `LLVMValueRef` and `LLVMBuilderRef` objects:

   * `LLVMGetValueContext`
   * `LLVMGetBuilderContext`

 * The new pass manager can now be invoked with a custom alias analysis pipeline, using
   the `LLVMPassBuilderOptionsSetAAPipeline` function.

 * It is now also possible to run the new pass manager on a single function, by calling
   `LLVMRunPassesOnFunction` instead of `LLVMRunPasses`.

 * Support for creating instructions with custom synchronization scopes has been added:

   * `LLVMGetSyncScopeID` to map a synchronization scope name to an ID.
   * `LLVMBuildFenceSyncScope`, `LLVMBuildAtomicRMWSyncScope` and
     `LLVMBuildAtomicCmpXchgSyncScope` versions of the existing builder functions
     with an additional synchronization scope ID parameter.
   * `LLVMGetAtomicSyncScopeID` and `LLVMSetAtomicSyncScopeID` to get and set the
     synchronization scope of any atomic instruction.
   * `LLVMIsAtomic` to check if an instruction is atomic, for use with the above functions.
     Because of backwards compatibility, `LLVMIsAtomicSingleThread` and
     `LLVMSetAtomicSingleThread` continue to work with any instruction type.

 * The `LLVMSetPersonalityFn` and `LLVMSetInitializer` APIs now support clearing the
   personality function and initializer respectively by passing a null pointer.

 * The following functions are added to allow iterating over debug records attached to
   instructions:

   * `LLVMGetFirstDbgRecord`
   * `LLVMGetLastDbgRecord`
   * `LLVMGetNextDbgRecord`
   * `LLVMGetPreviousDbgRecord`

 * Added `LLVMAtomicRMWBinOpUSubCond` and `LLVMAtomicRMWBinOpUSubSat` to `LLVMAtomicRMWBinOp` enum for AtomicRMW instructions.

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

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

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

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

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

 * LLDB can now read the `fpmr` register from AArch64 Linux processes and core
   files.

 * Program stdout/stderr redirection will now open the file with O_TRUNC flag, make sure to truncate the file if path already exists.
   * eg. `settings set target.output-path/target.error-path <path/to/file>`

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

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

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

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

 * A project...

 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).
	<!-- This document is written in Markdown and uses extra directives provided by
	MyST (https://myst-parser.readthedocs.io/en/latest/). -->

	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
	=================================================

	<!-- For small 1-3 sentence descriptions, just add an entry at the end of
	this list. If your description won't fit comfortably in one bullet
	point (e.g. maybe you would like to give an example of the
	functionality, or simply have a lot to talk about), see the comment below
	for adding a new subsection. -->

	* ...

	<!-- If you would like to document a larger change, then you can add a
	subsection about it right here. You can copy the following boilerplate:

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

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

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

	* The `x86_mmx` IR type has been removed. It will be translated to
	the standard vector type `<1 x i64>` in bitcode upgrade.
	* Renamed `llvm.experimental.stepvector` intrinsic to `llvm.stepvector`.

	* Added `usub_cond` and `usub_sat` operations to `atomicrmw`.

	* Introduced `noalias.addrspace` metadata.

	* Remove the following intrinsics which can be replaced with a `bitcast`:

	* `llvm.nvvm.bitcast.f2i`
	* `llvm.nvvm.bitcast.i2f`
	* `llvm.nvvm.bitcast.d2ll`
	* `llvm.nvvm.bitcast.ll2d`

	* Remove the following intrinsics which can be replaced with a funnel-shift:

	* `llvm.nvvm.rotate.b32`
	* `llvm.nvvm.rotate.right.b64`
	* `llvm.nvvm.rotate.b64`

	* Remove the following intrinsics which can be replaced with an
	`addrspacecast`:

	* `llvm.nvvm.ptr.gen.to.global`
	* `llvm.nvvm.ptr.gen.to.shared`
	* `llvm.nvvm.ptr.gen.to.constant`
	* `llvm.nvvm.ptr.gen.to.local`
	* `llvm.nvvm.ptr.global.to.gen`
	* `llvm.nvvm.ptr.shared.to.gen`
	* `llvm.nvvm.ptr.constant.to.gen`
	* `llvm.nvvm.ptr.local.to.gen`

	* Remove the following intrinsics which can be relaced with a load from
	addrspace(1) with an !invariant.load metadata

	* `llvm.nvvm.ldg.global.i`
	* `llvm.nvvm.ldg.global.f`
	* `llvm.nvvm.ldg.global.p`

	* Operand bundle values can now be metadata strings.

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

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

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

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

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

	* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
	the required alignment space with a sequence of `0x0` bytes (the requested
	fill value) rather than NOPs.

	* Assembler/disassembler support has been added for Armv9.6-A (2024)
	architecture extensions.

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

	* Removed `llvm.amdgcn.flat.atomic.fadd` and
	`llvm.amdgcn.global.atomic.fadd` intrinsics. Users should use the
	{ref}`atomicrmw <i_atomicrmw>` instruction with `fadd` and
	addrspace(0) or addrspace(1) instead.

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

	* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
	the required alignment space with a sequence of `0x0` bytes (the requested
	fill value) rather than NOPs.

	* The default behavior for frame pointers in leaf functions has been updated.
	When the `-fno-omit-frame-pointer` option is specified, `FPKeepKindStr` is
	set to `-mframe-pointer=all`, meaning the frame pointer (FP) is now retained
	in leaf functions by default. To eliminate the frame pointer in leaf functions,
	you must explicitly use the `-momit-leaf-frame-pointer` option.

	* When using the `MOVT` or `MOVW` instructions, the Assembler will now check to
	ensure that any addend that is used is within a 16-bit signed value range. If the
	addend falls outside of this range, the LLVM backend will emit an error like so
	`Relocation Not In Range`.

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

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

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

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

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

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

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

	* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
	the required alignment space with a sequence of `0x0` bytes (the requested
	fill value) rather than NOPs.
	* Added Syntacore SCR4 and SCR5 CPUs: `-mcpu=syntacore-scr4/5-rv32/64`
	* `-mcpu=sifive-p470` was added.
	* Added Hazard3 CPU as taped out for RP2350: `-mcpu=rp2350-hazard3` (32-bit
	only).
	* Fixed length vector support using RVV instructions now requires VLEN>=64. This
	means Zve32x and Zve32f will also require Zvl64b. The prior support was
	largely untested.
	* The `Zvbc32e` and `Zvkgs` extensions are now supported experimentally.
	* Added `Smctr`, `Ssctr` and `Svvptc` extensions.
	* `-mcpu=syntacore-scr7` was added.
	* The `Zacas` extension is no longer marked as experimental.
	* The `Smmpm`, `Smnpm`, `Ssnpm`, `Supm`, and `Sspm` pointer masking extensions
	are no longer marked as experimental.
	* The `Sha` extension is now supported.
	* The RVA23U64, RVA23S64, RVB23U64, and RVB23S64 profiles are no longer marked
	as experimental.

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

	The default target CPU, "generic", now enables the `-mnontrapping-fptoint`
	and `-mbulk-memory` flags, which correspond to the [Bulk Memory Operations]
	and [Non-trapping float-to-int Conversions] language features, which are
	[widely implemented in engines].

	[Bulk Memory Operations]: https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
	[Non-trapping float-to-int Conversions]: https://github.com/WebAssembly/spec/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md
	[widely implemented in engines]: https://webassembly.org/features/

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

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

	* `.balign N, 0x90`, `.p2align N, 0x90`, and `.align N, 0x90` in code sections
	now fill the required alignment space with repeating `0x90` bytes, rather than
	using optimised NOP filling. Optimised NOP filling fills the space with NOP
	instructions of various widths, not just those that use the `0x90` byte
	encoding. To use optimised NOP filling in a code section, leave off the
	"fillval" argument, i.e. `.balign N`, `.p2align N` or `.align N` respectively.

	* Due to the removal of the `x86_mmx` IR type, functions with
	`x86_mmx` arguments or return values will use a different,
	incompatible, calling convention ABI. Such functions are not
	generally seen in the wild (Clang never generates them!), so this is
	not expected to result in real-world compatibility problems.

	* Support ISA of `AVX10.2-256` and `AVX10.2-512`.

	* Supported instructions of `MOVRS AND AVX10.2`

	* Supported ISA of `SM4(EVEX)`.

	* Supported ISA of `MSR_IMM`.

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

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

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

	* The following symbols are deleted due to the removal of the `x86_mmx` IR type:

	* `LLVMX86_MMXTypeKind`
	* `LLVMX86MMXTypeInContext`
	* `LLVMX86MMXType`

	* The following functions are added to further support non-null-terminated strings:

	* `LLVMGetNamedFunctionWithLength`
	* `LLVMGetNamedGlobalWithLength`

	* The following functions are added to access the `LLVMContextRef` associated
	with `LLVMValueRef` and `LLVMBuilderRef` objects:

	* `LLVMGetValueContext`
	* `LLVMGetBuilderContext`

	* The new pass manager can now be invoked with a custom alias analysis pipeline, using
	the `LLVMPassBuilderOptionsSetAAPipeline` function.

	* It is now also possible to run the new pass manager on a single function, by calling
	`LLVMRunPassesOnFunction` instead of `LLVMRunPasses`.

	* Support for creating instructions with custom synchronization scopes has been added:

	* `LLVMGetSyncScopeID` to map a synchronization scope name to an ID.
	* `LLVMBuildFenceSyncScope`, `LLVMBuildAtomicRMWSyncScope` and
	`LLVMBuildAtomicCmpXchgSyncScope` versions of the existing builder functions
	with an additional synchronization scope ID parameter.
	* `LLVMGetAtomicSyncScopeID` and `LLVMSetAtomicSyncScopeID` to get and set the
	synchronization scope of any atomic instruction.
	* `LLVMIsAtomic` to check if an instruction is atomic, for use with the above functions.
	Because of backwards compatibility, `LLVMIsAtomicSingleThread` and
	`LLVMSetAtomicSingleThread` continue to work with any instruction type.

	* The `LLVMSetPersonalityFn` and `LLVMSetInitializer` APIs now support clearing the
	personality function and initializer respectively by passing a null pointer.

	* The following functions are added to allow iterating over debug records attached to
	instructions:

	* `LLVMGetFirstDbgRecord`
	* `LLVMGetLastDbgRecord`
	* `LLVMGetNextDbgRecord`
	* `LLVMGetPreviousDbgRecord`

	* Added `LLVMAtomicRMWBinOpUSubCond` and `LLVMAtomicRMWBinOpUSubSat` to `LLVMAtomicRMWBinOp` enum for AtomicRMW instructions.

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

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

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

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

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

	* LLDB can now read the `fpmr` register from AArch64 Linux processes and core
	files.

	* Program stdout/stderr redirection will now open the file with O_TRUNC flag, make sure to truncate the file if path already exists.
	* eg. `settings set target.output-path/target.error-path <path/to/file>`

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

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

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

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

	* A project...

	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).