Application Binary Interface for the LoongArch™ Architecture

This is the official documentation of the Application Binary Interface for the LoongArch™ Architecture.

Releases

The latest ABI documentation releases are available at https://github.com/loongson/la-abi-specs and are licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License.

Defect reports

Please report defects in or enhancements to the specifications in this folder to the issue tracker page on GitHub.

List of documents

specification	latest
Procedure Call Standard for the LoongArch™ Architecture	lapcs
ELF for the LoongArch™ Architecture	laelf
DWARF for the LoongArch™ Architecture	ladwarf

Contributing

Please refer to the contribution guidelines in CONTRIBUTING.

License

The ABI documents and their source files are currently licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License. Contributions to these files are accepted under the same license.

To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Revision History

Legacy versions of the documents were released at the Github repository LoongArch-Documentation. These include version 1.00, 2.00 and 2.01.

All changes to the documents in a subsequent release should be declared in their change history section respectively. Timestamps in the form YYYYMMDD should be used for versioning of the individual documents in this folder, and a global version number which correspond to a combination of individual document versions will still be assigned to every new release of this collection.

This global version number will continue to follow the legacy versioning scheme, where a change of the major version (currently 1 and 2) could potentially degrade binary compatibility between objects conforming to these specifications, while a change to the two-digit minor version signifies other bugfixes and improvements.

Please note that we do not expect the major version to change at any time in the forseeable future, and the minor version may increase by more than 1 in a new public release for project management purposes.

• v1.00

  • Add register usage convention, data type conventions and the list of ELF relocation types.

• v2.00

  • Add description of ILP32 data model.
  • Add description of return value register aliases.
  • Add relocation types with direct immediate-filling semantics.
  • Add ABI version porting guidelines for toolchain implementations.
  • Add link to SysV gABI documentation.
  • Adjust asciidoc code style.

• v2.01

  • Adjust description of ABI type encoding scheme.
  • Add header for all tables.

• v2.10

  • Split the original psABI documentation (v2.01) into the lapcs and laelf documents.
  • Add the DWARF standard for the LoongArch™ architecture (ladwarf) document.
  • Differentiate machine data types with the C/C++ types.
  • Clarify parameter passing rules for small structs that contain both floating-point and integer members.
  • Clarify parameter passing rules for structs that contain zero-length arrays or bitfields.

• v2.20

  • Revise the parameter passing rules of structures.
  • Add R_LARCH_CALL36 relocation type.
  • Remove R_LARCH_DELETE and mark its relocation number as reserved.
  • Remove R_LARCH_CFA and mark its relocation number as reserved.
  • Fix ULEB128 relocation name (R_LARCH_SUB_ULEB128).

• v2.30

  • Add vector arguments passing rules to the base ABI.
  • Add the Code Models chapter and require extreme code model instructions sequence to be adjacent.
  • Add relocation types for TLS descriptors.

I18n

This specification is written in both English and Chinese. In the event of any inconsistency between the same document version in two languages, the Chinese version shall prevail.