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ARM Compiler Migration and Compatibility Guide : Support level definitions

Support level definitions

Describes the levels of support for various ARM® Compiler features.

ARM Compiler 6 is built on Clang and LLVM technology and as such, has more functionality than the set of product features described in the documentation. The following definitions clarify the levels of support and guarantees on functionality that are expected from these features.

ARM welcomes feedback regarding the use of all ARM Compiler 6 features, and endeavors to support users to a level that is appropriate for that feature. You can contact support at

Identification in the documentation

All features that are documented in the ARM Compiler 6 documentation are product features, except where explicitly stated. The limitations of non-product features are explicitly stated.

Product features

Product features are suitable for use in a production environment. The functionality is well-tested, and is expected to be stable across feature and update releases.

  • ARM endeavors to give advance notice of significant functionality changes to product features.
  • If you have a support and maintenance contract, ARM provides full support for use of all product features.
  • ARM welcomes feedback on product features.
  • Any issues with product features that ARM encounters or is made aware of are considered for fixing in future versions of ARM Compiler.

In addition to fully supported product features, some product features are only alpha or beta quality.

Beta product features

Beta product features are implementation complete, but have not been sufficiently tested to be regarded as suitable for use in production environments.

Beta product features are indicated with [BETA].

  • ARM endeavors to document known limitations on beta product features.
  • Beta product features are expected to eventually become product features in a future release of ARM Compiler 6.
  • ARM encourages the use of beta product features, and welcomes feedback on them.
  • Any issues with beta product features that ARM encounters or is made aware of are considered for fixing in future versions of ARM Compiler.
Alpha product features

Alpha product features are not implementation complete, and are subject to change in future releases, therefore the stability level is lower than in beta product features.

Alpha product features are indicated with [ALPHA].

  • ARM endeavors to document known limitations of alpha product features.
  • ARM encourages the use of alpha product features, and welcomes feedback on them.
  • Any issues with alpha product features that ARM encounters or is made aware of are considered for fixing in future versions of ARM Compiler.

Community features

ARM Compiler 6 is built on LLVM technology and preserves the functionality of that technology where possible. This means that there are additional features available in ARM Compiler that are not listed in the documentation. These additional features are known as community features. For information on these community features, see the documentation for the Clang/LLVM project.

Where community features are referenced in the documentation, they are indicated with [COMMUNITY].

  • ARM makes no claims about the quality level or the degree of functionality of these features, except when explicitly stated in this documentation.
  • Functionality might change significantly between feature releases.
  • ARM makes no guarantees that community features are going to remain functional across update releases, although changes are expected to be unlikely.

Some community features might become product features in the future, but ARM provides no roadmap for this. ARM is interested in understanding your use of these features, and welcomes feedback on them. ARM supports customers using these features on a best-effort basis, unless the features are unsupported. ARM accepts defect reports on these features, but does not guarantee that these issues are going to be fixed in future releases.

Guidance on use of community features

There are several factors to consider when assessing the likelihood of a community feature being functional:

  • The following figure shows the structure of the ARM Compiler 6 toolchain:

    Figure 1-1 Integration boundaries in ARM Compiler 6.

    The dashed boxes are toolchain components, and any interaction between these components is an integration boundary. Community features that span an integration boundary might have significant limitations in functionality. The exception to this is if the interaction is codified in one of the standards supported by ARM Compiler 6. See Application Binary Interface (ABI) for the ARM® Architecture. Community features that do not span integration boundaries are more likely to work as expected.
  • Features primarily used when targeting hosted environments such as Linux or BSD, might have significant limitations, or might not be applicable, when targeting bare-metal environments.
  • The Clang implementations of compiler features, particularly those that have been present for a long time in other toolchains, are likely to be mature. The functionality of new features, such as support for new language features, is likely to be less mature and therefore more likely to have limited functionality.

Unsupported features

With both the product and community feature categories, specific features and use-cases are known not to function correctly, or are not intended for use with ARM Compiler 6.

Limitations of product features are stated in the documentation. ARM cannot provide an exhaustive list of unsupported features or use-cases for community features. The known limitations on community features are listed in Community features.

List of known unsupported features

The following is an incomplete list of unsupported features, and might change over time:

  • The Clang option -stdlib=libstdc++ is not supported.

  • The ARM Compiler 6 libc++ libraries do not support the Thread support library <thread>.
  • C++ static initialization of local variables is not thread-safe when linked against the standard C++ libraries. For thread-safety, you must provide your own implementation of thread-safe functions as described in Standard C++ library implementation definition.
  • Use of C11 library features is unsupported.
  • Any community feature that exclusively pertains to non-ARM architectures is not supported by ARM Compiler 6.
  • Compilation for targets that implement architectures older that ARMv7 or ARMv6-M is not supported.