diff options
Diffstat (limited to 'llvm/docs')
| -rw-r--r-- | llvm/docs/DirectXUsage.rst | 8 | ||||
| -rw-r--r-- | llvm/docs/LangRef.rst | 29 |
2 files changed, 33 insertions, 4 deletions
diff --git a/llvm/docs/DirectXUsage.rst b/llvm/docs/DirectXUsage.rst index 1d964e6..78f27d8 100644 --- a/llvm/docs/DirectXUsage.rst +++ b/llvm/docs/DirectXUsage.rst @@ -29,7 +29,7 @@ Initially the backend is aimed at supporting DirectX 12, and support for DirectX 11 is planned at a later date. The DirectX backend is currently experimental and is not shipped with any -release builds of LLVM tools. To enable building the DirectX backend locally add +release builds of LLVM tools. To build the DirectX backend locally, add ``DirectX`` to the ``LLVM_EXPERIMENTAL_TARGETS_TO_BUILD`` CMake option. For more information on building LLVM see the :doc:`CMake` documentation. @@ -38,7 +38,7 @@ information on building LLVM see the :doc:`CMake` documentation. Target Triples ============== -At present the DirectX target only supports the ``dxil`` architecture, which +At present, the DirectX target only supports the ``dxil`` architecture, which generates code for the `DirectX Intermediate Language. <https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/DXIL.rst>`_ @@ -46,8 +46,8 @@ In addition to target architecture, the DirectX backend also needs to know the target runtime version and pipeline stage. These are expressed using the OS and Environment triple component. -Presently the DirectX backend requires targeting the ``shadermodel`` OS, and -supports versions 6.0+ (at time of writing the latest announced version is 6.7). +Presently, the DirectX backend requires targeting the ``shadermodel`` OS, and +supports versions 6.0+ (as of writing, the latest announced version is 6.7). .. table:: DirectX Environments diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 8e86393..22b58bf 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -1489,6 +1489,8 @@ Currently, only the following parameter attributes are defined: function, returning a pointer to allocated storage disjoint from the storage for any other object accessible to the caller. +.. _captures_attr: + ``captures(...)`` This attribute restricts the ways in which the callee may capture the pointer. This is not a valid attribute for return values. This attribute @@ -7543,6 +7545,33 @@ The number of bytes known to be dereferenceable is specified by the integer value in the metadata node. This is analogous to the ''dereferenceable_or_null'' attribute on parameters and return values. +'``captures``' Metadata +^^^^^^^^^^^^^^^^^^^^^^^ + +The ``!captures`` metadata can only be applied to ``store`` instructions with +a pointer-typed value operand. It restricts the capturing behavior of the store +value operand in the same way the ``captures(...)`` attribute would do on a +call. See the :ref:`pointer capture section <pointercapture>` for a detailed +discussion of capture semantics. + +The ``!captures`` metadata accepts a non-empty list of strings from the same +set as the :ref:`captures attribute <captures_attr>`: +``!"address"``, ``!"address_is_null"``, ``!"provenance"`` and +``!"read_provenance"``. ``!"none"`` is not supported. + +For example ``store ptr %x, ptr %y, !captures !{!"address"}`` indicates that +the copy of pointer ``%x`` stored to location ``%y`` will only be used to +inspect its integral address value, and not dereferenced. Dereferencing the +pointer would result in undefined behavior. + +Similarly ``store ptr %x, ptr %y, !captures !{!"address", !"read_provenance"}`` +indicates that while reads through the stored pointer are allowed, writes would +result in undefined behavior. + +The ``!captures`` attribute makes no statement about other uses of ``%x``, or +uses of the stored-to memory location after it has been overwritten with a +different value. + .. _llvm.loop: '``llvm.loop``' |