[PATCH] D72798: [llvm][docs] LangRef for IR attribute `vector-function-abi-variants`.
Francesco Petrogalli via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 22 12:42:19 PST 2020
fpetrogalli updated this revision to Diff 239671.
fpetrogalli marked an inline comment as done.
fpetrogalli added a comment.
Fix a typo in the name of the attribute (remove trailing `s`).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D72798/new/
https://reviews.llvm.org/D72798
Files:
llvm/docs/LangRef.rst
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1865,6 +1865,73 @@
function has not changed between the function prolog and eiplog. It is
currently x86_64-specific.
+Call Site Attributes
+----------------------
+
+In addition to function attributes the following call site only
+attributes are supported:
+
+``vector-function-abi-variant`` This attribute can be attached to a
+ :ref:`call <i_call>` to list the vector functions associated to the
+ function. Notice that the attribute cannot be attached to a
+ :ref:`invoke <i_invoke>` or a :ref:`callbr <i_callbr>` instruction.
+ The attribute consists of a comma separated list of mangled names. The
+ syntax for the mangled names is as follows:
+
+ _ZGV<isa><mask><vlen><parameters>_<scalar_name>[(<vector_redirection>)]
+
+ When present, the attribute informs the compiler that the function
+ ``<scalar_name>`` has a corresponding vector variant that can be
+ used to perform the concurrent invocation of ``<scalar_name>`` on
+ vectors. The shape of the vector function is described by the
+ tokens between the prefix ``_ZGV`` and the ``<scalar_name>``
+ token. The standard name of the vector function is
+ ``_ZGV<isa><mask><vlen><parameters>_<scalar_name>``. When present,
+ the optional token ``(<vector_redirection>)`` informs the compiler
+ that a custom name is provided in addition to the standard one
+ (custom names can be provided for example via the use of ``declare
+ variant`` in OpenMP 5.0). The declaration of the variant must be
+ present in the IR Module. The signature of the vector variant is
+ determined by the rules of the Vector Function ABI (VFABI)
+ specifications of the target. For Arm and X86, the VFABI can be
+ found at https://github.com/ARM-software/software-standards and
+ https://software.intel.com/en-us/articles/vector-simd-function-abi,
+ respectively.
+
+ For X86 and Arm targets, the values of the tokens in the standard
+ name are those that are defined in the VFABI. LLVM has an internal
+ ``<isa>`` token that can be used to create scalar-to-vector
+ mappings for functions that are not directly associated to any
+ of the target ISAs (for example, some of the mappings stored in
+ the TargetLibraryInfo). Valid values for the ``<isa>`` token are:
+
+ <isa>:= b | c | d | e -> X86 SSE, AVX, AVX2, AVX512
+ | n | s -> Armv8 Advanced SIMD, SVE
+ | __LLVM__ -> Internal LLVM Vector ISA
+
+ For all targets currently supported (x86, Arm and Internal LLVM),
+ the remaining tokens can have the following values:
+
+ <mask>:= M | N -> mask | no mask
+
+ <vlen>:= number -> number of lanes
+ | x -> VLA (Vector Length Agnostic)
+
+ <parameters>:= v -> vector
+ | l | l <number> -> linear
+ | R | R <number> -> linear with ref modifier
+ | L | L <number> -> linear with val modifier
+ | U | U <number> -> linear with uval modifier
+ | ls <pos> -> runtime linear
+ | Rs <pos> -> runtime linear with ref modifier
+ | Ls <pos> -> runtime linear with val modifier
+ | Us <pos> -> runtime linear with uval modifier
+ | u -> uniform
+
+ <scalar_name>:= name of the scalar function
+
+ <vector_redirection>:= optional, custom name of the vector function
+
.. _glattrs:
Global Attributes
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