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[LangRef][VP] Document vp.load and vp.store intrinsics 

This patch fleshes out the missing documentation for two of the VP
intrinsics introduced in D99355: `llvm.vp.load` and `llvm.vp.store`. It
does so mostly by deferring to the `llvm.masked.load` and
`llvm.masked.store` intrinsics, respectively.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D112930
This commit is contained in:
Fraser Cormack 2021-11-01 14:40:09 +00:00
parent 737f540abd
commit 93e1802af3
1 changed files with 109 additions and 0 deletions
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llvm/docs/LangRef.rst
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@ -19604,6 +19604,115 @@ Examples:
llvm.experimental.vp.splice(<A,B,C,D>, <E,F,G,H>, -2, 3, 2) ==> <B, C, undef, undef> ; trailing elements
.. _int_vp_load:
'``llvm.vp.load``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Syntax:
"""""""
This is an overloaded intrinsic.
::
declare <4 x float> @llvm.vp.load.v4f32.p0v4f32(<4 x float>* %ptr, <4 x i1> %mask, i32 %evl)
declare <vscale x 2 x i16> @llvm.vp.load.nxv2i16.p0nxv2i16(<vscale x 2 x i16>* %ptr, <vscale x 2 x i1> %mask, i32 %evl)
declare <8 x float> @llvm.vp.load.v8f32.p1v8f32(<8 x float> addrspace(1)* %ptr, <8 x i1> %mask, i32 %evl)
declare <vscale x 1 x i64> @llvm.vp.load.nxv1i64.p6nxv1i64(<vscale x 1 x i64> addrspace(6)* %ptr, <vscale x 1 x i1> %mask, i32 %evl)
Overview:
"""""""""
The '``llvm.vp.load.*``' intrinsic is the vector length predicated version of
the :ref:`llvm.masked.load <int_mload>` intrinsic.
Arguments:
""""""""""
The first operand is the base pointer for the load. The second operand is a
vector of boolean values with the same number of elements as the return type.
The third is the explicit vector length of the operation. The return type and
underlying type of the base pointer are the same vector types.
Semantics:
""""""""""
The '``llvm.vp.load``' intrinsic reads a vector from memory in the same way as
the '``llvm.masked.load``' intrinsic, where the mask is taken from the
combination of the '``mask``' and '``evl``' operands in the usual VP way. Of
the '``llvm.masked.load``' operands not set by '``llvm.vp.load``': the
'``passthru``' operand is implicitly ``undef``; the '``alignment``' operand is
taken as the ABI alignment of the return type as specified by the
:ref:`datalayout string<langref_datalayout>`.
Examples:
"""""""""
.. code-block:: text
%r = call <8 x i8> @llvm.vp.load.v8i8.p0v8i8(<8 x i8>* %ptr, <8 x i1> %mask, i32 %evl)
;; For all lanes below %evl, %r is lane-wise equivalent to %also.r
;; Note that since the alignment is ultimately up to the data layout
;; string, 8 (the default) is used as an example.
%also.r = call <8 x i8> @llvm.masked.load.v8i8.p0v8i8(<8 x i8>* %ptr, i32 8, <8 x i1> %mask, <8 x i8> undef)
.. _int_vp_store:
'``llvm.vp.store``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Syntax:
"""""""
This is an overloaded intrinsic.
::
declare void @llvm.vp.store.v4f32.p0v4f32(<4 x float> %val, <4 x float>* %ptr, <4 x i1> %mask, i32 %evl)
declare void @llvm.vp.store.nxv2i16.p0nxv2i16(<vscale x 2 x i16> %val, <vscale x 2 x i16>* %ptr, <vscale x 2 x i1> %mask, i32 %evl)
declare void @llvm.vp.store.v8f32.p1v8f32(<8 x float> %val, <8 x float> addrspace(1)* %ptr, <8 x i1> %mask, i32 %evl)
declare void @llvm.vp.store.nxv1i64.p6nxv1i64(<vscale x 1 x i64> %val, <vscale x 1 x i64> addrspace(6)* %ptr, <vscale x 1 x i1> %mask, i32 %evl)
Overview:
"""""""""
The '``llvm.vp.store.*``' intrinsic is the vector length predicated version of
the :ref:`llvm.masked.store <int_mstore>` intrinsic.
Arguments:
""""""""""
The first operand is the vector value to be written to memory. The second
operand is the base pointer for the store. It has the same underlying type as
the value operand. The third operand is a vector of boolean values with the
same number of elements as the return type. The fourth is the explicit vector
length of the operation.
Semantics:
""""""""""
The '``llvm.vp.store``' intrinsic reads a vector from memory in the same way as
the '``llvm.masked.store``' intrinsic, where the mask is taken from the
combination of the '``mask``' and '``evl``' operands in the usual VP way. The
'``alignment``' operand of the '``llvm.masked.store``' intrinsic is not set by
'``llvm.vp.store``': it is taken as the ABI alignment of the type of the
'``value``' operand as specified by the :ref:`datalayout
string<langref_datalayout>`.
Examples:
"""""""""
.. code-block:: text
call void @llvm.vp.store.v8i8.p0v8i8(<8 x i8> %val, <8 x i8>* %ptr, <8 x i1> %mask, i32 %evl)
;; For all lanes below %evl, the call above is lane-wise equivalent to the call below.
;; Note that since the alignment is ultimately up to the data layout
;; string, 8 (the default) is used as an example.
call void @llvm.masked.store.v8i8.p0v8i8(<8 x i8> %val, <8 x i8>* %ptr, i32 8, <8 x i1> %mask)
.. _int_mload_mstore:
Masked Vector Load and Store Intrinsics