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| author | Kerry McLaughlin <kerry.mclaughlin@arm.com> | 2023-08-29 13:23:18 +0000 |
|---|---|---|
| committer | Kerry McLaughlin <kerry.mclaughlin@arm.com> | 2023-10-31 10:48:08 +0000 |
| commit | 3b786f2c7608964b4481b9fcd24ab29c7c42243d (patch) | |
| tree | 679c14f628cebc3469728ac4e6c4e892b06652ed /llvm/docs/LangRef.rst | |
| parent | 00a831421fdd94aec65221bdb37042c1aacfe8e0 (diff) | |
| download | llvm-3b786f2c7608964b4481b9fcd24ab29c7c42243d.zip llvm-3b786f2c7608964b4481b9fcd24ab29c7c42243d.tar.gz llvm-3b786f2c7608964b4481b9fcd24ab29c7c42243d.tar.bz2 | |
[AArch64] Add intrinsic to count trailing zero elements
This patch introduces an experimental intrinsic for counting the
trailing zero elements in a vector. The intrinsic has generic expansion
in SelectionDAGBuilder, and for AArch64 there is a pattern which matches
to brkb & cntp instructions where SVE is enabled.
The intrinsic has a second operand, is_zero_poison, similar to the
existing cttz intrinsic.
These changes have been split out from D158291.
Diffstat (limited to 'llvm/docs/LangRef.rst')
| -rw-r--r-- | llvm/docs/LangRef.rst | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 803503a..d867982 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -18497,6 +18497,45 @@ Arguments: Both arguments must be vectors of the same type whereby their logical concatenation matches the result type. +'``llvm.experimental.cttz.elts``' Intrinsic +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Syntax: +""""""" + +This is an overloaded intrinsic. You can use ```llvm.experimental.cttz.elts``` +on any vector of integer elements, both fixed width and scalable. + +:: + + declare i8 @llvm.experimental.cttz.elts.i8.v8i1(<8 x i1> <src>, i1 <is_zero_poison>) + +Overview: +""""""""" + +The '``llvm.experimental.cttz.elts``' intrinsic counts the number of trailing +zero elements of a vector. + +Arguments: +"""""""""" + +The first argument is the vector to be counted. This argument must be a vector +with integer element type. The return type must also be an integer type which is +wide enough to hold the maximum number of elements of the source vector. The +behaviour of this intrinsic is undefined if the return type is not wide enough +for the number of elements in the input vector. + +The second argument is a constant flag that indicates whether the intrinsic +returns a valid result if the first argument is all zero. If the first argument +is all zero and the second argument is true, the result is poison. + +Semantics: +"""""""""" + +The '``llvm.experimental.cttz.elts``' intrinsic counts the trailing (least +significant) zero elements in a vector. If ``src == 0`` the result is the +number of elements in the input vector. + '``llvm.experimental.vector.splice``' Intrinsic ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |