[PATCH] D94708: [IR] Introduce llvm.experimental.vector.splice intrinsic

[Vineet Kumar via Phabricator via llvm-commits]

vkmr added a comment.

FWIW, we have a similar intrinsic in our downstream compiler for RISC-V. We call it `experimental.vector.slideleftfill` and is same as flavour 2 of this (except the "offset" need not be an immediate) as suggested by @sdesmalen. We have a separate predicated version (`experimental.vector.vp.slideleftfill`) too which takes additional arguments for the explicit vector length of the two vectors.



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Comment at: llvm/docs/LangRef.rst:16243
+The first two operands are vectors with the same type. The third argument
+``trailing.elts`` is an integer constant that specifies the number of trailing
+elements to extract from the first vector, if this exceeds the known minimum
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Why is it required for the `trainling.elts` to be an immediate? I imagine there could be a scenario where this value is unknown at compile-time, for instance a recurrence where the order of recurrence is determined at runtime.


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