[LV] Support scalable interleave groups for factors 3,5,6 and 7 (#141865)

Currently the loop vectorizer can only vectorize interleave groups for
power-of-2 factors at scalable VFs by recursively interleaving
[de]interleave2 intrinsics.

However after https://github.com/llvm/llvm-project/pull/124825 and
#139893, we now have [de]interleave intrinsics for all factors up to 8,
which is enough to support all types of segmented loads and stores on
RISC-V.

Now that the interleaved access pass has been taught to lower these in
#139373 and #141512, this patch teaches the loop vectorizer to emit
these intrinsics for factors up to 8, which enables scalable
vectorization for non-power-of-2 factors.

As far as I'm aware, no in-tree target will vectorize a scalable
interelave group above factor 8 because the maximum interleave factor is
capped at 4 on AArch64 and 8 on RISC-V, and the
`-max-interleave-group-factor` CLI option defaults to 8, so the
recursive [de]interleaving code has been removed for now.

Factors of 3 with scalable VFs are also turned off in AArch64 since
there's no lowering for [de]interleave3 just yet either.

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index 968fd2f..63fccee 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -240,6 +240,30 @@ Intrinsic::ID llvm::getVectorIntrinsicIDForCall(const CallInst *CI,
   return Intrinsic::not_intrinsic;
 }
 
+struct InterleaveIntrinsic {
+  Intrinsic::ID Interleave, Deinterleave;
+};
+
+static InterleaveIntrinsic InterleaveIntrinsics[] = {
+    {Intrinsic::vector_interleave2, Intrinsic::vector_deinterleave2},
+    {Intrinsic::vector_interleave3, Intrinsic::vector_deinterleave3},
+    {Intrinsic::vector_interleave4, Intrinsic::vector_deinterleave4},
+    {Intrinsic::vector_interleave5, Intrinsic::vector_deinterleave5},
+    {Intrinsic::vector_interleave6, Intrinsic::vector_deinterleave6},
+    {Intrinsic::vector_interleave7, Intrinsic::vector_deinterleave7},
+    {Intrinsic::vector_interleave8, Intrinsic::vector_deinterleave8},
+};
+
+Intrinsic::ID llvm::getInterleaveIntrinsicID(unsigned Factor) {
+  assert(Factor >= 2 && Factor <= 8 && "Unexpected factor");
+  return InterleaveIntrinsics[Factor - 2].Interleave;
+}
+
+Intrinsic::ID llvm::getDeinterleaveIntrinsicID(unsigned Factor) {
+  assert(Factor >= 2 && Factor <= 8 && "Unexpected factor");
+  return InterleaveIntrinsics[Factor - 2].Deinterleave;
+}
+
 /// Given a vector and an element number, see if the scalar value is
 /// already around as a register, for example if it were inserted then extracted
 /// from the vector.