[llvm] [IA][RISCV] Add support for vp.load/vp.store with shufflevector (PR #135445)

[Luke Lau via llvm-commits]

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@@ -249,11 +249,217 @@ static bool isReInterleaveMask(ShuffleVectorInst *SVI, unsigned &Factor,
   return false;
 }
 
+// For an (de)interleave tree like this:
+//
+//   A   C B   D
+//   |___| |___|
+//     |_____|
+//        |
+//     A B C D
+//
+//  We will get ABCD at the end while the leaf operands/results
+//  are ACBD, which are also what we initially collected in
+//  getVectorInterleaveFactor / getVectorDeinterleaveFactor. But TLI
+//  hooks (e.g. lowerDeinterleaveIntrinsicToLoad) expect ABCD, so we need
+//  to reorder them by interleaving these values.
+static void interleaveLeafValues(MutableArrayRef<Value *> SubLeaves) {
+  unsigned NumLeaves = SubLeaves.size();
+  if (NumLeaves == 2)
+    return;
+
+  assert(isPowerOf2_32(NumLeaves) && NumLeaves > 1);
+
+  const unsigned HalfLeaves = NumLeaves / 2;
+  // Visit the sub-trees.
+  interleaveLeafValues(SubLeaves.take_front(HalfLeaves));
+  interleaveLeafValues(SubLeaves.drop_front(HalfLeaves));
+
+  SmallVector<Value *, 8> Buffer;
+  //    a0 a1 a2 a3 b0 b1 b2 b3
+  // -> a0 b0 a1 b1 a2 b2 a3 b3
+  for (unsigned i = 0U; i < NumLeaves; ++i)
+    Buffer.push_back(SubLeaves[i / 2 + (i % 2 ? HalfLeaves : 0)]);
+
+  llvm::copy(Buffer, SubLeaves.begin());
+}
+
+static bool
+getVectorInterleaveFactor(IntrinsicInst *II, SmallVectorImpl<Value *> &Operands,
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lukel97 wrote:

Did these functions change or is it just code motion? Is it possible to forward declare the functions here and move them in a later NFC just to shrink the diff a bit?

https://github.com/llvm/llvm-project/pull/135445