[clang] [llvm] [RISCV] Update Zvzip support to v0.3 (PR #210603)

[Boyao Wang via cfe-commits]

================
@@ -5379,14 +5360,34 @@ static SDValue getSingleShuffleSrc(MVT VT, SDValue V1, SDValue V2) {
   return SDValue();
 }
 
-static bool isLegalVTForZvzipOperand(MVT VT, const RISCVSubtarget &Subtarget) {
+static unsigned getLMULOctuple(MVT ContainerVT) {
+  assert(ContainerVT.isScalableVector() && "Expected scalable vector type");
+  unsigned MinSize = ContainerVT.getSizeInBits().getKnownMinValue();
+  assert(isPowerOf2_32(MinSize) && MinSize >= 8 && MinSize <= 512 &&
+         "Unexpected LMUL");
+  return MinSize / (RISCV::RVVBitsPerBlock / 8);
+}
+
+static bool
+isLegalVTForZvzipDeinterleavedOperand(MVT VT, const RISCVSubtarget &Subtarget) {
   MVT ContainerVT = VT;
   if (VT.isFixedLengthVector())
     ContainerVT = getContainerForFixedLengthVector(VT, Subtarget);
-  // Determine LMUL of the container vector.
   return RISCVTargetLowering::getLMUL(ContainerVT) != RISCVVType::LMUL_8;
 }
 
+static bool
+isLegalVTForZvzipInterleavedOperand(MVT VT, const RISCVSubtarget &Subtarget) {
+  MVT ContainerVT = VT;
+  if (VT.isFixedLengthVector())
----------------
BoyaoWang430 wrote:

This rejects a valid VZIP in the ZVL128B `interleave_v2i32` test. It uses an m1 result container, but `lowerZvzipVZIP` actually builds an m2 result from two m1 sources. This causes unnecessary slides and a merge.  

https://github.com/llvm/llvm-project/blob/429b8e199e1681b86836a49969f07c7584293be2/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-zvzip-zve32x.ll#L70-L85

```suggestion
  if (VT.isFixedLengthVector()) {
    ContainerVT = getContainerForFixedLengthVector(
        VT.getHalfNumVectorElementsVT(), Subtarget);
    ContainerVT = ContainerVT.getDoubleNumVectorElementsVT();
  }
```

https://github.com/llvm/llvm-project/pull/210603