[RISCV] Use RISCVSubtarget::getRealVLen() in more places. NFC

Catching a couple of more places where we can use the new query added in
8603a7b.

Author: lukel97

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -3848,11 +3848,10 @@ static SDValue lowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
 
   // If we're compiling for an exact VLEN value, we can split our work per
   // register in the register group.
-  const unsigned MinVLen = Subtarget.getRealMinVLen();
-  const unsigned MaxVLen = Subtarget.getRealMaxVLen();
-  if (MinVLen == MaxVLen && VT.getSizeInBits().getKnownMinValue() > MinVLen) {
+  if (const auto VLen = Subtarget.getRealVLen();
+      VLen && VT.getSizeInBits().getKnownMinValue() > *VLen) {
     MVT ElemVT = VT.getVectorElementType();
-    unsigned ElemsPerVReg = MinVLen / ElemVT.getFixedSizeInBits();
+    unsigned ElemsPerVReg = *VLen / ElemVT.getFixedSizeInBits();
     EVT ContainerVT = getContainerForFixedLengthVector(DAG, VT, Subtarget);
     MVT OneRegVT = MVT::getVectorVT(ElemVT, ElemsPerVReg);
     MVT M1VT = getContainerForFixedLengthVector(DAG, OneRegVT, Subtarget);
@@ -4763,9 +4762,8 @@ static SDValue lowerShuffleViaVRegSplitting(ShuffleVectorSDNode *SVN,
 
   // If we don't know exact data layout, not much we can do.  If this
   // is already m1 or smaller, no point in splitting further.
-  const unsigned MinVLen = Subtarget.getRealMinVLen();
-  const unsigned MaxVLen = Subtarget.getRealMaxVLen();
-  if (MinVLen != MaxVLen || VT.getSizeInBits().getFixedValue() <= MinVLen)
+  const auto VLen = Subtarget.getRealVLen();
+  if (!VLen || VT.getSizeInBits().getFixedValue() <= *VLen)
     return SDValue();
 
   // Avoid picking up bitrotate patterns which we have a linear-in-lmul
@@ -4776,7 +4774,7 @@ static SDValue lowerShuffleViaVRegSplitting(ShuffleVectorSDNode *SVN,
     return SDValue();
 
   MVT ElemVT = VT.getVectorElementType();
-  unsigned ElemsPerVReg = MinVLen / ElemVT.getFixedSizeInBits();
+  unsigned ElemsPerVReg = *VLen / ElemVT.getFixedSizeInBits();
   unsigned VRegsPerSrc = NumElts / ElemsPerVReg;
 
   SmallVector<std::pair<int, SmallVector<int>>>
@@ -8328,15 +8326,13 @@ SDValue RISCVTargetLowering::lowerEXTRACT_VECTOR_ELT(SDValue Op,
   // constant index, we can always perform the extract in m1 (or
   // smaller) as we can determine the register corresponding to
   // the index in the register group.
-  const unsigned MinVLen = Subtarget.getRealMinVLen();
-  const unsigned MaxVLen = Subtarget.getRealMaxVLen();
+  const auto VLen = Subtarget.getRealVLen();
   if (auto *IdxC = dyn_cast<ConstantSDNode>(Idx);
-      IdxC && MinVLen == MaxVLen &&
-      VecVT.getSizeInBits().getKnownMinValue() > MinVLen) {
+      IdxC && VLen && VecVT.getSizeInBits().getKnownMinValue() > *VLen) {
     MVT M1VT = getLMUL1VT(ContainerVT);
     unsigned OrigIdx = IdxC->getZExtValue();
     EVT ElemVT = VecVT.getVectorElementType();
-    unsigned ElemsPerVReg = MinVLen / ElemVT.getFixedSizeInBits();
+    unsigned ElemsPerVReg = *VLen / ElemVT.getFixedSizeInBits();
     unsigned RemIdx = OrigIdx % ElemsPerVReg;
     unsigned SubRegIdx = OrigIdx / ElemsPerVReg;
     unsigned ExtractIdx =
@@ -9797,15 +9793,14 @@ SDValue RISCVTargetLowering::lowerEXTRACT_SUBVECTOR(SDValue Op,
   if (OrigIdx == 0)
     return Op;
 
-  const unsigned MinVLen = Subtarget.getRealMinVLen();
-  const unsigned MaxVLen = Subtarget.getRealMaxVLen();
+  const auto VLen = Subtarget.getRealVLen();
 
   // If the subvector vector is a fixed-length type and we don't know VLEN
   // exactly, we cannot use subregister manipulation to simplify the codegen; we
   // don't know which register of a LMUL group contains the specific subvector
   // as we only know the minimum register size. Therefore we must slide the
   // vector group down the full amount.
-  if (SubVecVT.isFixedLengthVector() && MinVLen != MaxVLen) {
+  if (SubVecVT.isFixedLengthVector() && !VLen) {
     MVT ContainerVT = VecVT;
     if (VecVT.isFixedLengthVector()) {
       ContainerVT = getContainerForFixedLengthVector(VecVT);
@@ -9852,8 +9847,8 @@ SDValue RISCVTargetLowering::lowerEXTRACT_SUBVECTOR(SDValue Op,
   // and decomposeSubvectorInsertExtractToSubRegs takes this into account. So if
   // we have a fixed length subvector, we need to adjust the index by 1/vscale.
   if (SubVecVT.isFixedLengthVector()) {
-    assert(MinVLen == MaxVLen);
-    unsigned Vscale = MinVLen / RISCV::RVVBitsPerBlock;
+    assert(VLen);
+    unsigned Vscale = *VLen / RISCV::RVVBitsPerBlock;
     auto Decompose =
         RISCVTargetLowering::decomposeSubvectorInsertExtractToSubRegs(
             VecVT, ContainerSubVecVT, OrigIdx / Vscale, TRI);