[SVE] Ignore scalable vectors in InterleavedLoadCombinePass

I have changed the pass so that we ignore shuffle vectors with
scalable vector types, and replaced VectorType with FixedVectorType
in the rest of the pass. I couldn't think of an easy way to test
this change, since for scalable vectors we shouldn't be using
shufflevectors for interleaving. This change fixes up some
type size assert warnings I found in the following test:

  CodeGen/AArch64/sve-intrinsics-int-arith-imm.ll

Differential Revision: https://reviews.llvm.org/D79700

llvm/lib/CodeGen/InterleavedLoadCombinePass.cpp

@@ -673,9 +673,9 @@ struct VectorInfo {
   ElementInfo *EI;
 
   /// Vector Type
-  VectorType *const VTy;
+  FixedVectorType *const VTy;
 
-  VectorInfo(VectorType *VTy)
+  VectorInfo(FixedVectorType *VTy)
       : BB(nullptr), PV(nullptr), LIs(), Is(), SVI(nullptr), VTy(VTy) {
     EI = new ElementInfo[VTy->getNumElements()];
   }
@@ -735,7 +735,7 @@ struct VectorInfo {
     if (!Op)
       return false;
 
-    VectorType *VTy = dyn_cast<VectorType>(Op->getType());
+    FixedVectorType *VTy = dyn_cast<FixedVectorType>(Op->getType());
     if (!VTy)
       return false;
 
@@ -785,8 +785,8 @@ struct VectorInfo {
   /// \returns false if no sensible information can be gathered.
   static bool computeFromSVI(ShuffleVectorInst *SVI, VectorInfo &Result,
                              const DataLayout &DL) {
-    VectorType *ArgTy = dyn_cast<VectorType>(SVI->getOperand(0)->getType());
-    assert(ArgTy && "ShuffleVector Operand is not a VectorType");
+    FixedVectorType *ArgTy =
+        cast<FixedVectorType>(SVI->getOperand(0)->getType());
 
     // Compute the left hand vector information.
     VectorInfo LHS(ArgTy);
@@ -1201,7 +1201,7 @@ bool InterleavedLoadCombineImpl::combine(std::list<VectorInfo> &InterleavedLoad,
   Type *ETy = InterleavedLoad.front().SVI->getType()->getElementType();
   unsigned ElementsPerSVI =
       InterleavedLoad.front().SVI->getType()->getNumElements();
-  VectorType *ILTy = VectorType::get(ETy, Factor * ElementsPerSVI);
+  FixedVectorType *ILTy = FixedVectorType::get(ETy, Factor * ElementsPerSVI);
 
   SmallVector<unsigned, 4> Indices;
   for (unsigned i = 0; i < Factor; i++)
@@ -1265,8 +1265,11 @@ bool InterleavedLoadCombineImpl::run() {
     for (BasicBlock &BB : F) {
       for (Instruction &I : BB) {
         if (auto SVI = dyn_cast<ShuffleVectorInst>(&I)) {
+          // We don't support scalable vectors in this pass.
+          if (isa<ScalableVectorType>(SVI->getType()))
+            continue;
 
-          Candidates.emplace_back(SVI->getType());
+          Candidates.emplace_back(cast<FixedVectorType>(SVI->getType()));
 
           if (!VectorInfo::computeFromSVI(SVI, Candidates.back(), DL)) {
             Candidates.pop_back();