[SVE] Update EmitSVEPredicateCast to take a ScalableVectorType

[ctetreau]

Summary

Removes usage of VectorType::getNumElements identified by test located
at CodeGen/aarch64-sve-intrinsics/acle_sve_abs.c. Since the type is an
SVE predicate vector, it makes sense to specialize the code for scalable
vectors only.

[efriedma]

LGTM

[ctetreau]

rebase

clang/lib/CodeGen/CGBuiltin.cpp

 static llvm::ScalableVectorType *getSVEVectorForElementType(llvm::Type *EltTy) {
   unsigned NumElts = SVEBitsPerBlock / EltTy->getScalarSizeInBits();
   return llvm::ScalableVectorType::get(EltTy, NumElts);
 }
 
 // Reinterpret the input predicate so that it can be used to correctly isolate
 // the elements of the specified datatype.
 Value *CodeGenFunction::EmitSVEPredicateCast(Value *Pred,
-                                             llvm::VectorType *VTy) {
-  llvm::VectorType *RTy = llvm::VectorType::get(
-      IntegerType::get(getLLVMContext(), 1), VTy->getElementCount());
+                                             llvm::ScalableVectorType *VTy) {
+  auto *RTy = llvm::VectorType::get(IntegerType::get(getLLVMContext(), 1), VTy);
   if (Pred->getType() == RTy)
     return Pred;
 
   unsigned IntID;
   llvm::Type *IntrinsicTy;
-  switch (VTy->getNumElements()) {
+  switch (VTy->getMinNumElements()) {
   default:
     llvm_unreachable("unsupported element count!");
   case 2:
   case 4:
   case 8:
     IntID = Intrinsic::aarch64_sve_convert_from_svbool;
     IntrinsicTy = RTy;
     break;
else if (Builtin->LLVMIntrinsic != 0) {
 
     Function *F = CGM.getIntrinsic(Builtin->LLVMIntrinsic,
                                    getSVEOverloadTypes(TypeFlags, Ops));
     Value *Call = Builder.CreateCall(F, Ops);
 
     // Predicate results must be converted to svbool_t.
     if (auto PredTy = dyn_cast<llvm::VectorType>(Call->getType()))
       if (PredTy->getScalarType()->isIntegerTy(1))
-        Call = EmitSVEPredicateCast(Call, cast<llvm::VectorType>(Ty));
+        Call = EmitSVEPredicateCast(Call, cast<llvm::ScalableVectorType>(Ty));
 
     return Call;
   }
 
   switch (BuiltinID) {
   default:
     return nullptr;
   case SVE::BI__builtin_sve_svpfalse_b:

clang/lib/CodeGen/CodeGenFunction.h

public:
   llvm::Type *SVEBuiltinMemEltTy(SVETypeFlags TypeFlags);
 
   SmallVector<llvm::Type *, 2> getSVEOverloadTypes(SVETypeFlags TypeFlags,
                                                    ArrayRef<llvm::Value *> Ops);
   llvm::Type *getEltType(SVETypeFlags TypeFlags);
   llvm::ScalableVectorType *getSVEType(const SVETypeFlags &TypeFlags);
   llvm::ScalableVectorType *getSVEPredType(SVETypeFlags TypeFlags);
   llvm::Value *EmitSVEDupX(llvm::Value *Scalar);
-  llvm::Value *EmitSVEPredicateCast(llvm::Value *Pred, llvm::VectorType *VTy);
+  llvm::Value *EmitSVEPredicateCast(llvm::Value *Pred,
+                                    llvm::ScalableVectorType *VTy);
   llvm::Value *EmitSVEGatherLoad(SVETypeFlags TypeFlags,
                                  llvm::SmallVectorImpl<llvm::Value *> &Ops,
                                  unsigned IntID);
   llvm::Value *EmitSVEScatterStore(SVETypeFlags TypeFlags,
                                    llvm::SmallVectorImpl<llvm::Value *> &Ops,
                                    unsigned IntID);
   llvm::Value *EmitSVEMaskedLoad(const CallExpr *, llvm::Type *ReturnTy,
                                  SmallVectorImpl<llvm::Value *> &Ops,