[TLI] Added a guard for empty vector function name. (#68100)

A guard for empty vector function name was removed in #66656. This patch adds the guard back.

Author: JolantaJensen

llvm/lib/Analysis/TargetLibraryInfo.cpp

@@ -46,6 +46,7 @@ StringLiteral const TargetLibraryInfoImpl::StandardNames[LibFunc::NumLibFuncs] =
 };
 
 std::string VecDesc::getVectorFunctionABIVariantString() const {
+ assert(!VectorFnName.empty() && "Vector function name must not be empty.");
  SmallString<256> Buffer;
  llvm::raw_svector_ostream Out(Buffer);
  Out << VABIPrefix << "_" << ScalarFnName << "(" << VectorFnName << ")";

llvm/lib/Transforms/Utils/InjectTLIMappings.cpp

@@ -92,7 +92,7 @@ static void addMappingsFromTLI(const TargetLibraryInfo &TLI, CallInst &CI) {
 
  auto AddVariantDecl = [&](const ElementCount &VF, bool Predicate) {
  const VecDesc *VD = TLI.getVectorMappingInfo(ScalarName, VF, Predicate);
- if (VD) {
+ if (VD && !VD->getVectorFnName().empty()) {
  std::string MangledName = VD->getVectorFunctionABIVariantString();
  if (!OriginalSetOfMappings.count(MangledName)) {
  Mappings.push_back(MangledName);