[PPC] Try to fix builbots

Attempt to handle unsupported types, such as structs, in
getMemoryOpCost. The backend now checks for a supported type and
calls into BasicTTI as a fallback. BasicTTI will now also perform
the same check and will default to an expensive cost of 4 for 'Other'
MVTs.

Differential Revision: https://reviews.llvm.org/D80984

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -884,6 +884,9 @@ public:
                            TTI::TargetCostKind CostKind,
                            const Instruction *I = nullptr) {
     assert(!Src->isVoidTy() && "Invalid type");
+    // Assume types, such as structs, are expensive.
+    if (getTLI()->getValueType(DL, Src,  true) == MVT::Other)
+      return 4;
     std::pair<unsigned, MVT> LT = getTLI()->getTypeLegalizationCost(DL, Src);
 
     // Assuming that all loads of legal types cost 1.

llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp

@@ -859,6 +859,9 @@ int PPCTTIImpl::getMemoryOpCost(unsigned Opcode, Type *Src,
                                 MaybeAlign Alignment, unsigned AddressSpace,
                                 TTI::TargetCostKind CostKind,
                                 const Instruction *I) {
+  if (TLI->getValueType(DL, Src,  true) == MVT::Other)
+    return BaseT::getMemoryOpCost(Opcode, Src, Alignment, AddressSpace,
+                                  CostKind);
   // Legalize the type.
   std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);
   assert((Opcode == Instruction::Load || Opcode == Instruction::Store) &&