[PowerPC] Disable relative lookup table converter pass for AIX

XCOFF hasn't implemented lowerRelativeReference.
So we need to disable new pass introduced by https://reviews.llvm.org/D94355 for
AIX for now.

Reviewed By: gulfem

Differential Revision: https://reviews.llvm.org/D100584

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -380,7 +380,7 @@ public:
            TLI->isOperationLegalOrCustom(ISD::BRIND, MVT::Other);
   }
 
-  bool shouldBuildRelLookupTables() {
+  bool shouldBuildRelLookupTables() const {
     const TargetMachine &TM = getTLI()->getTargetMachine();
     // If non-PIC mode, do not generate a relative lookup table.
     if (!TM.isPositionIndependent())

llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp

@@ -1260,6 +1260,14 @@ bool PPCTTIImpl::isNumRegsMajorCostOfLSR() {
   return false;
 }
 
+bool PPCTTIImpl::shouldBuildRelLookupTables() const {
+  const PPCTargetMachine &TM = ST->getTargetMachine();
+  // XCOFF hasn't implemented lowerRelativeReference, disable non-ELF for now.
+  if (!TM.isELFv2ABI())
+    return false;
+  return BaseT::shouldBuildRelLookupTables();
+}
+
 bool PPCTTIImpl::getTgtMemIntrinsic(IntrinsicInst *Inst,
                                     MemIntrinsicInfo &Info) {
   switch (Inst->getIntrinsicID()) {

llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h

@@ -76,7 +76,7 @@ public:
   bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
                      TargetTransformInfo::LSRCost &C2);
   bool isNumRegsMajorCostOfLSR();
-
+  bool shouldBuildRelLookupTables() const;
   /// @}
 
   /// \name Vector TTI Implementations