[LoongArch] Add machine function pass to merge base + offset (#101139)

This commit references RISC-V to add a machine function pass to merge
the base address and offset.

Author: heiher

llvm/lib/Target/LoongArch/CMakeLists.txt

@@ -24,6 +24,7 @@ add_llvm_target(LoongArchCodeGen
   LoongArchISelDAGToDAG.cpp
   LoongArchISelLowering.cpp
   LoongArchMCInstLower.cpp
+  LoongArchMergeBaseOffset.cpp
   LoongArchOptWInstrs.cpp
   LoongArchRegisterInfo.cpp
   LoongArchSubtarget.cpp

llvm/lib/Target/LoongArch/LoongArch.h

@@ -36,12 +36,14 @@ bool lowerLoongArchMachineOperandToMCOperand(const MachineOperand &MO,
 FunctionPass *createLoongArchDeadRegisterDefinitionsPass();
 FunctionPass *createLoongArchExpandAtomicPseudoPass();
 FunctionPass *createLoongArchISelDag(LoongArchTargetMachine &TM);
+FunctionPass *createLoongArchMergeBaseOffsetOptPass();
 FunctionPass *createLoongArchOptWInstrsPass();
 FunctionPass *createLoongArchPreRAExpandPseudoPass();
 FunctionPass *createLoongArchExpandPseudoPass();
 void initializeLoongArchDAGToDAGISelLegacyPass(PassRegistry &);
 void initializeLoongArchDeadRegisterDefinitionsPass(PassRegistry &);
 void initializeLoongArchExpandAtomicPseudoPass(PassRegistry &);
+void initializeLoongArchMergeBaseOffsetOptPass(PassRegistry &);
 void initializeLoongArchOptWInstrsPass(PassRegistry &);
 void initializeLoongArchPreRAExpandPseudoPass(PassRegistry &);
 void initializeLoongArchExpandPseudoPass(PassRegistry &);

llvm/lib/Target/LoongArch/LoongArchAsmPrinter.cpp

@@ -130,10 +130,16 @@ bool LoongArchAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
   OS << "$" << LoongArchInstPrinter::getRegisterName(BaseMO.getReg());
   // Print the offset operand.
   const MachineOperand &OffsetMO = MI->getOperand(OpNo + 1);
+  MCOperand MCO;
+  if (!lowerOperand(OffsetMO, MCO))
+    return true;
   if (OffsetMO.isReg())
     OS << ", $" << LoongArchInstPrinter::getRegisterName(OffsetMO.getReg());
   else if (OffsetMO.isImm())
     OS << ", " << OffsetMO.getImm();
+  else if (OffsetMO.isGlobal() || OffsetMO.isBlockAddress() ||
+           OffsetMO.isMCSymbol())
+    OS << ", " << *MCO.getExpr();
   else
     return true;