[mips] [IAS] Give expandLoadAddressSym() more specific arguments. NFC.

[tomatabacu]

Summary

If we only pass the necessary operands, we don't have to determine the position of the symbol operand when entering expandLoadAddressSym().
This simplifies the expandLoadAddressSym() code.

[dsanders]

LGTM

[tomatabacu]

Rebased on top of new D9290 and made changes as required.

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

#include "MipsGenAsmMatcher.inc"
   bool expandLoadAddressImm(MCInst &Inst, bool Is32BitImm, SMLoc IDLoc,
                             SmallVectorImpl<MCInst> &Instructions);
 
   bool expandLoadAddressReg(MCInst &Inst, bool Is32BitImm, SMLoc IDLoc,
                             SmallVectorImpl<MCInst> &Instructions);
   bool expandUncondBranchMMPseudo(MCInst &Inst, SMLoc IDLoc,
                                   SmallVectorImpl<MCInst> &Instructions);
 
-  void expandLoadAddressSym(MCInst &Inst, SMLoc IDLoc,
-                            SmallVectorImpl<MCInst> &Instructions);
+  void expandLoadAddressSym(const MCOperand &DstRegOp, const MCOperand &SymOp,
+                            SMLoc IDLoc, SmallVectorImpl<MCInst> &Instructions);
 
   void expandMemInst(MCInst &Inst, SMLoc IDLoc,
                      SmallVectorImpl<MCInst> &Instructions, bool isLoad,
                      bool isImmOpnd);
 
   bool expandLoadStoreMultiple(MCInst &Inst, SMLoc IDLoc,
                                SmallVectorImpl<MCInst> &Instructions);
 
if (loadImmediate(ImmOp.getImm(), DstRegOp.getReg(), Mips::NoRegister,
     return true;
 
   return false;
 }
 
 bool
 MipsAsmParser::expandLoadAddressReg(MCInst &Inst, bool Is32BitImm, SMLoc IDLoc,
                                     SmallVectorImpl<MCInst> &Instructions) {
+  const MCOperand &DstRegOp = Inst.getOperand(0);
+  assert(DstRegOp.isReg() && "expected register operand kind");
+
   const MCOperand &ImmOp = Inst.getOperand(2);
   assert((ImmOp.isImm() || ImmOp.isExpr()) &&
          "expected immediate operand kind");
   if (!ImmOp.isImm()) {
-    expandLoadAddressSym(Inst, IDLoc, Instructions);
+    expandLoadAddressSym(DstRegOp, ImmOp, IDLoc, Instructions);
     return false;
   }
   const MCOperand &SrcRegOp = Inst.getOperand(1);
   assert(SrcRegOp.isReg() && "expected register operand kind");
-  const MCOperand &DstRegOp = Inst.getOperand(0);
-  assert(DstRegOp.isReg() && "expected register operand kind");
 
   if (loadImmediate(ImmOp.getImm(), DstRegOp.getReg(), SrcRegOp.getReg(),
                     Is32BitImm, IDLoc, Instructions))
     return true;
 
   return false;
 }
 
 bool
 MipsAsmParser::expandLoadAddressImm(MCInst &Inst, bool Is32BitImm, SMLoc IDLoc,
                                     SmallVectorImpl<MCInst> &Instructions) {
+  const MCOperand &DstRegOp = Inst.getOperand(0);
+  assert(DstRegOp.isReg() && "expected register operand kind");
+
   const MCOperand &ImmOp = Inst.getOperand(1);
   assert((ImmOp.isImm() || ImmOp.isExpr()) &&
          "expected immediate operand kind");
   if (!ImmOp.isImm()) {
-    expandLoadAddressSym(Inst, IDLoc, Instructions);
+    expandLoadAddressSym(DstRegOp, ImmOp, IDLoc, Instructions);
     return false;
   }
-  const MCOperand &DstRegOp = Inst.getOperand(0);
-  assert(DstRegOp.isReg() && "expected register operand kind");
 
   if (loadImmediate(ImmOp.getImm(), DstRegOp.getReg(), Mips::NoRegister,
                     Is32BitImm, IDLoc, Instructions))
     return true;
 
   return false;
 }
 
 void
-MipsAsmParser::expandLoadAddressSym(MCInst &Inst, SMLoc IDLoc,
+MipsAsmParser::expandLoadAddressSym(const MCOperand &DstRegOp,
+                                    const MCOperand &SymOp, SMLoc IDLoc,
                                     SmallVectorImpl<MCInst> &Instructions) {
-  // FIXME: If we do have a valid at register to use, we should generate a
-  // slightly shorter sequence here.
   MCInst tmpInst;
-  int ExprOperandNo = 1;
-  // Sometimes the assembly parser will get the immediate expression as
-  // a $zero + an immediate.
-  if (Inst.getNumOperands() == 3) {
-    assert(Inst.getOperand(1).getReg() ==
-           (isGP64bit() ? Mips::ZERO_64 : Mips::ZERO));
-    ExprOperandNo = 2;
-  }
-  const MCOperand &SymOp = Inst.getOperand(ExprOperandNo);
-  assert(SymOp.isExpr() && "expected symbol operand kind");
-  const MCOperand &RegOp = Inst.getOperand(0);
-  unsigned RegNo = RegOp.getReg();
+  unsigned RegNo = DstRegOp.getReg();
   const MCSymbolRefExpr *Symbol = cast<MCSymbolRefExpr>(SymOp.getExpr());
   const MCSymbolRefExpr *HiExpr =
       MCSymbolRefExpr::Create(Symbol->getSymbol().getName(),
                               MCSymbolRefExpr::VK_Mips_ABS_HI, getContext());
   const MCSymbolRefExpr *LoExpr =
       MCSymbolRefExpr::Create(Symbol->getSymbol().getName(),
                               MCSymbolRefExpr::VK_Mips_ABS_LO, getContext());
   if (isGP64bit()) {