MCValue: Simplify code with getSubSym

The MCValue::SymB MCSymbolRefExpr member might be replaced with a
MCSymbol in the future. Reduce direct access.

Author: MaskRay

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -8214,7 +8214,7 @@ bool AArch64AsmParser::classifySymbolRef(
   // Check that it looks like a symbol + an addend
   MCValue Res;
   bool Relocatable = Expr->evaluateAsRelocatable(Res, nullptr);
-  if (!Relocatable || Res.getSymB())
+  if (!Relocatable || Res.getSubSym())
     return false;
 
   // Treat expressions with an ELFSpec (like ":abs_g1:3", or

llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp

@@ -163,19 +163,18 @@ void ARMMachObjectWriter::recordARMScatteredHalfRelocation(
   uint64_t SecAddr = Writer->getSectionAddress(A->getFragment()->getParent());
   FixedValue += SecAddr;
 
-  if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    const MCSymbol *SB = &B->getSymbol();
-
+  if (const MCSymbol *SB = Target.getSubSym()) {
     if (!SB->getFragment()) {
-      Asm.getContext().reportError(Fixup.getLoc(),
-                         "symbol '" + B->getSymbol().getName() +
-                         "' can not be undefined in a subtraction expression");
+      Asm.getContext().reportError(
+          Fixup.getLoc(),
+          "symbol '" + SB->getName() +
+              "' can not be undefined in a subtraction expression");
       return;
     }
 
     // Select the appropriate difference relocation type.
     Type = MachO::ARM_RELOC_HALF_SECTDIFF;
-    Value2 = Writer->getSymbolAddress(B->getSymbol(), Asm);
+    Value2 = Writer->getSymbolAddress(*SB, Asm);
     FixedValue -= Writer->getSectionAddress(SB->getFragment()->getParent());
   }
 

llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp

@@ -455,7 +455,7 @@ bool LoongArchAsmBackend::handleAddSubRelocations(const MCAssembler &Asm,
   std::pair<MCFixupKind, MCFixupKind> FK;
   uint64_t FixedValueA, FixedValueB;
   const MCSymbol &SA = Target.getSymA()->getSymbol();
-  const MCSymbol &SB = Target.getSymB()->getSymbol();
+  const MCSymbol &SB = *Target.getSubSym();
 
   bool force = !SA.isInSection() || !SB.isInSection();
   if (!force) {

llvm/lib/Target/M68k/MCTargetDesc/M68kMCExpr.cpp

@@ -25,9 +25,8 @@ bool M68kMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
   if (!getSubExpr()->evaluateAsRelocatable(Res, Asm))
     return false;
 
-  Res =
-      MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), specifier);
-  return Res.getSymB() ? specifier == VK_None : true;
+  Res.setSpecifier(specifier);
+  return !Res.getSubSym();
 }
 
 void M68kMCExpr::visitUsedExpr(MCStreamer &S) const { S.visitUsedExpr(*Expr); }

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

@@ -585,7 +585,7 @@ class MipsAsmParser : public MCTargetAsmParser {
     MCValue Res;
     if (!JalExpr->evaluateAsRelocatable(Res, nullptr))
       return false;
-    if (Res.getSymB() != nullptr)
+    if (Res.getSubSym())
       return false;
     if (Res.getConstant() != 0)
       return ABI.IsN32() || ABI.IsN64();
@@ -2938,7 +2938,7 @@ bool MipsAsmParser::loadAndAddSymbolAddress(const MCExpr *SymExpr,
       Error(IDLoc, "expected relocatable expression");
       return true;
     }
-    if (Res.getSymB() != nullptr) {
+    if (Res.getSubSym()) {
       Error(IDLoc, "expected relocatable expression with only one symbol");
       return true;
     }
@@ -3768,7 +3768,7 @@ void MipsAsmParser::expandMem16Inst(MCInst &Inst, SMLoc IDLoc, MCStreamer &Out,
         Error(IDLoc, "expected relocatable expression");
         return;
       }
-      if (Res.getSymB() != nullptr) {
+      if (Res.getSubSym()) {
         Error(IDLoc, "expected relocatable expression with only one symbol");
         return;
       }

llvm/lib/Target/Xtensa/MCTargetDesc/XtensaMCExpr.cpp

@@ -45,7 +45,7 @@ bool XtensaMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
   if (!getSubExpr()->evaluateAsRelocatable(Res, Asm))
     return false;
   Res.setSpecifier(specifier);
-  return !Res.getSymB();
+  return !Res.getSubSym();
 }
 
 void XtensaMCExpr::visitUsedExpr(MCStreamer &Streamer) const {