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/MC/MCAssembler.cpp

@@ -175,7 +175,7 @@ bool MCAssembler::evaluateFixup(const MCFixup &Fixup, const MCFragment *DF,
   bool IsPCRel = FixupFlags & MCFixupKindInfo::FKF_IsPCRel;
   bool IsResolved = false;
   if (IsPCRel) {
-    if (Target.getSymB()) {
+    if (Target.getSubSym()) {
       IsResolved = false;
     } else if (!Target.getSymA()) {
       IsResolved = false;

llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp

@@ -222,7 +222,6 @@ void AArch64MachObjectWriter::recordRelocation(
     // Ltmp0:
     //    ... _foo@got - Ltmp0
     if (Target.getSymA()->getKind() == MCSymbolRefExpr::VK_GOT &&
-        Target.getSymB()->getKind() == MCSymbolRefExpr::VK_None &&
         Asm.getSymbolOffset(*B) ==
             Asm.getFragmentOffset(*Fragment) + Fixup.getOffset()) {
       // SymB is the PC, so use a PC-rel pointer-to-GOT relocation.
@@ -233,8 +232,7 @@ void AArch64MachObjectWriter::recordRelocation(
       MRE.r_word1 = (IsPCRel << 24) | (Log2Size << 25) | (Type << 28);
       Writer->addRelocation(A_Base, Fragment->getParent(), MRE);
       return;
-    } else if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
-               Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None) {
+    } else if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None) {
       // Otherwise, neither symbol can be modified.
       Asm.getContext().reportError(Fixup.getLoc(),
                                    "unsupported relocation of modified symbol");
@@ -411,7 +409,7 @@ void AArch64MachObjectWriter::recordRelocation(
       return;
     }
 
-    if (Target.getSymB()) {
+    if (Target.getSubSym()) {
       Asm.getContext().reportError(
           Fixup.getLoc(),
           "invalid auth relocation, can't reference two symbols");

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

@@ -272,20 +272,20 @@ void ARMMachObjectWriter::recordARMScatteredRelocation(
   FixedValue += SecAddr;
   uint32_t Value2 = 0;
 
-  if (const MCSymbolRefExpr *B = Target.getSymB()) {
+  if (const MCSymbol *SB = Target.getSubSym()) {
     assert(Type == MachO::ARM_RELOC_VANILLA && "invalid reloc for 2 symbols");
-    const MCSymbol *SB = &B->getSymbol();
 
     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_SECTDIFF;
-    Value2 = Writer->getSymbolAddress(B->getSymbol(), Asm);
+    Value2 = Writer->getSymbolAddress(*SB, Asm);
     FixedValue -= Writer->getSectionAddress(SB->getFragment()->getParent());
   }