Fix checks for AArch64MCExpr::VK_SABS flag

[rinon]

Summary

VK_SABS is part of the SymLoc bitfield in the variant kind which should be
compared for equality, not by checking the VK_SABS bit.

[efriedma]

LGTM

[rinon]

Thanks @efriedma. Could someone commit this for me? I don't have commit access yet.

llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp

if (AArch64MCExpr::getSymbolLoc(RefKind) == AArch64MCExpr::VK_SABS) {
       default:
         llvm_unreachable("Variant kind doesn't correspond to fixup");
       }
     }
 
     if (RefKind & AArch64MCExpr::VK_NC) {
       Value &= 0xFFFF;
     }
-    else if (RefKind & AArch64MCExpr::VK_SABS) {
+    else if (AArch64MCExpr::getSymbolLoc(RefKind) == AArch64MCExpr::VK_SABS) {
       if (SignedValue > 0xFFFF || SignedValue < -0xFFFF)
         Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
 
       // Invert the negative immediate because it will feed into a MOVN.
       if (SignedValue < 0)
         SignedValue = ~SignedValue;
       Value = static_cast<uint64_t>(SignedValue);
     }
for (unsigned i = 0; i != NumBytes; ++i) {
       Data[Offset + Idx] |= uint8_t((Value >> (i * 8)) & 0xff);
     }
   }
 
   // FIXME: getFixupKindInfo() and getFixupKindNumBytes() could be fixed to
   // handle this more cleanly. This may affect the output of -show-mc-encoding.
   AArch64MCExpr::VariantKind RefKind =
     static_cast<AArch64MCExpr::VariantKind>(Target.getRefKind());
-  if (RefKind & AArch64MCExpr::VK_SABS) {
+  if (AArch64MCExpr::getSymbolLoc(RefKind) == AArch64MCExpr::VK_SABS) {
     // If the immediate is negative, generate MOVN else MOVZ.
     // (Bit 30 = 0) ==> MOVN, (Bit 30 = 1) ==> MOVZ.
     if (SignedValue < 0)
       Data[Offset + 3] &= ~(1 << 6);
     else
       Data[Offset + 3] |= (1 << 6);
   }
 }