Add error and correct EndLoc

Author: svs-quic

llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp

@@ -2154,19 +2154,23 @@ ParseStatus RISCVAsmParser::parsePseudoQCJumpSymbol(OperandVector &Operands) {
 
   if (getLexer().getKind() != AsmToken::Identifier)
     return ParseStatus::NoMatch;
+
   std::string Identifier(getTok().getIdentifier());
+  SMLoc E = SMLoc::getFromPointer(S.getPointer() + Identifier.size());
 
   if (getLexer().peekTok().is(AsmToken::At)) {
     Lex();
     Lex();
+    SMLoc PLTLoc = getLoc();
     StringRef PLT;
     if (getParser().parseIdentifier(PLT) || PLT != "plt")
-      return ParseStatus::Failure;
+      return Error(PLTLoc,
+                   "'@plt' is the only valid operand for this instruction");
+    E = SMLoc::getFromPointer(S.getPointer() + /*@plt*/ 4);
   } else {
     Lex();
   }
 
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() + Identifier.size());
   RISCVMCExpr::Specifier Kind = RISCVMCExpr::VK_QC_E_JUMP_PLT;
 
   MCSymbol *Sym = getContext().getOrCreateSymbol(Identifier);

llvm/test/MC/RISCV/xqcilb-invalid.s

@@ -22,3 +22,6 @@ qc.e.jal 2147483649
 
 # CHECK-MINUS: :[[@LINE+1]]:1: error: instruction requires the following: 'Xqcilb' (Qualcomm uC Long Branch Extension)
 qc.e.jal 2147483640
+
+# CHECK: :[[@LINE+1]]:12: error: '@plt' is the only valid operand for this instruction
+qc.e.j foo@rlt