[RISCV] Improve tracking of EndLoc in the assembly parser.

[craig.topper]

Summary

The SMLoc::getFromPointer(S.getPointer() - 1) pattern used in
several place didn't make sense since that puts the End before the
Start location.

This patch corrects this to properly calculate the end location as
we parse. Unsure how much this matters, a lot of these are for custom
operand parsing. If the custom parsing succeeds, the instruction
matching probably won't fail, so the end loc won't be used to build
a range for a diagnostic.

I've also fixed the creation functions for the CSR and VType operands
to assign the EndLoc of the RISCVOperand class using the StartLoc
instead of an empty SMLoc. I don't think these will ever be accessed,
but it makes the code look less like we forgot to assign it. This is
consistent with some operands on the ARM target.

[luismarques]

LGTM.

If the custom parsing succeeds, the instruction matching probably won't fail, so the end loc won't be used to build a range for a diagnostic.

Indeed, currently that seems to be the case. Still, good idea to fix it. Thanks!

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

public:
 
   static std::unique_ptr<RISCVOperand>
   createSysReg(StringRef Str, SMLoc S, unsigned Encoding, bool IsRV64) {
     auto Op = std::make_unique<RISCVOperand>(KindTy::SystemRegister);
     Op->SysReg.Data = Str.data();
     Op->SysReg.Length = Str.size();
     Op->SysReg.Encoding = Encoding;
     Op->StartLoc = S;
+    Op->EndLoc = S;
     Op->IsRV64 = IsRV64;
     return Op;
   }
 
   static std::unique_ptr<RISCVOperand> createVType(unsigned VTypeI, SMLoc S,
                                                    bool IsRV64) {
     auto Op = std::make_unique<RISCVOperand>(KindTy::VType);
     Op->VType.Val = VTypeI;
     Op->StartLoc = S;
+    Op->EndLoc = S;
     Op->IsRV64 = IsRV64;
     return Op;
   }
 
   void addExpr(MCInst &Inst, const MCExpr *Expr) const {
     assert(Expr && "Expr shouldn't be null!");
     int64_t Imm = 0;
     RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
case AsmToken::Identifier:
     if (RegNo == RISCV::NoRegister) {
       if (HadParens)
         getLexer().UnLex(LParen);
       return MatchOperand_NoMatch;
     }
     if (HadParens)
       Operands.push_back(RISCVOperand::createToken("(", FirstS, isRV64()));
     SMLoc S = getLoc();
-    SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
+    SMLoc E = SMLoc::getFromPointer(S.getPointer() + Name.size());
     getLexer().Lex();
     Operands.push_back(RISCVOperand::createReg(RegNo, S, E, isRV64()));
   }
 
   if (HadParens) {
     getParser().Lex(); // Eat ')'
     Operands.push_back(RISCVOperand::createToken(")", getLoc(), isRV64()));
   }
RISCVAsmParser::parseCSRSystemRegister(OperandVector &Operands) {
   }
   }
 
   return MatchOperand_NoMatch;
 }
 
 OperandMatchResultTy RISCVAsmParser::parseImmediate(OperandVector &Operands) {
   SMLoc S = getLoc();
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
+  SMLoc E;
   const MCExpr *Res;
 
   switch (getLexer().getKind()) {
   default:
     return MatchOperand_NoMatch;
   case AsmToken::LParen:
   case AsmToken::Dot:
   case AsmToken::Minus:
   case AsmToken::Plus:
   case AsmToken::Exclaim:
   case AsmToken::Tilde:
   case AsmToken::Integer:
   case AsmToken::String:
   case AsmToken::Identifier:
-    if (getParser().parseExpression(Res))
+    if (getParser().parseExpression(Res, E))
       return MatchOperand_ParseFail;
     break;
   case AsmToken::Percent:
     return parseOperandWithModifier(Operands);
   }
 
   Operands.push_back(RISCVOperand::createImm(Res, S, E, isRV64()));
   return MatchOperand_Success;
 }
 
 OperandMatchResultTy
 RISCVAsmParser::parseOperandWithModifier(OperandVector &Operands) {
   SMLoc S = getLoc();
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
+  SMLoc E;
 
   if (getLexer().getKind() != AsmToken::Percent) {
     Error(getLoc(), "expected '%' for operand modifier");
     return MatchOperand_ParseFail;
   }
 
   getParser().Lex(); // Eat '%'
 
RISCVAsmParser::parseOperandWithModifier(OperandVector &Operands) {
 
   const MCExpr *ModExpr = RISCVMCExpr::create(SubExpr, VK, getContext());
   Operands.push_back(RISCVOperand::createImm(ModExpr, S, E, isRV64()));
   return MatchOperand_Success;
 }
 
 OperandMatchResultTy RISCVAsmParser::parseBareSymbol(OperandVector &Operands) {
   SMLoc S = getLoc();
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
   const MCExpr *Res;
 
   if (getLexer().getKind() != AsmToken::Identifier)
     return MatchOperand_NoMatch;
 
   StringRef Identifier;
   AsmToken Tok = getLexer().getTok();
 
   if (getParser().parseIdentifier(Identifier))
     return MatchOperand_ParseFail;
 
+  SMLoc E = SMLoc::getFromPointer(S.getPointer() + Identifier.size());
+
   if (Identifier.consume_back("@plt")) {
     Error(getLoc(), "'@plt' operand not valid for instruction");
     return MatchOperand_ParseFail;
   }
 
   MCSymbol *Sym = getContext().getOrCreateSymbol(Identifier);
 
   if (Sym->isVariable()) {
case AsmToken::Plus:
     Opcode = MCBinaryExpr::Add;
     break;
   case AsmToken::Minus:
     Opcode = MCBinaryExpr::Sub;
     break;
   }
 
   const MCExpr *Expr;
-  if (getParser().parseExpression(Expr))
+  if (getParser().parseExpression(Expr, E))
     return MatchOperand_ParseFail;
   Res = MCBinaryExpr::create(Opcode, Res, Expr, getContext());
   Operands.push_back(RISCVOperand::createImm(Res, S, E, isRV64()));
   return MatchOperand_Success;
 }
 
 OperandMatchResultTy RISCVAsmParser::parseCallSymbol(OperandVector &Operands) {
   SMLoc S = getLoc();
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
   const MCExpr *Res;
 
   if (getLexer().getKind() != AsmToken::Identifier)
     return MatchOperand_NoMatch;
 
   // Avoid parsing the register in `call rd, foo` as a call symbol.
   if (getLexer().peekTok().getKind() != AsmToken::EndOfStatement)
     return MatchOperand_NoMatch;
 
   StringRef Identifier;
   if (getParser().parseIdentifier(Identifier))
     return MatchOperand_ParseFail;
 
+  SMLoc E = SMLoc::getFromPointer(S.getPointer() + Identifier.size());
+
   RISCVMCExpr::VariantKind Kind = RISCVMCExpr::VK_RISCV_CALL;
   if (Identifier.consume_back("@plt"))
     Kind = RISCVMCExpr::VK_RISCV_CALL_PLT;
 
   MCSymbol *Sym = getContext().getOrCreateSymbol(Identifier);
   Res = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, getContext());
   Res = RISCVMCExpr::create(Res, Kind, getContext());
   Operands.push_back(RISCVOperand::createImm(Res, S, E, isRV64()));
   return MatchOperand_Success;
 }
 
 OperandMatchResultTy
 RISCVAsmParser::parsePseudoJumpSymbol(OperandVector &Operands) {
   SMLoc S = getLoc();
-  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
+  SMLoc E;
   const MCExpr *Res;
 
-  if (getParser().parseExpression(Res))
+  if (getParser().parseExpression(Res, E))
     return MatchOperand_ParseFail;
 
   if (Res->getKind() != MCExpr::ExprKind::SymbolRef ||
       cast<MCSymbolRefExpr>(Res)->getKind() ==
           MCSymbolRefExpr::VariantKind::VK_PLT) {
     Error(S, "operand must be a valid jump target");
     return MatchOperand_ParseFail;
   }
case AsmToken::Identifier:
     MCRegister RegNo;
     matchRegisterNameHelper(isRV32E(), RegNo, Name);
 
     if (RegNo == RISCV::NoRegister)
       return MatchOperand_NoMatch;
     if (RegNo != RISCV::V0)
       return MatchOperand_NoMatch;
     SMLoc S = getLoc();
-    SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
+    SMLoc E = SMLoc::getFromPointer(S.getPointer() + Name.size());
     getLexer().Lex();
     Operands.push_back(RISCVOperand::createReg(RegNo, S, E, isRV64()));
   }
 
   return MatchOperand_Success;
 }
 
 OperandMatchResultTy