[AArch64][AsmParser] Split index parsing from vector list.

[sdesmalen]

Summary

Place parsing of a vector index into a separate function to reduce
duplication, since the code is duplicated in both the parsing of a
Neon vector register operand and a Neon vector list.

This is patch [2/6] in a series to add assembler/disassembler support for
SVE's contiguous ST1 (scalar+imm) instructions.

[rengolin]

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

2963

This function doesn't look NEON specific, why the name change?

[sdesmalen]

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

2963

This is because matching the trailing index operand after a vector list is not used for SVE, so this patch makes the parseVectorList function generic and adds the index-operand parsing (Neon-specific) to parseNeonVectorList.

[rengolin]

LGTM.

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

2963

I see, makes sense.

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

private:
   bool parseSysAlias(StringRef Name, SMLoc NameLoc, OperandVector &Operands);
   void createSysAlias(uint16_t Encoding, OperandVector &Operands, SMLoc S);
   AArch64CC::CondCode parseCondCodeString(StringRef Cond);
   bool parseCondCode(OperandVector &Operands, bool invertCondCode);
   unsigned matchRegisterNameAlias(StringRef Name, RegKind Kind);
   int tryParseRegister();
   bool parseRegister(OperandVector &Operands);
   bool parseSymbolicImmVal(const MCExpr *&ImmVal);
-  bool parseVectorList(OperandVector &Operands);
+  bool parseNeonVectorList(OperandVector &Operands);
   bool parseOperand(OperandVector &Operands, bool isCondCode,
                     bool invertCondCode);
 
   bool showMatchError(SMLoc Loc, unsigned ErrCode, OperandVector &Operands);
 
   bool parseDirectiveArch(SMLoc L);
   bool parseDirectiveCPU(SMLoc L);
   bool parseDirectiveWord(unsigned Size, SMLoc L);
#include "AArch64GenAsmMatcher.inc"
   OperandMatchResultTy tryParsePrefetch(OperandVector &Operands);
   OperandMatchResultTy tryParsePSBHint(OperandVector &Operands);
   OperandMatchResultTy tryParseAdrpLabel(OperandVector &Operands);
   OperandMatchResultTy tryParseAdrLabel(OperandVector &Operands);
   OperandMatchResultTy tryParseFPImm(OperandVector &Operands);
   OperandMatchResultTy tryParseAddSubImm(OperandVector &Operands);
   OperandMatchResultTy tryParseGPR64sp0Operand(OperandVector &Operands);
   bool tryParseNeonVectorRegister(OperandVector &Operands);
+  OperandMatchResultTy tryParseVectorIndex(OperandVector &Operands);
   OperandMatchResultTy tryParseGPRSeqPair(OperandVector &Operands);
   template <bool ParseSuffix>
   OperandMatchResultTy tryParseSVEDataVector(OperandVector &Operands);
   OperandMatchResultTy tryParseSVEPredicateVector(OperandVector &Operands);
+  bool tryParseVectorList(OperandVector &Operands);
   OperandMatchResultTy tryParseSVEPattern(OperandVector &Operands);
 
 public:
   enum AArch64MatchResultTy {
     Match_InvalidSuffix = FIRST_TARGET_MATCH_RESULT_TY,
 #define GET_OPERAND_DIAGNOSTIC_TYPES
 #include "AArch64GenAsmMatcher.inc"
   };
Operands.push_back(
                                       S, getLoc(), getContext()));
 
   // If there was an explicit qualifier, that goes on as a literal text
   // operand.
   if (!Kind.empty())
     Operands.push_back(
         AArch64Operand::CreateToken(Kind, false, S, getContext()));
 
-  // If there is an index specifier following the register, parse that too.
+  return tryParseVectorIndex(Operands) == MatchOperand_ParseFail;
+}
+
+OperandMatchResultTy
+AArch64AsmParser::tryParseVectorIndex(OperandVector &Operands) {
   SMLoc SIdx = getLoc();
   if (parseOptionalToken(AsmToken::LBrac)) {
     const MCExpr *ImmVal;
     if (getParser().parseExpression(ImmVal))
-      return false;
+      return MatchOperand_NoMatch;
     const MCConstantExpr *MCE = dyn_cast<MCConstantExpr>(ImmVal);
     if (!MCE) {
       TokError("immediate value expected for vector index");
-      return false;
+      return MatchOperand_ParseFail;;
     }
 
     SMLoc E = getLoc();
 
     if (parseToken(AsmToken::RBrac, "']' expected"))
-      return false;
+      return MatchOperand_ParseFail;;
 
     Operands.push_back(AArch64Operand::CreateVectorIndex(MCE->getValue(), SIdx,
                                                          E, getContext()));
+    return MatchOperand_Success;
   }
 
-  return false;
+  return MatchOperand_NoMatch;
 }
 
 // tryParseVectorRegister - Try to parse a vector register name with
 // optional kind specifier. If it is a register specifier, eat the token
 // and return it.
 OperandMatchResultTy
 AArch64AsmParser::tryParseVectorRegister(int &Reg, StringRef &Kind,
                                          RegKind MatchKind) {
if (getParser().parseExpression(ImmVal))
     return true;
 
   if (HasELFModifier)
     ImmVal = AArch64MCExpr::create(ImmVal, RefKind, getContext());
 
   return false;
 }
 
-/// parseVectorList - Parse a vector list operand for AdvSIMD instructions.
-bool AArch64AsmParser::parseVectorList(OperandVector &Operands) {
+/// parseVectorList - Parse a vector list operand for vector instructions.
+bool AArch64AsmParser::tryParseVectorList(OperandVector &Operands) {
   MCAsmParser &Parser = getParser();
   assert(Parser.getTok().is(AsmToken::LCurly) && "Token is not a Left Bracket");
 
   // Wrapper around parse function
   auto ParseVector = [&](int &Reg, StringRef &Kind) {
     auto StartLoc = getLoc();
 
     if (tryParseVectorRegister(Reg, Kind, RegKind::NeonVector) ==
bool AArch64AsmParser::tryParseVectorList(OperandVector &Operands) {
   if (!Kind.empty()) {
     if (const auto &VK = parseVectorKind(Kind, RegKind::NeonVector))
       std::tie(NumElements, ElementWidth) = *VK;
   }
 
   Operands.push_back(AArch64Operand::CreateVectorList(
       FirstReg, Count, NumElements, ElementWidth, S, getLoc(), getContext()));
 
-  // If there is an index specifier following the list, parse that too.
-  SMLoc SIdx = getLoc();
-  if (parseOptionalToken(AsmToken::LBrac)) { // Eat left bracket token.
-    const MCExpr *ImmVal;
-    if (getParser().parseExpression(ImmVal))
-      return false;
-    const MCConstantExpr *MCE = dyn_cast<MCConstantExpr>(ImmVal);
-    if (!MCE) {
-      TokError("immediate value expected for vector index");
-      return false;
-    }
 
-    SMLoc E = getLoc();
-    if (parseToken(AsmToken::RBrac, "']' expected"))
-      return false;
+/// parseNeonVectorList - Parse a vector list operand for AdvSIMD instructions.
+bool AArch64AsmParser::parseNeonVectorList(OperandVector &Operands) {
+  if (tryParseVectorList(Operands))
+    return true;
 
-    Operands.push_back(AArch64Operand::CreateVectorIndex(MCE->getValue(), SIdx,
-                                                         E, getContext()));
-  }
-  return false;
+  return tryParseVectorIndex(Operands) == MatchOperand_ParseFail;
 }
 
 OperandMatchResultTy
 AArch64AsmParser::tryParseGPR64sp0Operand(OperandVector &Operands) {
   MCAsmParser &Parser = getParser();
   const AsmToken &Tok = Parser.getTok();
   if (!Tok.is(AsmToken::Identifier))
     return MatchOperand_NoMatch;
Operands.push_back(AArch64Operand::CreateToken("[", false, Loc,
                                                    getContext()));
     Parser.Lex(); // Eat '['
 
     // There's no comma after a '[', so we can parse the next operand
     // immediately.
     return parseOperand(Operands, false, false);
   }
   case AsmToken::LCurly:
-    return parseVectorList(Operands);
+    return parseNeonVectorList(Operands);
   case AsmToken::Identifier: {
     // If we're expecting a Condition Code operand, then just parse that.
     if (isCondCode)
       return parseCondCode(Operands, invertCondCode);
 
     // If it's a register name, parse it.
     if (!parseRegister(Operands))
       return false;