[TableGen] Make Record::getValueAsString and getValueAsListOfStrings return StringRefs instead of std::string

[craig.topper]

Summary

Internally both these methods just return the result of getValue on either a StringInit or a CodeInit object. In both cases this returns a StringRef pointing to a string allocated in the BumpPtrAllocator so its not going anywhere. So we can just pass that StringRef along.

This is a fairly naive patch that targets just the build failures caused by this change. There's additional work that can be done to avoid creating std::string at call sites that still think getValueAsString returns a std::string. I'll try to clean those up in future patches.

[craig.topper]

utils/TableGen/OptParserEmitter.cpp

57

This is a bit of a hack because the compare function expects a null terminated const char* array which the StringRef doesn't guarantee so I had to create a string first. This can be cleaned up in a future commit.

[dblaikie]

utils/TableGen/OptParserEmitter.cpp

57

Please leave a FIXME unless you're planning to do this follow up soon.

include/llvm/TableGen/Record.h

public:
   bool isValueUnset(StringRef FieldName) const {
     return isa<UnsetInit>(getValueInit(FieldName));
   }
 
   /// This method looks up the specified field and returns
   /// its value as a string, throwing an exception if the field does not exist
   /// or if the value is not a string.
   ///
-  std::string getValueAsString(StringRef FieldName) const;
+  StringRef getValueAsString(StringRef FieldName) const;
 
   /// This method looks up the specified field and returns
   /// its value as a BitsInit, throwing an exception if the field does not exist
   /// or if the value is not the right type.
   ///
   BitsInit *getValueAsBitsInit(StringRef FieldName) const;
 
   /// This method looks up the specified field and returns
public:
   /// field does not exist or if the value is not the right type.
   ///
   std::vector<int64_t> getValueAsListOfInts(StringRef FieldName) const;
 
   /// This method looks up the specified field and
   /// returns its value as a vector of strings, throwing an exception if the
   /// field does not exist or if the value is not the right type.
   ///
-  std::vector<std::string> getValueAsListOfStrings(StringRef FieldName) const;
+  std::vector<StringRef> getValueAsListOfStrings(StringRef FieldName) const;
 
   /// This method looks up the specified field and returns its
   /// value as a Record, throwing an exception if the field does not exist or if
   /// the value is not the right type.
   ///
   Record *getValueAsDef(StringRef FieldName) const;
 
   /// This method looks up the specified field and returns its

lib/TableGen/Record.cpp

 Init *Record::getValueInit(StringRef FieldName) const {
   const RecordVal *R = getValue(FieldName);
   if (!R || !R->getValue())
     PrintFatalError(getLoc(), "Record `" + getName() +
       "' does not have a field named `" + FieldName + "'!\n");
   return R->getValue();
 }
 
-std::string Record::getValueAsString(StringRef FieldName) const {
+StringRef Record::getValueAsString(StringRef FieldName) const {
   const RecordVal *R = getValue(FieldName);
   if (!R || !R->getValue())
     PrintFatalError(getLoc(), "Record `" + getName() +
       "' does not have a field named `" + FieldName + "'!\n");
 
   if (StringInit *SI = dyn_cast<StringInit>(R->getValue()))
     return SI->getValue();
   if (CodeInit *CI = dyn_cast<CodeInit>(R->getValue()))
if (IntInit *II = dyn_cast<IntInit>(I))
       Ints.push_back(II->getValue());
     else
       PrintFatalError(getLoc(), "Record `" + getName() + "', field `" +
         FieldName + "' does not have a list of ints initializer!");
   }
   return Ints;
 }
 
-std::vector<std::string>
+std::vector<StringRef>
 Record::getValueAsListOfStrings(StringRef FieldName) const {
   ListInit *List = getValueAsListInit(FieldName);
-  std::vector<std::string> Strings;
+  std::vector<StringRef> Strings;
   for (Init *I : List->getValues()) {
     if (StringInit *SI = dyn_cast<StringInit>(I))
       Strings.push_back(SI->getValue());
     else
       PrintFatalError(getLoc(), "Record `" + getName() + "', field `" +
         FieldName + "' does not have a list of strings initializer!");
   }
   return Strings;

utils/TableGen/AsmMatcherEmitter.cpp

for (unsigned i = 0, e = ToVec.size(); i != e; ++i) {
         continue;
       }
       if (R->getValueAsString("ToMnemonic") == AliasEntry.first)
         PrintFatalError(R->getLoc(), "MnemonicAlias to the same string");
 
       if (!MatchCode.empty())
         MatchCode += "else ";
       MatchCode += "if ((Features & " + FeatureMask + ") == "+FeatureMask+")\n";
-      MatchCode += "  Mnemonic = \"" +R->getValueAsString("ToMnemonic")+"\";\n";
+      MatchCode += "  Mnemonic = \"";
+      MatchCode += R->getValueAsString("ToMnemonic");
+      MatchCode += "\";\n";
     }
 
     if (AliasWithNoPredicate != -1) {
       Record *R = ToVec[AliasWithNoPredicate];
       if (!MatchCode.empty())
         MatchCode += "else\n  ";
-      MatchCode += "Mnemonic = \"" + R->getValueAsString("ToMnemonic")+"\";\n";
+      MatchCode += "Mnemonic = \"";
+      MatchCode += R->getValueAsString("ToMnemonic");
+      MatchCode += "\";\n";
     }
 
     MatchCode += "return;";
 
     Cases.push_back(std::make_pair(AliasEntry.first, MatchCode));
   }
   StringMatcher("Mnemonic", Cases, OS).Emit(Indent);
 }

utils/TableGen/AsmWriterEmitter.cpp

if (AltName == "" || AltName == "NoRegAltName") {
       unsigned Idx = 0, e;
       for (e = AltNameList.size();
            Idx < e && (AltNameList[Idx]->getName() != AltName);
            ++Idx)
         ;
       // If the register has an alternate name for this index, use it.
       // Otherwise, leave it empty as an error flag.
       if (Idx < e) {
-        std::vector<std::string> AltNames =
+        std::vector<StringRef> AltNames =
           Reg.TheDef->getValueAsListOfStrings("AltNames");
         if (AltNames.size() <= Idx)
           PrintFatalError(Reg.TheDef->getLoc(),
                           "Register definition missing alt name for '" +
                           AltName + "'.");
         AsmName = AltNames[Idx];
       }
     }

utils/TableGen/CodeEmitterGen.cpp

void CodeEmitterGen::run(raw_ostream &o) {
 
   // Construct all cases statement for each opcode
   for (std::vector<Record*>::iterator IC = Insts.begin(), EC = Insts.end();
         IC != EC; ++IC) {
     Record *R = *IC;
     if (R->getValueAsString("Namespace") == "TargetOpcode" ||
         R->getValueAsBit("isPseudo"))
       continue;
-    const std::string &InstName = R->getValueAsString("Namespace") + "::"
-      + R->getName().str();
+    std::string InstName =
+        (R->getValueAsString("Namespace") + "::" + R->getName()).str();
     std::string Case = getInstructionCase(R, Target);
 
-    CaseMap[Case].push_back(InstName);
+    CaseMap[Case].push_back(std::move(InstName));
   }
 
   // Emit initial function code
   o << "  const unsigned opcode = MI.getOpcode();\n"
     << "  uint64_t Value = InstBits[opcode];\n"
     << "  uint64_t op = 0;\n"
     << "  (void)op;  // suppress warning\n"
     << "  switch (opcode) {\n";

utils/TableGen/CodeGenDAGPatterns.cpp

#endif
   }
   // Sort so that different orders get canonicalized to the same string.
   std::sort(PredicateRecs.begin(), PredicateRecs.end(), LessRecord());
 
   SmallString<128> PredicateCheck;
   for (Record *Pred : PredicateRecs) {
     if (!PredicateCheck.empty())
       PredicateCheck += " && ";
-    PredicateCheck += "(" + Pred->getValueAsString("CondString") + ")";
+    PredicateCheck += "(";
+    PredicateCheck += Pred->getValueAsString("CondString");
+    PredicateCheck += ")";
   }
 
   return PredicateCheck.str();
 }
 
 //===----------------------------------------------------------------------===//
 // SDTypeConstraint implementation
 //

utils/TableGen/GlobalISelEmitter.cpp

for (const auto &P : N->getPredicateFns()) {
     if (P.isImmediatePattern())
       Explanation += " immediate";
   }
   return Explanation;
 }
 
 std::string explainOperator(Record *Operator) {
   if (Operator->isSubClassOf("SDNode"))
-    return " (" + Operator->getValueAsString("Opcode") + ")";
+    return (" (" + Operator->getValueAsString("Opcode") + ")").str();
 
   if (Operator->isSubClassOf("Intrinsic"))
     return (" (Operator is an Intrinsic, " + Operator->getName() + ")").str();
 
   return " (Operator not understood)";
 }
 
 /// Helper function to let the emitter report skip reason error messages.

utils/TableGen/OptParserEmitter.cpp

static int CompareOptionRecords(Record *const *Av, Record *const *Bv) {
   // Sentinel options precede all others and are only ordered by precedence.
   bool ASent = A->getValueAsDef("Kind")->getValueAsBit("Sentinel");
   bool BSent = B->getValueAsDef("Kind")->getValueAsBit("Sentinel");
   if (ASent != BSent)
     return ASent ? -1 : 1;
 
   // Compare options by name, unless they are sentinels.
   if (!ASent)
-    if (int Cmp = StrCmpOptionName(A->getValueAsString("Name").c_str(),
-                                   B->getValueAsString("Name").c_str()))
+    if (int Cmp = StrCmpOptionName(A->getValueAsString("Name").str().c_str(),
+                                   B->getValueAsString("Name").str().c_str()))
       return Cmp;
 
   if (!ASent) {
-    std::vector<std::string> APrefixes = A->getValueAsListOfStrings("Prefixes");
-    std::vector<std::string> BPrefixes = B->getValueAsListOfStrings("Prefixes");
+    std::vector<StringRef> APrefixes = A->getValueAsListOfStrings("Prefixes");
+    std::vector<StringRef> BPrefixes = B->getValueAsListOfStrings("Prefixes");
 
-    for (std::vector<std::string>::const_iterator APre = APrefixes.begin(),
-                                                  AEPre = APrefixes.end(),
-                                                  BPre = BPrefixes.begin(),
-                                                  BEPre = BPrefixes.end();
-                                                  APre != AEPre &&
-                                                  BPre != BEPre;
-                                                  ++APre, ++BPre) {
-      if (int Cmp = StrCmpOptionName(APre->c_str(), BPre->c_str()))
+    for (std::vector<StringRef>::const_iterator APre = APrefixes.begin(),
+      if (int Cmp = StrCmpOptionName(APre->str().c_str(), BPre->str().c_str()))
         return Cmp;
     }
   }
 
   // Then by the kind precedence;
   int APrec = A->getValueAsDef("Kind")->getValueAsInt("Precedence");
   int BPrec = B->getValueAsDef("Kind")->getValueAsInt("Precedence");
   if (APrec == BPrec &&
void EmitOptParser(RecordKeeper &Records, raw_ostream &OS) {
   // Generate prefix groups.
   typedef SmallVector<SmallString<2>, 2> PrefixKeyT;
   typedef std::map<PrefixKeyT, std::string> PrefixesT;
   PrefixesT Prefixes;
   Prefixes.insert(std::make_pair(PrefixKeyT(), "prefix_0"));
   unsigned CurPrefix = 0;
   for (unsigned i = 0, e = Opts.size(); i != e; ++i) {
     const Record &R = *Opts[i];
-    std::vector<std::string> prf = R.getValueAsListOfStrings("Prefixes");
+    std::vector<StringRef> prf = R.getValueAsListOfStrings("Prefixes");
     PrefixKeyT prfkey(prf.begin(), prf.end());
     unsigned NewPrefix = CurPrefix + 1;
     if (Prefixes.insert(std::make_pair(prfkey, (Twine("prefix_") +
                                               Twine(NewPrefix)).str())).second)
       CurPrefix = NewPrefix;
   }
 
   // Dump prefixes.
void EmitOptParser(RecordKeeper &Records, raw_ostream &OS) {
   OS << "// Options\n\n";
   for (unsigned i = 0, e = Opts.size(); i != e; ++i) {
     const Record &R = *Opts[i];
 
     // Start a single option entry.
     OS << "OPTION(";
 
     // The option prefix;
-    std::vector<std::string> prf = R.getValueAsListOfStrings("Prefixes");
+    std::vector<StringRef> prf = R.getValueAsListOfStrings("Prefixes");
     OS << Prefixes[PrefixKeyT(prf.begin(), prf.end())] << ", ";
 
     // The option string.
     write_cstring(OS, R.getValueAsString("Name"));
 
     // The option identifier name.
     OS  << ", "<< getOptionName(R);
 
for (unsigned i = 0, e = Opts.size(); i != e; ++i) {
     else
       OS << "INVALID";
 
     // The option alias arguments (if any).
     // Emitted as a \0 separated list in a string, e.g. ["foo", "bar"]
     // would become "foo\0bar\0". Note that the compiler adds an implicit
     // terminating \0 at the end.
     OS << ", ";
-    std::vector<std::string> AliasArgs = R.getValueAsListOfStrings("AliasArgs");
+    std::vector<StringRef> AliasArgs = R.getValueAsListOfStrings("AliasArgs");
     if (AliasArgs.size() == 0) {
       OS << "nullptr";
     } else {
       OS << "\"";
       for (size_t i = 0, e = AliasArgs.size(); i != e; ++i)
         OS << AliasArgs[i] << "\\0";
       OS << "\"";
     }