vendor/llvm/llvm-trunk-r304460

17 files changed, 113 insertions, 107 deletions

diff --git a/utils/TableGen/AsmMatcherEmitter.cpp b/utils/TableGen/AsmMatcherEmitter.cpp
index 264175ae96778..0980e08f67f71 100644
--- a/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/utils/TableGen/AsmMatcherEmitter.cpp
@@ -354,11 +354,11 @@ public:
 
 class AsmVariantInfo {
 public:
-  std::string RegisterPrefix;
-  std::string TokenizingCharacters;
-  std::string SeparatorCharacters;
-  std::string BreakCharacters;
-  std::string Name;
+  StringRef RegisterPrefix;
+  StringRef TokenizingCharacters;
+  StringRef SeparatorCharacters;
+  StringRef BreakCharacters;
+  StringRef Name;
   int AsmVariantNo;
 };
 
@@ -1438,8 +1438,8 @@ void AsmMatcherInfo::buildInfo() {
   unsigned VariantCount = Target.getAsmParserVariantCount();
   for (unsigned VC = 0; VC != VariantCount; ++VC) {
     Record *AsmVariant = Target.getAsmParserVariant(VC);
-    std::string CommentDelimiter =
-      AsmVariant->getValueAsString("CommentDelimiter");
+    StringRef CommentDelimiter =
+        AsmVariant->getValueAsString("CommentDelimiter");
     AsmVariantInfo Variant;
     Variant.RegisterPrefix = AsmVariant->getValueAsString("RegisterPrefix");
     Variant.TokenizingCharacters =
@@ -1463,7 +1463,7 @@ void AsmMatcherInfo::buildInfo() {
         continue;
 
       // Ignore instructions for different instructions
-      const std::string V = CGI->TheDef->getValueAsString("AsmVariantName");
+      StringRef V = CGI->TheDef->getValueAsString("AsmVariantName");
       if (!V.empty() && V != Variant.Name)
         continue;
 
@@ -1495,7 +1495,7 @@ void AsmMatcherInfo::buildInfo() {
             .startswith( MatchPrefix))
         continue;
 
-      const std::string V = Alias->TheDef->getValueAsString("AsmVariantName");
+      StringRef V = Alias->TheDef->getValueAsString("AsmVariantName");
       if (!V.empty() && V != Variant.Name)
         continue;
 
@@ -1564,8 +1564,8 @@ void AsmMatcherInfo::buildInfo() {
       // If the instruction has a two-operand alias, build up the
       // matchable here. We'll add them in bulk at the end to avoid
       // confusing this loop.
-      std::string Constraint =
-        II->TheDef->getValueAsString("TwoOperandAliasConstraint");
+      StringRef Constraint =
+          II->TheDef->getValueAsString("TwoOperandAliasConstraint");
       if (Constraint != "") {
         // Start by making a copy of the original matchable.
         auto AliasII = llvm::make_unique<MatchableInfo>(*II);
@@ -1898,10 +1898,10 @@ static void emitConvertFuncs(CodeGenTarget &Target, StringRef ClassName,
 
   for (auto &II : Infos) {
     // Check if we have a custom match function.
-    std::string AsmMatchConverter =
-      II->getResultInst()->TheDef->getValueAsString("AsmMatchConverter");
+    StringRef AsmMatchConverter =
+        II->getResultInst()->TheDef->getValueAsString("AsmMatchConverter");
     if (!AsmMatchConverter.empty() && II->UseInstAsmMatchConverter) {
-      std::string Signature = "ConvertCustom_" + AsmMatchConverter;
+      std::string Signature = ("ConvertCustom_" + AsmMatchConverter).str();
       II->ConversionFnKind = Signature;
 
       // Check if we have already generated this signature.
@@ -2443,7 +2443,7 @@ static void emitMnemonicAliasVariant(raw_ostream &OS,const AsmMatcherInfo &Info,
 
   for (Record *R : Aliases) {
     // FIXME: Allow AssemblerVariantName to be a comma separated list.
-    std::string AsmVariantName = R->getValueAsString("AsmVariantName");
+    StringRef AsmVariantName = R->getValueAsString("AsmVariantName");
     if (AsmVariantName != AsmParserVariantName)
       continue;
     AliasesFromMnemonic[R->getValueAsString("FromMnemonic")].push_back(R);
@@ -2486,14 +2486,18 @@ static void emitMnemonicAliasVariant(raw_ostream &OS,const AsmMatcherInfo &Info,
       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;";
@@ -2522,7 +2526,7 @@ static bool emitMnemonicAliases(raw_ostream &OS, const AsmMatcherInfo &Info,
   for (unsigned VC = 0; VC != VariantCount; ++VC) {
     Record *AsmVariant = Target.getAsmParserVariant(VC);
     int AsmParserVariantNo = AsmVariant->getValueAsInt("Variant");
-    std::string AsmParserVariantName = AsmVariant->getValueAsString("Name");
+    StringRef AsmParserVariantName = AsmVariant->getValueAsString("Name");
     OS << "    case " << AsmParserVariantNo << ":\n";
     emitMnemonicAliasVariant(OS, Info, Aliases, /*Indent=*/2,
                              AsmParserVariantName);
@@ -2710,7 +2714,7 @@ static void emitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
 void AsmMatcherEmitter::run(raw_ostream &OS) {
   CodeGenTarget Target(Records);
   Record *AsmParser = Target.getAsmParser();
-  std::string ClassName = AsmParser->getValueAsString("AsmParserClassName");
+  StringRef ClassName = AsmParser->getValueAsString("AsmParserClassName");
 
   // Compute the information on the instructions to match.
   AsmMatcherInfo Info(AsmParser, Target, Records);
@@ -3173,8 +3177,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
      << "    }\n\n";
 
   // Call the post-processing function, if used.
-  std::string InsnCleanupFn =
-    AsmParser->getValueAsString("AsmParserInstCleanup");
+  StringRef InsnCleanupFn = AsmParser->getValueAsString("AsmParserInstCleanup");
   if (!InsnCleanupFn.empty())
     OS << "    " << InsnCleanupFn << "(Inst);\n";
 
diff --git a/utils/TableGen/AsmWriterEmitter.cpp b/utils/TableGen/AsmWriterEmitter.cpp
index 40b7857ab994b..30d21984c4d35 100644
--- a/utils/TableGen/AsmWriterEmitter.cpp
+++ b/utils/TableGen/AsmWriterEmitter.cpp
@@ -272,7 +272,7 @@ static void UnescapeString(std::string &Str) {
 /// clearing the Instructions vector.
 void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
   Record *AsmWriter = Target.getAsmWriter();
-  std::string ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
+  StringRef ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
   bool PassSubtarget = AsmWriter->getValueAsInt("PassSubtarget");
 
   O <<
@@ -523,7 +523,7 @@ emitRegisterNameString(raw_ostream &O, StringRef AltName,
       // 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(),
@@ -553,12 +553,11 @@ emitRegisterNameString(raw_ostream &O, StringRef AltName,
 
 void AsmWriterEmitter::EmitGetRegisterName(raw_ostream &O) {
   Record *AsmWriter = Target.getAsmWriter();
-  std::string ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
+  StringRef ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
   const auto &Registers = Target.getRegBank().getRegisters();
   const std::vector<Record*> &AltNameIndices = Target.getRegAltNameIndices();
   bool hasAltNames = AltNameIndices.size() > 1;
-  std::string Namespace =
-      Registers.front().TheDef->getValueAsString("Namespace");
+  StringRef Namespace = Registers.front().TheDef->getValueAsString("Namespace");
 
   O <<
   "\n\n/// getRegisterName - This method is automatically generated by tblgen\n"
@@ -583,14 +582,16 @@ void AsmWriterEmitter::EmitGetRegisterName(raw_ostream &O) {
     O << "  switch(AltIdx) {\n"
       << "  default: llvm_unreachable(\"Invalid register alt name index!\");\n";
     for (const Record *R : AltNameIndices) {
-      const std::string &AltName = R->getName();
-      std::string Prefix = !Namespace.empty() ? Namespace + "::" : "";
-      O << "  case " << Prefix << AltName << ":\n"
-        << "    assert(*(AsmStrs" << AltName << "+RegAsmOffset"
-        << AltName << "[RegNo-1]) &&\n"
+      StringRef AltName = R->getName();
+      O << "  case ";
+      if (!Namespace.empty())
+        O << Namespace << "::";
+      O << AltName << ":\n"
+        << "    assert(*(AsmStrs" << AltName << "+RegAsmOffset" << AltName
+        << "[RegNo-1]) &&\n"
         << "           \"Invalid alt name index for register!\");\n"
-        << "    return AsmStrs" << AltName << "+RegAsmOffset"
-        << AltName << "[RegNo-1];\n";
+        << "    return AsmStrs" << AltName << "+RegAsmOffset" << AltName
+        << "[RegNo-1];\n";
     }
     O << "  }\n";
   } else {
@@ -762,7 +763,7 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
   //////////////////////////////
 
   // Emit the method that prints the alias instruction.
-  std::string ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
+  StringRef ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
   unsigned Variant = AsmWriter->getValueAsInt("Variant");
   bool PassSubtarget = AsmWriter->getValueAsInt("PassSubtarget");
 
@@ -807,7 +808,7 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
 
       IAPrinter IAP(CGA.Result->getAsString(), CGA.AsmString);
 
-      std::string Namespace = Target.getName();
+      StringRef Namespace = Target.getName();
       std::vector<Record *> ReqFeatures;
       if (PassSubtarget) {
         // We only consider ReqFeatures predicates if PassSubtarget
@@ -845,7 +846,7 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
           // code to use.
           if (Rec->isSubClassOf("RegisterOperand") ||
               Rec->isSubClassOf("Operand")) {
-            std::string PrintMethod = Rec->getValueAsString("PrintMethod");
+            StringRef PrintMethod = Rec->getValueAsString("PrintMethod");
             if (PrintMethod != "" && PrintMethod != "printOperand") {
               PrintMethodIdx =
                   llvm::find(PrintMethods, PrintMethod) - PrintMethods.begin();
@@ -886,8 +887,9 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
               } else
                 break; // No conditions on this operand at all
             }
-            Cond = Target.getName().str() + ClassName + "ValidateMCOperand(" +
-                   Op + ", STI, " + utostr(Entry) + ")";
+            Cond = (Target.getName() + ClassName + "ValidateMCOperand(" + Op +
+                    ", STI, " + utostr(Entry) + ")")
+                       .str();
           }
           // for all subcases of ResultOperand::K_Record:
           IAP.addCond(Cond);
@@ -923,7 +925,7 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
 
       for (auto I = ReqFeatures.cbegin(); I != ReqFeatures.cend(); I++) {
         Record *R = *I;
-        std::string AsmCondString = R->getValueAsString("AssemblerCondString");
+        StringRef AsmCondString = R->getValueAsString("AssemblerCondString");
 
         // AsmCondString has syntax [!]F(,[!]F)*
         SmallVector<StringRef, 4> Ops;
@@ -933,10 +935,12 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
         for (auto &Op : Ops) {
           assert(!Op.empty() && "Empty operator");
           if (Op[0] == '!')
-            Cond = "!STI.getFeatureBits()[" + Namespace + "::" +
-                   Op.substr(1).str() + "]";
+            Cond = ("!STI.getFeatureBits()[" + Namespace + "::" + Op.substr(1) +
+                    "]")
+                       .str();
           else
-            Cond = "STI.getFeatureBits()[" + Namespace + "::" + Op.str() + "]";
+            Cond =
+                ("STI.getFeatureBits()[" + Namespace + "::" + Op + "]").str();
           IAP.addCond(Cond);
         }
       }
diff --git a/utils/TableGen/Attributes.cpp b/utils/TableGen/Attributes.cpp
index 927f6e0e5b44b..d64d30e18c3e2 100644
--- a/utils/TableGen/Attributes.cpp
+++ b/utils/TableGen/Attributes.cpp
@@ -115,7 +115,7 @@ void Attributes::emitFnAttrCompatCheck(raw_ostream &OS, bool IsStringAttr) {
       Records.getAllDerivedDefinitions("CompatRule");
 
   for (auto *Rule : CompatRules) {
-    std::string FuncName = Rule->getValueAsString("CompatFunc");
+    StringRef FuncName = Rule->getValueAsString("CompatFunc");
     OS << "  Ret &= " << FuncName << "(Caller, Callee);\n";
   }
 
@@ -129,7 +129,7 @@ void Attributes::emitFnAttrCompatCheck(raw_ostream &OS, bool IsStringAttr) {
      << "                                const Function &Callee) {\n";
 
   for (auto *Rule : MergeRules) {
-    std::string FuncName = Rule->getValueAsString("MergeFunc");
+    StringRef FuncName = Rule->getValueAsString("MergeFunc");
     OS << "  " << FuncName << "(Caller, Callee);\n";
   }
 
diff --git a/utils/TableGen/CodeEmitterGen.cpp b/utils/TableGen/CodeEmitterGen.cpp
index 565235d82143c..b80dd5daefe0e 100644
--- a/utils/TableGen/CodeEmitterGen.cpp
+++ b/utils/TableGen/CodeEmitterGen.cpp
@@ -218,10 +218,12 @@ std::string CodeEmitterGen::getInstructionCase(Record *R,
     AddCodeToMergeInOperand(R, BI, Vals[i].getName(), NumberedOp,
                             NamedOpIndices, Case, Target);
   }
-  
-  std::string PostEmitter = R->getValueAsString("PostEncoderMethod");
+
+  StringRef PostEmitter = R->getValueAsString("PostEncoderMethod");
   if (!PostEmitter.empty()) {
-    Case += "      Value = " + PostEmitter + "(MI, Value";
+    Case += "      Value = ";
+    Case += PostEmitter;
+    Case += "(MI, Value";
     Case += ", STI";
     Case += ");\n";
   }
@@ -278,11 +280,11 @@ void CodeEmitterGen::run(raw_ostream &o) {
     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
diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index ef2cb4208eae6..231a6ad5706bc 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -893,7 +893,9 @@ std::string PatternToMatch::getPredicateCheck() const {
   for (Record *Pred : PredicateRecs) {
     if (!PredicateCheck.empty())
       PredicateCheck += " && ";
-    PredicateCheck += "(" + Pred->getValueAsString("CondString") + ")";
+    PredicateCheck += "(";
+    PredicateCheck += Pred->getValueAsString("CondString");
+    PredicateCheck += ")";
   }
 
   return PredicateCheck.str();
@@ -2450,7 +2452,7 @@ void CodeGenDAGPatterns::ParseNodeTransforms() {
   while (!Xforms.empty()) {
     Record *XFormNode = Xforms.back();
     Record *SDNode = XFormNode->getValueAsDef("Opcode");
-    std::string Code = XFormNode->getValueAsString("XFormFunction");
+    StringRef Code = XFormNode->getValueAsString("XFormFunction");
     SDNodeXForms.insert(std::make_pair(XFormNode, NodeXForm(SDNode, Code)));
 
     Xforms.pop_back();
diff --git a/utils/TableGen/CodeGenDAGPatterns.h b/utils/TableGen/CodeGenDAGPatterns.h
index 189d6e382ee7c..5c56fb644e7fe 100644
--- a/utils/TableGen/CodeGenDAGPatterns.h
+++ b/utils/TableGen/CodeGenDAGPatterns.h
@@ -223,8 +223,8 @@ struct SDTypeConstraint {
 /// processing.
 class SDNodeInfo {
   Record *Def;
-  std::string EnumName;
-  std::string SDClassName;
+  StringRef EnumName;
+  StringRef SDClassName;
   unsigned Properties;
   unsigned NumResults;
   int NumOperands;
@@ -238,8 +238,8 @@ public:
   /// variadic.
   int getNumOperands() const { return NumOperands; }
   Record *getRecord() const { return Def; }
-  const std::string &getEnumName() const { return EnumName; }
-  const std::string &getSDClassName() const { return SDClassName; }
+  StringRef getEnumName() const { return EnumName; }
+  StringRef getSDClassName() const { return SDClassName; }
 
   const std::vector<SDTypeConstraint> &getTypeConstraints() const {
     return TypeConstraints;
diff --git a/utils/TableGen/CodeGenRegisters.cpp b/utils/TableGen/CodeGenRegisters.cpp
index 627614d991d52..3907336221a44 100644
--- a/utils/TableGen/CodeGenRegisters.cpp
+++ b/utils/TableGen/CodeGenRegisters.cpp
@@ -679,11 +679,6 @@ CodeGenRegisterClass::CodeGenRegisterClass(CodeGenRegBank &RegBank, Record *R)
     Name(R->getName()),
     TopoSigs(RegBank.getNumTopoSigs()),
     EnumValue(-1) {
-  // Rename anonymous register classes.
-  if (R->getName().size() > 9 && R->getName()[9] == '.') {
-    static unsigned AnonCounter = 0;
-    R->setName("AnonRegClass_" + utostr(AnonCounter++));
-  }
 
   std::vector<Record*> TypeList = R->getValueAsListOfDefs("RegTypes");
   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
@@ -867,7 +862,7 @@ std::string CodeGenRegisterClass::getQualifiedName() const {
   if (Namespace.empty())
     return getName();
   else
-    return Namespace + "::" + getName();
+    return (Namespace + "::" + getName()).str();
 }
 
 // Compute sub-classes of all register classes.
diff --git a/utils/TableGen/CodeGenRegisters.h b/utils/TableGen/CodeGenRegisters.h
index 9366838c77cd0..1fcba8a135d18 100644
--- a/utils/TableGen/CodeGenRegisters.h
+++ b/utils/TableGen/CodeGenRegisters.h
@@ -308,13 +308,13 @@ namespace llvm {
 
   public:
     unsigned EnumValue;
-    std::string Namespace;
+    StringRef Namespace;
     SmallVector<MVT::SimpleValueType, 4> VTs;
     unsigned SpillSize;
     unsigned SpillAlignment;
     int CopyCost;
     bool Allocatable;
-    std::string AltOrderSelect;
+    StringRef AltOrderSelect;
     uint8_t AllocationPriority;
     /// Contains the combination of the lane masks of all subregisters.
     LaneBitmask LaneMask;
diff --git a/utils/TableGen/CodeGenSchedule.cpp b/utils/TableGen/CodeGenSchedule.cpp
index cae1cf4b861e7..20f6047052ff0 100644
--- a/utils/TableGen/CodeGenSchedule.cpp
+++ b/utils/TableGen/CodeGenSchedule.cpp
@@ -542,7 +542,7 @@ void CodeGenSchedModels::collectSchedClasses() {
     return;
 
   for (const CodeGenInstruction *Inst : Target.getInstructionsByEnumValue()) {
-    std::string InstName = Inst->TheDef->getName();
+    StringRef InstName = Inst->TheDef->getName();
     unsigned SCIdx = InstrClassMap.lookup(Inst->TheDef);
     if (!SCIdx) {
       if (!Inst->hasNoSchedulingInfo)
diff --git a/utils/TableGen/FixedLenDecoderEmitter.cpp b/utils/TableGen/FixedLenDecoderEmitter.cpp
index e1aaeccb08d09..75fd73082b9a5 100644
--- a/utils/TableGen/FixedLenDecoderEmitter.cpp
+++ b/utils/TableGen/FixedLenDecoderEmitter.cpp
@@ -1145,16 +1145,15 @@ bool FilterChooser::emitPredicateMatch(raw_ostream &o, unsigned &Indentation,
     if (!Pred->getValue("AssemblerMatcherPredicate"))
       continue;
 
-    std::string P = Pred->getValueAsString("AssemblerCondString");
+    StringRef P = Pred->getValueAsString("AssemblerCondString");
 
-    if (!P.length())
+    if (P.empty())
       continue;
 
     if (!IsFirstEmission)
       o << " && ";
 
-    StringRef SR(P);
-    std::pair<StringRef, StringRef> pairs = SR.split(',');
+    std::pair<StringRef, StringRef> pairs = P.split(',');
     while (!pairs.second.empty()) {
       emitSinglePredicateMatch(o, pairs.first, Emitter->PredicateNamespace);
       o << " && ";
@@ -1174,9 +1173,9 @@ bool FilterChooser::doesOpcodeNeedPredicate(unsigned Opc) const {
     if (!Pred->getValue("AssemblerMatcherPredicate"))
       continue;
 
-    std::string P = Pred->getValueAsString("AssemblerCondString");
+    StringRef P = Pred->getValueAsString("AssemblerCondString");
 
-    if (!P.length())
+    if (P.empty())
       continue;
 
     return true;
@@ -1744,7 +1743,7 @@ static bool populateInstruction(CodeGenTarget &Target,
 
   // If the instruction has specified a custom decoding hook, use that instead
   // of trying to auto-generate the decoder.
-  std::string InstDecoder = Def.getValueAsString("DecoderMethod");
+  StringRef InstDecoder = Def.getValueAsString("DecoderMethod");
   if (InstDecoder != "") {
     bool HasCompleteInstDecoder = Def.getValueAsBit("hasCompleteDecoder");
     InsnOperands.push_back(OperandInfo(InstDecoder, HasCompleteInstDecoder));
@@ -2261,7 +2260,7 @@ void FixedLenDecoderEmitter::run(raw_ostream &o) {
         Def->getValueAsBit("isCodeGenOnly"))
       continue;
 
-    std::string DecoderNamespace = Def->getValueAsString("DecoderNamespace");
+    StringRef DecoderNamespace = Def->getValueAsString("DecoderNamespace");
 
     if (Size) {
       if (populateInstruction(Target, *Inst, i, Operands)) {
diff --git a/utils/TableGen/GlobalISelEmitter.cpp b/utils/TableGen/GlobalISelEmitter.cpp
index e0303b7b1ab44..88ded1f25ffbd 100644
--- a/utils/TableGen/GlobalISelEmitter.cpp
+++ b/utils/TableGen/GlobalISelEmitter.cpp
@@ -118,7 +118,7 @@ static std::string explainPredicates(const TreePatternNode *N) {
 
 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();
diff --git a/utils/TableGen/OptParserEmitter.cpp b/utils/TableGen/OptParserEmitter.cpp
index c1b5e6510325c..04e6537f3d152 100644
--- a/utils/TableGen/OptParserEmitter.cpp
+++ b/utils/TableGen/OptParserEmitter.cpp
@@ -21,6 +21,8 @@ using namespace llvm;
 
 // Ordering on Info. The logic should match with the consumer-side function in
 // llvm/Option/OptTable.h.
+// FIXME: Mmake this take StringRefs instead of null terminated strings to
+// simplify callers.
 static int StrCmpOptionName(const char *A, const char *B) {
   const char *X = A, *Y = B;
   char a = tolower(*A), b = tolower(*B);
@@ -53,22 +55,22 @@ static int CompareOptionRecords(Record *const *Av, Record *const *Bv) {
 
   // 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");
-
-    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()))
+    std::vector<StringRef> APrefixes = A->getValueAsListOfStrings("Prefixes");
+    std::vector<StringRef> BPrefixes = B->getValueAsListOfStrings("Prefixes");
+
+    for (std::vector<StringRef>::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->str().c_str(), BPre->str().c_str()))
         return Cmp;
     }
   }
@@ -122,7 +124,7 @@ void EmitOptParser(RecordKeeper &Records, raw_ostream &OS) {
   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_") +
@@ -207,7 +209,7 @@ void EmitOptParser(RecordKeeper &Records, raw_ostream &OS) {
     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.
@@ -240,7 +242,7 @@ void EmitOptParser(RecordKeeper &Records, raw_ostream &OS) {
     // 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 {
diff --git a/utils/TableGen/RegisterBankEmitter.cpp b/utils/TableGen/RegisterBankEmitter.cpp
index bf066412b2860..3f11eff1d3717 100644
--- a/utils/TableGen/RegisterBankEmitter.cpp
+++ b/utils/TableGen/RegisterBankEmitter.cpp
@@ -44,7 +44,7 @@ public:
       : TheDef(TheDef), RCs(), RCWithLargestRegsSize(nullptr) {}
 
   /// Get the human-readable name for the bank.
-  std::string getName() const { return TheDef.getValueAsString("Name"); }
+  StringRef getName() const { return TheDef.getValueAsString("Name"); }
   /// Get the name of the enumerator in the ID enumeration.
   std::string getEnumeratorName() const { return (TheDef.getName() + "ID").str(); }
 
diff --git a/utils/TableGen/RegisterInfoEmitter.cpp b/utils/TableGen/RegisterInfoEmitter.cpp
index 5b56578a64b3b..12cfb93a0c4f3 100644
--- a/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/utils/TableGen/RegisterInfoEmitter.cpp
@@ -93,8 +93,7 @@ void RegisterInfoEmitter::runEnums(raw_ostream &OS,
   // Register enums are stored as uint16_t in the tables. Make sure we'll fit.
   assert(Registers.size() <= 0xffff && "Too many regs to fit in tables");
 
-  std::string Namespace =
-      Registers.front().TheDef->getValueAsString("Namespace");
+  StringRef Namespace = Registers.front().TheDef->getValueAsString("Namespace");
 
   emitSourceFileHeader("Target Register Enum Values", OS);
 
@@ -354,7 +353,7 @@ void RegisterInfoEmitter::EmitRegMappingTables(
     for (unsigned i = I->second.size(), e = maxLength; i != e; ++i)
       I->second.push_back(-1);
 
-  std::string Namespace = Regs.front().TheDef->getValueAsString("Namespace");
+  StringRef Namespace = Regs.front().TheDef->getValueAsString("Namespace");
 
   OS << "// " << Namespace << " Dwarf<->LLVM register mappings.\n";
 
@@ -464,7 +463,7 @@ void RegisterInfoEmitter::EmitRegMapping(
   if (!maxLength)
     return;
 
-  std::string Namespace = Regs.front().TheDef->getValueAsString("Namespace");
+  StringRef Namespace = Regs.front().TheDef->getValueAsString("Namespace");
 
   // Emit reverse information about the dwarf register numbers.
   for (unsigned j = 0; j < 2; ++j) {
diff --git a/utils/TableGen/SearchableTableEmitter.cpp b/utils/TableGen/SearchableTableEmitter.cpp
index 80f0b0d4aaf43..efd4e83eca906 100644
--- a/utils/TableGen/SearchableTableEmitter.cpp
+++ b/utils/TableGen/SearchableTableEmitter.cpp
@@ -112,8 +112,8 @@ private:
 void SearchableTableEmitter::emitMappingEnum(std::vector<Record *> &Items,
                                              Record *InstanceClass,
                                              raw_ostream &OS) {
-  std::string EnumNameField = InstanceClass->getValueAsString("EnumNameField");
-  std::string EnumValueField;
+  StringRef EnumNameField = InstanceClass->getValueAsString("EnumNameField");
+  StringRef EnumValueField;
   if (!InstanceClass->isValueUnset("EnumValueField"))
     EnumValueField = InstanceClass->getValueAsString("EnumValueField");
 
diff --git a/utils/TableGen/SubtargetEmitter.cpp b/utils/TableGen/SubtargetEmitter.cpp
index 1903f405d8598..7e9f552eccc0c 100644
--- a/utils/TableGen/SubtargetEmitter.cpp
+++ b/utils/TableGen/SubtargetEmitter.cpp
@@ -180,9 +180,9 @@ unsigned SubtargetEmitter::FeatureKeyValues(raw_ostream &OS) {
     // Next feature
     Record *Feature = FeatureList[i];
 
-    const std::string &Name = Feature->getName();
-    const std::string &CommandLineName = Feature->getValueAsString("Name");
-    const std::string &Desc = Feature->getValueAsString("Desc");
+    StringRef Name = Feature->getName();
+    StringRef CommandLineName = Feature->getValueAsString("Name");
+    StringRef Desc = Feature->getValueAsString("Desc");
 
     if (CommandLineName.empty()) continue;
 
@@ -237,7 +237,7 @@ unsigned SubtargetEmitter::CPUKeyValues(raw_ostream &OS) {
     // Next processor
     Record *Processor = ProcessorList[i];
 
-    const std::string &Name = Processor->getValueAsString("Name");
+    StringRef Name = Processor->getValueAsString("Name");
     const std::vector<Record*> &FeatureList =
       Processor->getValueAsListOfDefs("Features");
 
@@ -1212,7 +1212,7 @@ void SubtargetEmitter::EmitProcessorLookup(raw_ostream &OS) {
     // Next processor
     Record *Processor = ProcessorList[i];
 
-    const std::string &Name = Processor->getValueAsString("Name");
+    StringRef Name = Processor->getValueAsString("Name");
     const std::string &ProcModelName =
       SchedModels.getModelForProc(Processor).ModelName;
 
@@ -1360,9 +1360,9 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
 
   for (Record *R : Features) {
     // Next record
-    const std::string &Instance = R->getName();
-    const std::string &Value = R->getValueAsString("Value");
-    const std::string &Attribute = R->getValueAsString("Attribute");
+    StringRef Instance = R->getName();
+    StringRef Value = R->getValueAsString("Value");
+    StringRef Attribute = R->getValueAsString("Attribute");
 
     if (Value=="true" || Value=="false")
       OS << "  if (Bits[" << Target << "::"
diff --git a/utils/TableGen/X86FoldTablesEmitter.cpp b/utils/TableGen/X86FoldTablesEmitter.cpp
index 99429c5f96a25..b89cee2ce4bbb 100644
--- a/utils/TableGen/X86FoldTablesEmitter.cpp
+++ b/utils/TableGen/X86FoldTablesEmitter.cpp
@@ -292,7 +292,7 @@ getMemOperandSize(const Record *MemRec, const bool IntrinsicSensitive = false) {
         (MemRec->getName() == "sdmem" || MemRec->getName() == "ssmem"))
       return 128;
 
-    std::string Name =
+    StringRef Name =
         MemRec->getValueAsDef("ParserMatchClass")->getValueAsString("Name");
     if (Name == "Mem8")
       return 8;
@@ -368,7 +368,7 @@ static inline const CodeGenInstruction *
 getAltRegInst(const CodeGenInstruction *I, const RecordKeeper &Records,
               const CodeGenTarget &Target) {
 
-  std::string AltRegInstStr = I->TheDef->getValueAsString("FoldGenRegForm");
+  StringRef AltRegInstStr = I->TheDef->getValueAsString("FoldGenRegForm");
   Record *AltRegInstRec = Records.getDef(AltRegInstStr);
   assert(AltRegInstRec &&
          "Alternative register form instruction def not found");