[llvm] Avoid 'raw_string_ostream::str' (NFC)

Since `raw_string_ostream` doesn't own the string buffer, it is
desirable (in terms of memory safety) for users to directly reference
the string buffer rather than use `raw_string_ostream::str()`.

Work towards TODO item to remove `raw_string_ostream::str()`.

llvm/lib/CodeGen/MIRPrintingPass.cpp

@@ -52,7 +52,7 @@ struct MIRPrintingPass : public MachineFunctionPass {
     std::string Str;
     raw_string_ostream StrOS(Str);
     printMIR(StrOS, MF);
-    MachineFunctions.append(StrOS.str());
+    MachineFunctions.append(Str);
     return false;
   }
 

llvm/lib/FileCheck/FileCheck.cpp

@@ -1488,7 +1488,7 @@ std::string Check::FileCheckType::getModifiersDescription() const {
   if (isLiteralMatch())
     OS << "LITERAL";
   OS << '}';
-  return OS.str();
+  return Ret;
 }
 
 std::string Check::FileCheckType::getDescription(StringRef Prefix) const {

llvm/lib/IR/DiagnosticInfo.cpp

@@ -403,7 +403,7 @@ std::string DiagnosticInfoOptimizationBase::getMsg() const {
                                     ? Args.end()
                                     : Args.begin() + FirstExtraArgIndex))
     OS << Arg.Val;
-  return OS.str();
+  return Str;
 }
 
 DiagnosticInfoMisExpect::DiagnosticInfoMisExpect(const Instruction *Inst,

llvm/lib/Remarks/Remark.cpp

@@ -23,7 +23,7 @@ std::string Remark::getArgsAsMsg() const {
   raw_string_ostream OS(Str);
   for (const Argument &Arg : Args)
     OS << Arg.Val;
-  return OS.str();
+  return Str;
 }
 
 /// Returns the value of a specified key parsed from StringRef.

llvm/tools/llvm-opt-report/OptReport.cpp

@@ -370,10 +370,10 @@ static bool writeReport(LocationInfoTy &LocationInfo) {
 
           if (!Succinct) {
             RS << LLI.UnrollCount;
-            RS << std::string(UCDigits - RS.str().size(), ' ');
+            RS << std::string(UCDigits - R.size(), ' ');
           }
 
-          return RS.str();
+          return R;
         };
 
         auto VStr = [VFDigits,
@@ -383,10 +383,10 @@ static bool writeReport(LocationInfoTy &LocationInfo) {
 
           if (!Succinct) {
             RS << LLI.VectorizationFactor << "," << LLI.InterleaveCount;
-            RS << std::string(VFDigits + ICDigits + 1 - RS.str().size(), ' ');
+            RS << std::string(VFDigits + ICDigits + 1 - R.size(), ' ');
           }
 
-          return RS.str();
+          return R;
         };
 
         OS << llvm::format_decimal(L, LNDigits) << " ";

llvm/utils/TableGen/CompressInstEmitter.cpp

@@ -618,7 +618,7 @@ void CompressInstEmitter::emitCompressInstEmitter(raw_ostream &OS,
   }
 
   if (CompressPatterns.empty()) {
-    OS << FuncH.str();
+    OS << FH;
     OS.indent(2) << "return false;\n}\n";
     if (EType == EmitterType::Compress)
       OS << "\n#endif //GEN_COMPRESS_INSTR\n";
@@ -835,10 +835,10 @@ void CompressInstEmitter::emitCompressInstEmitter(raw_ostream &OS,
     }
     if (CompressOrUncompress)
       CodeStream.indent(6) << "OutInst.setLoc(MI.getLoc());\n";
-    mergeCondAndCode(CaseStream, CondStream.str(), CodeStream.str());
+    mergeCondAndCode(CaseStream, CondString, CodeString);
     PrevOp = CurOp;
   }
-  Func << CaseStream.str() << "\n";
+  Func << CaseString << "\n";
   // Close brace for the last case.
   Func.indent(4) << "} // case " << CurOp << "\n";
   Func.indent(2) << "} // switch\n";
@@ -876,8 +876,8 @@ void CompressInstEmitter::emitCompressInstEmitter(raw_ostream &OS,
        << "}\n\n";
   }
 
-  OS << FuncH.str();
-  OS << Func.str();
+  OS << FH;
+  OS << F;
 
   if (EType == EmitterType::Compress)
     OS << "\n#endif //GEN_COMPRESS_INSTR\n";

llvm/utils/TableGen/X86DisassemblerTables.cpp

@@ -1062,11 +1062,11 @@ void DisassemblerTables::emit(raw_ostream &o) const {
   i1--;
   emitContextDecisions(o1, o2, i1, i2, ModRMTableNum);
 
-  o << o1.str();
+  o << s1;
   o << "  0x0\n";
   o << "};\n";
   o << "\n";
-  o << o2.str();
+  o << s2;
   o << "\n";
   o << "\n";
 }