[llvm][misexpect][NFC] Fix Twine usage (#136446)

Author: ilovepi

llvm/include/llvm/IR/DiagnosticInfo.h

@@ -1090,7 +1090,7 @@ class DiagnosticInfoUnsupported : public DiagnosticInfoWithLocationBase {
 /// Diagnostic information for MisExpect analysis.
 class DiagnosticInfoMisExpect : public DiagnosticInfoWithLocationBase {
 public:
-  DiagnosticInfoMisExpect(const Instruction *Inst, Twine &Msg);
+  DiagnosticInfoMisExpect(const Instruction *Inst, const Twine &Msg);
 
   /// \see DiagnosticInfo::print.
   void print(DiagnosticPrinter &DP) const override;

llvm/lib/IR/DiagnosticInfo.cpp

@@ -443,7 +443,7 @@ std::string DiagnosticInfoOptimizationBase::getMsg() const {
 }
 
 DiagnosticInfoMisExpect::DiagnosticInfoMisExpect(const Instruction *Inst,
-                                                 Twine &Msg)
+                                                 const Twine &Msg)
     : DiagnosticInfoWithLocationBase(DK_MisExpect, DS_Warning,
                                      *Inst->getParent()->getParent(),
                                      Inst->getDebugLoc()),

llvm/lib/Transforms/Utils/MisExpect.cpp

@@ -106,10 +106,9 @@ void emitMisexpectDiagnostic(Instruction *I, LLVMContext &Ctx,
       "Potential performance regression from use of the llvm.expect intrinsic: "
       "Annotation was correct on {0} of profiled executions.",
       PerString);
-  Twine Msg(PerString);
   Instruction *Cond = getInstCondition(I);
   if (isMisExpectDiagEnabled(Ctx))
-    Ctx.diagnose(DiagnosticInfoMisExpect(Cond, Msg));
+    Ctx.diagnose(DiagnosticInfoMisExpect(Cond, Twine(PerString)));
   OptimizationRemarkEmitter ORE(I->getParent()->getParent());
   ORE.emit(OptimizationRemark(DEBUG_TYPE, "misexpect", Cond) << RemStr.str());
 }