Revert "[ADT] Make Twine's copy constructor private."

This reverts commit 4e4ee1c507e2707bb3c208e1e1b6551c3015cbf5.

This is failing due to some code that isn't built on MSVC
so I didn't catch.  Not immediately obvious how to fix this
at first glance, so I'm reverting for now.

llvm-svn: 315536

1 files changed, 11 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index c64c0408758..b968cb8c892 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -130,15 +130,18 @@ namespace {
 class IRBuilderPrefixedInserter : public IRBuilderDefaultInserter {
   std::string Prefix;
 
+  const Twine getNameWithPrefix(const Twine &Name) const {
+    return Name.isTriviallyEmpty() ? Name : Prefix + Name;
+  }
+
 public:
   void SetNamePrefix(const Twine &P) { Prefix = P.str(); }
 
 protected:
   void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
                     BasicBlock::iterator InsertPt) const {
-    const Twine &Prefixed = Prefix + Name;
-    IRBuilderDefaultInserter::InsertHelper(
-        I, Name.isTriviallyEmpty() ? Name : Prefixed, BB, InsertPt);
+    IRBuilderDefaultInserter::InsertHelper(I, getNameWithPrefix(Name), BB,
+                                           InsertPt);
   }
 };
 
@@ -1352,8 +1355,7 @@ static void speculateSelectInstLoads(SelectInst &SI) {
 /// This will return the BasePtr if that is valid, or build a new GEP
 /// instruction using the IRBuilder if GEP-ing is needed.
 static Value *buildGEP(IRBuilderTy &IRB, Value *BasePtr,
-                       SmallVectorImpl<Value *> &Indices,
-                       const Twine &NamePrefix) {
+                       SmallVectorImpl<Value *> &Indices, Twine NamePrefix) {
   if (Indices.empty())
     return BasePtr;
 
@@ -1378,7 +1380,7 @@ static Value *buildGEP(IRBuilderTy &IRB, Value *BasePtr,
 static Value *getNaturalGEPWithType(IRBuilderTy &IRB, const DataLayout &DL,
                                     Value *BasePtr, Type *Ty, Type *TargetTy,
                                     SmallVectorImpl<Value *> &Indices,
-                                    const Twine &NamePrefix) {
+                                    Twine NamePrefix) {
   if (Ty == TargetTy)
     return buildGEP(IRB, BasePtr, Indices, NamePrefix);
 
@@ -1423,7 +1425,7 @@ static Value *getNaturalGEPRecursively(IRBuilderTy &IRB, const DataLayout &DL,
                                        Value *Ptr, Type *Ty, APInt &Offset,
                                        Type *TargetTy,
                                        SmallVectorImpl<Value *> &Indices,
-                                       const Twine &NamePrefix) {
+                                       Twine NamePrefix) {
   if (Offset == 0)
     return getNaturalGEPWithType(IRB, DL, Ptr, Ty, TargetTy, Indices,
                                  NamePrefix);
@@ -1496,7 +1498,7 @@ static Value *getNaturalGEPRecursively(IRBuilderTy &IRB, const DataLayout &DL,
 static Value *getNaturalGEPWithOffset(IRBuilderTy &IRB, const DataLayout &DL,
                                       Value *Ptr, APInt Offset, Type *TargetTy,
                                       SmallVectorImpl<Value *> &Indices,
-                                      const Twine &NamePrefix) {
+                                      Twine NamePrefix) {
   PointerType *Ty = cast<PointerType>(Ptr->getType());
 
   // Don't consider any GEPs through an i8* as natural unless the TargetTy is
@@ -1534,8 +1536,7 @@ static Value *getNaturalGEPWithOffset(IRBuilderTy &IRB, const DataLayout &DL,
 /// a single GEP as possible, thus making each GEP more independent of the
 /// surrounding code.
 static Value *getAdjustedPtr(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr,
-                             APInt Offset, Type *PointerTy,
-                             const Twine &NamePrefix) {
+                             APInt Offset, Type *PointerTy, Twine NamePrefix) {
   // Even though we don't look through PHI nodes, we could be called on an
   // instruction in an unreachable block, which may be on a cycle.
   SmallPtrSet<Value *, 4> Visited;