Initial update to VMCore to use Twines for string arguments.

 - The only meat here is in Value.{h,cpp} the rest is essential 'const
   std::string &' -> 'const Twine &'.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77048 91177308-0d34-0410-b5e6-96231b3b80d8

19 files changed, 392 insertions, 276 deletions

diff --git a/docs/ProgrammersManual.html b/docs/ProgrammersManual.html
index dba7213697..1931a68060 100644
--- a/docs/ProgrammersManual.html
+++ b/docs/ProgrammersManual.html
@@ -29,6 +29,12 @@
     <ul>
       <li><a href="#isa">The <tt>isa&lt;&gt;</tt>, <tt>cast&lt;&gt;</tt>
 and <tt>dyn_cast&lt;&gt;</tt> templates</a> </li>
+      <li><a href="#string_apis">Passing strings (the <tt>StringRef</tt>
+and <tt>Twine</tt> classes)</li>
+        <ul>
+          <li><a href="#StringRef">The <tt>StringRef</tt> class</a> </li>
+          <li><a href="#Twine">The <tt>Twine</tt> class</a> </li>
+        </ul>
       <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro and <tt>-debug</tt>
 option</a>
         <ul>
@@ -424,6 +430,106 @@ are lots of examples in the LLVM source base.</p>
 
 </div>
 
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+  <a name="string_apis">Passing strings (the <tt>StringRef</tt>
+and <tt>Twine</tt> classes)</a>
+</div>
+
+<div class="doc_text">
+
+<p>Although LLVM generally does not do much string manipulation, we do have
+several important APIs which take string.  Several important examples are the
+Value class -- which has names for instructions, functions, etc. -- and the
+StringMap class which is used extensively in LLVM and Clang.</p>
+
+<p>These are generic classes, and they need to be able to accept strings which
+may have embedded null characters.  Therefore, they cannot simply take
+a <tt>const char *</tt>, and taking a <tt>const std::string&</tt> requires
+clients to perform a heap allocation which is usually unnecessary.  Instead,
+many LLVM APIs use a <tt>const StringRef&</tt> or a <tt>const Twine&</tt> for
+passing strings efficiently.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+  <a name="StringRef">The <tt>StringRef</tt> class</a>
+</div>
+
+<div class="doc_text">
+
+<p>The <tt>StringRef</tt> data type represents a reference to a constant string
+(a character array and a length) and supports the common operations available
+on <tt>std:string</tt>, but does not require heap allocation.</p>
+
+It can be implicitly constructed using either a C style null-terminated string
+or an <tt>std::string</tt>, or explicitly with a character pointer and length.
+For example, the <tt>StringRef</tt> find function is declared as:</p>
+<div class="doc_code">
+  iterator find(const StringRef &Key);
+</div>
+
+<p>and clients can call it using any one of:</p>
+
+<div class="doc_code">
+<pre>
+  Map.find("foo");                 <i>// Lookup "foo"</i>
+  Map.find(std::string("bar"));    <i>// Lookup "bar"</i>
+  Map.find(StringRef("\0baz", 4)); <i>// Lookup "\0baz"</i>
+</pre>
+</div>
+
+<p>Similarly, APIs which need to return a string may return a <tt>StringRef</tt>
+instance, which can be used directly or converted to an <tt>std::string</tt>
+using the <tt>str</tt> member function.  See 
+"<tt><a href="/doxygen/classllvm_1_1StringRef_8h-source.html">llvm/ADT/StringRef.h</a></tt>"
+for more information.</p>
+
+<p>You should rarely use the <tt>StringRef</tt> class directly, because it contains
+pointers to external memory it is not generally safe to store an instance of the
+class (since the external storage may be freed).</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+  <a name="Twine">The <tt>Twine</tt> class</a>
+</div>
+
+<div class="doc_text">
+
+<p>The <tt>Twine</tt> class is an efficient way for APIs to accept concatenated
+strings.  For example, a common LLVM paradigm is to name one instruction based on
+the name of another instruction with a suffix, for example:</p>
+
+<div class="doc_code">
+<pre>
+    New = CmpInst::Create(<i>...</i>, SO->getName() + ".cmp");
+</pre>
+</div>
+
+<p>The <tt>Twine</tt> class is effectively a
+lightweight <a href="http://en.wikipedia.org/wiki/Rope_(computer_science)">rope</a>
+which points to temporary (stack allocated) objects.  Twines can be implicitly
+constructed as the result of the plus operator applied to strings (i.e., a C
+strings, an <tt>std::string</tt>, or a <tt>StringRef</tt>).  The twine delays the
+actual concatentation of strings until it is actually required, at which point
+it can be efficiently rendered directly into a character array.  This avoids
+unnecessary heap allocation involved in constructing the temporary results of
+string concatenation. See
+"<tt><a href="/doxygen/classllvm_1_1Twine_8h-source.html">llvm/ADT/Twine.h</a></tt>"
+for more information.</p></tt>
+
+<p>As with a <tt>StringRef</tt>, <tt>Twine</tt> objects point to external memory
+and should almost never be stored or mentioned directly.  They are intended
+solely for use when defining a function which should be able to efficiently
+accept concatenated strings.</p>
+
+</div>
+
+
 <!-- ======================================================================= -->
 <div class="doc_subsection">
   <a name="DEBUG">The <tt>DEBUG()</tt> macro and <tt>-debug</tt> option</a>
diff --git a/docs/ReleaseNotes-2.6.html b/docs/ReleaseNotes-2.6.html
index f1b8852fe0..b6b6724e98 100644
--- a/docs/ReleaseNotes-2.6.html
+++ b/docs/ReleaseNotes-2.6.html
@@ -460,8 +460,14 @@ API changes are:</p>
 <li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
 longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
 used.</li>
+<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
+and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
+or <tt>std::string</tt>, as described in
+the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
+clients should be uneffected by this transition.</li>
 <li>llvm-dis now fails if output file exists, instead of dumping to stdout.
-FIXME: describe any other tool changes due to the raw_fd_ostream change</li>
+FIXME: describe any other tool changes due to the raw_fd_ostream change.  FIXME:
+This is not an API change, maybe there should be a tool changes section?</li>
 <li>temporarely due to Context API change passes should call doInitialization()
 method of the pass they inherit from, otherwise Context is NULL.
 FIXME: remove this entry when this is no longer needed.<li>
diff --git a/include/llvm/Argument.h b/include/llvm/Argument.h
index 9c06367798..3a846c2899 100644
--- a/include/llvm/Argument.h
+++ b/include/llvm/Argument.h
@@ -38,8 +38,7 @@ public:
   /// Argument ctor - If Function argument is specified, this argument is
   /// inserted at the end of the argument list for the function.
   ///
-  explicit Argument(const Type *Ty, const std::string &Name = "",
-                    Function *F = 0);
+  explicit Argument(const Type *Ty, const Twine &Name = "", Function *F = 0);
 
   inline const Function *getParent() const { return Parent; }
   inline       Function *getParent()       { return Parent; }
diff --git a/include/llvm/BasicBlock.h b/include/llvm/BasicBlock.h
index a20309fa84..eabc1a0d2b 100644
--- a/include/llvm/BasicBlock.h
+++ b/include/llvm/BasicBlock.h
@@ -83,7 +83,7 @@ private:
   /// is automatically inserted at either the end of the function (if
   /// InsertBefore is null), or before the specified basic block.
   ///
-  explicit BasicBlock(const std::string &Name = "", Function *Parent = 0,
+  explicit BasicBlock(const Twine &Name = "", Function *Parent = 0,
                       BasicBlock *InsertBefore = 0);
 public:
   /// getContext - Get the context in which this basic block lives,
@@ -97,7 +97,7 @@ public:
   /// Create - Creates a new BasicBlock. If the Parent parameter is specified,
   /// the basic block is automatically inserted at either the end of the
   /// function (if InsertBefore is 0), or before the specified basic block.
-  static BasicBlock *Create(const std::string &Name = "", Function *Parent = 0,
+  static BasicBlock *Create(const Twine &Name = "", Function *Parent = 0,
                             BasicBlock *InsertBefore = 0) {
     return new BasicBlock(Name, Parent, InsertBefore);
   }
@@ -232,7 +232,7 @@ public:
   /// cause a degenerate basic block to be formed, having a terminator inside of
   /// the basic block).
   ///
-  BasicBlock *splitBasicBlock(iterator I, const std::string &BBName = "");
+  BasicBlock *splitBasicBlock(iterator I, const Twine &BBName = "");
 };
 
 } // End llvm namespace
diff --git a/include/llvm/Function.h b/include/llvm/Function.h
index 3bf65ff475..57ebfb10a5 100644
--- a/include/llvm/Function.h
+++ b/include/llvm/Function.h
@@ -114,11 +114,11 @@ private:
   /// the module.
   ///
   Function(const FunctionType *Ty, LinkageTypes Linkage,
-           const std::string &N = "", Module *M = 0);
+           const Twine &N = "", Module *M = 0);
 
 public:
   static Function *Create(const FunctionType *Ty, LinkageTypes Linkage,
-                          const std::string &N = "", Module *M = 0) {
+                          const Twine &N = "", Module *M = 0) {
     return new(0) Function(Ty, Linkage, N, M);
   }
 
diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index b897f9f6bb..d53d49bfec 100644
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -56,10 +56,10 @@ public:
 
 protected:
   GlobalValue(const Type *ty, ValueTy vty, Use *Ops, unsigned NumOps,
-              LinkageTypes linkage, const std::string &name = "")
+              LinkageTypes linkage, const Twine &Name = "")
     : Constant(ty, vty, Ops, NumOps), Parent(0),
       Linkage(linkage), Visibility(DefaultVisibility), Alignment(0) {
-    if (!name.empty()) setName(name);
+    setName(Name);
   }
 
   Module *Parent;
diff --git a/include/llvm/GlobalVariable.h b/include/llvm/GlobalVariable.h
index 28eaa624e9..f18554d53b 100644
--- a/include/llvm/GlobalVariable.h
+++ b/include/llvm/GlobalVariable.h
@@ -52,13 +52,13 @@ public:
   /// automatically inserted into the end of the specified modules global list.
   GlobalVariable(LLVMContext &Context, const Type *Ty, bool isConstant,
                  LinkageTypes Linkage,
-                 Constant *Initializer = 0, const std::string &Name = "",
+                 Constant *Initializer = 0, const Twine &Name = "",
                  bool ThreadLocal = false, unsigned AddressSpace = 0);
   /// GlobalVariable ctor - This creates a global and inserts it before the
   /// specified other global.
   GlobalVariable(Module &M, const Type *Ty, bool isConstant,
                  LinkageTypes Linkage, Constant *Initializer,
-                 const std::string &Name,
+                 const Twine &Name,
                  GlobalVariable *InsertBefore = 0, bool ThreadLocal = false,
                  unsigned AddressSpace = 0);
 
diff --git a/include/llvm/InstrTypes.h b/include/llvm/InstrTypes.h
index c3c48af53f..43fe664003 100644
--- a/include/llvm/InstrTypes.h
+++ b/include/llvm/InstrTypes.h
@@ -144,9 +144,9 @@ class BinaryOperator : public Instruction {
 protected:
   void init(BinaryOps iType);
   BinaryOperator(BinaryOps iType, Value *S1, Value *S2, const Type *Ty,
-                 const std::string &Name, Instruction *InsertBefore);
+                 const Twine &Name, Instruction *InsertBefore);
   BinaryOperator(BinaryOps iType, Value *S1, Value *S2, const Type *Ty,
-                 const std::string &Name, BasicBlock *InsertAtEnd);
+                 const Twine &Name, BasicBlock *InsertAtEnd);
 public:
   // allocate space for exactly two operands
   void *operator new(size_t s) {
@@ -162,7 +162,7 @@ public:
   /// Instruction is allowed to be a dereferenced end iterator.
   ///
   static BinaryOperator *Create(BinaryOps Op, Value *S1, Value *S2,
-                                const std::string &Name = "",
+                                const Twine &Name = "",
                                 Instruction *InsertBefore = 0);
 
   /// Create() - Construct a binary instruction, given the opcode and the two
@@ -170,27 +170,26 @@ public:
   /// BasicBlock specified.
   ///
   static BinaryOperator *Create(BinaryOps Op, Value *S1, Value *S2,
-                                const std::string &Name,
-                                BasicBlock *InsertAtEnd);
+                                const Twine &Name, BasicBlock *InsertAtEnd);
 
   /// Create* - These methods just forward to Create, and are useful when you
   /// statically know what type of instruction you're going to create.  These
   /// helpers just save some typing.
 #define HANDLE_BINARY_INST(N, OPC, CLASS) \
   static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
-                                     const std::string &Name = "") {\
+                                     const Twine &Name = "") {\
     return Create(Instruction::OPC, V1, V2, Name);\
   }
 #include "llvm/Instruction.def"
 #define HANDLE_BINARY_INST(N, OPC, CLASS) \
   static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
-                                     const std::string &Name, BasicBlock *BB) {\
+                                     const Twine &Name, BasicBlock *BB) {\
     return Create(Instruction::OPC, V1, V2, Name, BB);\
   }
 #include "llvm/Instruction.def"
 #define HANDLE_BINARY_INST(N, OPC, CLASS) \
   static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
-                                     const std::string &Name, Instruction *I) {\
+                                     const Twine &Name, Instruction *I) {\
     return Create(Instruction::OPC, V1, V2, Name, I);\
   }
 #include "llvm/Instruction.def"
@@ -203,22 +202,22 @@ public:
   ///     instructions out of SUB and XOR instructions.
   ///
   static BinaryOperator *CreateNeg(LLVMContext &Context,
-                                   Value *Op, const std::string &Name = "",
+                                   Value *Op, const Twine &Name = "",
                                    Instruction *InsertBefore = 0);
   static BinaryOperator *CreateNeg(LLVMContext &Context,
-                                   Value *Op, const std::string &Name,
+                                   Value *Op, const Twine &Name,
                                    BasicBlock *InsertAtEnd);
   static BinaryOperator *CreateFNeg(LLVMContext &Context, 
-                                    Value *Op, const std::string &Name = "",
+                                    Value *Op, const Twine &Name = "",
                                     Instruction *InsertBefore = 0);
   static BinaryOperator *CreateFNeg(LLVMContext &Context,
-                                    Value *Op, const std::string &Name,
+                                    Value *Op, const Twine &Name,
                                     BasicBlock *InsertAtEnd);
   static BinaryOperator *CreateNot(LLVMContext &Context,
-                                   Value *Op, const std::string &Name = "",
+                                   Value *Op, const Twine &Name = "",
                                    Instruction *InsertBefore = 0);
   static BinaryOperator *CreateNot(LLVMContext &Context,
-                                   Value *Op, const std::string &Name,
+                                   Value *Op, const Twine &Name,
                                    BasicBlock *InsertAtEnd);
 
   /// isNeg, isFNeg, isNot - Check if the given Value is a
@@ -288,13 +287,13 @@ class CastInst : public UnaryInstruction {
 protected:
   /// @brief Constructor with insert-before-instruction semantics for subclasses
   CastInst(const Type *Ty, unsigned iType, Value *S,
-           const std::string &NameStr = "", Instruction *InsertBefore = 0)
+           const Twine &NameStr = "", Instruction *InsertBefore = 0)
     : UnaryInstruction(Ty, iType, S, InsertBefore) {
     setName(NameStr);
   }
   /// @brief Constructor with insert-at-end-of-block semantics for subclasses
   CastInst(const Type *Ty, unsigned iType, Value *S,
-           const std::string &NameStr, BasicBlock *InsertAtEnd)
+           const Twine &NameStr, BasicBlock *InsertAtEnd)
     : UnaryInstruction(Ty, iType, S, InsertAtEnd) {
     setName(NameStr);
   }
@@ -309,7 +308,7 @@ public:
     Instruction::CastOps,    ///< The opcode of the cast instruction
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
   /// Provides a way to construct any of the CastInst subclasses using an
@@ -322,7 +321,7 @@ public:
     Instruction::CastOps,    ///< The opcode for the cast instruction
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which operand is casted
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -330,7 +329,7 @@ public:
   static CastInst *CreateZExtOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -338,7 +337,7 @@ public:
   static CastInst *CreateZExtOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which operand is casted
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -346,7 +345,7 @@ public:
   static CastInst *CreateSExtOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -354,7 +353,7 @@ public:
   static CastInst *CreateSExtOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which operand is casted
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -362,7 +361,7 @@ public:
   static CastInst *CreatePointerCast(
     Value *S,                ///< The pointer value to be casted (operand 0)
     const Type *Ty,          ///< The type to which operand is casted
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -370,7 +369,7 @@ public:
   static CastInst *CreatePointerCast(
     Value *S,                ///< The pointer value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -379,7 +378,7 @@ public:
     Value *S,                ///< The pointer value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
     bool isSigned,           ///< Whether to regard S as signed or not
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -388,7 +387,7 @@ public:
     Value *S,                ///< The integer value to be casted (operand 0)
     const Type *Ty,          ///< The integer type to which operand is casted
     bool isSigned,           ///< Whether to regard S as signed or not
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -396,7 +395,7 @@ public:
   static CastInst *CreateFPCast(
     Value *S,                ///< The floating point value to be casted
     const Type *Ty,          ///< The floating point type to cast to
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -404,7 +403,7 @@ public:
   static CastInst *CreateFPCast(
     Value *S,                ///< The floating point value to be casted
     const Type *Ty,          ///< The floating point type to cast to
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -412,7 +411,7 @@ public:
   static CastInst *CreateTruncOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which cast should be made
-    const std::string &Name = "", ///< Name for the instruction
+    const Twine &Name = "", ///< Name for the instruction
     Instruction *InsertBefore = 0 ///< Place to insert the instruction
   );
 
@@ -420,7 +419,7 @@ public:
   static CastInst *CreateTruncOrBitCast(
     Value *S,                ///< The value to be casted (operand 0)
     const Type *Ty,          ///< The type to which operand is casted
-    const std::string &Name, ///< The name for the instruction
+    const Twine &Name, ///< The name for the instruction
     BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
   );
 
@@ -520,11 +519,11 @@ class CmpInst: public Instruction {
   CmpInst(); // do not implement
 protected:
   CmpInst(const Type *ty, Instruction::OtherOps op, unsigned short pred,
-          Value *LHS, Value *RHS, const std::string &Name = "",
+          Value *LHS, Value *RHS, const Twine &Name = "",
           Instruction *InsertBefore = 0);
 
   CmpInst(const Type *ty, Instruction::OtherOps op, unsigned short pred,
-          Value *LHS, Value *RHS, const std::string &Name,
+          Value *LHS, Value *RHS, const Twine &Name,
           BasicBlock *InsertAtEnd);
 
 public:
@@ -579,7 +578,7 @@ public:
   /// @brief Create a CmpInst
   static CmpInst *Create(LLVMContext &Context, OtherOps Op,
                          unsigned short predicate, Value *S1,
-                         Value *S2, const std::string &Name = "",
+                         Value *S2, const Twine &Name = "",
                          Instruction *InsertBefore = 0);
 
   /// Construct a compare instruction, given the opcode, the predicate and the
@@ -587,8 +586,7 @@ public:
   /// the BasicBlock specified.
   /// @brief Create a CmpInst
   static CmpInst *Create(OtherOps Op, unsigned short predicate, Value *S1,
-                         Value *S2, const std::string &Name,
-                         BasicBlock *InsertAtEnd);
+                         Value *S2, const Twine &Name, BasicBlock *InsertAtEnd);
 
   /// @brief Get the opcode casted to the right type
   OtherOps getOpcode() const {
diff --git a/include/llvm/Instructions.h b/include/llvm/Instructions.h
index 1afcc5fc05..2b53fac465 100644
--- a/include/llvm/Instructions.h
+++ b/include/llvm/Instructions.h
@@ -41,10 +41,10 @@ class LLVMContext;
 class AllocationInst : public UnaryInstruction {
 protected:
   AllocationInst(const Type *Ty, Value *ArraySize, 
-                 unsigned iTy, unsigned Align, const std::string &Name = "", 
+                 unsigned iTy, unsigned Align, const Twine &Name = "", 
                  Instruction *InsertBefore = 0);
   AllocationInst(const Type *Ty, Value *ArraySize,
-                 unsigned iTy, unsigned Align, const std::string &Name,
+                 unsigned iTy, unsigned Align, const Twine &Name,
                  BasicBlock *InsertAtEnd);
 public:
   // Out of line virtual method, so the vtable, etc. has a home.
@@ -102,28 +102,28 @@ class MallocInst : public AllocationInst {
   MallocInst(const MallocInst &MI);
 public:
   explicit MallocInst(const Type *Ty, Value *ArraySize = 0,
-                      const std::string &NameStr = "",
+                      const Twine &NameStr = "",
                       Instruction *InsertBefore = 0)
     : AllocationInst(Ty, ArraySize, Malloc,
                      0, NameStr, InsertBefore) {}
   MallocInst(const Type *Ty, Value *ArraySize,
-             const std::string &NameStr, BasicBlock *InsertAtEnd)
+             const Twine &NameStr, BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, ArraySize, Malloc, 0, NameStr, InsertAtEnd) {}
 
-  MallocInst(const Type *Ty, const std::string &NameStr,
+  MallocInst(const Type *Ty, const Twine &NameStr,
              Instruction *InsertBefore = 0)
     : AllocationInst(Ty, 0, Malloc, 0, NameStr, InsertBefore) {}
-  MallocInst(const Type *Ty, const std::string &NameStr,
+  MallocInst(const Type *Ty, const Twine &NameStr,
              BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, 0, Malloc, 0, NameStr, InsertAtEnd) {}
 
   MallocInst(const Type *Ty, Value *ArraySize,
-             unsigned Align, const std::string &NameStr,
+             unsigned Align, const Twine &NameStr,
              BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, ArraySize, Malloc,
                      Align, NameStr, InsertAtEnd) {}
   MallocInst(const Type *Ty, Value *ArraySize,
-             unsigned Align, const std::string &NameStr = "", 
+             unsigned Align, const Twine &NameStr = "", 
              Instruction *InsertBefore = 0)
     : AllocationInst(Ty, ArraySize,
                      Malloc, Align, NameStr, InsertBefore) {}
@@ -152,29 +152,29 @@ class AllocaInst : public AllocationInst {
 public:
   explicit AllocaInst(const Type *Ty,
                       Value *ArraySize = 0,
-                      const std::string &NameStr = "",
+                      const Twine &NameStr = "",
                       Instruction *InsertBefore = 0)
     : AllocationInst(Ty, ArraySize, Alloca,
                      0, NameStr, InsertBefore) {}
   AllocaInst(const Type *Ty,
-             Value *ArraySize, const std::string &NameStr,
+             Value *ArraySize, const Twine &NameStr,
              BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, ArraySize, Alloca, 0, NameStr, InsertAtEnd) {}
 
-  AllocaInst(const Type *Ty, const std::string &NameStr,
+  AllocaInst(const Type *Ty, const Twine &NameStr,
              Instruction *InsertBefore = 0)
     : AllocationInst(Ty, 0, Alloca, 0, NameStr, InsertBefore) {}
-  AllocaInst(const Type *Ty, const std::string &NameStr,
+  AllocaInst(const Type *Ty, const Twine &NameStr,
              BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, 0, Alloca, 0, NameStr, InsertAtEnd) {}
 
   AllocaInst(const Type *Ty, Value *ArraySize,
-             unsigned Align, const std::string &NameStr = "",
+             unsigned Align, const Twine &NameStr = "",
              Instruction *InsertBefore = 0)
     : AllocationInst(Ty, ArraySize, Alloca,
                      Align, NameStr, InsertBefore) {}
   AllocaInst(const Type *Ty, Value *ArraySize,
-             unsigned Align, const std::string &NameStr,
+             unsigned Align, const Twine &NameStr,
              BasicBlock *InsertAtEnd)
     : AllocationInst(Ty, ArraySize, Alloca,
                      Align, NameStr, InsertAtEnd) {}
@@ -246,15 +246,15 @@ class LoadInst : public UnaryInstruction {
   }
   void AssertOK();
 public:
-  LoadInst(Value *Ptr, const std::string &NameStr, Instruction *InsertBefore);
-  LoadInst(Value *Ptr, const std::string &NameStr, BasicBlock *InsertAtEnd);
-  LoadInst(Value *Ptr, const std::string &NameStr, bool isVolatile = false,
+  LoadInst(Value *Ptr, const Twine &NameStr, Instruction *InsertBefore);
+  LoadInst(Value *Ptr, const Twine &NameStr, BasicBlock *InsertAtEnd);
+  LoadInst(Value *Ptr, const Twine &NameStr, bool isVolatile = false,
            Instruction *InsertBefore = 0);
-  LoadInst(Value *Ptr, const std::string &NameStr, bool isVolatile,
+  LoadInst(Value *Ptr, const Twine &NameStr, bool isVolatile,
            unsigned Align, Instruction *InsertBefore = 0);
-  LoadInst(Value *Ptr, const std::string &NameStr, bool isVolatile,
+  LoadInst(Value *Ptr, const Twine &NameStr, bool isVolatile,
            BasicBlock *InsertAtEnd);
-  LoadInst(Value *Ptr, const std::string &NameStr, bool isVolatile,
+  LoadInst(Value *Ptr, const Twine &NameStr, bool isVolatile,
            unsigned Align, BasicBlock *InsertAtEnd);
 
   LoadInst(Value *Ptr, const char *NameStr, Instruction *InsertBefore);
@@ -399,12 +399,12 @@ static inline const Type *checkType(const Type *Ty) {
 class GetElementPtrInst : public Instruction {
   GetElementPtrInst(const GetElementPtrInst &GEPI);
   void init(Value *Ptr, Value* const *Idx, unsigned NumIdx,
-            const std::string &NameStr);
-  void init(Value *Ptr, Value *Idx, const std::string &NameStr);
+            const Twine &NameStr);
+  void init(Value *Ptr, Value *Idx, const Twine &NameStr);
 
   template<typename InputIterator>
   void init(Value *Ptr, InputIterator IdxBegin, InputIterator IdxEnd,
-            const std::string &NameStr,
+            const Twine &NameStr,
             // This argument ensures that we have an iterator we can
             // do arithmetic on in constant time
             std::random_access_iterator_tag) {
@@ -451,25 +451,25 @@ class GetElementPtrInst : public Instruction {
   inline GetElementPtrInst(Value *Ptr, InputIterator IdxBegin,
                            InputIterator IdxEnd,
                            unsigned Values,
-                           const std::string &NameStr,
+                           const Twine &NameStr,
                            Instruction *InsertBefore);
   template<typename InputIterator>
   inline GetElementPtrInst(Value *Ptr,
                            InputIterator IdxBegin, InputIterator IdxEnd,
                            unsigned Values,
-                           const std::string &NameStr, BasicBlock *InsertAtEnd);
+                           const Twine &NameStr, BasicBlock *InsertAtEnd);
 
   /// Constructors - These two constructors are convenience methods because one
   /// and two index getelementptr instructions are so common.
-  GetElementPtrInst(Value *Ptr, Value *Idx, const std::string &NameStr = "",
+  GetElementPtrInst(Value *Ptr, Value *Idx, const Twine &NameStr = "",
                     Instruction *InsertBefore = 0);
   GetElementPtrInst(Value *Ptr, Value *Idx,
-                    const std::string &NameStr, BasicBlock *InsertAtEnd);
+                    const Twine &NameStr, BasicBlock *InsertAtEnd);
 public:
   template<typename InputIterator>
   static GetElementPtrInst *Create(Value *Ptr, InputIterator IdxBegin,
                                    InputIterator IdxEnd,
-                                   const std::string &NameStr = "",
+                                   const Twine &NameStr = "",
                                    Instruction *InsertBefore = 0) {
     typename std::iterator_traits<InputIterator>::difference_type Values =
       1 + std::distance(IdxBegin, IdxEnd);
@@ -479,7 +479,7 @@ public:
   template<typename InputIterator>
   static GetElementPtrInst *Create(Value *Ptr,
                                    InputIterator IdxBegin, InputIterator IdxEnd,
-                                   const std::string &NameStr,
+                                   const Twine &NameStr,