reapply the patches reverted in r149470 that reenable ConstantDataArray,

but with a critical fix to the SelectionDAG code that optimizes copies
from strings into immediate stores: the previous code was stopping reading
string data at the first nul.  Address this by adding a new argument to
llvm::getConstantStringInfo, preserving the behavior before the patch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149800 91177308-0d34-0410-b5e6-96231b3b80d8

19 files changed, 277 insertions, 540 deletions

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index 300f51df37..dfd774b916 100644
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -17,14 +17,13 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/DataTypes.h"
-#include <string>
 
 namespace llvm {
-  template <typename T> class SmallVectorImpl;
   class Value;
   class Instruction;
   class APInt;
   class TargetData;
+  class StringRef;
   
   /// ComputeMaskedBits - Determine which of the bits specified in Mask are
   /// known to be either zero or one and return them in the KnownZero/KnownOne
@@ -125,16 +124,15 @@ namespace llvm {
     return GetPointerBaseWithConstantOffset(const_cast<Value*>(Ptr), Offset,TD);
   }
   
-  /// GetConstantStringInfo - This function computes the length of a
+  /// getConstantStringInfo - This function computes the length of a
   /// null-terminated C string pointed to by V.  If successful, it returns true
-  /// and returns the string in Str.  If unsuccessful, it returns false.  If
-  /// StopAtNul is set to true (the default), the returned string is truncated
-  /// by a nul character in the global.  If StopAtNul is false, the nul
-  /// character is included in the result string.
-  bool GetConstantStringInfo(const Value *V, std::string &Str,
-                             uint64_t Offset = 0,
-                             bool StopAtNul = true);
-                        
+  /// and returns the string in Str.  If unsuccessful, it returns false.  This
+  /// does not include the trailing nul character by default.  If TrimAtNul is
+  /// set to false, then this returns any trailing nul characters as well as any
+  /// other characters that come after it.
+  bool getConstantStringInfo(const Value *V, StringRef &Str,
+                             uint64_t Offset = 0, bool TrimAtNul = true);
+
   /// GetStringLength - If we can compute the length of the string pointed to by
   /// the specified pointer, return 'len+1'.  If we can't, return 0.
   uint64_t GetStringLength(Value *V);
diff --git a/include/llvm/Constants.h b/include/llvm/Constants.h
index 43f625a68f..a4723d37f0 100644
--- a/include/llvm/Constants.h
+++ b/include/llvm/Constants.h
@@ -352,17 +352,6 @@ public:
   // ConstantArray accessors
   static Constant *get(ArrayType *T, ArrayRef<Constant*> V);
                              
-  /// This method constructs a ConstantArray and initializes it with a text
-  /// string. The default behavior (AddNull==true) causes a null terminator to
-  /// be placed at the end of the array. This effectively increases the length
-  /// of the array by one (you've been warned).  However, in some situations 
-  /// this is not desired so if AddNull==false then the string is copied without
-  /// null termination.
-  
-  // FIXME Remove this.
-  static Constant *get(LLVMContext &Context, StringRef Initializer,
-                       bool AddNull = true);
-  
   /// Transparently provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
 
@@ -373,31 +362,6 @@ public:
     return reinterpret_cast<ArrayType*>(Value::getType());
   }
 
-  // FIXME: String methods will eventually be removed.
-  
-  
-  /// isString - This method returns true if the array is an array of i8 and
-  /// the elements of the array are all ConstantInt's.
-  bool isString() const;
-
-  /// isCString - This method returns true if the array is a string (see
-  /// @verbatim
-  /// isString) and it ends in a null byte \0 and does not contains any other
-  /// @endverbatim
-  /// null bytes except its terminator.
-  bool isCString() const;
-
-  /// getAsString - If this array is isString(), then this method converts the
-  /// array to an std::string and returns it.  Otherwise, it asserts out.
-  ///
-  std::string getAsString() const;
-
-  /// getAsCString - If this array is isCString(), then this method converts the
-  /// array (without the trailing null byte) to an std::string and returns it.
-  /// Otherwise, it asserts out.
-  ///
-  std::string getAsCString() const;
-
   virtual void destroyConstant();
   virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
 
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 121e334c4c..48e75a1d5d 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -476,9 +476,9 @@ Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
   
   // Instead of loading constant c string, use corresponding integer value
   // directly if string length is small enough.
-  std::string Str;
-  if (TD && GetConstantStringInfo(CE, Str) && !Str.empty()) {
-    unsigned StrLen = Str.length();
+  StringRef Str;
+  if (TD && getConstantStringInfo(CE, Str) && !Str.empty()) {
+    unsigned StrLen = Str.size();
     Type *Ty = cast<PointerType>(CE->getType())->getElementType();
     unsigned NumBits = Ty->getPrimitiveSizeInBits();
     // Replace load with immediate integer if the result is an integer or fp
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 6403f03b01..f0ed1b6246 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1369,25 +1369,21 @@ Value *llvm::isBytewiseValue(Value *V) {
     }
   }
   
-  // A ConstantArray is splatable if all its members are equal and also
-  // splatable.
-  if (ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
-    if (CA->getNumOperands() == 0)
-      return 0;
-    
-    Value *Val = isBytewiseValue(CA->getOperand(0));
+  // A ConstantDataArray/Vector is splatable if all its members are equal and
+  // also splatable.
+  if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(V)) {
+    Value *Elt = CA->getElementAsConstant(0);
+    Value *Val = isBytewiseValue(Elt);
     if (!Val)
       return 0;
     
-    for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I)
-      if (CA->getOperand(I-1) != CA->getOperand(I))
+    for (unsigned I = 1, E = CA->getNumElements(); I != E; ++I)
+      if (CA->getElementAsConstant(I) != Elt)
         return 0;
     
     return Val;
   }
 
-  // FIXME: Vector types (e.g., <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>).
-  
   // Conceptually, we could handle things like:
   //   %a = zext i8 %X to i16
   //   %b = shl i16 %a, 8
@@ -1607,33 +1603,19 @@ Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
 }
 
 
-/// GetConstantStringInfo - This function computes the length of a
+/// getConstantStringInfo - This function computes the length of a
 /// null-terminated C string pointed to by V.  If successful, it returns true
 /// and returns the string in Str.  If unsuccessful, it returns false.
-bool llvm::GetConstantStringInfo(const Value *V, std::string &Str,
-                                 uint64_t Offset, bool StopAtNul) {
-  // If V is NULL then return false;
-  if (V == NULL) return false;
-
-  // Look through bitcast instructions.
-  if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V))
-    return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul);
-  
-  // If the value is not a GEP instruction nor a constant expression with a
-  // GEP instruction, then return false because ConstantArray can't occur
-  // any other way.
-  const User *GEP = 0;
-  if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
-    GEP = GEPI;
-  } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
-    if (CE->getOpcode() == Instruction::BitCast)
-      return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul);
-    if (CE->getOpcode() != Instruction::GetElementPtr)
-      return false;
-    GEP = CE;
-  }
+bool llvm::getConstantStringInfo(const Value *V, StringRef &Str,
+                                 uint64_t Offset, bool TrimAtNul) {
+  assert(V);
+
+  // Look through bitcast instructions and geps.
+  V = V->stripPointerCasts();
   
-  if (GEP) {
+  // If the value is a GEP instructionor  constant expression, treat it as an
+  // offset.
+  if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
     // Make sure the GEP has exactly three arguments.
     if (GEP->getNumOperands() != 3)
       return false;
@@ -1658,51 +1640,48 @@ bool llvm::GetConstantStringInfo(const Value *V, std::string &Str,
       StartIdx = CI->getZExtValue();
     else
       return false;
-    return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset,
-                                 StopAtNul);
+    return getConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset);
   }
 
   // The GEP instruction, constant or instruction, must reference a global
   // variable that is a constant and is initialized. The referenced constant
   // initializer is the array that we'll use for optimization.
-  const GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
+  const GlobalVariable *GV = dyn_cast<GlobalVariable>(V);
   if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer())
     return false;
-  const Constant *GlobalInit = GV->getInitializer();
-  
+
   // Handle the all-zeros case
-  if (GlobalInit->isNullValue()) {
+  if (GV->getInitializer()->isNullValue()) {
     // This is a degenerate case. The initializer is constant zero so the
     // length of the string must be zero.
-    Str.clear();
+    Str = "";
     return true;
   }
   
   // Must be a Constant Array
-  const ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
-  if (Array == 0 || !Array->getType()->getElementType()->isIntegerTy(8))
+  const ConstantDataArray *Array =
+    dyn_cast<ConstantDataArray>(GV->getInitializer());
+  if (Array == 0 || !Array->isString())
     return false;
   
   // Get the number of elements in the array
-  uint64_t NumElts = Array->getType()->getNumElements();
-  
+  uint64_t NumElts = Array->getType()->getArrayNumElements();
+
+  // Start out with the entire array in the StringRef.
+  Str = Array->getAsString();
+
   if (Offset > NumElts)
     return false;
   
-  // Traverse the constant array from 'Offset' which is the place the GEP refers
-  // to in the array.
-  Str.reserve(NumElts-Offset);
-  for (unsigned i = Offset; i != NumElts; ++i) {
-    const Constant *Elt = Array->getOperand(i);
-    const ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
-    if (!CI) // This array isn't suitable, non-int initializer.
-      return false;
-    if (StopAtNul && CI->isZero())
-      return true; // we found end of string, success!
-    Str += (char)CI->getZExtValue();
-  }
+  // Skip over 'offset' bytes.
+  Str = Str.substr(Offset);
   
-  // The array isn't null terminated, but maybe this is a memcpy, not a strcpy.
+  if (TrimAtNul) {
+    // Trim off the \0 and anything after it.  If the array is not nul
+    // terminated, we just return the whole end of string.  The client may know
+    // some other way that the string is length-bound.
+    Str = Str.substr(0, Str.find('\0'));
+  }
   return true;
 }
 
@@ -1714,8 +1693,7 @@ bool llvm::GetConstantStringInfo(const Value *V, std::string &Str,
 /// the specified pointer, return 'len+1'.  If we can't, return 0.
 static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
   // Look through noop bitcast instructions.
-  if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
-    return GetStringLengthH(BCI->getOperand(0), PHIs);
+  V = V->stripPointerCasts();
 
   // If this is a PHI node, there are two cases: either we have already seen it
   // or we haven't.
@@ -1751,83 +1729,13 @@ static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
     if (Len1 != Len2) return 0;
     return Len1;
   }
-
-  // As a special-case, "@string = constant i8 0" is also a string with zero
-  // length, not wrapped in a bitcast or GEP.
-  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
-    if (GV->isConstant() && GV->hasDefinitiveInitializer())
-      if (GV->getInitializer()->isNullValue()) return 1;
-    return 0;
-  }
-
-  // If the value is not a GEP instruction nor a constant expression with a
-  // GEP instruction, then return unknown.
-  User *GEP = 0;
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
-    GEP = GEPI;
-  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
-    if (CE->getOpcode() != Instruction::GetElementPtr)
-      return 0;
-    GEP = CE;
-  } else {
-    return 0;
-  }
-
-  // Make sure the GEP has exactly three arguments.
-  if (GEP->getNumOperands() != 3)
-    return 0;
-
-  // Check to make sure that the first operand of the GEP is an integer and
-  // has value 0 so that we are sure we're indexing into the initializer.
-  if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
-    if (!Idx->isZero())
-      return 0;
-  } else
-    return 0;
-
-  // If the second index isn't a ConstantInt, then this is a variable index
-  // into the array.  If this occurs, we can't say anything meaningful about
-  // the string.
-  uint64_t StartIdx = 0;
-  if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
-    StartIdx = CI->getZExtValue();
-  else
-    return 0;
-
-  // The GEP instruction, constant or instruction, must reference a global
-  // variable that is a constant and is initialized. The referenced constant
-  // initializer is the array that we'll use for optimization.
-  GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
-  if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
-      GV->mayBeOverridden())
+  
+  // Otherwise, see if we can read the string.
+  StringRef StrData;
+  if (!getConstantStringInfo(V, StrData))
     return 0;
-  Constant *GlobalInit = GV->getInitializer();
-
-  // Handle the ConstantAggregateZero case, which is a degenerate case. The
-  // initializer is constant zero so the length of the string must be zero.
-  if (isa<ConstantAggregateZero>(GlobalInit))
-    return 1;  // Len = 0 offset by 1.
-
-  // Must be a Constant Array
-  ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
-  if (!Array || !Array->getType()->getElementType()->isIntegerTy(8))
-    return false;
-
-  // Get the number of elements in the array
-  uint64_t NumElts = Array->getType()->getNumElements();
-
-  // Traverse the constant array from StartIdx (derived above) which is
-  // the place the GEP refers to in the array.
-  for (unsigned i = StartIdx; i != NumElts; ++i) {
-    Constant *Elt = Array->getOperand(i);
-    ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
-    if (!CI) // This array isn't suitable, non-int initializer.
-      return 0;
-    if (CI->isZero())
-      return i-StartIdx+1; // We found end of string, success!
-  }
 
-  return 0; // The array isn't null terminated, conservatively return 'unknown'.
+  return StrData.size()+1;
 }
 
 /// GetStringLength - If we can compute the length of the string pointed to by
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index da72ba5faf..e9e16abddb 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -2018,7 +2018,8 @@ bool LLParser::ParseValID(ValID &ID, PerFunctionState *PFS) {
   }
   case lltok::kw_c:  // c "foo"
     Lex.Lex();
-    ID.ConstantVal = ConstantArray::get(Context, Lex.getStrVal(), false);
+    ID.ConstantVal = ConstantDataArray::getString(Context, Lex.getStrVal(),
+                                                  false);
     if (ParseToken(lltok::StringConstant, "expected string")) return true;
     ID.Kind = ValID::t_Constant;
     return false;
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 81d5720126..475bb526f9 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -845,32 +845,6 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
       } else {
         assert (0 && "Unknown FP type!");
       }
-    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
-      const ConstantArray *CA = cast<ConstantArray>(C);
-      // Emit constant strings specially.
-      unsigned NumOps = CA->getNumOperands();
-      // If this is a null-terminated string, use the denser CSTRING encoding.
-      if (CA->getOperand(NumOps-1)->isNullValue()) {
-        Code = bitc::CST_CODE_CSTRING;
-        --NumOps;  // Don't encode the null, which isn't allowed by char6.
-      } else {
-        Code = bitc::CST_CODE_STRING;
-        AbbrevToUse = String8Abbrev;
-      }
-      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
-      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
-      for (unsigned i = 0; i != NumOps; ++i) {
-        unsigned char V = cast<ConstantInt>(CA->getOperand(i))->getZExtValue();
-        Record.push_back(V);
-        isCStr7 &= (V & 128) == 0;
-        if (isCStrChar6)
-          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
-      }
-
-      if (isCStrChar6)
-        AbbrevToUse = CString6Abbrev;
-      else if (isCStr7)
-        AbbrevToUse = CString7Abbrev;
     } else if (isa<ConstantDataSequential>(C) &&
                cast<ConstantDataSequential>(C)->isString()) {
       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index 1c4d670b27..1ed9004eb5 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -321,10 +321,6 @@ void ValueEnumerator::EnumerateValue(const Value *V) {
   if (const Constant *C = dyn_cast<Constant>(V)) {
     if (isa<GlobalValue>(C)) {
       // Initializers for globals are handled explicitly elsewhere.
-    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
-      // Do not enumerate the initializers for an array of simple characters.
-      // The initializers just pollute the value table, and we emit the strings
-      // specially.
     } else if (C->getNumOperands()) {
       // If a constant has operands, enumerate them.  This makes sure that if a
       // constant has uses (for example an array of const ints), that they are
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 43af3423de..241f20097e 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1684,31 +1684,18 @@ static void EmitGlobalConstantDataSequential(const ConstantDataSequential *CDS,
 
 static void EmitGlobalConstantArray(const ConstantArray *CA, unsigned AddrSpace,
                                     AsmPrinter &AP) {
-  if (AddrSpace != 0 || !CA->isString()) {
-    // Not a string.  Print the values in successive locations.
+  // See if we can aggregate some values.  Make sure it can be
+  // represented as a series of bytes of the constant value.
+  int Value = isRepeatedByteSequence(CA, AP.TM);
 
-    // See if we can aggregate some values.  Make sure it can be
-    // represented as a series of bytes of the constant value.
-    int Value = isRepeatedByteSequence(CA, AP.TM);
-
-    if (Value != -1) {
-      uint64_t Bytes = AP.TM.getTargetData()->getTypeAllocSize(CA->getType());
-      AP.OutStreamer.EmitFill(Bytes, Value, AddrSpace);
-    }
-    else {
-      for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
-        EmitGlobalConstantImpl(CA->getOperand(i), AddrSpace, AP);
-    }
-    return;
+  if (Value != -1) {
+    uint64_t Bytes = AP.TM.getTargetData()->getTypeAllocSize(CA->getType());
+    AP.OutStreamer.EmitFill(Bytes, Value, AddrSpace);
+  }
+  else {
+    for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
+      EmitGlobalConstantImpl(CA->getOperand(i), AddrSpace, AP);
   }
-
-  // Otherwise, it can be emitted as .ascii.
-  SmallVector<char, 128> TmpVec;
-  TmpVec.reserve(CA->getNumOperands());
-  for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
-    TmpVec.push_back(cast<ConstantInt>(CA->getOperand(i))->getZExtValue());
-
-  AP.OutStreamer.EmitBytes(StringRef(TmpVec.data(), TmpVec.size()), AddrSpace);
 }
 
 static void EmitGlobalConstantVector(const ConstantVector *CV,
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 18de13dc0a..0f209789c1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3298,8 +3298,7 @@ static SDValue getMemsetValue(SDValue Value, EVT VT, SelectionDAG &DAG,
 /// used when a memcpy is turned into a memset when the source is a constant
 /// string ptr.
 static SDValue getMemsetStringVal(EVT VT, DebugLoc dl, SelectionDAG &DAG,
-                                  const TargetLowering &TLI,
-                                  std::string &Str, unsigned Offset) {
+                                  const TargetLowering &TLI, StringRef Str) {
   // Handle vector with all elements zero.
   if (Str.empty()) {
     if (VT.isInteger())
@@ -3317,15 +3316,18 @@ static SDValue getMemsetStringVal(EVT VT, DebugLoc dl, SelectionDAG &DAG,
   }
 
   assert(!VT.isVector() && "Can't handle vector type here!");
-  unsigned NumBits = VT.getSizeInBits();
-  unsigned MSB = NumBits / 8;
+  unsigned NumVTBytes = VT.getSizeInBits() / 8;
+  unsigned NumBytes = std::min(NumVTBytes, unsigned(Str.size()));
+
   uint64_t Val = 0;
-  if (TLI.isLittleEndian())
-    Offset = Offset + MSB - 1;
-  for (unsigned i = 0; i != MSB; ++i) {
-    Val = (Val << 8) | (unsigned char)Str[Offset];
-    Offset += TLI.isLittleEndian() ? -1 : 1;
+  if (TLI.isLittleEndian()) {
+    for (unsigned i = 0; i != NumBytes; ++i)
+      Val |= (uint64_t)(unsigned char)Str[i] << i*8;
+  } else {
+    for (unsigned i = 0; i != NumBytes; ++i)
+      Val |= (uint64_t)(unsigned char)Str[i] << (NumVTBytes-i-1)*8;
   }
+
   return DAG.getConstant(Val, VT);
 }
 
@@ -3340,7 +3342,7 @@ static SDValue getMemBasePlusOffset(SDValue Base, unsigned Offset,
 
 /// isMemSrcFromString - Returns true if memcpy source is a string constant.
 ///
-static bool isMemSrcFromString(SDValue Src, std::string &Str) {
+static bool isMemSrcFromString(SDValue Src, StringRef &Str) {
   unsigned SrcDelta = 0;
   GlobalAddressSDNode *G = NULL;
   if (Src.getOpcode() == ISD::GlobalAddress)
@@ -3354,11 +3356,7 @@ static bool isMemSrcFromString(SDValue Src, std::string &Str) {
   if (!G)
     return false;
 
-  const GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getGlobal());
-  if (GV && GetConstantStringInfo(GV, Str, SrcDelta, false))
-    return true;
-
-  return false;
+  return getConstantStringInfo(G->getGlobal(), Str, SrcDelta, false);
 }
 
 /// FindOptimalMemOpLowering - Determines the optimial series memory ops
@@ -3461,7 +3459,7 @@ static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, DebugLoc dl,
   unsigned SrcAlign = DAG.InferPtrAlignment(Src);
   if (Align > SrcAlign)
     SrcAlign = Align;
-  std::string Str;
+  StringRef Str;
   bool CopyFromStr = isMemSrcFromString(Src, Str);
   bool isZeroStr = CopyFromStr && Str.empty();
   unsigned Limit = AlwaysInline ? ~0U : TLI.getMaxStoresPerMemcpy(OptSize);
@@ -3498,7 +3496,7 @@ static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, DebugLoc dl,
       // We only handle zero vectors here.
       // FIXME: Handle other cases where store of vector immediate is done in
       // a single instruction.
-      Value = getMemsetStringVal(VT, dl, DAG, TLI, Str, SrcOff);
+      Value = getMemsetStringVal(VT, dl, DAG, TLI, Str.substr(SrcOff));
       Store = DAG.getStore(Chain, dl, Value,
                            getMemBasePlusOffset(Dst, DstOff, DAG),
                            DstPtrInfo.getWithOffset(DstOff), isVol,
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index b841a5c8d6..ecfc6533fd 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -558,73 +558,21 @@ raw_ostream &CWriter::printType(raw_ostream &Out, Type *Ty,
 }
 
 void CWriter::printConstantArray(ConstantArray *CPA, bool Static) {
-  // As a special case, print the array as a string if it is an array of
-  // ubytes or an array of sbytes with positive values.
-  //
-  if (CPA->isCString()) {
-    Out << '\"';
-    // Keep track of whether the last number was a hexadecimal escape.
-    bool LastWasHex = false;
-
-    // Do not include the last character, which we know is null
-    for (unsigned i = 0, e = CPA->getNumOperands()-1; i != e; ++i) {
-      unsigned char C = cast<ConstantInt>(CPA->getOperand(i))->getZExtValue();
-
-      // Print it out literally if it is a printable character.  The only thing
-      // to be careful about is when the last letter output was a hex escape
-      // code, in which case we have to be careful not to print out hex digits
-      // explicitly (the C compiler thinks it is a continuation of the previous
-      // character, sheesh...)
-      //
-      if (isprint(C) && (!LastWasHex || !isxdigit(C))) {
-        LastWasHex = false;
-        if (C == '"' || C == '\\')
-          Out << "\\" << (char)C;
-        else
-          Out << (char)C;
-      } else {
-        LastWasHex = false;
-        switch (C) {
-        case '\n': Out << "\\n"; break;
-        case '\t': Out << "\\t"; break;
-        case '\r': Out << "\\r"; break;
-        case '\v': Out << "\\v"; break;
-        case '\a': Out << "\\a"; break;
-        case '\"': Out << "\\\""; break;
-        case '\'': Out << "\\\'"; break;
-        default:
-          Out << "\\x";
-          Out << (char)(( C/16  < 10) ? ( C/16 +'0') : ( C/16 -10+'A'));
-          Out << (char)(((C&15) < 10) ? ((C&15)+'0') : ((C&15)-10+'A'));
-          LastWasHex = true;
-          break;
-        }
-      }
-    }
-    Out << '\"';
-  } else {
-    Out << '{';
-    if (CPA->getNumOperands()) {
-      Out << ' ';
-      printConstant(cast<Constant>(CPA->getOperand(0)), Static);
-      for (unsigned i = 1, e = CPA->getNumOperands(); i != e; ++i) {
-        Out << ", ";
-        printConstant(cast<Constant>(CPA->getOperand(i)), Static);
-      }
-    }
-    Out << " }";
+  Out << "{ ";
+  printConstant(cast<Constant>(CPA->getOperand(0)), Static);
+  for (unsigned i = 1, e = CPA->getNumOperands(); i != e; ++i) {
+    Out << ", ";
+    printConstant(cast<Constant>(CPA->getOperand(i)), Static);
   }
+  Out << " }";
 }
 
 void CWriter::printConstantVector(ConstantVector *CP, bool Static) {
-  Out << '{';
-  if (CP->getNumOperands()) {
-    Out << ' ';
-    printConstant(cast<Constant>(CP->getOperand(0)), Static);
-    for (unsigned i = 1, e = CP->getNumOperands(); i != e; ++i) {
-      Out << ", ";
-      printConstant(cast<Constant>(CP->getOperand(i)), Static);
-    }
+  Out << "{ ";
+  printConstant(cast<Constant>(CP->getOperand(0)), Static);
+  for (unsigned i = 1, e = CP->getNumOperands(); i != e; ++i) {
+    Out << ", ";
+    printConstant(cast<Constant>(CP->getOperand(i)), Static);
   }
   Out << " }";
 }
diff --git a/lib/Target/CppBackend/CPPBackend.cpp b/lib/Target/CppBackend/CPPBackend.cpp
index 956afcc317..64481b5f0c 100644
--- a/lib/Target/CppBackend/CPPBackend.cpp
+++ b/lib/Target/CppBackend/CPPBackend.cpp
@@ -698,36 +698,17 @@ void CppWriter::printConstant(const Constant *CV) {
     printCFP(CFP);
     Out << ";";
   } else if (const ConstantArray *CA = dyn_cast<ConstantArray>(CV)) {
-    if (CA->isString()) {
-      Out << "Constant* " << constName <<
-             " = ConstantArray::get(mod->getContext(), \"";
-      std::string tmp = CA->getAsString();
-      bool nullTerminate = false;
-      if (tmp[tmp.length()-1] == 0) {
-        tmp.erase(tmp.length()-1);
-        nullTerminate = true;
-      }
-      printEscapedString(tmp);
-      // Determine if we want null termination or not.
-      if (nullTerminate)
-        Out << "\", true"; // Indicate that the null terminator should be
-                           // added.
-      else
-        Out << "\", false";// No null terminator
-      Out << ");";
-    } else {
-      Out << "std::vector<Constant*> " << constName << "_elems;";
+    Out << "std::vector<Constant*> " << constName << "_elems;";
+    nl(Out);
+    unsigned N = CA->getNumOperands();
+    for (unsigned i = 0; i < N; ++i) {
+      printConstant(CA->getOperand(i)); // recurse to print operands
+      Out << constName << "_elems.push_back("
+          << getCppName(CA->getOperand(i)) << ");";
       nl(Out);
-      unsigned N = CA->getNumOperands();
-      for (unsigned i = 0; i < N; ++i) {
-        printConstant(CA->getOperand(i)); // recurse to print operands
-        Out << constName << "_elems.push_back("
-            << getCppName(CA->getOperand(i)) << ");";
-        nl(Out);
-      }
-      Out << "Constant* " << constName << " = ConstantArray::get("
-          << typeName << ", " << constName << "_elems);";
     }
+    Out << "Constant* " << constName << " = ConstantArray::get("
+        << typeName << ", " << constName << "_elems);";
   } else if (const ConstantStruct *CS = dyn_cast<ConstantStruct>(CV)) {
     Out << "std::vector<Constant*> " << constName << "_fields;";
     nl(Out);
@@ -740,14 +721,14 @@ void CppWriter::printConstant(const Constant *CV) {
     }
     Out << "Constant* " << constName << " = ConstantStruct::get("
         << typeName << ", " << constName << "_fields);";
-  } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
+  } else if (const ConstantVector *CV = dyn_cast<ConstantVector>(CV)) {
     Out << "std::vector<Constant*> " << constName << "_elems;";
     nl(Out);
-    unsigned N = CP->getNumOperands();
+    unsigned N = CV->getNumOperands();
     for (unsigned i = 0; i < N; ++i) {
-      printConstant(CP->getOperand(i));
+      printConstant(CV->getOperand(i));
       Out << constName << "_elems.push_back("
-          << getCppName(CP->getOperand(i)) << ");";
+          << getCppName(CV->getOperand(i)) << ");";
       nl(Out);
     }
     Out << "Constant* " << constName << " = ConstantVector::get("
@@ -760,7 +741,7 @@ void CppWriter::printConstant(const Constant *CV) {
     if (CDS->isString()) {
       Out << "Constant *" << constName <<
       " = ConstantDataArray::getString(mod->getContext(), \"";
-      StringRef Str = CA->getAsString();
+      StringRef Str = CDS->getAsString();
       bool nullTerminate = false;
       if (Str.back() == 0) {
         Str = Str.drop_back();
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index c6386009ef..b8ead89a8f 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -213,7 +213,7 @@ const char *AddressSanitizer::getPassName() const {
 
 // Create a constant for Str so that we can pass it to the run-time lib.
 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {