It's not necessary to do rounding for alloca operations when the requested

alignment is equal to the stack alignment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2021 insertions, 0 deletions

diff --git a/lib/Transforms/IPO/SimplifyLibCalls.cpp b/lib/Transforms/IPO/SimplifyLibCalls.cpp
new file mode 100644
index 0000000..b0f9128
--- /dev/null
+++ b/lib/Transforms/IPO/SimplifyLibCalls.cpp
@@ -0,0 +1,2021 @@
+//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a module pass that applies a variety of small
+// optimizations for calls to specific well-known function calls (e.g. runtime
+// library functions). For example, a call to the function "exit(3)" that
+// occurs within the main() function can be transformed into a simple "return 3"
+// instruction. Any optimization that takes this form (replace call to library
+// function with simpler code that provides the same result) belongs in this
+// file.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "simplify-libcalls"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/ADT/hash_map"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Config/config.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/IPO.h"
+using namespace llvm;
+
+/// This statistic keeps track of the total number of library calls that have
+/// been simplified regardless of which call it is.
+STATISTIC(SimplifiedLibCalls, "Number of library calls simplified");
+
+namespace {
+  // Forward declarations
+  class LibCallOptimization;
+  class SimplifyLibCalls;
+  
+/// This list is populated by the constructor for LibCallOptimization class.
+/// Therefore all subclasses are registered here at static initialization time
+/// and this list is what the SimplifyLibCalls pass uses to apply the individual
+/// optimizations to the call sites.
+/// @brief The list of optimizations deriving from LibCallOptimization
+static LibCallOptimization *OptList = 0;
+
+/// This class is the abstract base class for the set of optimizations that
+/// corresponds to one library call. The SimplifyLibCalls pass will call the
+/// ValidateCalledFunction method to ask the optimization if a given Function
+/// is the kind that the optimization can handle. If the subclass returns true,
+/// then SImplifyLibCalls will also call the OptimizeCall method to perform,
+/// or attempt to perform, the optimization(s) for the library call. Otherwise,
+/// OptimizeCall won't be called. Subclasses are responsible for providing the
+/// name of the library call (strlen, strcpy, etc.) to the LibCallOptimization
+/// constructor. This is used to efficiently select which call instructions to
+/// optimize. The criteria for a "lib call" is "anything with well known
+/// semantics", typically a library function that is defined by an international
+/// standard. Because the semantics are well known, the optimizations can
+/// generally short-circuit actually calling the function if there's a simpler
+/// way (e.g. strlen(X) can be reduced to a constant if X is a constant global).
+/// @brief Base class for library call optimizations
+class VISIBILITY_HIDDEN LibCallOptimization {
+  LibCallOptimization **Prev, *Next;
+  const char *FunctionName; ///< Name of the library call we optimize
+#ifndef NDEBUG
+  Statistic occurrences; ///< debug statistic (-debug-only=simplify-libcalls)
+#endif
+public:
+  /// The \p fname argument must be the name of the library function being
+  /// optimized by the subclass.
+  /// @brief Constructor that registers the optimization.
+  LibCallOptimization(const char *FName, const char *Description)
+    : FunctionName(FName) {
+      
+#ifndef NDEBUG
+    occurrences.construct("simplify-libcalls", Description);
+#endif
+    // Register this optimizer in the list of optimizations.
+    Next = OptList;
+    OptList = this;
+    Prev = &OptList;
+    if (Next) Next->Prev = &Next;
+  }
+  
+  /// getNext - All libcall optimizations are chained together into a list,
+  /// return the next one in the list.
+  LibCallOptimization *getNext() { return Next; }
+
+  /// @brief Deregister from the optlist
+  virtual ~LibCallOptimization() {
+    *Prev = Next;
+    if (Next) Next->Prev = Prev;
+  }
+
+  /// The implementation of this function in subclasses should determine if
+  /// \p F is suitable for the optimization. This method is called by
+  /// SimplifyLibCalls::runOnModule to short circuit visiting all the call
+  /// sites of such a function if that function is not suitable in the first
+  /// place.  If the called function is suitabe, this method should return true;
+  /// false, otherwise. This function should also perform any lazy
+  /// initialization that the LibCallOptimization needs to do, if its to return
+  /// true. This avoids doing initialization until the optimizer is actually
+  /// going to be called upon to do some optimization.
+  /// @brief Determine if the function is suitable for optimization
+  virtual bool ValidateCalledFunction(
+    const Function* F,    ///< The function that is the target of call sites
+    SimplifyLibCalls& SLC ///< The pass object invoking us
+  ) = 0;
+
+  /// The implementations of this function in subclasses is the heart of the
+  /// SimplifyLibCalls algorithm. Sublcasses of this class implement
+  /// OptimizeCall to determine if (a) the conditions are right for optimizing
+  /// the call and (b) to perform the optimization. If an action is taken
+  /// against ci, the subclass is responsible for returning true and ensuring
+  /// that ci is erased from its parent.
+  /// @brief Optimize a call, if possible.
+  virtual bool OptimizeCall(
+    CallInst* ci,          ///< The call instruction that should be optimized.
+    SimplifyLibCalls& SLC  ///< The pass object invoking us
+  ) = 0;
+
+  /// @brief Get the name of the library call being optimized
+  const char *getFunctionName() const { return FunctionName; }
+
+  bool ReplaceCallWith(CallInst *CI, Value *V) {
+    if (!CI->use_empty())
+      CI->replaceAllUsesWith(V);
+    CI->eraseFromParent();
+    return true;
+  }
+  
+  /// @brief Called by SimplifyLibCalls to update the occurrences statistic.
+  void succeeded() {
+#ifndef NDEBUG
+    DEBUG(++occurrences);
+#endif
+  }
+};
+
+/// This class is an LLVM Pass that applies each of the LibCallOptimization
+/// instances to all the call sites in a module, relatively efficiently. The
+/// purpose of this pass is to provide optimizations for calls to well-known
+/// functions with well-known semantics, such as those in the c library. The
+/// class provides the basic infrastructure for handling runOnModule.  Whenever
+/// this pass finds a function call, it asks the appropriate optimizer to
+/// validate the call (ValidateLibraryCall). If it is validated, then
+/// the OptimizeCall method is also called.
+/// @brief A ModulePass for optimizing well-known function calls.
+class VISIBILITY_HIDDEN SimplifyLibCalls : public ModulePass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  SimplifyLibCalls() : ModulePass((intptr_t)&ID) {}
+
+  /// We need some target data for accurate signature details that are
+  /// target dependent. So we require target data in our AnalysisUsage.
+  /// @brief Require TargetData from AnalysisUsage.
+  virtual void getAnalysisUsage(AnalysisUsage& Info) const {
+    // Ask that the TargetData analysis be performed before us so we can use
+    // the target data.
+    Info.addRequired<TargetData>();
+  }
+
+  /// For this pass, process all of the function calls in the module, calling
+  /// ValidateLibraryCall and OptimizeCall as appropriate.
+  /// @brief Run all the lib call optimizations on a Module.
+  virtual bool runOnModule(Module &M) {
+    reset(M);
+
+    bool result = false;
+    hash_map<std::string, LibCallOptimization*> OptznMap;
+    for (LibCallOptimization *Optzn = OptList; Optzn; Optzn = Optzn->getNext())
+      OptznMap[Optzn->getFunctionName()] = Optzn;
+
+    // The call optimizations can be recursive. That is, the optimization might
+    // generate a call to another function which can also be optimized. This way
+    // we make the LibCallOptimization instances very specific to the case they
+    // handle. It also means we need to keep running over the function calls in
+    // the module until we don't get any more optimizations possible.
+    bool found_optimization = false;
+    do {
+      found_optimization = false;
+      for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
+        // All the "well-known" functions are external and have external linkage
+        // because they live in a runtime library somewhere and were (probably)
+        // not compiled by LLVM.  So, we only act on external functions that
+        // have external or dllimport linkage and non-empty uses.
+        if (!FI->isDeclaration() ||
+            !(FI->hasExternalLinkage() || FI->hasDLLImportLinkage()) ||
+            FI->use_empty())
+          continue;
+
+        // Get the optimization class that pertains to this function
+        hash_map<std::string, LibCallOptimization*>::iterator OMI =
+          OptznMap.find(FI->getName());
+        if (OMI == OptznMap.end()) continue;
+        
+        LibCallOptimization *CO = OMI->second;
+
+        // Make sure the called function is suitable for the optimization
+        if (!CO->ValidateCalledFunction(FI, *this))
+          continue;
+
+        // Loop over each of the uses of the function
+        for (Value::use_iterator UI = FI->use_begin(), UE = FI->use_end();
+             UI != UE ; ) {
+          // If the use of the function is a call instruction
+          if (CallInst* CI = dyn_cast<CallInst>(*UI++)) {
+            // Do the optimization on the LibCallOptimization.
+            if (CO->OptimizeCall(CI, *this)) {
+              ++SimplifiedLibCalls;
+              found_optimization = result = true;
+              CO->succeeded();
+            }
+          }
+        }
+      }
+    } while (found_optimization);
+    
+    return result;
+  }
+
+  /// @brief Return the *current* module we're working on.
+  Module* getModule() const { return M; }
+
+  /// @brief Return the *current* target data for the module we're working on.
+  TargetData* getTargetData() const { return TD; }
+
+  /// @brief Return the size_t type -- syntactic shortcut
+  const Type* getIntPtrType() const { return TD->getIntPtrType(); }
+
+  /// @brief Return a Function* for the putchar libcall
+  Constant *get_putchar() {
+    if (!putchar_func)
+      putchar_func = 
+        M->getOrInsertFunction("putchar", Type::Int32Ty, Type::Int32Ty, NULL);
+    return putchar_func;
+  }
+
+  /// @brief Return a Function* for the puts libcall
+  Constant *get_puts() {
+    if (!puts_func)
+      puts_func = M->getOrInsertFunction("puts", Type::Int32Ty,
+                                         PointerType::get(Type::Int8Ty),
+                                         NULL);
+    return puts_func;
+  }
+
+  /// @brief Return a Function* for the fputc libcall
+  Constant *get_fputc(const Type* FILEptr_type) {
+    if (!fputc_func)
+      fputc_func = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
+                                          FILEptr_type, NULL);
+    return fputc_func;
+  }
+
+  /// @brief Return a Function* for the fputs libcall
+  Constant *get_fputs(const Type* FILEptr_type) {
+    if (!fputs_func)
+      fputs_func = M->getOrInsertFunction("fputs", Type::Int32Ty,
+                                          PointerType::get(Type::Int8Ty),
+                                          FILEptr_type, NULL);
+    return fputs_func;
+  }
+
+  /// @brief Return a Function* for the fwrite libcall
+  Constant *get_fwrite(const Type* FILEptr_type) {
+    if (!fwrite_func)
+      fwrite_func = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
+                                           PointerType::get(Type::Int8Ty),
+                                           TD->getIntPtrType(),
+                                           TD->getIntPtrType(),
+                                           FILEptr_type, NULL);
+    return fwrite_func;
+  }
+
+  /// @brief Return a Function* for the sqrt libcall
+  Constant *get_sqrt() {
+    if (!sqrt_func)
+      sqrt_func = M->getOrInsertFunction("sqrt", Type::DoubleTy, 
+                                         Type::DoubleTy, NULL);
+    return sqrt_func;
+  }
+
+  /// @brief Return a Function* for the strcpy libcall
+  Constant *get_strcpy() {
+    if (!strcpy_func)
+      strcpy_func = M->getOrInsertFunction("strcpy",
+                                           PointerType::get(Type::Int8Ty),
+                                           PointerType::get(Type::Int8Ty),
+                                           PointerType::get(Type::Int8Ty),
+                                           NULL);
+    return strcpy_func;
+  }
+
+  /// @brief Return a Function* for the strlen libcall
+  Constant *get_strlen() {
+    if (!strlen_func)
+      strlen_func = M->getOrInsertFunction("strlen", TD->getIntPtrType(),
+                                           PointerType::get(Type::Int8Ty),
+                                           NULL);
+    return strlen_func;
+  }
+
+  /// @brief Return a Function* for the memchr libcall
+  Constant *get_memchr() {
+    if (!memchr_func)
+      memchr_func = M->getOrInsertFunction("memchr",
+                                           PointerType::get(Type::Int8Ty),
+                                           PointerType::get(Type::Int8Ty),
+                                           Type::Int32Ty, TD->getIntPtrType(),
+                                           NULL);
+    return memchr_func;
+  }
+
+  /// @brief Return a Function* for the memcpy libcall
+  Constant *get_memcpy() {
+    if (!memcpy_func) {
+      const Type *SBP = PointerType::get(Type::Int8Ty);
+      const char *N = TD->getIntPtrType() == Type::Int32Ty ?
+                            "llvm.memcpy.i32" : "llvm.memcpy.i64";
+      memcpy_func = M->getOrInsertFunction(N, Type::VoidTy, SBP, SBP,
+                                           TD->getIntPtrType(), Type::Int32Ty,
+                                           NULL);
+    }
+    return memcpy_func;
+  }
+
+  Constant *getUnaryFloatFunction(const char *Name, Constant *&Cache) {
+    if (!Cache)
+      Cache = M->getOrInsertFunction(Name, Type::FloatTy, Type::FloatTy, NULL);
+    return Cache;
+  }
+  
+  Constant *get_floorf() { return getUnaryFloatFunction("floorf", floorf_func);}
+  Constant *get_ceilf()  { return getUnaryFloatFunction( "ceilf",  ceilf_func);}
+  Constant *get_roundf() { return getUnaryFloatFunction("roundf", roundf_func);}
+  Constant *get_rintf()  { return getUnaryFloatFunction( "rintf",  rintf_func);}
+  Constant *get_nearbyintf() { return getUnaryFloatFunction("nearbyintf",
+                                                            nearbyintf_func); }
+private:
+  /// @brief Reset our cached data for a new Module
+  void reset(Module& mod) {
+    M = &mod;
+    TD = &getAnalysis<TargetData>();
+    putchar_func = 0;
+    puts_func = 0;
+    fputc_func = 0;
+    fputs_func = 0;
+    fwrite_func = 0;
+    memcpy_func = 0;
+    memchr_func = 0;
+    sqrt_func   = 0;
+    strcpy_func = 0;
+    strlen_func = 0;
+    floorf_func = 0;
+    ceilf_func = 0;
+    roundf_func = 0;
+    rintf_func = 0;
+    nearbyintf_func = 0;
+  }
+
+private:
+  /// Caches for function pointers.
+  Constant *putchar_func, *puts_func;
+  Constant *fputc_func, *fputs_func, *fwrite_func;
+  Constant *memcpy_func, *memchr_func;
+  Constant *sqrt_func;
+  Constant *strcpy_func, *strlen_func;
+  Constant *floorf_func, *ceilf_func, *roundf_func;
+  Constant *rintf_func, *nearbyintf_func;
+  Module *M;             ///< Cached Module
+  TargetData *TD;        ///< Cached TargetData
+};
+
+char SimplifyLibCalls::ID = 0;
+// Register the pass
+RegisterPass<SimplifyLibCalls>
+X("simplify-libcalls", "Simplify well-known library calls");
+
+} // anonymous namespace
+
+// The only public symbol in this file which just instantiates the pass object
+ModulePass *llvm::createSimplifyLibCallsPass() {
+  return new SimplifyLibCalls();
+}
+
+// Classes below here, in the anonymous namespace, are all subclasses of the
+// LibCallOptimization class, each implementing all optimizations possible for a
+// single well-known library call. Each has a static singleton instance that
+// auto registers it into the "optlist" global above.
+namespace {
+
+// Forward declare utility functions.
+static bool GetConstantStringInfo(Value *V, std::string &Str);
+static Value *CastToCStr(Value *V, Instruction *IP);
+
+/// This LibCallOptimization will find instances of a call to "exit" that occurs
+/// within the "main" function and change it to a simple "ret" instruction with
+/// the same value passed to the exit function. When this is done, it splits the
+/// basic block at the exit(3) call and deletes the call instruction.
+/// @brief Replace calls to exit in main with a simple return
+struct VISIBILITY_HIDDEN ExitInMainOptimization : public LibCallOptimization {
+  ExitInMainOptimization() : LibCallOptimization("exit",
+      "Number of 'exit' calls simplified") {}
+
+  // Make sure the called function looks like exit (int argument, int return
+  // type, external linkage, not varargs).
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    return F->arg_size() >= 1 && F->arg_begin()->getType()->isInteger();
+  }
+
+  virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
+    // To be careful, we check that the call to exit is coming from "main", that
+    // main has external linkage, and the return type of main and the argument
+    // to exit have the same type.
+    Function *from = ci->getParent()->getParent();
+    if (from->hasExternalLinkage())
+      if (from->getReturnType() == ci->getOperand(1)->getType())
+        if (from->getName() == "main") {
+          // Okay, time to actually do the optimization. First, get the basic
+          // block of the call instruction
+          BasicBlock* bb = ci->getParent();
+
+          // Create a return instruction that we'll replace the call with.
+          // Note that the argument of the return is the argument of the call
+          // instruction.
+          new ReturnInst(ci->getOperand(1), ci);
+
+          // Split the block at the call instruction which places it in a new
+          // basic block.
+          bb->splitBasicBlock(ci);
+
+          // The block split caused a branch instruction to be inserted into
+          // the end of the original block, right after the return instruction
+          // that we put there. That's not a valid block, so delete the branch
+          // instruction.
+          bb->getInstList().pop_back();
+
+          // Now we can finally get rid of the call instruction which now lives
+          // in the new basic block.
+          ci->eraseFromParent();
+
+          // Optimization succeeded, return true.
+          return true;
+        }
+    // We didn't pass the criteria for this optimization so return false
+    return false;
+  }
+} ExitInMainOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strcat library
+/// function. The simplification is possible only if the string being
+/// concatenated is a constant array or a constant expression that results in
+/// a constant string. In this case we can replace it with strlen + llvm.memcpy
+/// of the constant string. Both of these calls are further reduced, if possible
+/// on subsequent passes.
+/// @brief Simplify the strcat library function.
+struct VISIBILITY_HIDDEN StrCatOptimization : public LibCallOptimization {
+public:
+  /// @brief Default constructor
+  StrCatOptimization() : LibCallOptimization("strcat",
+      "Number of 'strcat' calls simplified") {}
+
+public:
+
+  /// @brief Make sure that the "strcat" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 2 &&
+           FT->getReturnType() == PointerType::get(Type::Int8Ty) &&
+           FT->getParamType(0) == FT->getReturnType() &&
+           FT->getParamType(1) == FT->getReturnType();
+  }
+
+  /// @brief Optimize the strcat library function
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // Extract some information from the instruction
+    Value *Dst = CI->getOperand(1);
+    Value *Src = CI->getOperand(2);
+
+    // Extract the initializer (while making numerous checks) from the
+    // source operand of the call to strcat.
+    std::string SrcStr;
+    if (!GetConstantStringInfo(Src, SrcStr))
+      return false;
+
+    // Handle the simple, do-nothing case
+    if (SrcStr.empty())
+      return ReplaceCallWith(CI, Dst);
+
+    // We need to find the end of the destination string.  That's where the
+    // memory is to be moved to. We just generate a call to strlen.
+    CallInst *DstLen = new CallInst(SLC.get_strlen(), Dst,
+                                    Dst->getName()+".len", CI);
+
+    // Now that we have the destination's length, we must index into the
+    // destination's pointer to get the actual memcpy destination (end of
+    // the string .. we're concatenating).
+    Dst = new GetElementPtrInst(Dst, DstLen, Dst->getName()+".indexed", CI);
+
+    // We have enough information to now generate the memcpy call to
+    // do the concatenation for us.
+    Value *Vals[] = {
+      Dst, Src,
+      ConstantInt::get(SLC.getIntPtrType(), SrcStr.size()+1), // copy nul byte.
+      ConstantInt::get(Type::Int32Ty, 1)  // alignment
+    };
+    new CallInst(SLC.get_memcpy(), Vals, 4, "", CI);
+
+    return ReplaceCallWith(CI, Dst);
+  }
+} StrCatOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strchr library
+/// function.  It optimizes out cases where the arguments are both constant
+/// and the result can be determined statically.
+/// @brief Simplify the strcmp library function.
+struct VISIBILITY_HIDDEN StrChrOptimization : public LibCallOptimization {
+public:
+  StrChrOptimization() : LibCallOptimization("strchr",
+      "Number of 'strchr' calls simplified") {}
+
+  /// @brief Make sure that the "strchr" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 2 &&
+           FT->getReturnType() == PointerType::get(Type::Int8Ty) &&
+           FT->getParamType(0) == FT->getReturnType() &&
+           isa<IntegerType>(FT->getParamType(1));
+  }
+
+  /// @brief Perform the strchr optimizations
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // Check that the first argument to strchr is a constant array of sbyte.
+    std::string Str;
+    if (!GetConstantStringInfo(CI->getOperand(1), Str))
+      return false;
+
+    // If the second operand is not constant, just lower this to memchr since we
+    // know the length of the input string.
+    ConstantInt *CSI = dyn_cast<ConstantInt>(CI->getOperand(2));
+    if (!CSI) {
+      Value *Args[3] = {
+        CI->getOperand(1),
+        CI->getOperand(2),
+        ConstantInt::get(SLC.getIntPtrType(), Str.size()+1)
+      };
+      return ReplaceCallWith(CI, new CallInst(SLC.get_memchr(), Args, 3,
+                                              CI->getName(), CI));
+    }
+
+    // strchr can find the nul character.
+    Str += '\0';
+    
+    // Get the character we're looking for
+    char CharValue = CSI->getSExtValue();
+
+    // Compute the offset
+    uint64_t i = 0;
+    while (1) {
+      if (i == Str.size())    // Didn't find the char.  strchr returns null.
+        return ReplaceCallWith(CI, Constant::getNullValue(CI->getType()));
+      // Did we find our match?
+      if (Str[i] == CharValue)
+        break;
+      ++i;
+    }
+
+    // strchr(s+n,c)  -> gep(s+n+i,c)
+    //    (if c is a constant integer and s is a constant string)
+    Value *Idx = ConstantInt::get(Type::Int64Ty, i);
+    Value *GEP = new GetElementPtrInst(CI->getOperand(1), Idx, 
+                                       CI->getOperand(1)->getName() +
+                                       ".strchr", CI);
+    return ReplaceCallWith(CI, GEP);
+  }
+} StrChrOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strcmp library
+/// function.  It optimizes out cases where one or both arguments are constant
+/// and the result can be determined statically.
+/// @brief Simplify the strcmp library function.
+struct VISIBILITY_HIDDEN StrCmpOptimization : public LibCallOptimization {
+public:
+  StrCmpOptimization() : LibCallOptimization("strcmp",
+      "Number of 'strcmp' calls simplified") {}
+
+  /// @brief Make sure that the "strcmp" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getReturnType() == Type::Int32Ty && FT->getNumParams() == 2 &&
+           FT->getParamType(0) == FT->getParamType(1) &&
+           FT->getParamType(0) == PointerType::get(Type::Int8Ty);
+  }
+
+  /// @brief Perform the strcmp optimization
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // First, check to see if src and destination are the same. If they are,
+    // then the optimization is to replace the CallInst with a constant 0
+    // because the call is a no-op.
+    Value *Str1P = CI->getOperand(1);
+    Value *Str2P = CI->getOperand(2);
+    if (Str1P == Str2P)      // strcmp(x,x)  -> 0
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
+
+    std::string Str1;
+    if (!GetConstantStringInfo(Str1P, Str1))
+      return false;
+    if (Str1.empty()) {
+      // strcmp("", x) -> *x
+      Value *V = new LoadInst(Str2P, CI->getName()+".load", CI);
+      V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
+      return ReplaceCallWith(CI, V);
+    }
+
+    std::string Str2;
+    if (!GetConstantStringInfo(Str2P, Str2))
+      return false;
+    if (Str2.empty()) {
+      // strcmp(x,"") -> *x
+      Value *V = new LoadInst(Str1P, CI->getName()+".load", CI);
+      V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
+      return ReplaceCallWith(CI, V);
+    }
+
+    // strcmp(x, y)  -> cnst  (if both x and y are constant strings)
+    int R = strcmp(Str1.c_str(), Str2.c_str());
+    return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), R));
+  }
+} StrCmpOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strncmp library
+/// function.  It optimizes out cases where one or both arguments are constant
+/// and the result can be determined statically.
+/// @brief Simplify the strncmp library function.
+struct VISIBILITY_HIDDEN StrNCmpOptimization : public LibCallOptimization {
+public:
+  StrNCmpOptimization() : LibCallOptimization("strncmp",
+      "Number of 'strncmp' calls simplified") {}
+
+  /// @brief Make sure that the "strncmp" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getReturnType() == Type::Int32Ty && FT->getNumParams() == 3 &&
+           FT->getParamType(0) == FT->getParamType(1) &&
+           FT->getParamType(0) == PointerType::get(Type::Int8Ty) &&
+           isa<IntegerType>(FT->getParamType(2));
+    return false;
+  }
+
+  /// @brief Perform the strncmp optimization
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // First, check to see if src and destination are the same. If they are,
+    // then the optimization is to replace the CallInst with a constant 0
+    // because the call is a no-op.
+    Value *Str1P = CI->getOperand(1);
+    Value *Str2P = CI->getOperand(2);
+    if (Str1P == Str2P)  // strncmp(x,x, n)  -> 0
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
+    
+    // Check the length argument, if it is Constant zero then the strings are
+    // considered equal.
+    uint64_t Length;
+    if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
+      Length = LengthArg->getZExtValue();
+    else
+      return false;
+    
+    if (Length == 0) // strncmp(x,y,0)   -> 0
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
+    
+    std::string Str1;
+    if (!GetConstantStringInfo(Str1P, Str1))
+      return false;
+    if (Str1.empty()) {
+      // strncmp("", x, n) -> *x
+      Value *V = new LoadInst(Str2P, CI->getName()+".load", CI);
+      V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
+      return ReplaceCallWith(CI, V);
+    }
+    
+    std::string Str2;
+    if (!GetConstantStringInfo(Str2P, Str2))
+      return false;
+    if (Str2.empty()) {
+      // strncmp(x, "", n) -> *x
+      Value *V = new LoadInst(Str1P, CI->getName()+".load", CI);
+      V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
+      return ReplaceCallWith(CI, V);
+    }
+    
+    // strncmp(x, y, n)  -> cnst  (if both x and y are constant strings)
+    int R = strncmp(Str1.c_str(), Str2.c_str(), Length);
+    return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), R));
+  }
+} StrNCmpOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strcpy library
+/// function.  Two optimizations are possible:
+/// (1) If src and dest are the same and not volatile, just return dest
+/// (2) If the src is a constant then we can convert to llvm.memmove
+/// @brief Simplify the strcpy library function.
+struct VISIBILITY_HIDDEN StrCpyOptimization : public LibCallOptimization {
+public:
+  StrCpyOptimization() : LibCallOptimization("strcpy",
+      "Number of 'strcpy' calls simplified") {}
+
+  /// @brief Make sure that the "strcpy" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 2 &&
+           FT->getParamType(0) == FT->getParamType(1) &&
+           FT->getReturnType() == FT->getParamType(0) &&
+           FT->getParamType(0) == PointerType::get(Type::Int8Ty);
+  }
+
+  /// @brief Perform the strcpy optimization
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // First, check to see if src and destination are the same. If they are,
+    // then the optimization is to replace the CallInst with the destination
+    // because the call is a no-op. Note that this corresponds to the
+    // degenerate strcpy(X,X) case which should have "undefined" results
+    // according to the C specification. However, it occurs sometimes and
+    // we optimize it as a no-op.
+    Value *Dst = CI->getOperand(1);
+    Value *Src = CI->getOperand(2);
+    if (Dst == Src) {
+      // strcpy(x, x) -> x
+      return ReplaceCallWith(CI, Dst);
+    }
+    
+    // Get the length of the constant string referenced by the Src operand.
+    std::string SrcStr;
+    if (!GetConstantStringInfo(Src, SrcStr))
+      return false;
+    
+    // If the constant string's length is zero we can optimize this by just
+    // doing a store of 0 at the first byte of the destination
+    if (SrcStr.size() == 0) {
+      new StoreInst(ConstantInt::get(Type::Int8Ty, 0), Dst, CI);
+      return ReplaceCallWith(CI, Dst);
+    }
+
+    // We have enough information to now generate the memcpy call to
+    // do the concatenation for us.
+    Value *MemcpyOps[] = {
+      Dst, Src, // Pass length including nul byte.
+      ConstantInt::get(SLC.getIntPtrType(), SrcStr.size()+1),
+      ConstantInt::get(Type::Int32Ty, 1) // alignment
+    };
+    new CallInst(SLC.get_memcpy(), MemcpyOps, 4, "", CI);
+
+    return ReplaceCallWith(CI, Dst);
+  }
+} StrCpyOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strlen library
+/// function by replacing it with a constant value if the string provided to
+/// it is a constant array.
+/// @brief Simplify the strlen library function.
+struct VISIBILITY_HIDDEN StrLenOptimization : public LibCallOptimization {
+  StrLenOptimization() : LibCallOptimization("strlen",
+      "Number of 'strlen' calls simplified") {}
+
+  /// @brief Make sure that the "strlen" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 1 &&
+           FT->getParamType(0) == PointerType::get(Type::Int8Ty) &&
+           isa<IntegerType>(FT->getReturnType());
+  }
+
+  /// @brief Perform the strlen optimization
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // Make sure we're dealing with an sbyte* here.
+    Value *Src = CI->getOperand(1);
+
+    // Does the call to strlen have exactly one use?
+    if (CI->hasOneUse()) {
+      // Is that single use a icmp operator?
+      if (ICmpInst *Cmp = dyn_cast<ICmpInst>(CI->use_back()))
+        // Is it compared against a constant integer?
+        if (ConstantInt *Cst = dyn_cast<ConstantInt>(Cmp->getOperand(1))) {
+          // If its compared against length 0 with == or !=
+          if (Cst->getZExtValue() == 0 && Cmp->isEquality()) {
+            // strlen(x) != 0 -> *x != 0
+            // strlen(x) == 0 -> *x == 0
+            Value *V = new LoadInst(Src, Src->getName()+".first", CI);
+            V = new ICmpInst(Cmp->getPredicate(), V, 
+                             ConstantInt::get(Type::Int8Ty, 0),
+                             Cmp->getName()+".strlen", CI);
+            Cmp->replaceAllUsesWith(V);
+            Cmp->eraseFromParent();
+            return ReplaceCallWith(CI, 0);  // no uses.
+          }
+        }
+    }
+
+    // Get the length of the constant string operand
+    std::string Str;
+    if (!GetConstantStringInfo(Src, Str))
+      return false;
+      
+    // strlen("xyz") -> 3 (for example)
+    return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), Str.size()));
+  }
+} StrLenOptimizer;
+
+/// IsOnlyUsedInEqualsComparison - Return true if it only matters that the value
+/// is equal or not-equal to zero. 
+static bool IsOnlyUsedInEqualsZeroComparison(Instruction *I) {
+  for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+       UI != E; ++UI) {
+    if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
+      if (IC->isEquality())
+        if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
+          if (C->isNullValue())
+            continue;
+    // Unknown instruction.
+    return false;
+  }
+  return true;
+}
+
+/// This memcmpOptimization will simplify a call to the memcmp library
+/// function.
+struct VISIBILITY_HIDDEN memcmpOptimization : public LibCallOptimization {
+  /// @brief Default Constructor
+  memcmpOptimization()
+    : LibCallOptimization("memcmp", "Number of 'memcmp' calls simplified") {}
+  
+  /// @brief Make sure that the "memcmp" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
+    Function::const_arg_iterator AI = F->arg_begin();
+    if (F->arg_size() != 3 || !isa<PointerType>(AI->getType())) return false;
+    if (!isa<PointerType>((++AI)->getType())) return false;
+    if (!(++AI)->getType()->isInteger()) return false;
+    if (!F->getReturnType()->isInteger()) return false;
+    return true;
+  }
+  
+  /// Because of alignment and instruction information that we don't have, we
+  /// leave the bulk of this to the code generators.
+  ///
+  /// Note that we could do much more if we could force alignment on otherwise
+  /// small aligned allocas, or if we could indicate that loads have a small
+  /// alignment.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &TD) {
+    Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
+
+    // If the two operands are the same, return zero.
+    if (LHS == RHS) {
+      // memcmp(s,s,x) -> 0
+      return ReplaceCallWith(CI, Constant::getNullValue(CI->getType()));
+    }
+    
+    // Make sure we have a constant length.
+    ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
+    if (!LenC) return false;
+    uint64_t Len = LenC->getZExtValue();
+      
+    // If the length is zero, this returns 0.
+    switch (Len) {
+    case 0:
+      // memcmp(s1,s2,0) -> 0
+      return ReplaceCallWith(CI, Constant::getNullValue(CI->getType()));
+    case 1: {
+      // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
+      const Type *UCharPtr = PointerType::get(Type::Int8Ty);
+      CastInst *Op1Cast = CastInst::create(
+          Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
+      CastInst *Op2Cast = CastInst::create(
+          Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
+      Value *S1V = new LoadInst(Op1Cast, LHS->getName()+".val", CI);
+      Value *S2V = new LoadInst(Op2Cast, RHS->getName()+".val", CI);
+      Value *RV = BinaryOperator::createSub(S1V, S2V, CI->getName()+".diff",CI);
+      if (RV->getType() != CI->getType())
+        RV = CastInst::createIntegerCast(RV, CI->getType(), false, 
+                                         RV->getName(), CI);
+      return ReplaceCallWith(CI, RV);
+    }
+    case 2:
+      if (IsOnlyUsedInEqualsZeroComparison(CI)) {
+        // TODO: IF both are aligned, use a short load/compare.
+      
+        // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
+        const Type *UCharPtr = PointerType::get(Type::Int8Ty);
+        CastInst *Op1Cast = CastInst::create(
+            Instruction::BitCast, LHS, UCharPtr, LHS->getName(), CI);
+        CastInst *Op2Cast = CastInst::create(
+            Instruction::BitCast, RHS, UCharPtr, RHS->getName(), CI);
+        Value *S1V1 = new LoadInst(Op1Cast, LHS->getName()+".val1", CI);
+        Value *S2V1 = new LoadInst(Op2Cast, RHS->getName()+".val1", CI);
+        Value *D1 = BinaryOperator::createSub(S1V1, S2V1,
+                                              CI->getName()+".d1", CI);
+        Constant *One = ConstantInt::get(Type::Int32Ty, 1);
+        Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
+        Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
+        Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
+        Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
+        Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
+                                              CI->getName()+".d1", CI);
+        Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
+        if (Or->getType() != CI->getType())
+          Or = CastInst::createIntegerCast(Or, CI->getType(), false /*ZExt*/, 
+                                           Or->getName(), CI);
+        return ReplaceCallWith(CI, Or);
+      }
+      break;
+    default:
+      break;
+    }
+    
+    return false;
+  }
+} memcmpOptimizer;
+
+
+/// This LibCallOptimization will simplify a call to the memcpy library
+/// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
+/// bytes depending on the length of the string and the alignment. Additional
+/// optimizations are possible in code generation (sequence of immediate store)
+/// @brief Simplify the memcpy library function.
+struct VISIBILITY_HIDDEN LLVMMemCpyMoveOptzn : public LibCallOptimization {
+  LLVMMemCpyMoveOptzn(const char* fname, const char* desc)
+  : LibCallOptimization(fname, desc) {}
+
+  /// @brief Make sure that the "memcpy" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& TD) {
+    // Just make sure this has 4 arguments per LLVM spec.
+    return (f->arg_size() == 4);
+  }
+
+  /// Because of alignment and instruction information that we don't have, we
+  /// leave the bulk of this to the code generators. The optimization here just
+  /// deals with a few degenerate cases where the length of the string and the
+  /// alignment match the sizes of our intrinsic types so we can do a load and
+  /// store instead of the memcpy call.
+  /// @brief Perform the memcpy optimization.
+  virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& TD) {
+    // Make sure we have constant int values to work with
+    ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
+    if (!LEN)
+      return false;
+    ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
+    if (!ALIGN)
+      return false;
+
+    // If the length is larger than the alignment, we can't optimize
+    uint64_t len = LEN->getZExtValue();
+    uint64_t alignment = ALIGN->getZExtValue();
+    if (alignment == 0)
+      alignment = 1; // Alignment 0 is identity for alignment 1
+    if (len > alignment)
+      return false;
+
+    // Get the type we will cast to, based on size of the string
+    Value* dest = ci->getOperand(1);
+    Value* src = ci->getOperand(2);
+    const Type* castType = 0;
+    switch (len) {
+      case 0:
+        // memcpy(d,s,0,a) -> d
+        return ReplaceCallWith(ci, 0);
+      case 1: castType = Type::Int8Ty; break;
+      case 2: castType = Type::Int16Ty; break;
+      case 4: castType = Type::Int32Ty; break;
+      case 8: castType = Type::Int64Ty; break;
+      default:
+        return false;
+    }
+
+    // Cast source and dest to the right sized primitive and then load/store
+    CastInst* SrcCast = CastInst::create(Instruction::BitCast,
+        src, PointerType::get(castType), src->getName()+".cast", ci);
+    CastInst* DestCast = CastInst::create(Instruction::BitCast,
+        dest, PointerType::get(castType),dest->getName()+".cast", ci);
+    LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
+    new StoreInst(LI, DestCast, ci);
+    return ReplaceCallWith(ci, 0);
+  }
+};
+
+/// This LibCallOptimization will simplify a call to the memcpy/memmove library
+/// functions.
+LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer32("llvm.memcpy.i32",
+                                    "Number of 'llvm.memcpy' calls simplified");
+LLVMMemCpyMoveOptzn LLVMMemCpyOptimizer64("llvm.memcpy.i64",
+                                   "Number of 'llvm.memcpy' calls simplified");
+LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer32("llvm.memmove.i32",
+                                   "Number of 'llvm.memmove' calls simplified");
+LLVMMemCpyMoveOptzn LLVMMemMoveOptimizer64("llvm.memmove.i64",
+                                   "Number of 'llvm.memmove' calls simplified");
+
+/// This LibCallOptimization will simplify a call to the memset library
+/// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
+/// bytes depending on the length argument.
+struct VISIBILITY_HIDDEN LLVMMemSetOptimization : public LibCallOptimization {
+  /// @brief Default Constructor
+  LLVMMemSetOptimization(const char *Name) : LibCallOptimization(Name,
+      "Number of 'llvm.memset' calls simplified") {}
+
+  /// @brief Make sure that the "memset" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &TD) {
+    // Just make sure this has 3 arguments per LLVM spec.
+    return F->arg_size() == 4;
+  }
+
+  /// Because of alignment and instruction information that we don't have, we
+  /// leave the bulk of this to the code generators. The optimization here just
+  /// deals with a few degenerate cases where the length parameter is constant
+  /// and the alignment matches the sizes of our intrinsic types so we can do
+  /// store instead of the memcpy call. Other calls are transformed into the
+  /// llvm.memset intrinsic.
+  /// @brief Perform the memset optimization.
+  virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &TD) {
+    // Make sure we have constant int values to work with
+    ConstantInt* LEN = dyn_cast<ConstantInt>(ci->getOperand(3));
+    if (!LEN)
+      return false;
+    ConstantInt* ALIGN = dyn_cast<ConstantInt>(ci->getOperand(4));
+    if (!ALIGN)
+      return false;
+
+    // Extract the length and alignment
+    uint64_t len = LEN->getZExtValue();
+    uint64_t alignment = ALIGN->getZExtValue();
+
+    // Alignment 0 is identity for alignment 1
+    if (alignment == 0)
+      alignment = 1;
+
+    // If the length is zero, this is a no-op
+    if (len == 0) {
+      // memset(d,c,0,a) -> noop
+      return ReplaceCallWith(ci, 0);
+    }
+
+    // If the length is larger than the alignment, we can't optimize
+    if (len > alignment)
+      return false;
+
+    // Make sure we have a constant ubyte to work with so we can extract
+    // the value to be filled.
+    ConstantInt* FILL = dyn_cast<ConstantInt>(ci->getOperand(2));
+    if (!FILL)
+      return false;
+    if (FILL->getType() != Type::Int8Ty)
+      return false;
+
+    // memset(s,c,n) -> store s, c (for n=1,2,4,8)
+
+    // Extract the fill character
+    uint64_t fill_char = FILL->getZExtValue();
+    uint64_t fill_value = fill_char;
+
+    // Get the type we will cast to, based on size of memory area to fill, and
+    // and the value we will store there.
+    Value* dest = ci->getOperand(1);
+    const Type* castType = 0;
+    switch (len) {
+      case 1:
+        castType = Type::Int8Ty;
+        break;
+      case 2:
+        castType = Type::Int16Ty;
+        fill_value |= fill_char << 8;
+        break;
+      case 4:
+        castType = Type::Int32Ty;
+        fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
+        break;
+      case 8:
+        castType = Type::Int64Ty;
+        fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
+        fill_value |= fill_char << 32 | fill_char << 40 | fill_char << 48;
+        fill_value |= fill_char << 56;
+        break;
+      default:
+        return false;
+    }
+
+    // Cast dest to the right sized primitive and then load/store
+    CastInst* DestCast = new BitCastInst(dest, PointerType::get(castType), 
+                                         dest->getName()+".cast", ci);
+    new StoreInst(ConstantInt::get(castType,fill_value),DestCast, ci);
+    return ReplaceCallWith(ci, 0);
+  }
+};
+
+LLVMMemSetOptimization MemSet32Optimizer("llvm.memset.i32");
+LLVMMemSetOptimization MemSet64Optimizer("llvm.memset.i64");
+
+
+/// This LibCallOptimization will simplify calls to the "pow" library
+/// function. It looks for cases where the result of pow is well known and
+/// substitutes the appropriate value.
+/// @brief Simplify the pow library function.
+struct VISIBILITY_HIDDEN PowOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  PowOptimization() : LibCallOptimization("pow",
+      "Number of 'pow' calls simplified") {}
+
+  /// @brief Make sure that the "pow" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
+    // Just make sure this has 2 arguments
+    return (f->arg_size() == 2);
+  }
+
+  /// @brief Perform the pow optimization.
+  virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
+    const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
+    Value* base = ci->getOperand(1);
+    Value* expn = ci->getOperand(2);
+    if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
+      double Op1V = Op1->getValue();
+      if (Op1V == 1.0) // pow(1.0,x) -> 1.0
+        return ReplaceCallWith(ci, ConstantFP::get(Ty, 1.0));
+    }  else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
+      double Op2V = Op2->getValue();
+      if (Op2V == 0.0) {
+        // pow(x,0.0) -> 1.0
+        return ReplaceCallWith(ci, ConstantFP::get(Ty,1.0));
+      } else if (Op2V == 0.5) {
+        // pow(x,0.5) -> sqrt(x)
+        CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
+            ci->getName()+".pow",ci);
+        return ReplaceCallWith(ci, sqrt_inst);
+      } else if (Op2V == 1.0) {
+        // pow(x,1.0) -> x
+        return ReplaceCallWith(ci, base);
+      } else if (Op2V == -1.0) {
+        // pow(x,-1.0)    -> 1.0/x
+        Value *div_inst = 
+          BinaryOperator::createFDiv(ConstantFP::get(Ty, 1.0), base,
+                                     ci->getName()+".pow", ci);
+        return ReplaceCallWith(ci, div_inst);
+      }
+    }
+    return false; // opt failed
+  }
+} PowOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "printf" library
+/// function. It looks for cases where the result of printf is not used and the
+/// operation can be reduced to something simpler.
+/// @brief Simplify the printf library function.
+struct VISIBILITY_HIDDEN PrintfOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  PrintfOptimization() : LibCallOptimization("printf",
+      "Number of 'printf' calls simplified") {}
+
+  /// @brief Make sure that the "printf" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    // Just make sure this has at least 1 argument and returns an integer or
+    // void type.
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() >= 1 &&
+          (isa<IntegerType>(FT->getReturnType()) ||
+           FT->getReturnType() == Type::VoidTy);
+  }
+
+  /// @brief Perform the printf optimization.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // All the optimizations depend on the length of the first argument and the
+    // fact that it is a constant string array. Check that now
+    std::string FormatStr;
+    if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
+      return false;
+    
+    // If this is a simple constant string with no format specifiers that ends
+    // with a \n, turn it into a puts call.
+    if (FormatStr.empty()) {
+      // Tolerate printf's declared void.
+      if (CI->use_empty()) return ReplaceCallWith(CI, 0);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
+    }
+    
+    if (FormatStr.size() == 1) {
+      // Turn this into a putchar call, even if it is a %.
+      Value *V = ConstantInt::get(Type::Int32Ty, FormatStr[0]);
+      new CallInst(SLC.get_putchar(), V, "", CI);
+      if (CI->use_empty()) return ReplaceCallWith(CI, 0);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 1));
+    }
+
+    // Check to see if the format str is something like "foo\n", in which case
+    // we convert it to a puts call.  We don't allow it to contain any format
+    // characters.
+    if (FormatStr[FormatStr.size()-1] == '\n' &&
+        FormatStr.find('%') == std::string::npos) {
+      // Create a string literal with no \n on it.  We expect the constant merge
+      // pass to be run after this pass, to merge duplicate strings.
+      FormatStr.erase(FormatStr.end()-1);
+      Constant *Init = ConstantArray::get(FormatStr, true);
+      Constant *GV = new GlobalVariable(Init->getType(), true,
+                                        GlobalVariable::InternalLinkage,
+                                        Init, "str",
+                                     CI->getParent()->getParent()->getParent());
+      // Cast GV to be a pointer to char.
+      GV = ConstantExpr::getBitCast(GV, PointerType::get(Type::Int8Ty));
+      new CallInst(SLC.get_puts(), GV, "", CI);
+
+      if (CI->use_empty()) return ReplaceCallWith(CI, 0);
+      return ReplaceCallWith(CI,
+                             ConstantInt::get(CI->getType(), FormatStr.size()));
+    }
+    
+    
+    // Only support %c or "%s\n" for now.
+    if (FormatStr.size() < 2 || FormatStr[0] != '%')
+      return false;
+
+    // Get the second character and switch on its value
+    switch (FormatStr[1]) {
+    default:  return false;
+    case 's':
+      if (FormatStr != "%s\n" || CI->getNumOperands() < 3 ||
+          // TODO: could insert strlen call to compute string length.
+          !CI->use_empty())
+        return false;
+
+      // printf("%s\n",str) -> puts(str)
+      new CallInst(SLC.get_puts(), CastToCStr(CI->getOperand(2), CI),
+                   CI->getName(), CI);
+      return ReplaceCallWith(CI, 0);
+    case 'c': {
+      // printf("%c",c) -> putchar(c)
+      if (FormatStr.size() != 2 || CI->getNumOperands() < 3)
+        return false;
+      
+      Value *V = CI->getOperand(2);
+      if (!isa<IntegerType>(V->getType()) ||
+          cast<IntegerType>(V->getType())->getBitWidth() > 32)
+        return false;
+
+      V = CastInst::createZExtOrBitCast(V, Type::Int32Ty, CI->getName()+".int",
+                                        CI);
+      new CallInst(SLC.get_putchar(), V, "", CI);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 1));
+    }
+    }
+  }
+} PrintfOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "fprintf" library
+/// function. It looks for cases where the result of fprintf is not used and the
+/// operation can be reduced to something simpler.
+/// @brief Simplify the fprintf library function.
+struct VISIBILITY_HIDDEN FPrintFOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  FPrintFOptimization() : LibCallOptimization("fprintf",
+      "Number of 'fprintf' calls simplified") {}
+
+  /// @brief Make sure that the "fprintf" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 2 &&  // two fixed arguments.
+           FT->getParamType(1) == PointerType::get(Type::Int8Ty) &&
+           isa<PointerType>(FT->getParamType(0)) &&
+           isa<IntegerType>(FT->getReturnType());
+  }
+
+  /// @brief Perform the fprintf optimization.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // If the call has more than 3 operands, we can't optimize it
+    if (CI->getNumOperands() != 3 && CI->getNumOperands() != 4)
+      return false;
+
+    // All the optimizations depend on the format string.
+    std::string FormatStr;
+    if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
+      return false;
+
+    // If this is just a format string, turn it into fwrite.
+    if (CI->getNumOperands() == 3) {
+      for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
+        if (FormatStr[i] == '%')
+          return false; // we found a format specifier
+
+      // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
+      const Type *FILEty = CI->getOperand(1)->getType();
+
+      Value *FWriteArgs[] = {
+        CI->getOperand(2),
+        ConstantInt::get(SLC.getIntPtrType(), FormatStr.size()),
+        ConstantInt::get(SLC.getIntPtrType(), 1),
+        CI->getOperand(1)
+      };
+      new CallInst(SLC.get_fwrite(FILEty), FWriteArgs, 4, CI->getName(), CI);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 
+                                                  FormatStr.size()));
+    }
+    
+    // The remaining optimizations require the format string to be length 2:
+    // "%s" or "%c".
+    if (FormatStr.size() != 2 || FormatStr[0] != '%')
+      return false;
+
+    // Get the second character and switch on its value
+    switch (FormatStr[1]) {
+    case 'c': {
+      // fprintf(file,"%c",c) -> fputc(c,file)
+      const Type *FILETy = CI->getOperand(1)->getType();
+      Value *C = CastInst::createZExtOrBitCast(CI->getOperand(3), Type::Int32Ty,
+                                               CI->getName()+".int", CI);
+      new CallInst(SLC.get_fputc(FILETy), C, CI->getOperand(1), "", CI);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 1));
+    }
+    case 's': {
+      const Type *FILETy = CI->getOperand(1)->getType();
+      
+      // If the result of the fprintf call is used, we can't do this.
+      // TODO: we should insert a strlen call.
+      if (!CI->use_empty())
+        return false;
+      
+      // fprintf(file,"%s",str) -> fputs(str,file)
+      new CallInst(SLC.get_fputs(FILETy), CastToCStr(CI->getOperand(3), CI),
+                   CI->getOperand(1), CI->getName(), CI);
+      return ReplaceCallWith(CI, 0);
+    }
+    default:
+      return false;
+    }
+  }
+} FPrintFOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "sprintf" library
+/// function. It looks for cases where the result of sprintf is not used and the
+/// operation can be reduced to something simpler.
+/// @brief Simplify the sprintf library function.
+struct VISIBILITY_HIDDEN SPrintFOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  SPrintFOptimization() : LibCallOptimization("sprintf",
+      "Number of 'sprintf' calls simplified") {}
+
+  /// @brief Make sure that the "sprintf" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 2 &&  // two fixed arguments.
+           FT->getParamType(1) == PointerType::get(Type::Int8Ty) &&
+           FT->getParamType(0) == FT->getParamType(1) &&
+           isa<IntegerType>(FT->getReturnType());
+  }
+
+  /// @brief Perform the sprintf optimization.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // If the call has more than 3 operands, we can't optimize it
+    if (CI->getNumOperands() != 3 && CI->getNumOperands() != 4)
+      return false;
+
+    std::string FormatStr;
+    if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
+      return false;
+    
+    if (CI->getNumOperands() == 3) {
+      // Make sure there's no % in the constant array
+      for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
+        if (FormatStr[i] == '%')
+          return false; // we found a format specifier
+      
+      // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
+      Value *MemCpyArgs[] = {
+        CI->getOperand(1), CI->getOperand(2),
+        ConstantInt::get(SLC.getIntPtrType(), 
+                         FormatStr.size()+1), // Copy the nul byte.
+        ConstantInt::get(Type::Int32Ty, 1)
+      };
+      new CallInst(SLC.get_memcpy(), MemCpyArgs, 4, "", CI);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 
+                                                  FormatStr.size()));
+    }
+
+    // The remaining optimizations require the format string to be "%s" or "%c".
+    if (FormatStr.size() != 2 || FormatStr[0] != '%')
+      return false;
+
+    // Get the second character and switch on its value
+    switch (FormatStr[1]) {
+    case 'c': {
+      // sprintf(dest,"%c",chr) -> store chr, dest
+      Value *V = CastInst::createTruncOrBitCast(CI->getOperand(3),
+                                                Type::Int8Ty, "char", CI);
+      new StoreInst(V, CI->getOperand(1), CI);
+      Value *Ptr = new GetElementPtrInst(CI->getOperand(1),
+                                         ConstantInt::get(Type::Int32Ty, 1),
+                                         CI->getOperand(1)->getName()+".end",
+                                         CI);
+      new StoreInst(ConstantInt::get(Type::Int8Ty,0), Ptr, CI);
+      return ReplaceCallWith(CI, ConstantInt::get(Type::Int32Ty, 1));
+    }
+    case 's': {
+      // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
+      Value *Len = new CallInst(SLC.get_strlen(),
+                                CastToCStr(CI->getOperand(3), CI),
+                                CI->getOperand(3)->getName()+".len", CI);
+      Value *UnincLen = Len;
+      Len = BinaryOperator::createAdd(Len, ConstantInt::get(Len->getType(), 1),
+                                      Len->getName()+"1", CI);
+      Value *MemcpyArgs[4] = {
+        CI->getOperand(1),
+        CastToCStr(CI->getOperand(3), CI),
+        Len,
+        ConstantInt::get(Type::Int32Ty, 1)
+      };
+      new CallInst(SLC.get_memcpy(), MemcpyArgs, 4, "", CI);
+      
+      // The strlen result is the unincremented number of bytes in the string.
+      if (!CI->use_empty()) {
+        if (UnincLen->getType() != CI->getType())
+          UnincLen = CastInst::createIntegerCast(UnincLen, CI->getType(), false, 
+                                                 Len->getName(), CI);
+        CI->replaceAllUsesWith(UnincLen);
+      }
+      return ReplaceCallWith(CI, 0);
+    }
+    }
+    return false;
+  }
+} SPrintFOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "fputs" library
+/// function. It looks for cases where the result of fputs is not used and the
+/// operation can be reduced to something simpler.
+/// @brief Simplify the fputs library function.
+struct VISIBILITY_HIDDEN FPutsOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  FPutsOptimization() : LibCallOptimization("fputs",
+      "Number of 'fputs' calls simplified") {}
+
+  /// @brief Make sure that the "fputs" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    // Just make sure this has 2 arguments
+    return F->arg_size() == 2;
+  }
+
+  /// @brief Perform the fputs optimization.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // If the result is used, none of these optimizations work.
+    if (!CI->use_empty())
+      return false;
+
+    // All the optimizations depend on the length of the first argument and the
+    // fact that it is a constant string array. Check that now
+    std::string Str;
+    if (!GetConstantStringInfo(CI->getOperand(1), Str))
+      return false;
+
+    const Type *FILETy = CI->getOperand(2)->getType();
+    // fputs(s,F)  -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
+    Value *FWriteParms[4] = {
+      CI->getOperand(1),
+      ConstantInt::get(SLC.getIntPtrType(), Str.size()),
+      ConstantInt::get(SLC.getIntPtrType(), 1),
+      CI->getOperand(2)
+    };
+    new CallInst(SLC.get_fwrite(FILETy), FWriteParms, 4, "", CI);
+    return ReplaceCallWith(CI, 0);  // Known to have no uses (see above).
+  }
+} FPutsOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "fwrite" function.
+struct VISIBILITY_HIDDEN FWriteOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  FWriteOptimization() : LibCallOptimization("fwrite",
+                                       "Number of 'fwrite' calls simplified") {}
+  
+  /// @brief Make sure that the "fputs" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    const FunctionType *FT = F->getFunctionType();
+    return FT->getNumParams() == 4 && 
+           FT->getParamType(0) == PointerType::get(Type::Int8Ty) &&
+           FT->getParamType(1) == FT->getParamType(2) &&
+           isa<IntegerType>(FT->getParamType(1)) &&
+           isa<PointerType>(FT->getParamType(3)) &&
+           isa<IntegerType>(FT->getReturnType());
+  }
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // Get the element size and count.
+    uint64_t EltSize, EltCount;
+    if (ConstantInt *C = dyn_cast<ConstantInt>(CI->getOperand(2)))
+      EltSize = C->getZExtValue();
+    else
+      return false;
+    if (ConstantInt *C = dyn_cast<ConstantInt>(CI->getOperand(3)))
+      EltCount = C->getZExtValue();
+    else
+      return false;
+    
+    // If this is writing zero records, remove the call (it's a noop).
+    if (EltSize * EltCount == 0)
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
+    
+    // If this is writing one byte, turn it into fputc.
+    if (EltSize == 1 && EltCount == 1) {
+      // fwrite(s,1,1,F) -> fputc(s[0],F)
+      Value *Ptr = CI->getOperand(1);
+      Value *Val = new LoadInst(Ptr, Ptr->getName()+".byte", CI);
+      Val = new ZExtInst(Val, Type::Int32Ty, Val->getName()+".int", CI);
+      const Type *FILETy = CI->getOperand(4)->getType();
+      new CallInst(SLC.get_fputc(FILETy), Val, CI->getOperand(4), "", CI);
+      return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 1));
+    }
+    return false;
+  }
+} FWriteOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "isdigit" library
+/// function. It simply does range checks the parameter explicitly.
+/// @brief Simplify the isdigit library function.
+struct VISIBILITY_HIDDEN isdigitOptimization : public LibCallOptimization {
+public:
+  isdigitOptimization() : LibCallOptimization("isdigit",
+      "Number of 'isdigit' calls simplified") {}
+
+  /// @brief Make sure that the "isdigit" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
+    // Just make sure this has 1 argument
+    return (f->arg_size() == 1);
+  }
+
+  /// @brief Perform the toascii optimization.
+  virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
+    if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1))) {
+      // isdigit(c)   -> 0 or 1, if 'c' is constant
+      uint64_t val = CI->getZExtValue();
+      if (val >= '0' && val <= '9')
+        return ReplaceCallWith(ci, ConstantInt::get(Type::Int32Ty, 1));
+      else
+        return ReplaceCallWith(ci, ConstantInt::get(Type::Int32Ty, 0));
+    }
+
+    // isdigit(c)   -> (unsigned)c - '0' <= 9
+    CastInst* cast = CastInst::createIntegerCast(ci->getOperand(1),
+        Type::Int32Ty, false/*ZExt*/, ci->getOperand(1)->getName()+".uint", ci);
+    BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
+        ConstantInt::get(Type::Int32Ty,0x30),
+        ci->getOperand(1)->getName()+".sub",ci);
+    ICmpInst* setcond_inst = new ICmpInst(ICmpInst::ICMP_ULE,sub_inst,
+        ConstantInt::get(Type::Int32Ty,9),
+        ci->getOperand(1)->getName()+".cmp",ci);
+    CastInst* c2 = new ZExtInst(setcond_inst, Type::Int32Ty, 
+        ci->getOperand(1)->getName()+".isdigit", ci);
+    return ReplaceCallWith(ci, c2);
+  }
+} isdigitOptimizer;
+
+struct VISIBILITY_HIDDEN isasciiOptimization : public LibCallOptimization {
+public:
+  isasciiOptimization()
+    : LibCallOptimization("isascii", "Number of 'isascii' calls simplified") {}
+  
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    return F->arg_size() == 1 && F->arg_begin()->getType()->isInteger() && 
+           F->getReturnType()->isInteger();
+  }
+  
+  /// @brief Perform the isascii optimization.
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+    // isascii(c)   -> (unsigned)c < 128
+    Value *V = CI->getOperand(1);
+    Value *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, V, 
+                              ConstantInt::get(V->getType(), 128), 
+                              V->getName()+".isascii", CI);
+    if (Cmp->getType() != CI->getType())
+      Cmp = new ZExtInst(Cmp, CI->getType(), Cmp->getName(), CI);
+    return ReplaceCallWith(CI, Cmp);
+  }
+} isasciiOptimizer;
+
+
+/// This LibCallOptimization will simplify calls to the "toascii" library
+/// function. It simply does the corresponding and operation to restrict the
+/// range of values to the ASCII character set (0-127).
+/// @brief Simplify the toascii library function.
+struct VISIBILITY_HIDDEN ToAsciiOptimization : public LibCallOptimization {
+public:
+  /// @brief Default Constructor
+  ToAsciiOptimization() : LibCallOptimization("toascii",
+      "Number of 'toascii' calls simplified") {}
+
+  /// @brief Make sure that the "fputs" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
+    // Just make sure this has 2 arguments
+    return (f->arg_size() == 1);
+  }
+
+  /// @brief Perform the toascii optimization.
+  virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
+    // toascii(c)   -> (c & 0x7f)
+    Value *chr = ci->getOperand(1);
+    Value *and_inst = BinaryOperator::createAnd(chr,
+        ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
+    return ReplaceCallWith(ci, and_inst);
+  }
+} ToAsciiOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "ffs" library
+/// calls which find the first set bit in an int, long, or long long. The
+/// optimization is to compute the result at compile time if the argument is
+/// a constant.
+/// @brief Simplify the ffs library function.
+struct VISIBILITY_HIDDEN FFSOptimization : public LibCallOptimization {
+protected:
+  /// @brief Subclass Constructor
+  FFSOptimization(const char* funcName, const char* description)
+    : LibCallOptimization(funcName, description) {}
+
+public:
+  /// @brief Default Constructor
+  FFSOptimization() : LibCallOptimization("ffs",
+      "Number of 'ffs' calls simplified") {}
+
+  /// @brief Make sure that the "ffs" function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    // Just make sure this has 2 arguments
+    return F->arg_size() == 1 && F->getReturnType() == Type::Int32Ty;
+  }
+
+  /// @brief Perform the ffs optimization.
+  virtual bool OptimizeCall(CallInst *TheCall, SimplifyLibCalls &SLC) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(TheCall->getOperand(1))) {
+      // ffs(cnst)  -> bit#
+      // ffsl(cnst) -> bit#
+      // ffsll(cnst) -> bit#
+      uint64_t val = CI->getZExtValue();
+      int result = 0;
+      if (val) {
+        ++result;
+        while ((val & 1) == 0) {
+          ++result;
+          val >>= 1;
+        }
+      }
+      return ReplaceCallWith(TheCall, ConstantInt::get(Type::Int32Ty, result));
+    }
+
+    // ffs(x)   -> x == 0 ? 0 : llvm.cttz(x)+1
+    // ffsl(x)  -> x == 0 ? 0 : llvm.cttz(x)+1
+    // ffsll(x) -> x == 0 ? 0 : llvm.cttz(x)+1
+    const Type *ArgType = TheCall->getOperand(1)->getType();
+    const char *CTTZName;
+    assert(ArgType->getTypeID() == Type::IntegerTyID &&
+           "llvm.cttz argument is not an integer?");
+    unsigned BitWidth = cast<IntegerType>(ArgType)->getBitWidth();
+    if (BitWidth == 8)
+      CTTZName = "llvm.cttz.i8";
+    else if (BitWidth == 16)
+      CTTZName = "llvm.cttz.i16"; 
+    else if (BitWidth == 32)
+      CTTZName = "llvm.cttz.i32";
+    else {
+      assert(BitWidth == 64 && "Unknown bitwidth");
+      CTTZName = "llvm.cttz.i64";
+    }
+    
+    Constant *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
+                                                       ArgType, NULL);
+    Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType, 
+                                           false/*ZExt*/, "tmp", TheCall);
+    Value *V2 = new CallInst(F, V, "tmp", TheCall);
+    V2 = CastInst::createIntegerCast(V2, Type::Int32Ty, false/*ZExt*/, 
+                                     "tmp", TheCall);
+    V2 = BinaryOperator::createAdd(V2, ConstantInt::get(Type::Int32Ty, 1),
+                                   "tmp", TheCall);
+    Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, V, 
+                               Constant::getNullValue(V->getType()), "tmp", 
+                               TheCall);
+    V2 = new SelectInst(Cond, ConstantInt::get(Type::Int32Ty, 0), V2,
+                        TheCall->getName(), TheCall);
+    return ReplaceCallWith(TheCall, V2);
+  }
+} FFSOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "ffsl" library
+/// calls. It simply uses FFSOptimization for which the transformation is
+/// identical.
+/// @brief Simplify the ffsl library function.
+struct VISIBILITY_HIDDEN FFSLOptimization : public FFSOptimization {
+public:
+  /// @brief Default Constructor
+  FFSLOptimization() : FFSOptimization("ffsl",
+      "Number of 'ffsl' calls simplified") {}
+
+} FFSLOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "ffsll" library
+/// calls. It simply uses FFSOptimization for which the transformation is
+/// identical.
+/// @brief Simplify the ffsl library function.
+struct VISIBILITY_HIDDEN FFSLLOptimization : public FFSOptimization {
+public:
+  /// @brief Default Constructor
+  FFSLLOptimization() : FFSOptimization("ffsll",
+      "Number of 'ffsll' calls simplified") {}
+
+} FFSLLOptimizer;
+
+/// This optimizes unary functions that take and return doubles.
+struct UnaryDoubleFPOptimizer : public LibCallOptimization {
+  UnaryDoubleFPOptimizer(const char *Fn, const char *Desc)
+  : LibCallOptimization(Fn, Desc) {}
+  
+  // Make sure that this function has the right prototype
+  virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+    return F->arg_size() == 1 && F->arg_begin()->getType() == Type::DoubleTy &&
+           F->getReturnType() == Type::DoubleTy;
+  }
+
+  /// ShrinkFunctionToFloatVersion - If the input to this function is really a
+  /// float, strength reduce this to a float version of the function,
+  /// e.g. floor((double)FLT) -> (double)floorf(FLT).  This can only be called
+  /// when the target supports the destination function and where there can be
+  /// no precision loss.
+  static bool ShrinkFunctionToFloatVersion(CallInst *CI, SimplifyLibCalls &SLC,
+                                           Constant *(SimplifyLibCalls::*FP)()){
+    if (FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1)))
+      if (Cast->getOperand(0)->getType() == Type::FloatTy) {
+        Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
+                                  CI->getName(), CI);
+        New = new FPExtInst(New, Type::DoubleTy, CI->getName(), CI);
+        CI->replaceAllUsesWith(New);
+        CI->eraseFromParent();
+        if (Cast->use_empty())
+          Cast->eraseFromParent();
+        return true;
+      }
+    return false;
+  }
+};
+
+
+struct VISIBILITY_HIDDEN FloorOptimization : public UnaryDoubleFPOptimizer {
+  FloorOptimization()
+    : UnaryDoubleFPOptimizer("floor", "Number of 'floor' calls simplified") {}
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+#ifdef HAVE_FLOORF
+    // If this is a float argument passed in, convert to floorf.
+    if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_floorf))
+      return true;
+#endif
+    return false; // opt failed
+  }
+} FloorOptimizer;
+
+struct VISIBILITY_HIDDEN CeilOptimization : public UnaryDoubleFPOptimizer {
+  CeilOptimization()
+  : UnaryDoubleFPOptimizer("ceil", "Number of 'ceil' calls simplified") {}
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+#ifdef HAVE_CEILF
+    // If this is a float argument passed in, convert to ceilf.
+    if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_ceilf))
+      return true;
+#endif
+    return false; // opt failed
+  }
+} CeilOptimizer;
+
+struct VISIBILITY_HIDDEN RoundOptimization : public UnaryDoubleFPOptimizer {
+  RoundOptimization()
+  : UnaryDoubleFPOptimizer("round", "Number of 'round' calls simplified") {}
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+#ifdef HAVE_ROUNDF
+    // If this is a float argument passed in, convert to roundf.
+    if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_roundf))
+      return true;
+#endif
+    return false; // opt failed
+  }
+} RoundOptimizer;
+
+struct VISIBILITY_HIDDEN RintOptimization : public UnaryDoubleFPOptimizer {
+  RintOptimization()
+  : UnaryDoubleFPOptimizer("rint", "Number of 'rint' calls simplified") {}
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+#ifdef HAVE_RINTF
+    // If this is a float argument passed in, convert to rintf.
+    if (ShrinkFunctionToFloatVersion(CI, SLC, &SimplifyLibCalls::get_rintf))
+      return true;
+#endif
+    return false; // opt failed
+  }
+} RintOptimizer;
+
+struct VISIBILITY_HIDDEN NearByIntOptimization : public UnaryDoubleFPOptimizer {
+  NearByIntOptimization()
+  : UnaryDoubleFPOptimizer("nearbyint",
+                           "Number of 'nearbyint' calls simplified") {}
+  
+  virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
+#ifdef HAVE_NEARBYINTF
+    // If this is a float argument passed in, convert to nearbyintf.
+    if (ShrinkFunctionToFloatVersion(CI, SLC,&SimplifyLibCalls::get_nearbyintf))
+      return true;
+#endif
+    return false; // opt failed
+  }
+} NearByIntOptimizer;
+
+/// GetConstantStringInfo - This function computes the length of a
+/// null-terminated constant array of integers.  This function can't rely on the
+/// size of the constant array because there could be a null terminator in the
+/// middle of the array.
+///
+/// We also have to bail out if we find a non-integer constant initializer
+/// of one of the elements or if there is no null-terminator. The logic
+/// below checks each of these conditions and will return true only if all
+/// conditions are met.  If the conditions aren't met, this returns false.
+///
+/// If successful, the \p Array param is set to the constant array being
+/// indexed, the \p Length parameter is set to the length of the null-terminated
+/// string pointed to by V, the \p StartIdx value is set to the first
+/// element of the Array that V points to, and true is returned.
+static bool GetConstantStringInfo(Value *V, std::string &Str) {
+  // Look through noop bitcast instructions.
+  if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) {
+    if (BCI->getType() == BCI->getOperand(0)->getType())
+      return GetConstantStringInfo(BCI->getOperand(0), Str);
+    return false;
+  }
+  
+  // 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
+  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 false;
+    GEP = CE;
+  } else {
+    return false;
+  }
+
+  // Make sure the GEP has exactly three arguments.
+  if (GEP->getNumOperands() != 3)
+    return false;
+
+  // 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 false;
+  } else
+    return false;
+
+  // 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 false;
+
+  // 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())
+    return false;
+  Constant *GlobalInit = GV->getInitializer();
+
+  // Handle the ConstantAggregateZero case
+  if (isa<ConstantAggregateZero>(GlobalInit)) {
+    // This is a degenerate case. The initializer is constant zero so the
+    // length of the string must be zero.
+    Str.clear();
+    return true;
+  }
+
+  // Must be a Constant Array
+  ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
+  if (!Array) 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 false;
+    if (CI->isZero())
+      return true; // we found end of string, success!
+    Str += (char)CI->getZExtValue();
+  }
+  
+  return false; // The array isn't null terminated.
+}
+
+/// CastToCStr - Return V if it is an sbyte*, otherwise cast it to sbyte*,
+/// inserting the cast before IP, and return the cast.
+/// @brief Cast a value to a "C" string.
+static Value *CastToCStr(Value *V, Instruction *IP) {
+  assert(isa<PointerType>(V->getType()) && 
+         "Can't cast non-pointer type to C string type");
+  const Type *SBPTy = PointerType::get(Type::Int8Ty);
+  if (V->getType() != SBPTy)
+    return new BitCastInst(V, SBPTy, V->getName(), IP);
+  return V;
+}
+
+// TODO:
+//   Additional cases that we need to add to this file:
+//
+// cbrt:
+//   * cbrt(expN(X))  -> expN(x/3)
+//   * cbrt(sqrt(x))  -> pow(x,1/6)
+//   * cbrt(sqrt(x))  -> pow(x,1/9)
+//
+// cos, cosf, cosl:
+//   * cos(-x)  -> cos(x)
+//
+// exp, expf, expl:
+//   * exp(log(x))  -> x
+//
+// log, logf, logl:
+//   * log(exp(x))   -> x
+//   * log(x**y)     -> y*log(x)
+//   * log(exp(y))   -> y*log(e)
+//   * log(exp2(y))  -> y*log(2)
+//   * log(exp10(y)) -> y*log(10)
+//   * log(sqrt(x))  -> 0.5*log(x)
+//   * log(pow(x,y)) -> y*log(x)
+//
+// lround, lroundf, lroundl:
+//   * lround(cnst) -> cnst'
+//
+// memcmp:
+//   * memcmp(x,y,l)   -> cnst
+//      (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
+//
+// memmove:
+//   * memmove(d,s,l,a) -> memcpy(d,s,l,a)
+//       (if s is a global constant array)
+//
+// pow, powf, powl:
+//   * pow(exp(x),y)  -> exp(x*y)
+//   * pow(sqrt(x),y) -> pow(x,y*0.5)
+//   * pow(pow(x,y),z)-> pow(x,y*z)
+//
+// puts:
+//   * puts("") -> putchar("\n")
+//
+// round, roundf, roundl:
+//   * round(cnst) -> cnst'
+//
+// signbit:
+//   * signbit(cnst) -> cnst'
+//   * signbit(nncst) -> 0 (if pstv is a non-negative constant)
+//
+// sqrt, sqrtf, sqrtl:
+//   * sqrt(expN(x))  -> expN(x*0.5)
+//   * sqrt(Nroot(x)) -> pow(x,1/(2*N))
+//   * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
+//
+// stpcpy:
+//   * stpcpy(str, "literal") ->
+//           llvm.memcpy(str,"literal",strlen("literal")+1,1)
+// strrchr:
+//   * strrchr(s,c) -> reverse_offset_of_in(c,s)
+//      (if c is a constant integer and s is a constant string)
+//   * strrchr(s1,0) -> strchr(s1,0)
+//
+// strncat:
+//   * strncat(x,y,0) -> x
+//   * strncat(x,y,0) -> x (if strlen(y) = 0)
+//   * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
+//
+// strncpy:
+//   * strncpy(d,s,0) -> d
+//   * strncpy(d,s,l) -> memcpy(d,s,l,1)
+//      (if s and l are constants)
+//
+// strpbrk:
+//   * strpbrk(s,a) -> offset_in_for(s,a)
+//      (if s and a are both constant strings)
+//   * strpbrk(s,"") -> 0
+//   * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
+//
+// strspn, strcspn:
+//   * strspn(s,a)   -> const_int (if both args are constant)
+//   * strspn("",a)  -> 0
+//   * strspn(s,"")  -> 0
+//   * strcspn(s,a)  -> const_int (if both args are constant)
+//   * strcspn("",a) -> 0
+//   * strcspn(s,"") -> strlen(a)
+//
+// strstr:
+//   * strstr(x,x)  -> x
+//   * strstr(s1,s2) -> offset_of_s2_in(s1)
+//       (if s1 and s2 are constant strings)
+//
+// tan, tanf, tanl:
+//   * tan(atan(x)) -> x
+//
+// trunc, truncf, truncl:
+//   * trunc(cnst) -> cnst'
+//
+//
+}