diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/IPO/SimplifyLibCalls.cpp | 2214 | ||||
| -rw-r--r-- | lib/Transforms/Scalar/SimplifyLibCalls.cpp | 1437 |
2 files changed, 1437 insertions, 2214 deletions
diff --git a/lib/Transforms/IPO/SimplifyLibCalls.cpp b/lib/Transforms/IPO/SimplifyLibCalls.cpp deleted file mode 100644 index cac25c33df..0000000000 --- a/lib/Transforms/IPO/SimplifyLibCalls.cpp +++ /dev/null @@ -1,2214 +0,0 @@ -//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===// -// -// The LLVM Compiler Infrastructure -// -// This file 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/Intrinsics.h" -#include "llvm/Module.h" -#include "llvm/Pass.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/StringMap.h" -#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" -#include <cstring> -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; - StringMap<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 - StringMap<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::getUnqual(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::getUnqual(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::getUnqual(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::getUnqual(Type::Int8Ty), - PointerType::getUnqual(Type::Int8Ty), - PointerType::getUnqual(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::getUnqual(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::getUnqual(Type::Int8Ty), - PointerType::getUnqual(Type::Int8Ty), - Type::Int32Ty, TD->getIntPtrType(), - NULL); - return memchr_func; - } - - /// @brief Return a Function* for the memcpy libcall - Constant *get_memcpy() { - if (!memcpy_func) { - Intrinsic::ID IID = (TD->getIntPtrType() == Type::Int32Ty) ? - Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64; - memcpy_func = Intrinsic::getDeclaration(M, IID); - } - return memcpy_func; - } - - Constant *getUnaryFloatFunction(const char *BaseName, const Type *T = 0) { - if (T == 0) T = Type::FloatTy; - - char NameBuffer[20]; - const char *Name; - if (T == Type::DoubleTy) - Name = BaseName; // floor - else { - Name = NameBuffer; - unsigned NameLen = strlen(BaseName); - assert(NameLen < sizeof(NameBuffer)-2 && "Buffer too small"); - memcpy(NameBuffer, BaseName, NameLen); - if (T == Type::FloatTy) - NameBuffer[NameLen] = 'f'; // floorf - else - NameBuffer[NameLen] = 'l'; // floorl - NameBuffer[NameLen+1] = 0; - } - - return M->getOrInsertFunction(Name, T, T, NULL); - } - - Constant *get_floorf() { return getUnaryFloatFunction("floor"); } - Constant *get_ceilf() { return getUnaryFloatFunction( "ceil"); } - Constant *get_roundf() { return getUnaryFloatFunction("round"); } - Constant *get_rintf() { return getUnaryFloatFunction( "rint"); } - Constant *get_nearbyintf() { return getUnaryFloatFunction("nearbyint"); } - - - -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; - } - -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; - 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(); -} - -// Forward declare utility functions. -static bool GetConstantStringInfo(Value *V, std::string &Str); -static Value *CastToCStr(Value *V, Instruction *IP); -static uint64_t GetStringLength(Value *V); - - -// 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 { - -/// 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() - && !isa<StructType>(from->getReturnType())) - 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. - ReturnInst::Create(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::getUnqual(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); - - // See if we can get the length of the input string. - uint64_t Len = GetStringLength(Src); - if (Len == 0) return false; - --Len; // Unbias length. - - // Handle the simple, do-nothing case - if (Len == 0) - 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 = CallInst::Create(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 = GetElementPtrInst::Create(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(), Len+1), // copy nul byte. - ConstantInt::get(Type::Int32Ty, 1) // alignment - }; - CallInst::Create(SLC.get_memcpy(), Vals, 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::getUnqual(Type::Int8Ty) && - FT->getParamType(0) == FT->getReturnType() && - isa<IntegerType>(FT->getParamType(1)); - } - - /// @brief Perform the strchr optimizations - virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) { - Value *SrcStr = CI->getOperand(1); - // If the second operand is not constant, see if we can compute the length - // and turn this into memchr. - ConstantInt *CSI = dyn_cast<ConstantInt>(CI->getOperand(2)); - if (CSI == 0) { - uint64_t Len = GetStringLength(SrcStr); - if (Len == 0) return false; - - Value *Args[3] = { - CI->getOperand(1), - CI->getOperand(2), - ConstantInt::get(SLC.getIntPtrType(), Len) // include nul. - }; - return ReplaceCallWith(CI, CallInst::Create(SLC.get_memchr(), - Args, Args + 3, - CI->getName(), CI)); - } - - // Otherwise, the character is a constant, see if the first argument is - // a string literal. If so, we can constant fold. - std::string Str; - if (!GetConstantStringInfo(SrcStr, Str)) - return false; - - // 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 = GetElementPtrInst::Create(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::getUnqual(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::getUnqual(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::getUnqual(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); - } - - // See if we can get the length of the input string. - uint64_t Len = GetStringLength(Src); - if (Len == 0) return false; - --Len; // Unbias length. - - // 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 (Len == 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, - ConstantInt::get(SLC.getIntPtrType(), Len+1),// Length including nul byte. - ConstantInt::get(Type::Int32Ty, 1) // alignment - }; - CallInst::Create(SLC.get_memcpy(), MemcpyOps, 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::getUnqual(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 - // strlen("xyz") -> 3 (for example) - if (uint64_t Len = GetStringLength(Src)) - return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), Len-1)); - return false; - } -} 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::getUnqual(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::getUnqual(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 = GetElementPtrInst::Create(Op1Cast, One, "next1v", CI); - Value *G2 = GetElementPtrInst::Create(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. It simply converts them into calls to llvm.memcpy.*; -/// the resulting call should be optimized later. -/// @brief Simplify the memcpy library function. -struct VISIBILITY_HIDDEN MemCpyOptimization : public LibCallOptimization { -public: - MemCpyOptimization() : LibCallOptimization("memcpy", - "Number of 'memcpy' calls simplified") {} - - /// @brief Make sure that the "memcpy" function has the right prototype - virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){ - const FunctionType *FT = F->getFunctionType(); - const Type* voidPtr = PointerType::getUnqual(Type::Int8Ty); - return FT->getReturnType() == voidPtr && FT->getNumParams() == 3 && - FT->getParamType(0) == voidPtr && - FT->getParamType(1) == voidPtr && - FT->getParamType(2) == SLC.getIntPtrType(); - } - - /// @brief Perform the memcpy optimization - virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) { - Value *MemcpyOps[] = { - CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), - ConstantInt::get(Type::Int32Ty, 1) // align = 1 always. - }; - CallInst::Create(SLC.get_memcpy(), MemcpyOps, MemcpyOps + 4, "", CI); - // memcpy always returns the destination - return ReplaceCallWith(CI, CI->getOperand(1)); - } -} MemCpyOptimizer; - -/// 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::getUnqual(castType), src->getName()+".cast", ci); - CastInst* DestCast = CastInst::create(Instruction::BitCast, - dest, PointerType::getUnqual(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::getUnqual(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(const char *Name) : LibCallOptimization(Name, - "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 of the same FP type, which match the - // result type. - const FunctionType *FT = F->getFunctionType(); - return FT->getNumParams() == 2 && - FT->getParamType(0) == FT->getParamType(1) && - FT->getParamType(0) == FT->getReturnType() && - FT->getParamType(0)->isFloatingPoint(); - } - - /// @brief Perform the pow optimization. - virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) { - Value *Op1 = CI->getOperand(1); - Value *Op2 = CI->getOperand(2); - if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) { - if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0 - return ReplaceCallWith(CI, Op1C); - if (Op1C->isExactlyValue(2.0)) {// pow(2.0, x) -> exp2(x) - Value *Exp2 = SLC.getUnaryFloatFunction("exp2", CI->getType()); - Value *Res = CallInst::Create(Exp2, Op2, CI->getName()+"exp2", CI); - return ReplaceCallWith(CI, Res); - } - } - - ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2); - if (Op2C == 0) return false; - - if (Op2C->getValueAPF().isZero()) { - // pow(x, 0.0) -> 1.0 - return ReplaceCallWith(CI, ConstantFP::get(CI->getType(), 1.0)); - } else if (Op2C->isExactlyValue(0.5)) { - // FIXME: This is not safe for -0.0 and -inf. This can only be done when - // 'unsafe' math optimizations are allowed. - // x pow(x, 0.5) sqrt(x) - // --------------------------------------------- - // -0.0 +0.0 -0.0 - // -inf +inf NaN -#if 0 - // pow(x, 0.5) -> sqrt(x) - Value *Sqrt = CallInst::Create(SLC.get_sqrt(), Op1, "sqrt", CI); - return ReplaceCallWith(CI, Sqrt); -#endif - } else if (Op2C->isExactlyValue(1.0)) { - // pow(x, 1.0) -> x - return ReplaceCallWith(CI, Op1); - } else if (Op2C->isExactlyValue(2.0)) { - // pow(x, 2.0) -> x*x - Value *Sq = BinaryOperator::createMul(Op1, Op1, "pow2", CI); - return ReplaceCallWith(CI, Sq); - } else if (Op2C->isExactlyValue(-1.0)) { - // pow(x, -1.0) -> 1.0/x - Value *R = BinaryOperator::createFDiv(ConstantFP::get(CI->getType(), 1.0), - Op1, CI->getName()+".pow", CI); - return ReplaceCallWith(CI, R); - } - return false; // opt failed - } -}; - -PowOptimization PowFOptimizer("powf"); -PowOptimization PowOptimizer("pow"); -PowOptimization PowLOptimizer("powl"); - - -/// 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]); - CallInst::Create(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::getUnqual(Type::Int8Ty)); - CallInst::Create(SLC.get_puts(), GV, "", CI); - - if (CI->use_empty()) return ReplaceCallWith(CI, 0); - // The return value from printf includes the \n we just removed, so +1. - return ReplaceCallWith(CI, - ConstantInt::get(CI->getType(), - FormatStr.size()+1)); - } - - - // 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) - CallInst::Create(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); - CallInst::Create(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::getUnqual(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) - }; - CallInst::Create(SLC.get_fwrite(FILEty), FWriteArgs, 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); - SmallVector<Value *, 2> Args; - Args.push_back(C); - Args.push_back(CI->getOperand(1)); - CallInst::Create(SLC.get_fputc(FILETy), Args.begin(), Args.end(), "", 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() || !isa<PointerType>(CI->getOperand(3)->getType())) - return false; - - // fprintf(file,"%s",str) -> fputs(str,file) - SmallVector<Value *, 2> Args; - Args.push_back(CastToCStr(CI->getOperand(3), CI)); - Args.push_back(CI->getOperand(1)); - CallInst::Create(SLC.get_fputs(FILETy), Args.begin(), - Args.end(), 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::getUnqual(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) - }; - CallInst::Create(SLC.get_memcpy(), MemCpyArgs, 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 = GetElementPtrInst::Create(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 = CallInst::Create(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) - }; - CallInst::Create(SLC.get_memcpy(), MemcpyArgs, 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. - uint64_t Len = GetStringLength(CI->getOperand(1)); - if (!Len) return false; - - const Type *FILETy = CI->getOperand(2)->getType(); - // fputs(s,F) -> fwrite(s,1,strlen(s),F) - Value *Ops[4] = { - CI->getOperand(1), - ConstantInt::get(SLC.getIntPtrType(), Len-1), - ConstantInt::get(SLC.getIntPtrType(), 1), - CI->getOperand(2) - }; - CallInst::Create(SLC.get_fwrite(FILETy), Ops, Ops + 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::getUnqual(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) { - SmallVector<Value *, 2> Args; - // fwrite(s,1,1,F) -> fputc(s[0],F) - Value *Ptr = CI->getOperand(1); - Value *Val = new LoadInst(Ptr, Ptr->getName()+".byte", CI); - Args.push_back(new ZExtInst(Val, Type::Int32Ty, Val->getName()+".int", CI)); - Args.push_back(CI->getOperand(4)); - const Type *FILETy = CI->getOperand(4)->getType(); - CallInst::Create(SLC.get_fputc(FILETy), Args.begin(), Args.end(), "", 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(); - assert(ArgType->getTypeID() == Type::IntegerTyID && - "llvm.cttz argument is not an integer?"); - Constant *F = Intrinsic::getDeclaration(SLC.getModule(), - Intrinsic::cttz, &ArgType, 1); - - Value *V = CastInst::createIntegerCast(TheCall->getOperand(1), ArgType, - false/*ZExt*/, "tmp", TheCall); - Value *V2 = CallInst::Create(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 = SelectInst::Create(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 = CallInst::Create((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; -} // end anon namespace - -/// 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. -} - -/// GetStringLengthH - If we can compute the length of the string pointed to by -/// 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); - - // If this is a PHI node, there are two cases: either we have already seen it - // or we haven't. - if (PHINode *PN = dyn_cast<PHINode>(V)) { - if (!PHIs.insert(PN)) - return ~0ULL; // already in the set. - - // If it was new, see if all the input strings are the same length. - uint64_t LenSoFar = ~0ULL; - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { - uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs); - if (Len == 0) return 0; // Unknown length -> unknown. - - if (Len == ~0ULL) continue; - - if (Len != LenSoFar && LenSoFar != ~0ULL) - return 0; // Disagree -> unknown. - LenSoFar = Len; - } - - // Success, all agree. - return LenSoFar; - } - - // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) - if (SelectInst *SI = dyn_cast<SelectInst>(V)) { - uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs); - if (Len1 == 0) return 0; - uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs); - if (Len2 == 0) return 0; - if (Len1 == ~0ULL) return Len2; - if (Len2 == ~0ULL) return Len1; - if (Len1 != Len2) return 0; - return Len1; - } - - // 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()) - 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() != Type::Int8Ty) - 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'. -} - -/// 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. -static uint64_t GetStringLength(Value *V) { - if (!isa<PointerType>(V->getType())) return 0; - - SmallPtrSet<PHINode*, 32> PHIs; - uint64_t Len = GetStringLengthH(V, PHIs); - // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return - // an empty string as a length. - return Len == ~0ULL ? 1 : Len; -} - - - -/// 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::getUnqual(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' -// -// diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp new file mode 100644 index 0000000000..a03bc7e9cf --- /dev/null +++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp @@ -0,0 +1,1437 @@ +//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements a simple 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/Transforms/Scalar.h" +#include "llvm/Intrinsics.h" +#include "llvm/Module.h" +#include "llvm/Pass.h" +#include "llvm/Support/IRBuilder.h" +#include "llvm/Target/TargetData.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Config/config.h" +using namespace llvm; + +STATISTIC(NumSimplified, "Number of library calls simplified"); + +//===----------------------------------------------------------------------===// +// Optimizer Base Class +//===----------------------------------------------------------------------===// + +/// This class is the abstract base class for the set of optimizations that +/// corresponds to one library call. +namespace { +class VISIBILITY_HIDDEN LibCallOptimization { +protected: + Function *Caller; + const TargetData *TD; +public: + LibCallOptimization() { } + virtual ~LibCallOptimization() {} + + /// CallOptimizer - This pure virtual method is implemented by base classes to + /// do various optimizations. If this returns null then no transformation was + /// performed. If it returns CI, then it transformed the call and CI is to be + /// deleted. If it returns something else, replace CI with the new value and + /// delete CI. + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) =0; + + Value *OptimizeCall(CallInst *CI, const TargetData &TD, IRBuilder &B) { + Caller = CI->getParent()->getParent(); + this->TD = &TD; + return CallOptimizer(CI->getCalledFunction(), CI, B); + } + + /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*. + Value *CastToCStr(Value *V, IRBuilder &B); + + /// EmitStrLen - Emit a call to the strlen function to the builder, for the + /// specified pointer. Ptr is required to be some pointer type, and the + /// return value has 'intptr_t' type. + Value *EmitStrLen(Value *Ptr, IRBuilder &B); + + /// EmitMemCpy - Emit a call to the memcpy function to the builder. This + /// always expects that the size has type 'intptr_t' and Dst/Src are pointers. + Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len, + unsigned Align, IRBuilder &B); + + /// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is + /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value. + Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder &B); + + /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g. + /// 'floor'). This function is known to take a single of type matching 'Op' + /// and returns one value with the same type. If 'Op' is a long double, 'l' + /// is added as the suffix of name, if 'Op' is a float, we add a 'f' suffix. + Value *EmitUnaryFloatFnCall(Value *Op, const char *Name, IRBuilder &B); + + /// EmitPutChar - Emit a call to the putchar function. This assumes that Char + /// is an integer. + void EmitPutChar(Value *Char, IRBuilder &B); + + /// EmitPutS - Emit a call to the puts function. This assumes that Str is + /// some pointer. + void EmitPutS(Value *Str, IRBuilder &B); + + /// EmitFPutC - Emit a call to the fputc function. This assumes that Char is + /// an i32, and File is a pointer to FILE. + void EmitFPutC(Value *Char, Value *File, IRBuilder &B); + + /// EmitFPutS - Emit a call to the puts function. Str is required to be a + /// pointer and File is a pointer to FILE. + void EmitFPutS(Value *Str, Value *File, IRBuilder &B); + + /// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is + /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE. + void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder &B); + +}; +} // End anonymous namespace. + +/// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*. +Value *LibCallOptimization::CastToCStr(Value *V, IRBuilder &B) { + return B.CreateBitCast(V, PointerType::getUnqual(Type::Int8Ty), "cstr"); +} + +/// EmitStrLen - Emit a call to the strlen function to the builder, for the +/// specified pointer. This always returns an integer value of size intptr_t. +Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder &B) { + Module *M = Caller->getParent(); + Constant *StrLen =M->getOrInsertFunction("strlen", TD->getIntPtrType(), + PointerType::getUnqual(Type::Int8Ty), + NULL); + return B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen"); +} + +/// EmitMemCpy - Emit a call to the memcpy function to the builder. This always +/// expects that the size has type 'intptr_t' and Dst/Src are pointers. +Value *LibCallOptimization::EmitMemCpy(Value *Dst, Value *Src, Value *Len, + unsigned Align, IRBuilder &B) { + Module *M = Caller->getParent(); + Intrinsic::ID IID = TD->getIntPtrType() == Type::Int32Ty ? + Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64; + Value *MemCpy = Intrinsic::getDeclaration(M, IID); + return B.CreateCall4(MemCpy, CastToCStr(Dst, B), CastToCStr(Src, B), Len, + ConstantInt::get(Type::Int32Ty, Align)); +} + +/// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is +/// a pointer, Val is an i32 value, and Len is an 'intptr_t' value. +Value *LibCallOptimization::EmitMemChr(Value *Ptr, Value *Val, + Value *Len, IRBuilder &B) { + Module *M = Caller->getParent(); + Value *MemChr = M->getOrInsertFunction("memchr", + PointerType::getUnqual(Type::Int8Ty), + PointerType::getUnqual(Type::Int8Ty), + Type::Int32Ty, TD->getIntPtrType(), + NULL); + return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr"); +} + +/// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g. +/// 'floor'). This function is known to take a single of type matching 'Op' and +/// returns one value with the same type. If 'Op' is a long double, 'l' is +/// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix. +Value *LibCallOptimization::EmitUnaryFloatFnCall(Value *Op, const char *Name, + IRBuilder &B) { + char NameBuffer[20]; + if (Op->getType() != Type::DoubleTy) { + // If we need to add a suffix, copy into NameBuffer. + unsigned NameLen = strlen(Name); + assert(NameLen < sizeof(NameBuffer)-2); + memcpy(NameBuffer, Name, NameLen); + if (Op->getType() == Type::FloatTy) + NameBuffer[NameLen] = 'f'; // floorf + else + NameBuffer[NameLen] = 'l'; // floorl + NameBuffer[NameLen+1] = 0; + Name = NameBuffer; + } + + Module *M = Caller->getParent(); + Value *Callee = M->getOrInsertFunction(Name, Op->getType(), + Op->getType(), NULL); + return B.CreateCall(Callee, Op, Name); +} + +/// EmitPutChar - Emit a call to the putchar function. This assumes that Char +/// is an integer. +void LibCallOptimization::EmitPutChar(Value *Char, IRBuilder &B) { + Module *M = Caller->getParent(); + Value *F = M->getOrInsertFunction("putchar", Type::Int32Ty, + Type::Int32Ty, NULL); + B.CreateCall(F, B.CreateIntCast(Char, Type::Int32Ty, "chari"), "putchar"); +} + +/// EmitPutS - Emit a call to the puts function. This assumes that Str is +/// some pointer. +void LibCallOptimization::EmitPutS(Value *Str, IRBuilder &B) { + Module *M = Caller->getParent(); + Value *F = M->getOrInsertFunction("puts", Type::Int32Ty, + PointerType::getUnqual(Type::Int8Ty), NULL); + B.CreateCall(F, CastToCStr(Str, B), "puts"); +} + +/// EmitFPutC - Emit a call to the fputc function. This assumes that Char is +/// an integer and File is a pointer to FILE. +void LibCallOptimization::EmitFPutC(Value *Char, Value *File, IRBuilder &B) { + Module *M = Caller->getParent(); + Constant *F = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty, + File->getType(), NULL); + Char = B.CreateIntCast(Char, Type::Int32Ty, "chari"); + B.CreateCall2(F, Char, File, "fputc"); +} + +/// EmitFPutS - Emit a call to the puts function. Str is required to be a +/// pointer and File is a pointer to FILE. +void LibCallOptimization::EmitFPutS(Value *Str, Value *File, IRBuilder &B) { + Module *M = Caller->getParent(); + Constant *F = M->getOrInsertFunction("fputs", Type::Int32Ty, + PointerType::getUnqual(Type::Int8Ty), + File->getType(), NULL); + B.CreateCall2(F, CastToCStr(Str, B), File, "fputs"); +} + +/// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is +/// a pointer, Size is an 'intptr_t', and File is a pointer to FILE. +void LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File, + IRBuilder &B) { + Module *M = Caller->getParent(); + Constant *F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(), + PointerType::getUnqual(Type::Int8Ty), + TD->getIntPtrType(), TD->getIntPtrType(), + File->getType(), NULL); + B.CreateCall4(F, CastToCStr(Ptr, B), Size, + ConstantInt::get(TD->getIntPtrType(), 1), File); +} + +//===----------------------------------------------------------------------===// +// Helper Functions +//===----------------------------------------------------------------------===// + +/// 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. +static bool GetConstantStringInfo(Value *V, std::string &Str) { + // Look bitcast instructions. + if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) + return GetConstantStringInfo(BCI->getOperand(0), Str); + + // 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 == 0 || Array->getType()->getElementType() != Type::Int8Ty) + 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. +} + +/// GetStringLengthH - If we can compute the length of the string pointed to by +/// 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); + + // If this is a PHI node, there are two cases: either we have already seen it + // or we haven't. + if (PHINode *PN = dyn_cast<PHINode>(V)) { + if (!PHIs.insert(PN)) + return ~0ULL; // already in the set. + + // If it was new, see if all the input strings are the same length. + uint64_t LenSoFar = ~0ULL; + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { + uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs); + if (Len == 0) return 0; // Unknown length -> unknown. + + if (Len == ~0ULL) continue; + + if (Len != LenSoFar && LenSoFar != ~0ULL) + return 0; // Disagree -> unknown. + LenSoFar = Len; + } + + // Success, all agree. + return LenSoFar; + } + + // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) + if (SelectInst *SI = dyn_cast<SelectInst>(V)) { + uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs); + if (Len1 == 0) return 0; + uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs); + if (Len2 == 0) return 0; + if (Len1 == ~0ULL) return Len2; + if (Len2 == ~0ULL) return Len1; + if (Len1 != Len2) return 0; + return Len1; + } + + // 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()) + 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() != Type::Int8Ty) + 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'. +} + +/// 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. +static uint64_t GetStringLength(Value *V) { + if (!isa<PointerType>(V->getType())) return 0; + + SmallPtrSet<PHINode*, 32> PHIs; + uint64_t Len = GetStringLengthH(V, PHIs); + // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return + // an empty string as a length. + return Len == ~0ULL ? 1 : Len; +} + +/// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the +/// value is equal or not-equal to zero. +static bool IsOnlyUsedInZeroEqualityComparison(Value *V) { + for (Value::use_iterator UI = V->use_begin(), E = V->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; +} + +//===----------------------------------------------------------------------===// +// Miscellaneous LibCall Optimizations +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// 'exit' Optimizations + +/// ExitOpt - int main() { exit(4); } --> int main() { return 4; } +struct VISIBILITY_HIDDEN ExitOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify we have a reasonable prototype for exit. + if (Callee->arg_size() == 0 || !CI->use_empty()) + return 0; + + // Verify the caller is main, and that the result type of main matches the + // argument type of exit. + if (!Caller->isName("main") || !Caller->hasExternalLinkage() || + Caller->getReturnType() != CI->getOperand(1)->getType()) + return 0; + + TerminatorInst *OldTI = CI->getParent()->getTerminator(); + + // Create the return after the call. + ReturnInst *RI = B.CreateRet(CI->getOperand(1)); + + // Drop all successor phi node entries. + for (unsigned i = 0, e = OldTI->getNumSuccessors(); i != e; ++i) + OldTI->getSuccessor(i)->removePredecessor(CI->getParent()); + + // Erase all instructions from after our return instruction until the end of + // the block. + BasicBlock::iterator FirstDead = RI; ++FirstDead; + CI->getParent()->getInstList().erase(FirstDead, CI->getParent()->end()); + return CI; + } +}; + +//===----------------------------------------------------------------------===// +// String and Memory LibCall Optimizations +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// 'strcat' Optimizations + +struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify the "strcat" function prototype. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || + FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) || + FT->getParamType(0) != FT->getReturnType() || + FT->getParamType(1) != FT->getReturnType()) + return 0; + + // Extract some information from the instruction + Value *Dst = CI->getOperand(1); + Value *Src = CI->getOperand(2); + + // See if we can get the length of the input string. + uint64_t Len = GetStringLength(Src); + if (Len == 0) return false; + --Len; // Unbias length. + + // Handle the simple, do-nothing case: strcat(x, "") -> x + if (Len == 0) + return 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. + Value *DstLen = EmitStrLen(Dst, B); + + // 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 = B.CreateGEP(Dst, DstLen, "endptr"); + + // We have enough information to now generate the memcpy call to do the + // concatenation for us. Make a memcpy to copy the nul byte with align = 1. + EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len+1), 1, B); + return Dst; + } +}; + +//===---------------------------------------===// +// 'strchr' Optimizations + +struct VISIBILITY_HIDDEN StrChrOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify the "strchr" function prototype. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || + FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) || + FT->getParamType(0) != FT->getReturnType()) + return 0; + + Value *SrcStr = CI->getOperand(1); + + // If the second operand is non-constant, see if we can compute the length + // of the input string and turn this into memchr. + ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getOperand(2)); + if (CharC == 0) { + uint64_t Len = GetStringLength(SrcStr); + if (Len == 0 || FT->getParamType(1) != Type::Int32Ty) // memchr needs i32. + return 0; + + return EmitMemChr(SrcStr, CI->getOperand(2), // include nul. + ConstantInt::get(TD->getIntPtrType(), Len), B); + } + + // Otherwise, the character is a constant, see if the first argument is + // a string literal. If so, we can constant fold. + std::string Str; + if (!GetConstantStringInfo(SrcStr, Str)) + return false; + + // strchr can find the nul character. + Str += '\0'; + char CharValue = CharC->getSExtValue(); + + // Compute the offset. + uint64_t i = 0; + while (1) { + if (i == Str.size()) // Didn't find the char. strchr returns null. + return Constant::getNullValue(CI->getType()); + // Did we find our match? + if (Str[i] == CharValue) + break; + ++i; + } + + // strchr(s+n,c) -> gep(s+n+i,c) + Value *Idx = ConstantInt::get(Type::Int64Ty, i); + return B.CreateGEP(SrcStr, Idx, "strchr"); + } +}; + +//===---------------------------------------===// +// 'strcmp' Optimizations + +struct VISIBILITY_HIDDEN StrCmpOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify the "strcmp" function prototype. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getReturnType() != Type::Int32Ty || + FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty)) + return 0; + + Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2); + if (Str1P == Str2P) // strcmp(x,x) -> 0 + return ConstantInt::get(CI->getType(), 0); + + std::string Str1, Str2; + bool HasStr1 = GetConstantStringInfo(Str1P, Str1); + bool HasStr2 = GetConstantStringInfo(Str2P, Str2); + + if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x + return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType()); + + if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x + return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType()); + + // strcmp(x, y) -> cnst (if both x and y are constant strings) + if (HasStr1 && HasStr2) + return ConstantInt::get(CI->getType(), strcmp(Str1.c_str(),Str2.c_str())); + return 0; + } +}; + +//===---------------------------------------===// +// 'strncmp' Optimizations + +struct VISIBILITY_HIDDEN StrNCmpOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify the "strncmp" function prototype. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || FT->getReturnType() != Type::Int32Ty || + FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) || + !isa<IntegerType>(FT->getParamType(2))) + return 0; + + Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2); + if (Str1P == Str2P) // strncmp(x,x,n) -> 0 + return ConstantInt::get(CI->getType(), 0); + + // Get the length argument if it is constant. + uint64_t Length; + if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3))) + Length = LengthArg->getZExtValue(); + else + return 0; + + if (Length == 0) // strncmp(x,y,0) -> 0 + return ConstantInt::get(CI->getType(), 0); + + std::string Str1, Str2; + bool HasStr1 = GetConstantStringInfo(Str1P, Str1); + bool HasStr2 = GetConstantStringInfo(Str2P, Str2); + + if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x + return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType()); + + if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x + return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType()); + + // strncmp(x, y) -> cnst (if both x and y are constant strings) + if (HasStr1 && HasStr2) + return ConstantInt::get(CI->getType(), + strncmp(Str1.c_str(), Str2.c_str(), Length)); + return 0; + } +}; + + +//===---------------------------------------===// +// 'strcpy' Optimizations + +struct VISIBILITY_HIDDEN StrCpyOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Verify the "strcpy" function prototype. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty)) + return 0; + + Value *Dst = CI->getOperand(1), *Src = CI->getOperand(2); + if (Dst == Src) // strcpy(x,x) -> x + return Src; + + // See if we can get the length of the input string. + uint64_t Len = GetStringLength(Src); + if (Len == 0) return false; + + // We have enough information to now generate the memcpy call to do the + // concatenation for us. Make a memcpy to copy the nul byte with align = 1. + EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len), 1, B); + return Dst; + } +}; + + + +//===---------------------------------------===// +// 'strlen' Optimizations + +struct VISIBILITY_HIDDEN StrLenOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 1 || + FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) || + !isa<IntegerType>(FT->getReturnType())) + return 0; + + Value *Src = CI->getOperand(1); + + // Constant folding: strlen("xyz") -> 3 + if (uint64_t Len = GetStringLength(Src)) + return ConstantInt::get(CI->getType(), Len-1); + + // Handle strlen(p) != 0. + if (!IsOnlyUsedInZeroEqualityComparison(CI)) return 0; + + // strlen(x) != 0 --> *x != 0 + // strlen(x) == 0 --> *x == 0 + return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType()); + } +}; + +//===---------------------------------------===// +// 'memcmp' Optimizations + +struct VISIBILITY_HIDDEN MemCmpOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || !isa<PointerType>(FT->getParamType(0)) || + !isa<PointerType>(FT->getParamType(1)) || + FT->getReturnType() != Type::Int32Ty) + return 0; + + Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2); + + if (LHS == RHS) // memcmp(s,s,x) -> 0 + return 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 (Len == 0) // memcmp(s1,s2,0) -> 0 + return Constant::getNullValue(CI->getType()); + + if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS + Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv"); + Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv"); + return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType()); + } + + // memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0 + // memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS) != 0 + if ((Len == 2 || Len == 4) && IsOnlyUsedInZeroEqualityComparison(CI)) { + LHS = B.CreateBitCast(LHS, PointerType::getUnqual(Type::Int16Ty), "tmp"); + RHS = B.CreateBitCast(RHS, LHS->getType(), "tmp"); + LoadInst *LHSV = B.CreateLoad(LHS, "lhsv"); + LoadInst *RHSV = B.CreateLoad(RHS, "rhsv"); + LHSV->setAlignment(1); RHSV->setAlignment(1); // Unaligned loads. + return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType()); + } + + return 0; + } +}; + +//===---------------------------------------===// +// 'memcpy' Optimizations + +struct VISIBILITY_HIDDEN MemCpyOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) || + !isa<PointerType>(FT->getParamType(0)) || + !isa<PointerType>(FT->getParamType(1)) || + FT->getParamType(2) != TD->getIntPtrType()) + return 0; + + // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1) + EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B); + return CI->getOperand(1); + } +}; + +//===----------------------------------------------------------------------===// +// Math Library Optimizations +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// 'pow*' Optimizations + +struct VISIBILITY_HIDDEN PowOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 2 arguments of the same FP type, which match the + // result type. + if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != FT->getParamType(1) || + !FT->getParamType(0)->isFloatingPoint()) + return 0; + + Value *Op1 = CI->getOperand(1), *Op2 = CI->getOperand(2); + if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) { + if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0 + return Op1C; + if (Op1C->isExactlyValue(2.0)) // pow(2.0, x) -> exp2(x) + return EmitUnaryFloatFnCall(Op2, "exp2", B); + } + + ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2); + if (Op2C == 0) return 0; + + if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0 + return ConstantFP::get(CI->getType(), 1.0); + + if (Op2C->isExactlyValue(0.5)) { + // FIXME: This is not safe for -0.0 and -inf. This can only be done when + // 'unsafe' math optimizations are allowed. + // x pow(x, 0.5) sqrt(x) + // --------------------------------------------- + // -0.0 +0.0 -0.0 + // -inf +inf NaN +#if 0 + // pow(x, 0.5) -> sqrt(x) + return B.CreateCall(get_sqrt(), Op1, "sqrt"); +#endif + } + + if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x + return Op1; + if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x + return B.CreateMul(Op1, Op1, "pow2"); + if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x + return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), Op1, "powrecip"); + return 0; + } +}; + +//===---------------------------------------===// +// Double -> Float Shrinking Optimizations for Unary Functions like 'floor' + +struct VISIBILITY_HIDDEN UnaryDoubleFPOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 1 || FT->getReturnType() != Type::DoubleTy || + FT->getParamType(0) != Type::DoubleTy) + return 0; + + // If this is something like 'floor((double)floatval)', convert to floorf. + FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1)); + if (Cast == 0 || Cast->getOperand(0)->getType() != Type::FloatTy) + return 0; + + // floor((double)floatval) -> (double)floorf(floatval) + Value *V = Cast->getOperand(0); + V = EmitUnaryFloatFnCall(V, Callee->getNameStart(), B); + return B.CreateFPExt(V, Type::DoubleTy); + } +}; + +//===----------------------------------------------------------------------===// +// Integer Optimizations +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// 'ffs*' Optimizations + +struct VISIBILITY_HIDDEN FFSOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 2 arguments of the same FP type, which match the + // result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != Type::Int32Ty || + !isa<IntegerType>(FT->getParamType(0))) + return 0; + + Value *Op = CI->getOperand(1); + + // Constant fold. + if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) { + if (CI->getValue() == 0) // ffs(0) -> 0. + return Constant::getNullValue(CI->getType()); + return ConstantInt::get(Type::Int32Ty, // ffs(c) -> cttz(c)+1 + CI->getValue().countTrailingZeros()+1); + } + + // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0 + const Type *ArgType = Op->getType(); + Value *F = Intrinsic::getDeclaration(Callee->getParent(), + Intrinsic::cttz, &ArgType, 1); + Value *V = B.CreateCall(F, Op, "cttz"); + V = B.CreateAdd(V, ConstantInt::get(Type::Int32Ty, 1), "tmp"); + V = B.CreateIntCast(V, Type::Int32Ty, false, "tmp"); + + Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp"); + return B.CreateSelect(Cond, V, ConstantInt::get(Type::Int32Ty, 0)); + } +}; + +//===---------------------------------------===// +// 'isdigit' Optimizations + +struct VISIBILITY_HIDDEN IsDigitOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + // We require integer(i32) + if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) || + FT->getParamType(0) != Type::Int32Ty) + return 0; + + // isdigit(c) -> (c-'0') <u 10 + Value *Op = CI->getOperand(1); + Op = B.CreateSub(Op, ConstantInt::get(Type::Int32Ty, '0'), "isdigittmp"); + Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 10), "isdigit"); + return B.CreateZExt(Op, CI->getType()); + } +}; + +//===---------------------------------------===// +// 'isascii' Optimizations + +struct VISIBILITY_HIDDEN IsAsciiOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + // We require integer(i32) + if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) || + FT->getParamType(0) != Type::Int32Ty) + return 0; + + // isascii(c) -> c <u 128 + Value *Op = CI->getOperand(1); + Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 128), "isascii"); + return B.CreateZExt(Op, CI->getType()); + } +}; + +//===---------------------------------------===// +// 'toascii' Optimizations + +struct VISIBILITY_HIDDEN ToAsciiOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + const FunctionType *FT = Callee->getFunctionType(); + // We require i32(i32) + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != Type::Int32Ty) + return 0; + + // isascii(c) -> c & 0x7f + return B.CreateAnd(CI->getOperand(1), ConstantInt::get(CI->getType(),0x7F)); + } +}; + +//===----------------------------------------------------------------------===// +// Formatting and IO Optimizations +//===----------------------------------------------------------------------===// + +//===---------------------------------------===// +// 'printf' Optimizations + +struct VISIBILITY_HIDDEN PrintFOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Require one fixed pointer argument and an integer/void result. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() < 1 || !isa<PointerType>(FT->getParamType(0)) || + !(isa<IntegerType>(FT->getReturnType()) || + FT->getReturnType() == Type::VoidTy)) + return 0; + + // Check for a fixed format string. + std::string FormatStr; + if (!GetConstantStringInfo(CI->getOperand(1), FormatStr)) + return false; + + // Empty format string -> noop. + if (FormatStr.empty()) // Tolerate printf's declared void. + return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 0); + + // printf("x") -> putchar('x'), even for '%'. + if (FormatStr.size() == 1) { + EmitPutChar(ConstantInt::get(Type::Int32Ty, FormatStr[0]), B); + return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1); + } + + // printf("foo\n") --> puts("foo") + if (FormatStr[FormatStr.size()-1] == '\n' && + FormatStr.find('%') == std::string::npos) { // no format characters. + // 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 *C = ConstantArray::get(FormatStr, true); + C = new GlobalVariable(C->getType(), true,GlobalVariable::InternalLinkage, + C, "str", Callee->getParent()); + EmitPutS(C, B); + return CI->use_empty() ? (Value*)CI : + ConstantInt::get(CI->getType(), FormatStr.size()+1); + } + + // Optimize specific format strings. + // printf("%c", chr) --> putchar(*(i8*)dst) + if (FormatStr == "%c" && CI->getNumOperands() > 2 && + isa<IntegerType>(CI->getOperand(2)->getType())) { + EmitPutChar(CI->getOperand(2), B); + return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1); + } + + // printf("%s\n", str) --> puts(str) + if (FormatStr == "%s\n" && CI->getNumOperands() > 2 && + isa<PointerType>(CI->getOperand(2)->getType()) && + CI->use_empty()) { + EmitPutS(CI->getOperand(2), B); + return CI; + } + return 0; + } +}; + +//===---------------------------------------===// +// 'sprintf' Optimizations + +struct VISIBILITY_HIDDEN SPrintFOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Require two fixed pointer arguments and an integer result. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) || + !isa<PointerType>(FT->getParamType(1)) || + !isa<IntegerType>(FT->getReturnType())) + return 0; + + // Check for a fixed format string. + std::string FormatStr; + if (!GetConstantStringInfo(CI->getOperand(2), FormatStr)) + return false; + + // If we just have a format string (nothing else crazy) transform it. + if (CI->getNumOperands() == 3) { + // Make sure there's no % in the constant array. We could try to handle + // %% -> % in the future if we cared. + for (unsigned i = 0, e = FormatStr.size(); i != e; ++i) + if (FormatStr[i] == '%') + return 0; // we found a format specifier, bail out. + + // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1) + EmitMemCpy(CI->getOperand(1), CI->getOperand(2), // Copy the nul byte. + ConstantInt::get(TD->getIntPtrType(), FormatStr.size()+1),1,B); + return ConstantInt::get(CI->getType(), FormatStr.size()); + } + + // The remaining optimizations require the format string to be "%s" or "%c" + // and have an extra operand. + if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4) + return 0; + + // Decode the second character of the format string. + if (FormatStr[1] == 'c') { + // sprintf(dst, "%c", chr) --> *(i8*)dst = chr + if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0; + Value *V = B.CreateTrunc(CI->getOperand(3), Type::Int8Ty, "char"); + B.CreateStore(V, CastToCStr(CI->getOperand(1), B)); + return ConstantInt::get(CI->getType(), 1); + } + + if (FormatStr[1] == 's') { + // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1) + if (!isa<PointerType>(CI->getOperand(3)->getType())) return 0; + + Value *Len = EmitStrLen(CI->getOperand(3), B); + Value *IncLen = B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), + "leninc"); + EmitMemCpy(CI->getOperand(1), CI->getOperand(3), IncLen, 1, B); + + // The sprintf result is the unincremented number of bytes in the string. + return B.CreateIntCast(Len, CI->getType(), false); + } + return 0; + } +}; + +//===---------------------------------------===// +// 'fwrite' Optimizations + +struct VISIBILITY_HIDDEN FWriteOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Require a pointer, an integer, an integer, a pointer, returning integer. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 4 || !isa<PointerType>(FT->getParamType(0)) || + !isa<IntegerType>(FT->getParamType(1)) || + !isa<IntegerType>(FT->getParamType(2)) || + !isa<PointerType>(FT->getParamType(3)) || + !isa<IntegerType>(FT->getReturnType())) + return 0; + + // Get the element size and count. + ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getOperand(2)); + ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getOperand(3)); + if (!SizeC || !CountC) return 0; + uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue(); + + // If this is writing zero records, remove the call (it's a noop). + if (Bytes == 0) + return ConstantInt::get(CI->getType(), 0); + + // If this is writing one byte, turn it into fputc. + if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F) + Value *Char = B.CreateLoad(CastToCStr(CI->getOperand(1), B), "char"); + EmitFPutC(Char, CI->getOperand(4), B); + return ConstantInt::get(CI->getType(), 1); + } + + return 0; + } +}; + +//===---------------------------------------===// +// 'fputs' Optimizations + +struct VISIBILITY_HIDDEN FPutsOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Require two pointers. Also, we can't optimize if return value is used. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) || + !isa<PointerType>(FT->getParamType(1)) || + !CI->use_empty()) + return 0; + + // fputs(s,F) --> fwrite(s,1,strlen(s),F) + uint64_t Len = GetStringLength(CI->getOperand(1)); + if (!Len) return false; + EmitFWrite(CI->getOperand(1), ConstantInt::get(TD->getIntPtrType(), Len-1), + CI->getOperand(2), B); + return CI; // Known to have no uses (see above). + } +}; + +//===---------------------------------------===// +// 'fprintf' Optimizations + +struct VISIBILITY_HIDDEN FPrintFOpt : public LibCallOptimization { + virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) { + // Require two fixed paramters as pointers and integer result. + const FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) || + !isa<PointerType>(FT->getParamType(1)) || + !isa<IntegerType>(FT->getReturnType())) + return 0; + + // All the optimizations depend on the format string. + std::string FormatStr; + if (!GetConstantStringInfo(CI->getOperand(2), FormatStr)) + return false; + + // fprintf(F, "foo") --> fwrite("foo", 3, 1, F) + if (CI->getNumOperands() == 3) { + for (unsigned i = 0, e = FormatStr.size(); i != e; ++i) + if (FormatStr[i] == '%') // Could handle %% -> % if we cared. + return false; // We found a format specifier. + + EmitFWrite(CI->getOperand(2), ConstantInt::get(TD->getIntPtrType(), + FormatStr.size()), + CI->getOperand(1), B); + return ConstantInt::get(CI->getType(), FormatStr.size()); + } + + // The remaining optimizations require the format string to be "%s" or "%c" + // and have an extra operand. + if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4) + return 0; + + // Decode the second character of the format string. + if (FormatStr[1] == 'c') { + // fprintf(F, "%c", chr) --> *(i8*)dst = chr + if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0; + EmitFPutC(CI->getOperand(3), CI->getOperand(1), B); + return ConstantInt::get(CI->getType(), 1); + } + + if (FormatStr[1] == 's') { + // fprintf(F, "%s", str) -> fputs(str, F) + if (!isa<PointerType>(CI->getOperand(3)->getType()) || !CI->use_empty()) + return 0; + EmitFPutS(CI->getOperand(3), CI->getOperand(1), B); + return CI; + } + return 0; + } +}; + + +//===----------------------------------------------------------------------===// +// SimplifyLibCalls Pass Implementation +//===----------------------------------------------------------------------===// + +namespace { + /// This pass optimizes well known library functions from libc and libm. + /// + class VISIBILITY_HIDDEN SimplifyLibCalls : public FunctionPass { + StringMap<LibCallOptimization*> Optimizations; + // Miscellaneous LibCall Optimizations + ExitOpt Exit; + // String and Memory LibCall Optimizations + StrCatOpt StrCat; StrChrOpt StrChr; StrCmpOpt StrCmp; StrNCmpOpt StrNCmp; + StrCpyOpt StrCpy; StrLenOpt StrLen; MemCmpOpt MemCmp; MemCpyOpt MemCpy; + // Math Library Optimizations + PowOpt Pow; UnaryDoubleFPOpt UnaryDoubleFP; + // Integer Optimizations + FFSOpt FFS; IsDigitOpt IsDigit; IsAsciiOpt IsAscii; ToAsciiOpt ToAscii; + // Formatting and IO Optimizations + SPrintFOpt SPrintF; PrintFOpt PrintF; + FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF; + public: + static char ID; // Pass identification + SimplifyLibCalls() : FunctionPass((intptr_t)&ID) {} + + void InitOptimizations(); + bool runOnFunction(Function &F); + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired<TargetData>(); + } + }; + char SimplifyLibCalls::ID = 0; +} // end anonymous namespace. + +static RegisterPass<SimplifyLibCalls> +X("simplify-libcalls", "Simplify well-known library calls"); + +// Public interface to the Simplify LibCalls pass. +FunctionPass *llvm::createSimplifyLibCallsPass() { + return new SimplifyLibCalls(); +} + +/// Optimizations - Populate the Optimizations map with all the optimizations +/// we know. +void SimplifyLibCalls::InitOptimizations() { + // Miscellaneous LibCall Optimizations + Optimizations["exit"] = &Exit; + + // String and Memory LibCall Optimizations + Optimizations["strcat"] = &StrCat; + Optimizations["strchr"] = &StrChr; + Optimizations["strcmp"] = &StrCmp; + Optimizations["strncmp"] = &StrNCmp; + Optimizations["strcpy"] = &StrCpy; + Optimizations["strlen"] = &StrLen; + Optimizations["memcmp"] = &MemCmp; + Optimizations["memcpy"] = &MemCpy; + + // Math Library Optimizations + Optimizations["powf"] = &Pow; + Optimizations["pow"] = &Pow; + Optimizations["powl"] = &Pow; +#ifdef HAVE_FLOORF + Optimizations["floor"] = &UnaryDoubleFP; +#endif +#ifdef HAVE_CEILF + Optimizations["ceil"] = &UnaryDoubleFP; +#endif +#ifdef HAVE_ROUNDF + Optimizations["round"] = &UnaryDoubleFP; +#endif +#ifdef HAVE_RINTF + Optimizations["rint"] = &UnaryDoubleFP; +#endif +#ifdef HAVE_NEARBYINTF + Optimizations["nearbyint"] = &UnaryDoubleFP; +#endif + + // Integer Optimizations + Optimizations["ffs"] = &FFS; + Optimizations["ffsl"] = &FFS; + Optimizations["ffsll"] = &FFS; + Optimizations["isdigit"] = &IsDigit; + Optimizations["isascii"] = &IsAscii; + Optimizations["toascii"] = &ToAscii; + + // Formatting and IO Optimizations + Optimizations["sprintf"] = &SPrintF; + Optimizations["printf"] = &PrintF; + Optimizations["fwrite"] = &FWrite; + Optimizations["fputs"] = &FPuts; + Optimizations["fprintf"] = &FPrintF; +} + + +/// runOnFunction - Top level algorithm. +/// +bool SimplifyLibCalls::runOnFunction(Function &F) { + if (Optimizations.empty()) + InitOptimizations(); + + const TargetData &TD = getAnalysis<TargetData>(); + + IRBuilder Builder; + + bool Changed = false; + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { + // Ignore non-calls. + CallInst *CI = dyn_cast<CallInst>(I++); + if (!CI) continue; + + // Ignore indirect calls and calls to non-external functions. + Function *Callee = CI->getCalledFunction(); + if (Callee == 0 || !Callee->isDeclaration() || + !(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage())) + continue; + + // Ignore unknown calls. + const char *CalleeName = Callee->getNameStart(); + StringMap<LibCallOptimization*>::iterator OMI = + Optimizations.find(CalleeName, CalleeName+Callee->getNameLen()); + if (OMI == Optimizations.end()) continue; + + // Set the builder to the instruction after the call. + Builder.SetInsertPoint(BB, I); + + // Try to optimize this call. + Value *Result = OMI->second->OptimizeCall(CI, TD, Builder); + if (Result == 0) continue; + + // Something changed! + Changed = true; + ++NumSimplified; + + // Inspect the instruction after the call (which was potentially just + // added) next. + I = CI; ++I; + + if (CI != Result && !CI->use_empty()) { + CI->replaceAllUsesWith(Result); + if (!Result->hasName()) + Result->takeName(CI); + } + CI->eraseFromParent(); + } + } + return Changed; +} + + +// 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' +// +// |