-//===- SimplifyLibCalls.cpp - Optimize specific well-known librayr calls --===//
+//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
//
// The LLVM Compiler Infrastructure
//
-// This file was developed by Reid Spencer group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file was developed by Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
-// This file implements a variety of small optimizations for calls to specific
-// well-known (e.g. runtime library) function calls. For example, a call to the
-// function "exit(3)" that occurs within the main() function can be transformed
-// into a simple "return 3" instruction. Many of the ideas for these
-// optimizations were taken from GCC's "builtins.c" file but their
-// implementation here is completely knew and LLVM-centric
+// 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.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/IPO.h"
+#define DEBUG_TYPE "simplify-libcalls"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
-#include "llvm/Instructions.h"
+#include "llvm/ADT/hash_map"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Config/config.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/IPO.h"
using namespace llvm;
namespace {
- Statistic<> SimplifiedLibCalls("simplified-lib-calls",
- "Number of well-known library calls simplified");
- /// This class is the base class for a set of small but important
- /// optimizations of calls to well-known functions, such as those in the c
- /// library. This class provides the basic infrastructure for handling
- /// runOnModule. Subclasses register themselves and provide two methods:
- /// RecognizeCall and OptimizeCall. Whenever this class finds a function call,
- /// it asks the subclasses to recognize the call. If it is recognized, then
- /// the OptimizeCall method is called on that subclass instance. In this way
- /// the subclasses implement the calling conditions on which they trigger and
- /// the action to perform, making it easy to add new optimizations of this
- /// form.
- /// @brief A ModulePass for optimizing well-known function calls
- struct SimplifyLibCalls : public ModulePass {
+/// This statistic keeps track of the total number of library calls that have
+/// been simplified regardless of which call it is.
+Statistic<> SimplifiedLibCalls("simplify-libcalls",
+ "Number of library calls simplified");
+// Forward declarations
+class LibCallOptimization;
+class SimplifyLibCalls;
- /// For this pass, process all of the function calls in the module, calling
- /// RecognizeCall and OptimizeCall as appropriate.
- virtual bool runOnModule(Module &M);
+/// 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 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("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; }
- RegisterOpt<SimplifyLibCalls>
- X("simplify-libcalls","Simplify well-known library calls");
+ /// @brief Deregister from the optlist
+ virtual ~LibCallOptimization() {
+ *Prev = Next;
+ if (Next) Next->Prev = Prev;
+ }
- struct CallOptimizer
- {
- /// @brief Constructor that registers the optimization
- CallOptimizer();
-
- virtual ~CallOptimizer();
-
- /// 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.
- /// @param ci the call instruction under consideration
- /// @param f the function that ci calls.
- /// @brief Optimize a call, if possible.
- virtual bool OptimizeCall(CallInst* ci, const Function* f) const = 0;
- };
-
- /// @brief The list of optimizations deriving from CallOptimizer
- std::vector<struct CallOptimizer*> optlist;
-
- CallOptimizer::CallOptimizer()
- {
- // Register this call optimizer
- optlist.push_back(this);
+ /// 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; }
+
+ /// @brief Called by SimplifyLibCalls to update the occurrences statistic.
+ void succeeded() {
+#ifndef NDEBUG
+ DEBUG(++occurrences);
+#endif
}
+};
- /// Make sure we get our virtual table in this file.
- CallOptimizer::~CallOptimizer() {}
-}
+/// 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 SimplifyLibCalls : public ModulePass {
+public:
+ /// 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>();
+ }
-ModulePass *llvm::createSimplifyLibCallsPass()
-{
- return new SimplifyLibCalls();
-}
+ /// 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 SimplifyLibCalls::runOnModule(Module &M)
-{
- for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI)
- {
- // All the "well-known" functions are external because they live in a
- // runtime library somewhere and were (probably) not compiled by LLVM.
- // So, we only act on external functions that have non-empty uses.
- if (FI->isExternal() && !FI->use_empty())
- {
- // Loop over each of the uses of the function
- for (Value::use_iterator UI = FI->use_begin(), UE = FI->use_end();
- UI != UE ; )
- {
- CallInst* CI = dyn_cast<CallInst>(*UI);
- ++UI;
+ bool result = false;
+ hash_map<std::string, LibCallOptimization*> OptznMap;
+ for (LibCallOptimization *Optzn = OptList; Optzn; Optzn = Optzn->getNext())
+ OptznMap[Optzn->getFunctionName()] = Optzn;
- // If the use of the function is a call instruction
- if (CI)
- {
- // Loop over each of the registered optimizations and find the one
- // that can optimize this call.
- std::vector<CallOptimizer*>::iterator OI = optlist.begin();
- std::vector<CallOptimizer*>::iterator OE = optlist.end();
- for ( ; OI != OE ; ++OI)
- {
- if ((*OI)->OptimizeCall(CI,&(*FI)))
- {
+ // 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->isExternal() ||
+ !(FI->hasExternalLinkage() || FI->hasDLLImportLinkage()) ||
+ FI->use_empty())
+ continue;
+
+ // Get the optimization class that pertains to this function
+ hash_map<std::string, LibCallOptimization*>::iterator OMI =
+ OptznMap.find(FI->getName());
+ if (OMI == OptznMap.end()) continue;
+
+ LibCallOptimization *CO = OMI->second;
+
+ // Make sure the called function is suitable for the optimization
+ if (!CO->ValidateCalledFunction(FI, *this))
+ continue;
+
+ // Loop over each of the uses of the function
+ for (Value::use_iterator UI = FI->use_begin(), UE = FI->use_end();
+ UI != UE ; ) {
+ // If the use of the function is a call instruction
+ if (CallInst* CI = dyn_cast<CallInst>(*UI++)) {
+ // Do the optimization on the LibCallOptimization.
+ if (CO->OptimizeCall(CI, *this)) {
++SimplifiedLibCalls;
- break;
+ 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
+ Function* get_putchar() {
+ if (!putchar_func)
+ putchar_func = M->getOrInsertFunction("putchar", Type::IntTy, Type::IntTy,
+ NULL);
+ return putchar_func;
+ }
+
+ /// @brief Return a Function* for the puts libcall
+ Function* get_puts() {
+ if (!puts_func)
+ puts_func = M->getOrInsertFunction("puts", Type::IntTy,
+ PointerType::get(Type::SByteTy),
+ NULL);
+ return puts_func;
+ }
+
+ /// @brief Return a Function* for the fputc libcall
+ Function* get_fputc(const Type* FILEptr_type) {
+ if (!fputc_func)
+ fputc_func = M->getOrInsertFunction("fputc", Type::IntTy, Type::IntTy,
+ FILEptr_type, NULL);
+ return fputc_func;
+ }
+
+ /// @brief Return a Function* for the fputs libcall
+ Function* get_fputs(const Type* FILEptr_type) {
+ if (!fputs_func)
+ fputs_func = M->getOrInsertFunction("fputs", Type::IntTy,
+ PointerType::get(Type::SByteTy),
+ FILEptr_type, NULL);
+ return fputs_func;
+ }
+
+ /// @brief Return a Function* for the fwrite libcall
+ Function* get_fwrite(const Type* FILEptr_type) {
+ if (!fwrite_func)
+ fwrite_func = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
+ PointerType::get(Type::SByteTy),
+ TD->getIntPtrType(),
+ TD->getIntPtrType(),
+ FILEptr_type, NULL);
+ return fwrite_func;
+ }
+
+ /// @brief Return a Function* for the sqrt libcall
+ Function* get_sqrt() {
+ if (!sqrt_func)
+ sqrt_func = M->getOrInsertFunction("sqrt", Type::DoubleTy,
+ Type::DoubleTy, NULL);
+ return sqrt_func;
+ }
+
+ /// @brief Return a Function* for the strlen libcall
+ Function* get_strcpy() {
+ if (!strcpy_func)
+ strcpy_func = M->getOrInsertFunction("strcpy",
+ PointerType::get(Type::SByteTy),
+ PointerType::get(Type::SByteTy),
+ PointerType::get(Type::SByteTy),
+ NULL);
+ return strcpy_func;
+ }
+
+ /// @brief Return a Function* for the strlen libcall
+ Function* get_strlen() {
+ if (!strlen_func)
+ strlen_func = M->getOrInsertFunction("strlen", TD->getIntPtrType(),
+ PointerType::get(Type::SByteTy),
+ NULL);
+ return strlen_func;
+ }
+
+ /// @brief Return a Function* for the memchr libcall
+ Function* get_memchr() {
+ if (!memchr_func)
+ memchr_func = M->getOrInsertFunction("memchr",
+ PointerType::get(Type::SByteTy),
+ PointerType::get(Type::SByteTy),
+ Type::IntTy, TD->getIntPtrType(),
+ NULL);
+ return memchr_func;
+ }
+
+ /// @brief Return a Function* for the memcpy libcall
+ Function* get_memcpy() {
+ if (!memcpy_func) {
+ const Type *SBP = PointerType::get(Type::SByteTy);
+ const char *N = TD->getIntPtrType() == Type::UIntTy ?
+ "llvm.memcpy.i32" : "llvm.memcpy.i64";
+ memcpy_func = M->getOrInsertFunction(N, Type::VoidTy, SBP, SBP,
+ TD->getIntPtrType(), Type::UIntTy,
+ NULL);
}
+ return memcpy_func;
}
- return true;
+
+ Function *getUnaryFloatFunction(const char *Name, Function *&Cache) {
+ if (!Cache)
+ Cache = M->getOrInsertFunction(Name, Type::FloatTy, Type::FloatTy, NULL);
+ return Cache;
+ }
+
+ Function *get_floorf() { return getUnaryFloatFunction("floorf", floorf_func);}
+ Function *get_ceilf() { return getUnaryFloatFunction( "ceilf", ceilf_func);}
+ Function *get_roundf() { return getUnaryFloatFunction("roundf", roundf_func);}
+ Function *get_rintf() { return getUnaryFloatFunction( "rintf", rintf_func);}
+ Function *get_nearbyintf() { return getUnaryFloatFunction("nearbyintf",
+ nearbyintf_func); }
+private:
+ /// @brief Reset our cached data for a new Module
+ void reset(Module& mod) {
+ M = &mod;
+ TD = &getAnalysis<TargetData>();
+ putchar_func = 0;
+ puts_func = 0;
+ fputc_func = 0;
+ fputs_func = 0;
+ fwrite_func = 0;
+ memcpy_func = 0;
+ memchr_func = 0;
+ sqrt_func = 0;
+ strcpy_func = 0;
+ strlen_func = 0;
+ floorf_func = 0;
+ ceilf_func = 0;
+ roundf_func = 0;
+ rintf_func = 0;
+ nearbyintf_func = 0;
+ }
+
+private:
+ /// Caches for function pointers.
+ Function *putchar_func, *puts_func;
+ Function *fputc_func, *fputs_func, *fwrite_func;
+ Function *memcpy_func, *memchr_func;
+ Function* sqrt_func;
+ Function *strcpy_func, *strlen_func;
+ Function *floorf_func, *ceilf_func, *roundf_func;
+ Function *rintf_func, *nearbyintf_func;
+ Module *M; ///< Cached Module
+ TargetData *TD; ///< Cached TargetData
+};
+
+// Register the pass
+RegisterPass<SimplifyLibCalls>
+X("simplify-libcalls", "Simplify well-known library calls");
+
+} // anonymous namespace
+
+// The only public symbol in this file which just instantiates the pass object
+ModulePass *llvm::createSimplifyLibCallsPass() {
+ return new SimplifyLibCalls();
}
+// Classes below here, in the anonymous namespace, are all subclasses of the
+// LibCallOptimization class, each implementing all optimizations possible for a
+// single well-known library call. Each has a static singleton instance that
+// auto registers it into the "optlist" global above.
namespace {
-/// This CallOptimizer will find instances of a call to "exit" that occurs
+// Forward declare utility functions.
+bool getConstantStringLength(Value* V, uint64_t& len, ConstantArray** A = 0 );
+Value *CastToCStr(Value *V, Instruction &IP);
+
+/// This LibCallOptimization will find instances of a call to "exit" that occurs
/// within the "main" function and change it to a simple "ret" instruction with
-/// the same value as passed to the exit function. It assumes that the
-/// instructions after the call to exit(3) can be deleted since they are
-/// unreachable anyway.
+/// 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 ExitInMainOptimization : public CallOptimizer
-{
-virtual ~ExitInMainOptimization() {}
-bool OptimizeCall(CallInst* ci, const Function* func) const
-{
- // If this isn't the exit function then we don't act
- if (func->getName() != "exit")
+struct ExitInMainOptimization : public LibCallOptimization {
+ ExitInMainOptimization() : LibCallOptimization("exit",
+ "Number of 'exit' calls simplified") {}
+
+ // Make sure the called function looks like exit (int argument, int return
+ // type, external linkage, not varargs).
+ virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+ return F->arg_size() >= 1 && F->arg_begin()->getType()->isInteger();
+ }
+
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
+ // To be careful, we check that the call to exit is coming from "main", that
+ // main has external linkage, and the return type of main and the argument
+ // to exit have the same type.
+ Function *from = ci->getParent()->getParent();
+ if (from->hasExternalLinkage())
+ if (from->getReturnType() == ci->getOperand(1)->getType())
+ if (from->getName() == "main") {
+ // Okay, time to actually do the optimization. First, get the basic
+ // block of the call instruction
+ BasicBlock* bb = ci->getParent();
+
+ // Create a return instruction that we'll replace the call with.
+ // Note that the argument of the return is the argument of the call
+ // instruction.
+ new ReturnInst(ci->getOperand(1), ci);
+
+ // Split the block at the call instruction which places it in a new
+ // basic block.
+ bb->splitBasicBlock(ci);
+
+ // The block split caused a branch instruction to be inserted into
+ // the end of the original block, right after the return instruction
+ // that we put there. That's not a valid block, so delete the branch
+ // instruction.
+ bb->getInstList().pop_back();
+
+ // Now we can finally get rid of the call instruction which now lives
+ // in the new basic block.
+ ci->eraseFromParent();
+
+ // Optimization succeeded, return true.
+ return true;
+ }
+ // We didn't pass the criteria for this optimization so return false
return false;
+ }
+} ExitInMainOptimizer;
+
+/// This LibCallOptimization will simplify a call to the strcat library
+/// function. The simplification is possible only if the string being
+/// concatenated is a constant array or a constant expression that results in
+/// a constant string. In this case we can replace it with strlen + llvm.memcpy
+/// of the constant string. Both of these calls are further reduced, if possible
+/// on subsequent passes.
+/// @brief Simplify the strcat library function.
+struct StrCatOptimization : public LibCallOptimization {
+public:
+ /// @brief Default constructor
+ StrCatOptimization() : LibCallOptimization("strcat",
+ "Number of 'strcat' calls simplified") {}
+
+public:
- // If the call isn't coming from main then we don't act
- if (const Function* f = ci->getParent()->getParent())
- if (f->getName() != "main")
+ /// @brief Make sure that the "strcat" function has the right prototype
+ virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
+ if (f->getReturnType() == PointerType::get(Type::SByteTy))
+ if (f->arg_size() == 2)
+ {
+ Function::const_arg_iterator AI = f->arg_begin();
+ if (AI++->getType() == PointerType::get(Type::SByteTy))
+ if (AI->getType() == PointerType::get(Type::SByteTy))
+ {
+ // Indicate this is a suitable call type.
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /// @brief Optimize the strcat library function
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
+ // Extract some information from the instruction
+ Value* dest = ci->getOperand(1);
+ Value* src = ci->getOperand(2);
+
+ // Extract the initializer (while making numerous checks) from the
+ // source operand of the call to strcat. If we get null back, one of
+ // a variety of checks in get_GVInitializer failed
+ uint64_t len = 0;
+ if (!getConstantStringLength(src,len))
return false;
- // Okay, time to replace it. Get the basic block of the call instruction
- BasicBlock* bb = ci->getParent();
+ // Handle the simple, do-nothing case
+ if (len == 0) {
+ ci->replaceAllUsesWith(dest);
+ ci->eraseFromParent();
+ return true;
+ }
- // 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* ri = new ReturnInst(ci->getOperand(1), ci);
+ // Increment the length because we actually want to memcpy the null
+ // terminator as well.
+ len++;
- // Erase everything from the call instruction to the end of the block. There
- // really shouldn't be anything other than the call instruction, but just in
- // case there is we delete it all because its now dead.
- bb->getInstList().erase(ci, bb->end());
+ // 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 (further
+ // optimized in another pass). Note that the SLC.get_strlen() call
+ // caches the Function* for us.
+ CallInst* strlen_inst =
+ new CallInst(SLC.get_strlen(), dest, dest->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).
+ std::vector<Value*> idx;
+ idx.push_back(strlen_inst);
+ GetElementPtrInst* gep =
+ new GetElementPtrInst(dest,idx,dest->getName()+".indexed",ci);
+
+ // We have enough information to now generate the memcpy call to
+ // do the concatenation for us.
+ std::vector<Value*> vals;
+ vals.push_back(gep); // destination
+ vals.push_back(ci->getOperand(2)); // source
+ vals.push_back(ConstantUInt::get(SLC.getIntPtrType(),len)); // length
+ vals.push_back(ConstantUInt::get(Type::UIntTy,1)); // alignment
+ new CallInst(SLC.get_memcpy(), vals, "", ci);
+
+ // Finally, substitute the first operand of the strcat call for the
+ // strcat call itself since strcat returns its first operand; and,
+ // kill the strcat CallInst.
+ ci->replaceAllUsesWith(dest);
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 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){
+ if (f->getReturnType() == PointerType::get(Type::SByteTy) &&
+ f->arg_size() == 2)
+ return true;
+ return false;
+ }
+
+ /// @brief Perform the strchr optimizations
+ virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
+ // If there aren't three operands, bail
+ if (ci->getNumOperands() != 3)
+ return false;
+
+ // Check that the first argument to strchr is a constant array of sbyte.
+ // If it is, get the length and data, otherwise return false.
+ uint64_t len = 0;
+ ConstantArray* CA;
+ if (!getConstantStringLength(ci->getOperand(1),len,&CA))
+ return false;
+
+ // Check that the second argument to strchr is a constant int, return false
+ // if it isn't
+ ConstantSInt* CSI = dyn_cast<ConstantSInt>(ci->getOperand(2));
+ if (!CSI) {
+ // Just lower this to memchr since we know the length of the string as
+ // it is constant.
+ Function* f = SLC.get_memchr();
+ std::vector<Value*> args;
+ args.push_back(ci->getOperand(1));
+ args.push_back(ci->getOperand(2));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),len));
+ ci->replaceAllUsesWith( new CallInst(f,args,ci->getName(),ci));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // Get the character we're looking for
+ int64_t chr = CSI->getValue();
+
+ // Compute the offset
+ uint64_t offset = 0;
+ bool char_found = false;
+ for (uint64_t i = 0; i < len; ++i) {
+ if (ConstantSInt* CI = dyn_cast<ConstantSInt>(CA->getOperand(i))) {
+ // Check for the null terminator
+ if (CI->isNullValue())
+ break; // we found end of string
+ else if (CI->getValue() == chr) {
+ char_found = true;
+ offset = i;
+ break;
+ }
+ }
+ }
+
+ // strchr(s,c) -> offset_of_in(c,s)
+ // (if c is a constant integer and s is a constant string)
+ if (char_found) {
+ std::vector<Value*> indices;
+ indices.push_back(ConstantUInt::get(Type::ULongTy,offset));
+ GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1),indices,
+ ci->getOperand(1)->getName()+".strchr",ci);
+ ci->replaceAllUsesWith(GEP);
+ } else {
+ ci->replaceAllUsesWith(
+ ConstantPointerNull::get(PointerType::get(Type::SByteTy)));
+ }
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 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){
+ return F->getReturnType() == Type::IntTy && F->arg_size() == 2;
+ }
+ /// @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* s1 = ci->getOperand(1);
+ Value* s2 = ci->getOperand(2);
+ if (s1 == s2) {
+ // strcmp(x,x) -> 0
+ ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ bool isstr_1 = false;
+ uint64_t len_1 = 0;
+ ConstantArray* A1;
+ if (getConstantStringLength(s1,len_1,&A1)) {
+ isstr_1 = true;
+ if (len_1 == 0) {
+ // strcmp("",x) -> *x
+ LoadInst* load =
+ new LoadInst(CastToCStr(s2,*ci), ci->getName()+".load",ci);
+ CastInst* cast =
+ new CastInst(load,Type::IntTy,ci->getName()+".int",ci);
+ ci->replaceAllUsesWith(cast);
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ bool isstr_2 = false;
+ uint64_t len_2 = 0;
+ ConstantArray* A2;
+ if (getConstantStringLength(s2, len_2, &A2)) {
+ isstr_2 = true;
+ if (len_2 == 0) {
+ // strcmp(x,"") -> *x
+ LoadInst* load =
+ new LoadInst(CastToCStr(s1,*ci),ci->getName()+".val",ci);
+ CastInst* cast =
+ new CastInst(load,Type::IntTy,ci->getName()+".int",ci);
+ ci->replaceAllUsesWith(cast);
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ if (isstr_1 && isstr_2) {
+ // strcmp(x,y) -> cnst (if both x and y are constant strings)
+ std::string str1 = A1->getAsString();
+ std::string str2 = A2->getAsString();
+ int result = strcmp(str1.c_str(), str2.c_str());
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,result));
+ ci->eraseFromParent();
+ return true;
+ }
+ return false;
+ }
+} 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 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){
+ if (f->getReturnType() == Type::IntTy && f->arg_size() == 3)
+ return true;
+ return false;
+ }
+
+ /// @brief Perform the strncpy 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* s1 = ci->getOperand(1);
+ Value* s2 = ci->getOperand(2);
+ if (s1 == s2) {
+ // strncmp(x,x,l) -> 0
+ ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // Check the length argument, if it is Constant zero then the strings are
+ // considered equal.
+ uint64_t len_arg = 0;
+ bool len_arg_is_const = false;
+ if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
+ len_arg_is_const = true;
+ len_arg = len_CI->getRawValue();
+ if (len_arg == 0) {
+ // strncmp(x,y,0) -> 0
+ ci->replaceAllUsesWith(ConstantInt::get(Type::IntTy,0));
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ bool isstr_1 = false;
+ uint64_t len_1 = 0;
+ ConstantArray* A1;
+ if (getConstantStringLength(s1, len_1, &A1)) {
+ isstr_1 = true;
+ if (len_1 == 0) {
+ // strncmp("",x) -> *x
+ LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
+ CastInst* cast =
+ new CastInst(load,Type::IntTy,ci->getName()+".int",ci);
+ ci->replaceAllUsesWith(cast);
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ bool isstr_2 = false;
+ uint64_t len_2 = 0;
+ ConstantArray* A2;
+ if (getConstantStringLength(s2,len_2,&A2)) {
+ isstr_2 = true;
+ if (len_2 == 0) {
+ // strncmp(x,"") -> *x
+ LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
+ CastInst* cast =
+ new CastInst(load,Type::IntTy,ci->getName()+".int",ci);
+ ci->replaceAllUsesWith(cast);
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ if (isstr_1 && isstr_2 && len_arg_is_const) {
+ // strncmp(x,y,const) -> constant
+ std::string str1 = A1->getAsString();
+ std::string str2 = A2->getAsString();
+ int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,result));
+ ci->eraseFromParent();
+ return true;
+ }
+ return false;
+ }
+} 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 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){
+ if (f->getReturnType() == PointerType::get(Type::SByteTy))
+ if (f->arg_size() == 2) {
+ Function::const_arg_iterator AI = f->arg_begin();
+ if (AI++->getType() == PointerType::get(Type::SByteTy))
+ if (AI->getType() == PointerType::get(Type::SByteTy)) {
+ // Indicate this is a suitable call type.
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /// @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* dest = ci->getOperand(1);
+ Value* src = ci->getOperand(2);
+ if (dest == src) {
+ ci->replaceAllUsesWith(dest);
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // Get the length of the constant string referenced by the second operand,
+ // the "src" parameter. Fail the optimization if we can't get the length
+ // (note that getConstantStringLength does lots of checks to make sure this
+ // is valid).
+ uint64_t len = 0;
+ if (!getConstantStringLength(ci->getOperand(2),len))
+ return false;
+
+ // If the constant string's length is zero we can optimize this by just
+ // doing a store of 0 at the first byte of the destination
+ if (len == 0) {
+ new StoreInst(ConstantInt::get(Type::SByteTy,0),ci->getOperand(1),ci);
+ ci->replaceAllUsesWith(dest);
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // Increment the length because we actually want to memcpy the null
+ // terminator as well.
+ len++;
+
+ // We have enough information to now generate the memcpy call to
+ // do the concatenation for us.
+ std::vector<Value*> vals;
+ vals.push_back(dest); // destination
+ vals.push_back(src); // source
+ vals.push_back(ConstantUInt::get(SLC.getIntPtrType(),len)); // length
+ vals.push_back(ConstantUInt::get(Type::UIntTy,1)); // alignment
+ new CallInst(SLC.get_memcpy(), vals, "", ci);
+
+ // Finally, substitute the first operand of the strcat call for the
+ // strcat call itself since strcat returns its first operand; and,
+ // kill the strcat CallInst.
+ ci->replaceAllUsesWith(dest);
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 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)
+ {
+ if (f->getReturnType() == SLC.getTargetData()->getIntPtrType())
+ if (f->arg_size() == 1)
+ if (Function::const_arg_iterator AI = f->arg_begin())
+ if (AI->getType() == PointerType::get(Type::SByteTy))
+ return true;
+ return false;
+ }
+
+ /// @brief Perform the strlen optimization
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
+ {
+ // Make sure we're dealing with an sbyte* here.
+ Value* str = ci->getOperand(1);
+ if (str->getType() != PointerType::get(Type::SByteTy))
+ return false;
+
+ // Does the call to strlen have exactly one use?
+ if (ci->hasOneUse())
+ // Is that single use a binary operator?
+ if (BinaryOperator* bop = dyn_cast<BinaryOperator>(ci->use_back()))
+ // Is it compared against a constant integer?
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(bop->getOperand(1)))
+ {
+ // Get the value the strlen result is compared to
+ uint64_t val = CI->getRawValue();
+
+ // If its compared against length 0 with == or !=
+ if (val == 0 &&
+ (bop->getOpcode() == Instruction::SetEQ ||
+ bop->getOpcode() == Instruction::SetNE))
+ {
+ // strlen(x) != 0 -> *x != 0
+ // strlen(x) == 0 -> *x == 0
+ LoadInst* load = new LoadInst(str,str->getName()+".first",ci);
+ BinaryOperator* rbop = BinaryOperator::create(bop->getOpcode(),
+ load, ConstantSInt::get(Type::SByteTy,0),
+ bop->getName()+".strlen", ci);
+ bop->replaceAllUsesWith(rbop);
+ bop->eraseFromParent();
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+
+ // Get the length of the constant string operand
+ uint64_t len = 0;
+ if (!getConstantStringLength(ci->getOperand(1),len))
+ return false;
+
+ // strlen("xyz") -> 3 (for example)
+ const Type *Ty = SLC.getTargetData()->getIntPtrType();
+ if (Ty->isSigned())
+ ci->replaceAllUsesWith(ConstantSInt::get(Ty, len));
+ else
+ ci->replaceAllUsesWith(ConstantUInt::get(Ty, len));
+
+ ci->eraseFromParent();
+ return true;
+ }
+} 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) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (User->getOpcode() == Instruction::SetNE ||
+ User->getOpcode() == Instruction::SetEQ) {
+ if (isa<Constant>(User->getOperand(1)) &&
+ cast<Constant>(User->getOperand(1))->isNullValue())
+ continue;
+ } else if (CastInst *CI = dyn_cast<CastInst>(User))
+ if (CI->getType() == Type::BoolTy)
+ continue;
+ // Unknown instruction.
+ return false;
+ }
return true;
}
-} ExitInMainOptimizer;
+/// This memcmpOptimization will simplify a call to the memcmp library
+/// function.
+struct 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
+ CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+ CI->eraseFromParent();
+ return true;
+ }
+
+ // Make sure we have a constant length.
+ ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
+ if (!LenC) return false;
+ uint64_t Len = LenC->getRawValue();
+
+ // If the length is zero, this returns 0.
+ switch (Len) {
+ case 0:
+ // memcmp(s1,s2,0) -> 0
+ CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+ CI->eraseFromParent();
+ return true;
+ case 1: {
+ // memcmp(S1,S2,1) -> *(ubyte*)S1 - *(ubyte*)S2
+ const Type *UCharPtr = PointerType::get(Type::UByteTy);
+ CastInst *Op1Cast = new CastInst(LHS, UCharPtr, LHS->getName(), CI);
+ CastInst *Op2Cast = new CastInst(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 = new CastInst(RV, CI->getType(), RV->getName(), CI);
+ CI->replaceAllUsesWith(RV);
+ CI->eraseFromParent();
+ return true;
+ }
+ case 2:
+ if (IsOnlyUsedInEqualsZeroComparison(CI)) {
+ // TODO: IF both are aligned, use a short load/compare.
+
+ // memcmp(S1,S2,2) -> S1[0]-S2[0] | S1[1]-S2[1] iff only ==/!= 0 matters
+ const Type *UCharPtr = PointerType::get(Type::UByteTy);
+ CastInst *Op1Cast = new CastInst(LHS, UCharPtr, LHS->getName(), CI);
+ CastInst *Op2Cast = new CastInst(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::IntTy, 1);
+ Value *G1 = new GetElementPtrInst(Op1Cast, One, "next1v", CI);
+ Value *G2 = new GetElementPtrInst(Op2Cast, One, "next2v", CI);
+ Value *S1V2 = new LoadInst(G1, LHS->getName()+".val2", CI);
+ Value *S2V2 = new LoadInst(G2, RHS->getName()+".val2", CI);
+ Value *D2 = BinaryOperator::createSub(S1V2, S2V2,
+ CI->getName()+".d1", CI);
+ Value *Or = BinaryOperator::createOr(D1, D2, CI->getName()+".res", CI);
+ if (Or->getType() != CI->getType())
+ Or = new CastInst(Or, CI->getType(), Or->getName(), CI);
+ CI->replaceAllUsesWith(Or);
+ CI->eraseFromParent();
+ return true;
+ }
+ break;
+ default:
+ break;
+ }
+
+ return false;
+ }
+} memcmpOptimizer;
+
+
+/// This LibCallOptimization will simplify a call to the memcpy library
+/// function by expanding it out to a single store of size 0, 1, 2, 4, or 8
+/// bytes depending on the length of the string and the alignment. Additional
+/// optimizations are possible in code generation (sequence of immediate store)
+/// @brief Simplify the memcpy library function.
+struct 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->getRawValue();
+ uint64_t alignment = ALIGN->getRawValue();
+ 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);
+ Type* castType = 0;
+ switch (len)
+ {
+ case 0:
+ // memcpy(d,s,0,a) -> noop
+ ci->eraseFromParent();
+ return true;
+ case 1: castType = Type::SByteTy; break;
+ case 2: castType = Type::ShortTy; break;
+ case 4: castType = Type::IntTy; break;
+ case 8: castType = Type::LongTy; break;
+ default:
+ return false;
+ }
+
+ // Cast source and dest to the right sized primitive and then load/store
+ CastInst* SrcCast =
+ new CastInst(src,PointerType::get(castType),src->getName()+".cast",ci);
+ CastInst* DestCast =
+ new CastInst(dest,PointerType::get(castType),dest->getName()+".cast",ci);
+ LoadInst* LI = new LoadInst(SrcCast,SrcCast->getName()+".val",ci);
+ StoreInst* SI = new StoreInst(LI, DestCast, ci);
+ ci->eraseFromParent();
+ return true;
+ }
+};
+
+/// 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 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->getRawValue();
+ uint64_t alignment = ALIGN->getRawValue();
+
+ // 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
+ ci->eraseFromParent();
+ return true;
+ }
+ // 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.
+ ConstantUInt* FILL = dyn_cast<ConstantUInt>(ci->getOperand(2));
+ if (!FILL)
+ return false;
+ if (FILL->getType() != Type::UByteTy)
+ return false;
+
+ // memset(s,c,n) -> store s, c (for n=1,2,4,8)
+
+ // Extract the fill character
+ uint64_t fill_char = FILL->getValue();
+ 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);
+ Type* castType = 0;
+ switch (len) {
+ case 1:
+ castType = Type::UByteTy;
+ break;
+ case 2:
+ castType = Type::UShortTy;
+ fill_value |= fill_char << 8;
+ break;
+ case 4:
+ castType = Type::UIntTy;
+ fill_value |= fill_char << 8 | fill_char << 16 | fill_char << 24;
+ break;
+ case 8:
+ castType = Type::ULongTy;
+ 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 CastInst(dest,PointerType::get(castType),dest->getName()+".cast",ci);
+ new StoreInst(ConstantUInt::get(castType,fill_value),DestCast, ci);
+ ci->eraseFromParent();
+ return true;
+ }
+};
+
+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 PowOptimization : public LibCallOptimization {
+public:
+ /// @brief Default Constructor
+ PowOptimization() : LibCallOptimization("pow",
+ "Number of 'pow' calls simplified") {}
+
+ /// @brief Make sure that the "pow" function has the right prototype
+ virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
+ // Just make sure this has 2 arguments
+ return (f->arg_size() == 2);
+ }
+
+ /// @brief Perform the pow optimization.
+ virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
+ const Type *Ty = cast<Function>(ci->getOperand(0))->getReturnType();
+ Value* base = ci->getOperand(1);
+ Value* expn = ci->getOperand(2);
+ if (ConstantFP *Op1 = dyn_cast<ConstantFP>(base)) {
+ double Op1V = Op1->getValue();
+ if (Op1V == 1.0) {
+ // pow(1.0,x) -> 1.0
+ ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
+ ci->eraseFromParent();
+ return true;
+ }
+ } else if (ConstantFP* Op2 = dyn_cast<ConstantFP>(expn)) {
+ double Op2V = Op2->getValue();
+ if (Op2V == 0.0) {
+ // pow(x,0.0) -> 1.0
+ ci->replaceAllUsesWith(ConstantFP::get(Ty,1.0));
+ ci->eraseFromParent();
+ return true;
+ } else if (Op2V == 0.5) {
+ // pow(x,0.5) -> sqrt(x)
+ CallInst* sqrt_inst = new CallInst(SLC.get_sqrt(), base,
+ ci->getName()+".pow",ci);
+ ci->replaceAllUsesWith(sqrt_inst);
+ ci->eraseFromParent();
+ return true;
+ } else if (Op2V == 1.0) {
+ // pow(x,1.0) -> x
+ ci->replaceAllUsesWith(base);
+ ci->eraseFromParent();
+ return true;
+ } else if (Op2V == -1.0) {
+ // pow(x,-1.0) -> 1.0/x
+ BinaryOperator* div_inst= BinaryOperator::createDiv(
+ ConstantFP::get(Ty,1.0), base, ci->getName()+".pow", ci);
+ ci->replaceAllUsesWith(div_inst);
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+ return false; // opt failed
+ }
+} PowOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "printf" library
+/// function. It looks for cases where the result of printf is not used and the
+/// operation can be reduced to something simpler.
+/// @brief Simplify the printf library function.
+struct 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 arguments
+ return (f->arg_size() >= 1);
+ }
+
+ /// @brief Perform the printf optimization.
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
+ // If the call has more than 2 operands, we can't optimize it
+ if (ci->getNumOperands() > 3 || ci->getNumOperands() <= 2)
+ return false;
+
+ // If the result of the printf call is used, none of these optimizations
+ // can be made.
+ if (!ci->use_empty())
+ return false;
+
+ // All the optimizations depend on the length of the first argument and the
+ // fact that it is a constant string array. Check that now
+ uint64_t len = 0;
+ ConstantArray* CA = 0;
+ if (!getConstantStringLength(ci->getOperand(1), len, &CA))
+ return false;
+
+ if (len != 2 && len != 3)
+ return false;
+
+ // The first character has to be a %
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
+ if (CI->getRawValue() != '%')
+ return false;
+
+ // Get the second character and switch on its value
+ ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
+ switch (CI->getRawValue()) {
+ case 's':
+ {
+ if (len != 3 ||
+ dyn_cast<ConstantInt>(CA->getOperand(2))->getRawValue() != '\n')
+ return false;
+
+ // printf("%s\n",str) -> puts(str)
+ Function* puts_func = SLC.get_puts();
+ if (!puts_func)
+ return false;
+ std::vector<Value*> args;
+ args.push_back(CastToCStr(ci->getOperand(2), *ci));
+ new CallInst(puts_func,args,ci->getName(),ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,len));
+ break;
+ }
+ case 'c':
+ {
+ // printf("%c",c) -> putchar(c)
+ if (len != 2)
+ return false;
+
+ Function* putchar_func = SLC.get_putchar();
+ if (!putchar_func)
+ return false;
+ CastInst* cast = new CastInst(ci->getOperand(2), Type::IntTy,
+ CI->getName()+".int", ci);
+ new CallInst(putchar_func, cast, "", ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy, 1));
+ break;
+ }
+ default:
+ return false;
+ }
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 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){
+ // Just make sure this has at least 2 arguments
+ return (f->arg_size() >= 2);
+ }
+
+ /// @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() > 4 || ci->getNumOperands() <= 2)
+ return false;
+
+ // If the result of the fprintf call is used, none of these optimizations
+ // can be made.
+ if (!ci->use_empty())
+ return false;
+
+ // All the optimizations depend on the length of the second argument and the
+ // fact that it is a constant string array. Check that now
+ uint64_t len = 0;
+ ConstantArray* CA = 0;
+ if (!getConstantStringLength(ci->getOperand(2), len, &CA))
+ return false;
+
+ if (ci->getNumOperands() == 3) {
+ // Make sure there's no % in the constant array
+ for (unsigned i = 0; i < len; ++i) {
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
+ // Check for the null terminator
+ if (CI->getRawValue() == '%')
+ return false; // we found end of string
+ } else {
+ return false;
+ }
+ }
+
+ // fprintf(file,fmt) -> fwrite(fmt,strlen(fmt),file)
+ const Type* FILEptr_type = ci->getOperand(1)->getType();
+ Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
+ if (!fwrite_func)
+ return false;
+
+ // Make sure that the fprintf() and fwrite() functions both take the
+ // same type of char pointer.
+ if (ci->getOperand(2)->getType() !=
+ fwrite_func->getFunctionType()->getParamType(0))
+ return false;
+
+ std::vector<Value*> args;
+ args.push_back(ci->getOperand(2));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),len));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),1));
+ args.push_back(ci->getOperand(1));
+ new CallInst(fwrite_func,args,ci->getName(),ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,len));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // The remaining optimizations require the format string to be length 2
+ // "%s" or "%c".
+ if (len != 2)
+ return false;
+
+ // The first character has to be a %
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
+ if (CI->getRawValue() != '%')
+ return false;
+
+ // Get the second character and switch on its value
+ ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
+ switch (CI->getRawValue()) {
+ case 's':
+ {
+ uint64_t len = 0;
+ ConstantArray* CA = 0;
+ if (getConstantStringLength(ci->getOperand(3), len, &CA)) {
+ // fprintf(file,"%s",str) -> fwrite(str,strlen(str),1,file)
+ const Type* FILEptr_type = ci->getOperand(1)->getType();
+ Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
+ if (!fwrite_func)
+ return false;
+ std::vector<Value*> args;
+ args.push_back(CastToCStr(ci->getOperand(3), *ci));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),len));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),1));
+ args.push_back(ci->getOperand(1));
+ new CallInst(fwrite_func,args,ci->getName(),ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,len));
+ } else {
+ // fprintf(file,"%s",str) -> fputs(str,file)
+ const Type* FILEptr_type = ci->getOperand(1)->getType();
+ Function* fputs_func = SLC.get_fputs(FILEptr_type);
+ if (!fputs_func)
+ return false;
+ std::vector<Value*> args;
+ args.push_back(CastToCStr(ci->getOperand(3), *ci));
+ args.push_back(ci->getOperand(1));
+ new CallInst(fputs_func,args,ci->getName(),ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,len));
+ }
+ break;
+ }
+ case 'c':
+ {
+ // fprintf(file,"%c",c) -> fputc(c,file)
+ const Type* FILEptr_type = ci->getOperand(1)->getType();
+ Function* fputc_func = SLC.get_fputc(FILEptr_type);
+ if (!fputc_func)
+ return false;
+ CastInst* cast = new CastInst(ci->getOperand(3), Type::IntTy,
+ CI->getName()+".int", ci);
+ new CallInst(fputc_func,cast,ci->getOperand(1),"",ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,1));
+ break;
+ }
+ default:
+ return false;
+ }
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 SPrintFOptimization : public LibCallOptimization {
+public:
+ /// @brief Default Constructor
+ SPrintFOptimization() : LibCallOptimization("sprintf",
+ "Number of 'sprintf' calls simplified") {}
+
+ /// @brief Make sure that the "fprintf" function has the right prototype
+ virtual bool ValidateCalledFunction(const Function *f, SimplifyLibCalls &SLC){
+ // Just make sure this has at least 2 arguments
+ return (f->getReturnType() == Type::IntTy && f->arg_size() >= 2);
+ }
+
+ /// @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() > 4 || ci->getNumOperands() < 3)
+ return false;
+
+ // All the optimizations depend on the length of the second argument and the
+ // fact that it is a constant string array. Check that now
+ uint64_t len = 0;
+ ConstantArray* CA = 0;
+ if (!getConstantStringLength(ci->getOperand(2), len, &CA))
+ return false;
+
+ if (ci->getNumOperands() == 3) {
+ if (len == 0) {
+ // If the length is 0, we just need to store a null byte
+ new StoreInst(ConstantInt::get(Type::SByteTy,0),ci->getOperand(1),ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,0));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // Make sure there's no % in the constant array
+ for (unsigned i = 0; i < len; ++i) {
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) {
+ // Check for the null terminator
+ if (CI->getRawValue() == '%')
+ return false; // we found a %, can't optimize
+ } else {
+ return false; // initializer is not constant int, can't optimize
+ }
+ }
+
+ // Increment length because we want to copy the null byte too
+ len++;
+
+ // sprintf(str,fmt) -> llvm.memcpy(str,fmt,strlen(fmt),1)
+ Function* memcpy_func = SLC.get_memcpy();
+ if (!memcpy_func)
+ return false;
+ std::vector<Value*> args;
+ args.push_back(ci->getOperand(1));
+ args.push_back(ci->getOperand(2));
+ args.push_back(ConstantUInt::get(SLC.getIntPtrType(),len));
+ args.push_back(ConstantUInt::get(Type::UIntTy,1));
+ new CallInst(memcpy_func,args,"",ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,len));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // The remaining optimizations require the format string to be length 2
+ // "%s" or "%c".
+ if (len != 2)
+ return false;
+
+ // The first character has to be a %
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(0)))
+ if (CI->getRawValue() != '%')
+ return false;
+
+ // Get the second character and switch on its value
+ ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(1));
+ switch (CI->getRawValue()) {
+ case 's': {
+ // sprintf(dest,"%s",str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
+ Function* strlen_func = SLC.get_strlen();
+ Function* memcpy_func = SLC.get_memcpy();
+ if (!strlen_func || !memcpy_func)
+ return false;
+
+ Value *Len = new CallInst(strlen_func, CastToCStr(ci->getOperand(3), *ci),
+ ci->getOperand(3)->getName()+".len", ci);
+ Value *Len1 = BinaryOperator::createAdd(Len,
+ ConstantInt::get(Len->getType(), 1),
+ Len->getName()+"1", ci);
+ if (Len1->getType() != SLC.getIntPtrType())
+ Len1 = new CastInst(Len1, SLC.getIntPtrType(), Len1->getName(), ci);
+ std::vector<Value*> args;
+ args.push_back(CastToCStr(ci->getOperand(1), *ci));
+ args.push_back(CastToCStr(ci->getOperand(3), *ci));
+ args.push_back(Len1);
+ args.push_back(ConstantUInt::get(Type::UIntTy,1));
+ new CallInst(memcpy_func, args, "", ci);
+
+ // The strlen result is the unincremented number of bytes in the string.
+ if (!ci->use_empty()) {
+ if (Len->getType() != ci->getType())
+ Len = new CastInst(Len, ci->getType(), Len->getName(), ci);
+ ci->replaceAllUsesWith(Len);
+ }
+ ci->eraseFromParent();
+ return true;
+ }
+ case 'c': {
+ // sprintf(dest,"%c",chr) -> store chr, dest
+ CastInst* cast = new CastInst(ci->getOperand(3),Type::SByteTy,"char",ci);
+ new StoreInst(cast, ci->getOperand(1), ci);
+ GetElementPtrInst* gep = new GetElementPtrInst(ci->getOperand(1),
+ ConstantUInt::get(Type::UIntTy,1),ci->getOperand(1)->getName()+".end",
+ ci);
+ new StoreInst(ConstantInt::get(Type::SByteTy,0),gep,ci);
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,1));
+ ci->eraseFromParent();
+ return true;
+ }
+ }
+ 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 puts library function.
+struct PutsOptimization : public LibCallOptimization {
+public:
+ /// @brief Default Constructor
+ PutsOptimization() : LibCallOptimization("fputs",
+ "Number of 'fputs' calls simplified") {}
+
+ /// @brief Make sure that the "fputs" function has the right prototype
+ virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
+ // Just make sure this has 2 arguments
+ return F->arg_size() == 2;
+ }
+
+ /// @brief Perform the fputs optimization.
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC) {
+ // If the result is used, none of these optimizations work
+ if (!ci->use_empty())
+ return false;
+
+ // All the optimizations depend on the length of the first argument and the
+ // fact that it is a constant string array. Check that now
+ uint64_t len = 0;
+ if (!getConstantStringLength(ci->getOperand(1), len))
+ return false;
+
+ switch (len) {
+ case 0:
+ // fputs("",F) -> noop
+ break;
+ case 1:
+ {
+ // fputs(s,F) -> fputc(s[0],F) (if s is constant and strlen(s) == 1)
+ const Type* FILEptr_type = ci->getOperand(2)->getType();
+ Function* fputc_func = SLC.get_fputc(FILEptr_type);
+ if (!fputc_func)
+ return false;
+ LoadInst* loadi = new LoadInst(ci->getOperand(1),
+ ci->getOperand(1)->getName()+".byte",ci);
+ CastInst* casti = new CastInst(loadi,Type::IntTy,
+ loadi->getName()+".int",ci);
+ new CallInst(fputc_func,casti,ci->getOperand(2),"",ci);
+ break;
+ }
+ default:
+ {
+ // fputs(s,F) -> fwrite(s,1,len,F) (if s is constant and strlen(s) > 1)
+ const Type* FILEptr_type = ci->getOperand(2)->getType();
+ Function* fwrite_func = SLC.get_fwrite(FILEptr_type);
+ if (!fwrite_func)
+ return false;
+ std::vector<Value*> parms;
+ parms.push_back(ci->getOperand(1));
+ parms.push_back(ConstantUInt::get(SLC.getIntPtrType(),len));
+ parms.push_back(ConstantUInt::get(SLC.getIntPtrType(),1));
+ parms.push_back(ci->getOperand(2));
+ new CallInst(fwrite_func,parms,"",ci);
+ break;
+ }
+ }
+ ci->eraseFromParent();
+ return true; // success
+ }
+} PutsOptimizer;
+
+/// 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 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->getRawValue();
+ if (val >= '0' && val <='9')
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,1));
+ else
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy,0));
+ ci->eraseFromParent();
+ return true;
+ }
+
+ // isdigit(c) -> (unsigned)c - '0' <= 9
+ CastInst* cast =
+ new CastInst(ci->getOperand(1),Type::UIntTy,
+ ci->getOperand(1)->getName()+".uint",ci);
+ BinaryOperator* sub_inst = BinaryOperator::createSub(cast,
+ ConstantUInt::get(Type::UIntTy,0x30),
+ ci->getOperand(1)->getName()+".sub",ci);
+ SetCondInst* setcond_inst = new SetCondInst(Instruction::SetLE,sub_inst,
+ ConstantUInt::get(Type::UIntTy,9),
+ ci->getOperand(1)->getName()+".cmp",ci);
+ CastInst* c2 =
+ new CastInst(setcond_inst,Type::IntTy,
+ ci->getOperand(1)->getName()+".isdigit",ci);
+ ci->replaceAllUsesWith(c2);
+ ci->eraseFromParent();
+ return true;
+ }
+} isdigitOptimizer;
+
+struct 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);
+ if (V->getType()->isSigned())
+ V = new CastInst(V, V->getType()->getUnsignedVersion(), V->getName(), CI);
+ Value *Cmp = BinaryOperator::createSetLT(V, ConstantUInt::get(V->getType(),
+ 128),
+ V->getName()+".isascii", CI);
+ if (Cmp->getType() != CI->getType())
+ Cmp = new CastInst(Cmp, CI->getType(), Cmp->getName(), CI);
+ CI->replaceAllUsesWith(Cmp);
+ CI->eraseFromParent();
+ return true;
+ }
+} 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 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);
+ BinaryOperator* and_inst = BinaryOperator::createAnd(chr,
+ ConstantInt::get(chr->getType(),0x7F),ci->getName()+".toascii",ci);
+ ci->replaceAllUsesWith(and_inst);
+ ci->eraseFromParent();
+ return true;
+ }
+} 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 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::IntTy;
+ }
+
+ /// @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->getRawValue();
+ int result = 0;
+ if (val) {
+ ++result;
+ while ((val & 1) == 0) {
+ ++result;
+ val >>= 1;
+ }
+ }
+ TheCall->replaceAllUsesWith(ConstantSInt::get(Type::IntTy, result));
+ TheCall->eraseFromParent();
+ return true;
+ }
+
+ // 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();
+ ArgType = ArgType->getUnsignedVersion();
+ const char *CTTZName;
+ switch (ArgType->getTypeID()) {
+ default: assert(0 && "Unknown unsigned type!");
+ case Type::UByteTyID : CTTZName = "llvm.cttz.i8" ; break;
+ case Type::UShortTyID: CTTZName = "llvm.cttz.i16"; break;
+ case Type::UIntTyID : CTTZName = "llvm.cttz.i32"; break;
+ case Type::ULongTyID : CTTZName = "llvm.cttz.i64"; break;
+ }
+
+ Function *F = SLC.getModule()->getOrInsertFunction(CTTZName, ArgType,
+ ArgType, NULL);
+ Value *V = new CastInst(TheCall->getOperand(1), ArgType, "tmp", TheCall);
+ Value *V2 = new CallInst(F, V, "tmp", TheCall);
+ V2 = new CastInst(V2, Type::IntTy, "tmp", TheCall);
+ V2 = BinaryOperator::createAdd(V2, ConstantSInt::get(Type::IntTy, 1),
+ "tmp", TheCall);
+ Value *Cond =
+ BinaryOperator::createSetEQ(V, Constant::getNullValue(V->getType()),
+ "tmp", TheCall);
+ V2 = new SelectInst(Cond, ConstantInt::get(Type::IntTy, 0), V2,
+ TheCall->getName(), TheCall);
+ TheCall->replaceAllUsesWith(V2);
+ TheCall->eraseFromParent();
+ return true;
+ }
+} 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 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 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,
+ Function *(SimplifyLibCalls::*FP)()){
+ if (CastInst *Cast = dyn_cast<CastInst>(CI->getOperand(1)))
+ if (Cast->getOperand(0)->getType() == Type::FloatTy) {
+ Value *New = new CallInst((SLC.*FP)(), Cast->getOperand(0),
+ CI->getName(), CI);
+ New = new CastInst(New, Type::DoubleTy, CI->getName(), CI);
+ CI->replaceAllUsesWith(New);
+ CI->eraseFromParent();
+ if (Cast->use_empty())
+ Cast->eraseFromParent();
+ return true;
+ }
+ return false;
+ }
+};
+
+
+struct 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 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 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 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 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;
+
+/// A function to compute 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. In that case, the \p len parameter is set to the length
+/// of the null-terminated string. If false is returned, the conditions were
+/// not met and len is set to 0.
+/// @brief Get the length of a constant string (null-terminated array).
+bool getConstantStringLength(Value *V, uint64_t &len, ConstantArray **CA) {
+ assert(V != 0 && "Invalid args to getConstantStringLength");
+ len = 0; // make sure we initialize this
+ User* GEP = 0;
+ // 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
+ if (GetElementPtrInst* GEPI = dyn_cast<GetElementPtrInst>(V))
+ GEP = GEPI;
+ else if (ConstantExpr* CE = dyn_cast<ConstantExpr>(V))
+ if (CE->getOpcode() == Instruction::GetElementPtr)
+ GEP = CE;
+ else
+ return false;
+ 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* op1 = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
+ if (!op1->isNullValue())
+ return false;
+ } else
+ return false;
+
+ // Ensure that the second operand is a ConstantInt. If it isn't then this
+ // GEP is wonky and we're not really sure what were referencing into and
+ // better of not optimizing it. While we're at it, get the second index
+ // value. We'll need this later for indexing the ConstantArray.
+ uint64_t start_idx = 0;
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
+ start_idx = CI->getRawValue();
+ 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;
+
+ // Get the initializer.
+ Constant* INTLZR = GV->getInitializer();
+
+ // Handle the ConstantAggregateZero case
+ if (ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(INTLZR)) {
+ // This is a degenerate case. The initializer is constant zero so the
+ // length of the string must be zero.
+ len = 0;
+ return true;
+ }
+
+ // Must be a Constant Array
+ ConstantArray* A = dyn_cast<ConstantArray>(INTLZR);
+ if (!A)
+ return false;
+
+ // Get the number of elements in the array
+ uint64_t max_elems = A->getType()->getNumElements();
+
+ // Traverse the constant array from start_idx (derived above) which is
+ // the place the GEP refers to in the array.
+ for (len = start_idx; len < max_elems; len++) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(A->getOperand(len))) {
+ // Check for the null terminator
+ if (CI->isNullValue())
+ break; // we found end of string
+ } else
+ return false; // This array isn't suitable, non-int initializer
+ }
+
+ if (len >= max_elems)
+ return false; // This array isn't null terminated
+
+ // Subtract out the initial value from the length
+ len -= start_idx;
+ if (CA)
+ *CA = A;
+ return true; // success!
+}
+
+/// 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.
+Value *CastToCStr(Value *V, Instruction &IP) {
+ const Type *SBPTy = PointerType::get(Type::SByteTy);
+ if (V->getType() != SBPTy)
+ return new CastInst(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("") -> fputc("\n",stdout) (how do we get "stdout"?)
+//
+// 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'
+//
+//
}
projects / oota-llvm.git / blobdiff