X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FIPO%2FDeadTypeElimination.cpp;h=a1860a92e959dcb30859b6ebf0019e4f153eb711;hb=a92f696b74a99325026ebbdbffd2a44317e0c10b;hp=801cdffb7e7852e10d661237bddfb887883dcae1;hpb=bd0ef77cde9c9e82f2b4ad33e4982c46274d6540;p=oota-llvm.git diff --git a/lib/Transforms/IPO/DeadTypeElimination.cpp b/lib/Transforms/IPO/DeadTypeElimination.cpp index 801cdffb7e7..a1860a92e95 100644 --- a/lib/Transforms/IPO/DeadTypeElimination.cpp +++ b/lib/Transforms/IPO/DeadTypeElimination.cpp @@ -1,259 +1,50 @@ -//===- CleanupGCCOutput.cpp - Cleanup GCC Output ----------------------------=// +//===- DeadTypeElimination.cpp - Eliminate unused types for symbol table --===// // -// This pass is used to cleanup the output of GCC. GCC's output is -// unneccessarily gross for a couple of reasons. This pass does the following -// things to try to clean it up: -// -// * Eliminate names for GCC types that we know can't be needed by the user. -// * Eliminate names for types that are unused in the entire translation unit -// -// Note: This code produces dead declarations, it is a good idea to run DCE -// after this pass. +// This pass is used to cleanup the output of GCC. It eliminate names for types +// that are unused in the entire translation unit, using the FindUsedTypes pass. // //===----------------------------------------------------------------------===// -#include "llvm/Transforms/CleanupGCCOutput.h" +#include "llvm/Transforms/IPO.h" #include "llvm/Analysis/FindUsedTypes.h" -#include "TransformInternals.h" #include "llvm/Module.h" #include "llvm/SymbolTable.h" #include "llvm/DerivedTypes.h" -#include "llvm/iPHINode.h" -#include "llvm/iMemory.h" -#include "llvm/iTerminators.h" -#include "llvm/iOther.h" -#include "llvm/Support/CFG.h" -#include "llvm/Pass.h" -#include -#include -using std::vector; -using std::string; -using std::cerr; +#include "Support/Statistic.h" -static const Type *PtrSByte = 0; // 'sbyte*' type +using std::vector; namespace { - struct CleanupGCCOutput : public MethodPass { + struct DTE : public Pass { // doPassInitialization - For this pass, it removes global symbol table // entries for primitive types. These are never used for linking in GCC and // they make the output uglier to look at, so we nuke them. // // Also, initialize instance variables. // - bool doInitialization(Module *M); - - // doPerMethodWork - This method simplifies the specified method hopefully. - // - bool runOnMethod(Method *M); - - // doPassFinalization - Strip out type names that are unused by the program - bool doFinalization(Module *M); - - // getAnalysisUsageInfo - This function needs FindUsedTypes to do its job... + bool run(Module &M); + + // getAnalysisUsage - This function needs FindUsedTypes to do its job... // - virtual void getAnalysisUsageInfo(Pass::AnalysisSet &Required, - Pass::AnalysisSet &Destroyed, - Pass::AnalysisSet &Provided) { - // FIXME: Invalidates the CFG - Required.push_back(FindUsedTypes::ID); + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired(); } }; + RegisterOpt X("deadtypeelim", "Dead Type Elimination"); + Statistic<> + NumKilled("deadtypeelim", "Number of unused typenames removed from symtab"); } - - -// ConvertCallTo - Convert a call to a varargs function with no arg types -// specified to a concrete nonvarargs method. -// -static void ConvertCallTo(CallInst *CI, Method *Dest) { - const MethodType::ParamTypes &ParamTys = - Dest->getMethodType()->getParamTypes(); - BasicBlock *BB = CI->getParent(); - - // Get an iterator to where we want to insert cast instructions if the - // argument types don't agree. - // - BasicBlock::iterator BBI = find(BB->begin(), BB->end(), CI); - assert(BBI != BB->end() && "CallInst not in parent block?"); - - assert(CI->getNumOperands()-1 == ParamTys.size()&& - "Method calls resolved funny somehow, incompatible number of args"); - - vector Params; - - // Convert all of the call arguments over... inserting cast instructions if - // the types are not compatible. - for (unsigned i = 1; i < CI->getNumOperands(); ++i) { - Value *V = CI->getOperand(i); - - if (V->getType() != ParamTys[i-1]) { // Must insert a cast... - Instruction *Cast = new CastInst(V, ParamTys[i-1]); - BBI = BB->getInstList().insert(BBI, Cast)+1; - V = Cast; - } - - Params.push_back(V); - } - - // Replace the old call instruction with a new call instruction that calls - // the real method. - // - ReplaceInstWithInst(BB->getInstList(), BBI, new CallInst(Dest, Params)); +Pass *createDeadTypeEliminationPass() { + return new DTE(); } -// PatchUpMethodReferences - Go over the methods that are in the module and -// look for methods that have the same name. More often than not, there will -// be things like: -// void "foo"(...) -// void "foo"(int, int) -// because of the way things are declared in C. If this is the case, patch -// things up. -// -static bool PatchUpMethodReferences(Module *M) { - SymbolTable *ST = M->getSymbolTable(); - if (!ST) return false; - - std::map > Methods; - - // Loop over the entries in the symbol table. If an entry is a method pointer, - // then add it to the Methods map. We do a two pass algorithm here to avoid - // problems with iterators getting invalidated if we did a one pass scheme. - // - for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I) - if (const PointerType *PT = dyn_cast(I->first)) - if (isa(PT->getElementType())) { - SymbolTable::VarMap &Plane = I->second; - for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end(); - PI != PE; ++PI) { - const string &Name = PI->first; - Method *M = cast(PI->second); - Methods[Name].push_back(M); - } - } - - bool Changed = false; - - // Now we have a list of all methods with a particular name. If there is more - // than one entry in a list, merge the methods together. - // - for (std::map >::iterator I = Methods.begin(), - E = Methods.end(); I != E; ++I) { - vector &Methods = I->second; - Method *Implementation = 0; // Find the implementation - Method *Concrete = 0; - for (unsigned i = 0; i < Methods.size(); ) { - if (!Methods[i]->isExternal()) { // Found an implementation - assert(Implementation == 0 && "Multiple definitions of the same" - " method. Case not handled yet!"); - Implementation = Methods[i]; - } else { - // Ignore methods that are never used so they don't cause spurious - // warnings... here we will actually DCE the function so that it isn't - // used later. - // - if (Methods[i]->use_size() == 0) { - M->getMethodList().remove(Methods[i]); - delete Methods[i]; - Methods.erase(Methods.begin()+i); - Changed = true; - continue; - } - } - - if (Methods[i] && (!Methods[i]->getMethodType()->isVarArg())) { - if (Concrete) { // Found two different methods types. Can't choose - Concrete = 0; - break; - } - Concrete = Methods[i]; - } - ++i; - } - - if (Methods.size() > 1) { // Found a multiply defined method. - // We should find exactly one non-vararg method definition, which is - // probably the implementation. Change all of the method definitions - // and uses to use it instead. - // - if (!Concrete) { - cerr << "Warning: Found methods types that are not compatible:\n"; - for (unsigned i = 0; i < Methods.size(); ++i) { - cerr << "\t" << Methods[i]->getType()->getDescription() << " %" - << Methods[i]->getName() << "\n"; - } - cerr << " No linkage of methods named '" << Methods[0]->getName() - << "' performed!\n"; - } else { - for (unsigned i = 0; i < Methods.size(); ++i) - if (Methods[i] != Concrete) { - Method *Old = Methods[i]; - const MethodType *OldMT = Old->getMethodType(); - const MethodType *ConcreteMT = Concrete->getMethodType(); - bool Broken = false; - - assert(Old->getReturnType() == Concrete->getReturnType() && - "Differing return types not handled yet!"); - assert(OldMT->getParamTypes().size() <= - ConcreteMT->getParamTypes().size() && - "Concrete type must have more specified parameters!"); - - // Check to make sure that if there are specified types, that they - // match... - // - for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i) - if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) { - cerr << "Parameter types conflict for" << OldMT - << " and " << ConcreteMT; - Broken = true; - } - if (Broken) break; // Can't process this one! - - - // Attempt to convert all of the uses of the old method to the - // concrete form of the method. If there is a use of the method - // that we don't understand here we punt to avoid making a bad - // transformation. - // - // At this point, we know that the return values are the same for - // our two functions and that the Old method has no varargs methods - // specified. In otherwords it's just (...) - // - for (unsigned i = 0; i < Old->use_size(); ) { - User *U = *(Old->use_begin()+i); - if (CastInst *CI = dyn_cast(U)) { - // Convert casts directly - assert(CI->getOperand(0) == Old); - CI->setOperand(0, Concrete); - Changed = true; - } else if (CallInst *CI = dyn_cast(U)) { - // Can only fix up calls TO the argument, not args passed in. - if (CI->getCalledValue() == Old) { - ConvertCallTo(CI, Concrete); - Changed = true; - } else { - cerr << "Couldn't cleanup this function call, must be an" - << " argument or something!" << CI; - ++i; - } - } else { - cerr << "Cannot convert use of method: " << U << "\n"; - ++i; - } - } - } - } - } - } - - return Changed; -} - // ShouldNukSymtabEntry - Return true if this module level symbol table entry // should be eliminated. // -static inline bool ShouldNukeSymtabEntry(const std::pair &E) { +static inline bool ShouldNukeSymtabEntry(const std::pair&E){ // Nuke all names for primitive types! if (cast(E.second)->isPrimitiveType()) return true; @@ -261,32 +52,20 @@ static inline bool ShouldNukeSymtabEntry(const std::pair &E) { if (const PointerType *PT = dyn_cast(E.second)) if (PT->getElementType()->isPrimitiveType()) return true; - // The only types that could contain .'s in the program are things generated - // by GCC itself, including "complex.float" and friends. Nuke them too. - if (E.first.find('.') != string::npos) return true; - return false; } -// doInitialization - For this pass, it removes global symbol table -// entries for primitive types. These are never used for linking in GCC and -// they make the output uglier to look at, so we nuke them. +// run - For this pass, it removes global symbol table entries for primitive +// types. These are never used for linking in GCC and they make the output +// uglier to look at, so we nuke them. Also eliminate types that are never used +// in the entire program as indicated by FindUsedTypes. // -bool CleanupGCCOutput::doInitialization(Module *M) { +bool DTE::run(Module &M) { bool Changed = false; - if (PtrSByte == 0) - PtrSByte = PointerType::get(Type::SByteTy); - - if (M->hasSymbolTable()) { - SymbolTable *ST = M->getSymbolTable(); - - // Go over the methods that are in the module and look for methods that have - // the same name. More often than not, there will be things like: - // void "foo"(...) and void "foo"(int, int) because of the way things are - // declared in C. If this is the case, patch things up. - // - Changed |= PatchUpMethodReferences(M); + if (SymbolTable *ST = M.getSymbolTable()) { + const std::set &UsedTypes = + getAnalysis().getTypes(); // Check the symbol table for superfluous type entries... // @@ -296,13 +75,18 @@ bool CleanupGCCOutput::doInitialization(Module *M) { // Loop over all entries in the type plane... SymbolTable::VarMap &Plane = STI->second; for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();) - if (ShouldNukeSymtabEntry(*PI)) { // Should we remove this entry? + // If this entry should be unconditionally removed, or if we detect that + // the type is not used, remove it. + // + if (ShouldNukeSymtabEntry(*PI) || + !UsedTypes.count(cast(PI->second))) { #if MAP_IS_NOT_BRAINDEAD PI = Plane.erase(PI); // STD C++ Map should support this! #else Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH* PI = Plane.begin(); #endif + ++NumKilled; Changed = true; } else { ++PI; @@ -312,271 +96,3 @@ bool CleanupGCCOutput::doInitialization(Module *M) { return Changed; } - - -// FixCastsAndPHIs - The LLVM GCC has a tendancy to intermix Cast instructions -// in with the PHI nodes. These cast instructions are potentially there for two -// different reasons: -// -// 1. The cast could be for an early PHI, and be accidentally inserted before -// another PHI node. In this case, the PHI node should be moved to the end -// of the PHI nodes in the basic block. We know that it is this case if -// the source for the cast is a PHI node in this basic block. -// -// 2. If not #1, the cast must be a source argument for one of the PHI nodes -// in the current basic block. If this is the case, the cast should be -// lifted into the basic block for the appropriate predecessor. -// -static inline bool FixCastsAndPHIs(BasicBlock *BB) { - bool Changed = false; - - BasicBlock::iterator InsertPos = BB->begin(); - - // Find the end of the interesting instructions... - while (isa(*InsertPos) || isa(*InsertPos)) ++InsertPos; - - // Back the InsertPos up to right after the last PHI node. - while (InsertPos != BB->begin() && isa(*(InsertPos-1))) --InsertPos; - - // No PHI nodes, quick exit. - if (InsertPos == BB->begin()) return false; - - // Loop over all casts trapped between the PHI's... - BasicBlock::iterator I = BB->begin(); - while (I != InsertPos) { - if (CastInst *CI = dyn_cast(*I)) { // Fix all cast instructions - Value *Src = CI->getOperand(0); - - // Move the cast instruction to the current insert position... - --InsertPos; // New position for cast to go... - std::swap(*InsertPos, *I); // Cast goes down, PHI goes up - - if (isa(Src) && // Handle case #1 - cast(Src)->getParent() == BB) { - // We're done for case #1 - } else { // Handle case #2 - // In case #2, we have to do a few things: - // 1. Remove the cast from the current basic block. - // 2. Identify the PHI node that the cast is for. - // 3. Find out which predecessor the value is for. - // 4. Move the cast to the end of the basic block that it SHOULD be - // - - // Remove the cast instruction from the basic block. The remove only - // invalidates iterators in the basic block that are AFTER the removed - // element. Because we just moved the CastInst to the InsertPos, no - // iterators get invalidated. - // - BB->getInstList().remove(InsertPos); - - // Find the PHI node. Since this cast was generated specifically for a - // PHI node, there can only be a single PHI node using it. - // - assert(CI->use_size() == 1 && "Exactly one PHI node should use cast!"); - PHINode *PN = cast(*CI->use_begin()); - - // Find out which operand of the PHI it is... - unsigned i; - for (i = 0; i < PN->getNumIncomingValues(); ++i) - if (PN->getIncomingValue(i) == CI) - break; - assert(i != PN->getNumIncomingValues() && "PHI doesn't use cast!"); - - // Get the predecessor the value is for... - BasicBlock *Pred = PN->getIncomingBlock(i); - - // Reinsert the cast right before the terminator in Pred. - Pred->getInstList().insert(Pred->end()-1, CI); - } - } else { - ++I; - } - } - - - return Changed; -} - -// RefactorPredecessor - When we find out that a basic block is a repeated -// predecessor in a PHI node, we have to refactor the method until there is at -// most a single instance of a basic block in any predecessor list. -// -static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) { - Method *M = BB->getParent(); - assert(find(pred_begin(BB), pred_end(BB), Pred) != pred_end(BB) && - "Pred is not a predecessor of BB!"); - - // Create a new basic block, adding it to the end of the method. - BasicBlock *NewBB = new BasicBlock("", M); - - // Add an unconditional branch to BB to the new block. - NewBB->getInstList().push_back(new BranchInst(BB)); - - // Get the terminator that causes a branch to BB from Pred. - TerminatorInst *TI = Pred->getTerminator(); - - // Find the first use of BB in the terminator... - User::op_iterator OI = find(TI->op_begin(), TI->op_end(), BB); - assert(OI != TI->op_end() && "Pred does not branch to BB!!!"); - - // Change the use of BB to point to the new stub basic block - *OI = NewBB; - - // Now we need to loop through all of the PHI nodes in BB and convert their - // first incoming value for Pred to reference the new basic block instead. - // - for (BasicBlock::iterator I = BB->begin(); - PHINode *PN = dyn_cast(*I); ++I) { - int BBIdx = PN->getBasicBlockIndex(Pred); - assert(BBIdx != -1 && "PHI node doesn't have an entry for Pred!"); - - // The value that used to look like it came from Pred now comes from NewBB - PN->setIncomingBlock((unsigned)BBIdx, NewBB); - } -} - - -// CheckIncomingValueFor - Make sure that the specified PHI node has an entry -// for the provided basic block. If it doesn't, add one and return true. -// -static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) { - if (PN->getBasicBlockIndex(BB) != -1) return; // Already has value - - Value *NewVal = 0; - const Type *Ty = PN->getType(); - - if (const PointerType *PT = dyn_cast(Ty)) - NewVal = ConstantPointerNull::get(PT); - else if (Ty == Type::BoolTy) - NewVal = ConstantBool::True; - else if (Ty == Type::FloatTy || Ty == Type::DoubleTy) - NewVal = ConstantFP::get(Ty, 42); - else if (Ty->isIntegral()) - NewVal = ConstantInt::get(Ty, 42); - - assert(NewVal && "Unknown PHI node type!"); - PN->addIncoming(NewVal, BB); -} - -// fixLocalProblems - Loop through the method and fix problems with the PHI -// nodes in the current method. The two problems that are handled are: -// -// 1. PHI nodes with multiple entries for the same predecessor. GCC sometimes -// generates code that looks like this: -// -// bb7: br bool %cond1004, label %bb8, label %bb8 -// bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ] -// -// which is completely illegal LLVM code. To compensate for this, we insert -// an extra basic block, and convert the code to look like this: -// -// bb7: br bool %cond1004, label %bbX, label %bb8 -// bbX: br label bb8 -// bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ] -// -// -// 2. PHI nodes with fewer arguments than predecessors. -// These can be generated by GCC if a variable is uninitalized over a path -// in the CFG. We fix this by adding an entry for the missing predecessors -// that is initialized to either 42 for a numeric/FP value, or null if it's -// a pointer value. This problem can be generated by code that looks like -// this: -// int foo(int y) { -// int X; -// if (y) X = 1; -// return X; -// } -// -static bool fixLocalProblems(Method *M) { - bool Changed = false; - // Don't use iterators because invalidation gets messy... - for (unsigned MI = 0; MI < M->size(); ++MI) { - BasicBlock *BB = M->getBasicBlocks()[MI]; - - Changed |= FixCastsAndPHIs(BB); - - if (isa(BB->front())) { - const vector Preds(pred_begin(BB), pred_end(BB)); - - // Handle Problem #1. Sort the list of predecessors so that it is easy to - // decide whether or not duplicate predecessors exist. - vector SortedPreds(Preds); - sort(SortedPreds.begin(), SortedPreds.end()); - - // Loop over the predecessors, looking for adjacent BB's that are equal. - BasicBlock *LastOne = 0; - for (unsigned i = 0; i < Preds.size(); ++i) { - if (SortedPreds[i] == LastOne) { // Found a duplicate. - RefactorPredecessor(BB, SortedPreds[i]); - Changed = true; - } - LastOne = SortedPreds[i]; - } - - // Loop over all of the PHI nodes in the current BB. These PHI nodes are - // guaranteed to be at the beginning of the basic block. - // - for (BasicBlock::iterator I = BB->begin(); - PHINode *PN = dyn_cast(*I); ++I) { - - // Handle problem #2. - if (PN->getNumIncomingValues() != Preds.size()) { - assert(PN->getNumIncomingValues() <= Preds.size() && - "Can't handle extra arguments to PHI nodes!"); - for (unsigned i = 0; i < Preds.size(); ++i) - CheckIncomingValueFor(PN, Preds[i]); - Changed = true; - } - } - } - } - return Changed; -} - - - - -// doPerMethodWork - This method simplifies the specified method hopefully. -// -bool CleanupGCCOutput::runOnMethod(Method *M) { - return fixLocalProblems(M); -} - -bool CleanupGCCOutput::doFinalization(Module *M) { - bool Changed = false; - - - if (M->hasSymbolTable()) { - SymbolTable *ST = M->getSymbolTable(); - const std::set &UsedTypes = - getAnalysis().getTypes(); - - // Check the symbol table for superfluous type entries that aren't used in - // the program - // - // Grab the 'type' plane of the module symbol... - SymbolTable::iterator STI = ST->find(Type::TypeTy); - if (STI != ST->end()) { - // Loop over all entries in the type plane... - SymbolTable::VarMap &Plane = STI->second; - for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();) - if (!UsedTypes.count(cast(PI->second))) { -#if MAP_IS_NOT_BRAINDEAD - PI = Plane.erase(PI); // STD C++ Map should support this! -#else - Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH* - PI = Plane.begin(); // N^2 algorithms are fun. :( -#endif - Changed = true; - } else { - ++PI; - } - } - } - return Changed; -} - -Pass *createCleanupGCCOutputPass() { - return new CleanupGCCOutput(); -} -