-//===- 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:
+// The LLVM Compiler Infrastructure
//
-// * 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
-// but only if they do not name a structure type!
-// - Replace calls to 'sbyte *%malloc(uint)' and 'void %free(sbyte *)' with
-// malloc and free instructions.
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
-// 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 "TransformInternals.h"
-#include "llvm/SymbolTable.h"
+#define DEBUG_TYPE "deadtypeelim"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Analysis/FindUsedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/TypeSymbolTable.h"
#include "llvm/DerivedTypes.h"
-#include "llvm/iOther.h"
-#include "llvm/iMemory.h"
-#include "llvm/iTerminators.h"
-#include <algorithm>
-
-static const Type *PtrArrSByte = 0; // '[sbyte]*' type
-static const Type *PtrSByte = 0; // 'sbyte*' type
-
-// 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?");
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
- assert(CI->getNumOperands()-1 == ParamTys.size()&&
- "Method calls resolved funny somehow, incompatible number of args");
+STATISTIC(NumKilled, "Number of unused typenames removed from symtab");
- vector<Value*> Params;
+namespace {
+ struct VISIBILITY_HIDDEN DTE : public ModulePass {
+ static char ID; // Pass identification, replacement for typeid
+ DTE() : ModulePass((intptr_t)&ID) {}
- // 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);
+ // 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 runOnModule(Module &M);
- 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;
+ // getAnalysisUsage - This function needs FindUsedTypes to do its job...
+ //
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<FindUsedTypes>();
}
-
- 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));
+ };
+ char DTE::ID = 0;
+ RegisterPass<DTE> X("deadtypeelim", "Dead Type Elimination");
}
-
-// 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.
-//
-bool CleanupGCCOutput::PatchUpMethodReferences(Module *M) {
- SymbolTable *ST = M->getSymbolTable();
- if (!ST) return false;
-
- map<string, vector<Method*> > 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<PointerType>(I->first))
- if (const MethodType *MT = dyn_cast<MethodType>(PT->getValueType())) {
- 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<Method>(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 (map<string, vector<Method*> >::iterator I = Methods.begin(),
- E = Methods.end(); I != E; ++I) {
- vector<Method*> &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;
- }
- }
-
- if (Methods[i] && (!Methods[i]->getMethodType()->isVarArg() ||
- Methods[i]->getMethodType()->getParamTypes().size())) {
- 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() << endl;
- }
- 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];
- assert(Old->getReturnType() == Concrete->getReturnType() &&
- "Differing return types not handled yet!");
- assert(Old->getMethodType()->getParamTypes().size() == 0 &&
- "Cannot handle varargs fn's with specified element types!");
-
- // 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 <retty> (...)
- //
- for (unsigned i = 0; i < Old->use_size(); ) {
- User *U = *(Old->use_begin()+i);
- if (CastInst *CI = dyn_cast<CastInst>(U)) {
- // Convert casts directly
- assert(CI->getOperand(0) == Old);
- CI->setOperand(0, Concrete);
- Changed = true;
- } else if (CallInst *CI = dyn_cast<CallInst>(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 << endl;
- ++i;
- }
- }
- }
- }
- }
- }
-
- return Changed;
+ModulePass *llvm::createDeadTypeEliminationPass() {
+ return new DTE();
}
-// ShouldNukSymtabEntry - Return true if this module level symbol table entry
+// ShouldNukeSymtabEntry - Return true if this module level symbol table entry
// should be eliminated.
//
-static inline bool ShouldNukeSymtabEntry(const pair<string, Value*> &E) {
+static inline bool ShouldNukeSymtabEntry(const Type *Ty){
// Nuke all names for primitive types!
- if (cast<Type>(E.second)->isPrimitiveType()) return true;
+ if (Ty->isPrimitiveType() || Ty->isInteger())
+ 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;
+ // Nuke all pointers to primitive types as well...
+ if (const PointerType *PT = dyn_cast<PointerType>(Ty))
+ if (PT->getElementType()->isPrimitiveType() ||
+ PT->getElementType()->isInteger())
+ return true;
return false;
}
-// 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.
+// 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::doPassInitialization(Module *M) {
+bool DTE::runOnModule(Module &M) {
bool Changed = false;
- if (PtrArrSByte == 0) {
- PtrArrSByte = PointerType::get(ArrayType::get(Type::SByteTy));
- 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 the module has a symbol table, they might be referring to the malloc
- // and free functions. If this is the case, grab the method pointers that
- // the module is using.
- //
- // Lookup %malloc and %free in the symbol table, for later use. If they
- // don't exist, or are not external, we do not worry about converting calls
- // to that function into the appropriate instruction.
- //
- const PointerType *MallocType = // Get the type for malloc
- PointerType::get(MethodType::get(PointerType::get(Type::SByteTy),
- vector<const Type*>(1, Type::UIntTy), false));
- Malloc = cast_or_null<Method>(ST->lookup(MallocType, "malloc"));
- if (Malloc && !Malloc->isExternal())
- Malloc = 0; // Don't mess with locally defined versions of the fn
-
- const PointerType *FreeType = // Get the type for free
- PointerType::get(MethodType::get(Type::VoidTy,
- vector<const Type*>(1, PointerType::get(Type::SByteTy)), false));
- Free = cast_or_null<Method>(ST->lookup(FreeType, "free"));
- if (Free && !Free->isExternal())
- Free = 0; // Don't mess with locally defined versions of the fn
-
-
- // Check the symbol table for superfluous type entries...
- //
- // 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 (ShouldNukeSymtabEntry(*PI)) { // Should we remove this entry?
-#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
- Changed = true;
- } else {
- ++PI;
- }
- }
- }
-
- return Changed;
-}
-
-
-// doOneCleanupPass - Do one pass over the input method, fixing stuff up.
-//
-bool CleanupGCCOutput::doOneCleanupPass(Method *M) {
- bool Changed = false;
- for (Method::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) {
- BasicBlock *BB = *MI;
- BasicBlock::InstListType &BIL = BB->getInstList();
-
- for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
- Instruction *I = *BI;
+ TypeSymbolTable &ST = M.getTypeSymbolTable();
+ std::set<const Type *> UsedTypes = getAnalysis<FindUsedTypes>().getTypes();
- if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (CI->getCalledValue() == Malloc) { // Replace call to malloc?
- MallocInst *MallocI = new MallocInst(PtrArrSByte, CI->getOperand(1),
- CI->getName());
- CI->setName("");
- BI = BIL.insert(BI, MallocI)+1;
- ReplaceInstWithInst(BIL, BI, new CastInst(MallocI, PtrSByte));
- Changed = true;
- continue; // Skip the ++BI
- } else if (CI->getCalledValue() == Free) { // Replace call to free?
- ReplaceInstWithInst(BIL, BI, new FreeInst(CI->getOperand(1)));
- Changed = true;
- continue; // Skip the ++BI
- }
- }
-
- ++BI;
- }
- }
-
- 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<PHINode>(*InsertPos) || isa<CastInst>(*InsertPos)) ++InsertPos;
-
- // Back the InsertPos up to right after the last PHI node.
- while (InsertPos != BB->begin() && isa<CastInst>(*(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<CastInst>(*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...
- swap(*InsertPos, *I); // Cast goes down, PHI goes up
-
- if (isa<PHINode>(Src) && // Handle case #1
- cast<PHINode>(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<PHINode>(*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);
- }
+ // Check the symbol table for superfluous type entries...
+ //
+ // Grab the 'type' plane of the module symbol...
+ TypeSymbolTable::iterator TI = ST.begin();
+ TypeSymbolTable::iterator TE = ST.end();
+ while ( TI != TE ) {
+ // If this entry should be unconditionally removed, or if we detect that
+ // the type is not used, remove it.
+ const Type *RHS = TI->second;
+ if (ShouldNukeSymtabEntry(RHS) || !UsedTypes.count(RHS)) {
+ ST.remove(TI++);
+ ++NumKilled;
+ Changed = true;
} else {
- ++I;
+ ++TI;
+ // We only need to leave one name for each type.
+ UsedTypes.erase(RHS);
}
}
-
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(BB->pred_begin(), BB->pred_end(), Pred) != BB->pred_end() &&
- "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<PHINode>(*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<PointerType>(Ty))
- NewVal = ConstPoolPointerNull::get(PT);
- else if (Ty == Type::BoolTy)
- NewVal = ConstPoolBool::True;
- else if (Ty == Type::FloatTy || Ty == Type::DoubleTy)
- NewVal = ConstPoolFP::get(Ty, 42);
- else if (Ty->isIntegral())
- NewVal = ConstPoolInt::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<PHINode>(BB->front())) {
- const vector<BasicBlock*> Preds(BB->pred_begin(), BB->pred_end());
-
- // Handle Problem #1. Sort the list of predecessors so that it is easy to
- // decide whether or not duplicate predecessors exist.
- vector<BasicBlock*> 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<PHINode>(*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::doPerMethodWork(Method *M) {
- bool Changed = fixLocalProblems(M);
- while (doOneCleanupPass(M)) Changed = true;
- return Changed;
-}
+// vim: sw=2
projects / oota-llvm.git / blobdiff