1 //===- CleanupGCCOutput.cpp - Cleanup GCC Output --------------------------===//
3 // This pass is used to cleanup the output of GCC. GCC's output is
4 // unneccessarily gross for a couple of reasons. This pass does the following
5 // things to try to clean it up:
7 // * Eliminate names for GCC types that we know can't be needed by the user.
8 // * Eliminate names for types that are unused in the entire translation unit
9 // * Fix various problems that we might have in PHI nodes and casts
10 // * Link uses of 'void %foo(...)' to 'void %foo(sometypes)'
12 // Note: This code produces dead declarations, it is a good idea to run DCE
15 //===----------------------------------------------------------------------===//
17 #include "llvm/Transforms/CleanupGCCOutput.h"
18 #include "llvm/Analysis/FindUsedTypes.h"
19 #include "TransformInternals.h"
20 #include "llvm/Module.h"
21 #include "llvm/SymbolTable.h"
22 #include "llvm/DerivedTypes.h"
23 #include "llvm/iPHINode.h"
24 #include "llvm/iMemory.h"
25 #include "llvm/iTerminators.h"
26 #include "llvm/iOther.h"
27 #include "llvm/Support/CFG.h"
28 #include "llvm/Pass.h"
35 static const Type *PtrSByte = 0; // 'sbyte*' type
38 struct CleanupGCCOutput : public FunctionPass {
39 // doPassInitialization - For this pass, it removes global symbol table
40 // entries for primitive types. These are never used for linking in GCC and
41 // they make the output uglier to look at, so we nuke them.
43 // Also, initialize instance variables.
45 bool doInitialization(Module *M);
47 // runOnFunction - This method simplifies the specified function hopefully.
49 bool runOnFunction(Function *F);
51 // doPassFinalization - Strip out type names that are unused by the program
52 bool doFinalization(Module *M);
54 // getAnalysisUsage - This function needs FindUsedTypes to do its job...
56 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
57 AU.addRequired(FindUsedTypes::ID);
62 Pass *createCleanupGCCOutputPass() {
63 return new CleanupGCCOutput();
68 // ShouldNukSymtabEntry - Return true if this module level symbol table entry
69 // should be eliminated.
71 static inline bool ShouldNukeSymtabEntry(const std::pair<string, Value*> &E) {
72 // Nuke all names for primitive types!
73 if (cast<Type>(E.second)->isPrimitiveType()) return true;
75 // Nuke all pointers to primitive types as well...
76 if (const PointerType *PT = dyn_cast<PointerType>(E.second))
77 if (PT->getElementType()->isPrimitiveType()) return true;
79 // The only types that could contain .'s in the program are things generated
80 // by GCC itself, including "complex.float" and friends. Nuke them too.
81 if (E.first.find('.') != string::npos) return true;
86 // doInitialization - For this pass, it removes global symbol table
87 // entries for primitive types. These are never used for linking in GCC and
88 // they make the output uglier to look at, so we nuke them.
90 bool CleanupGCCOutput::doInitialization(Module *M) {
94 PtrSByte = PointerType::get(Type::SByteTy);
96 if (M->hasSymbolTable()) {
97 SymbolTable *ST = M->getSymbolTable();
99 // Check the symbol table for superfluous type entries...
101 // Grab the 'type' plane of the module symbol...
102 SymbolTable::iterator STI = ST->find(Type::TypeTy);
103 if (STI != ST->end()) {
104 // Loop over all entries in the type plane...
105 SymbolTable::VarMap &Plane = STI->second;
106 for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
107 if (ShouldNukeSymtabEntry(*PI)) { // Should we remove this entry?
108 #if MAP_IS_NOT_BRAINDEAD
109 PI = Plane.erase(PI); // STD C++ Map should support this!
111 Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH*
125 // FixCastsAndPHIs - The LLVM GCC has a tendancy to intermix Cast instructions
126 // in with the PHI nodes. These cast instructions are potentially there for two
127 // different reasons:
129 // 1. The cast could be for an early PHI, and be accidentally inserted before
130 // another PHI node. In this case, the PHI node should be moved to the end
131 // of the PHI nodes in the basic block. We know that it is this case if
132 // the source for the cast is a PHI node in this basic block.
134 // 2. If not #1, the cast must be a source argument for one of the PHI nodes
135 // in the current basic block. If this is the case, the cast should be
136 // lifted into the basic block for the appropriate predecessor.
138 static inline bool FixCastsAndPHIs(BasicBlock *BB) {
139 bool Changed = false;
141 BasicBlock::iterator InsertPos = BB->begin();
143 // Find the end of the interesting instructions...
144 while (isa<PHINode>(*InsertPos) || isa<CastInst>(*InsertPos)) ++InsertPos;
146 // Back the InsertPos up to right after the last PHI node.
147 while (InsertPos != BB->begin() && isa<CastInst>(*(InsertPos-1))) --InsertPos;
149 // No PHI nodes, quick exit.
150 if (InsertPos == BB->begin()) return false;
152 // Loop over all casts trapped between the PHI's...
153 BasicBlock::iterator I = BB->begin();
154 while (I != InsertPos) {
155 if (CastInst *CI = dyn_cast<CastInst>(*I)) { // Fix all cast instructions
156 Value *Src = CI->getOperand(0);
158 // Move the cast instruction to the current insert position...
159 --InsertPos; // New position for cast to go...
160 std::swap(*InsertPos, *I); // Cast goes down, PHI goes up
162 if (isa<PHINode>(Src) && // Handle case #1
163 cast<PHINode>(Src)->getParent() == BB) {
164 // We're done for case #1
165 } else { // Handle case #2
166 // In case #2, we have to do a few things:
167 // 1. Remove the cast from the current basic block.
168 // 2. Identify the PHI node that the cast is for.
169 // 3. Find out which predecessor the value is for.
170 // 4. Move the cast to the end of the basic block that it SHOULD be
173 // Remove the cast instruction from the basic block. The remove only
174 // invalidates iterators in the basic block that are AFTER the removed
175 // element. Because we just moved the CastInst to the InsertPos, no
176 // iterators get invalidated.
178 BB->getInstList().remove(InsertPos);
180 // Find the PHI node. Since this cast was generated specifically for a
181 // PHI node, there can only be a single PHI node using it.
183 assert(CI->use_size() == 1 && "Exactly one PHI node should use cast!");
184 PHINode *PN = cast<PHINode>(*CI->use_begin());
186 // Find out which operand of the PHI it is...
188 for (i = 0; i < PN->getNumIncomingValues(); ++i)
189 if (PN->getIncomingValue(i) == CI)
191 assert(i != PN->getNumIncomingValues() && "PHI doesn't use cast!");
193 // Get the predecessor the value is for...
194 BasicBlock *Pred = PN->getIncomingBlock(i);
196 // Reinsert the cast right before the terminator in Pred.
197 Pred->getInstList().insert(Pred->end()-1, CI);
207 // RefactorPredecessor - When we find out that a basic block is a repeated
208 // predecessor in a PHI node, we have to refactor the function until there is at
209 // most a single instance of a basic block in any predecessor list.
211 static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
212 Function *M = BB->getParent();
213 assert(find(pred_begin(BB), pred_end(BB), Pred) != pred_end(BB) &&
214 "Pred is not a predecessor of BB!");
216 // Create a new basic block, adding it to the end of the function.
217 BasicBlock *NewBB = new BasicBlock("", M);
219 // Add an unconditional branch to BB to the new block.
220 NewBB->getInstList().push_back(new BranchInst(BB));
222 // Get the terminator that causes a branch to BB from Pred.
223 TerminatorInst *TI = Pred->getTerminator();
225 // Find the first use of BB in the terminator...
226 User::op_iterator OI = find(TI->op_begin(), TI->op_end(), BB);
227 assert(OI != TI->op_end() && "Pred does not branch to BB!!!");
229 // Change the use of BB to point to the new stub basic block
232 // Now we need to loop through all of the PHI nodes in BB and convert their
233 // first incoming value for Pred to reference the new basic block instead.
235 for (BasicBlock::iterator I = BB->begin();
236 PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
237 int BBIdx = PN->getBasicBlockIndex(Pred);
238 assert(BBIdx != -1 && "PHI node doesn't have an entry for Pred!");
240 // The value that used to look like it came from Pred now comes from NewBB
241 PN->setIncomingBlock((unsigned)BBIdx, NewBB);
246 // runOnFunction - Loop through the function and fix problems with the PHI nodes
247 // in the current function. The problem is that PHI nodes might exist with
248 // multiple entries for the same predecessor. GCC sometimes generates code that
251 // bb7: br bool %cond1004, label %bb8, label %bb8
252 // bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
254 // which is completely illegal LLVM code. To compensate for this, we insert
255 // an extra basic block, and convert the code to look like this:
257 // bb7: br bool %cond1004, label %bbX, label %bb8
259 // bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
262 bool CleanupGCCOutput::runOnFunction(Function *M) {
263 bool Changed = false;
264 // Don't use iterators because invalidation gets messy...
265 for (unsigned MI = 0; MI < M->size(); ++MI) {
266 BasicBlock *BB = M->getBasicBlocks()[MI];
268 Changed |= FixCastsAndPHIs(BB);
270 if (isa<PHINode>(BB->front())) {
271 const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
273 // Handle the problem. Sort the list of predecessors so that it is easy
274 // to decide whether or not duplicate predecessors exist.
275 vector<BasicBlock*> SortedPreds(Preds);
276 sort(SortedPreds.begin(), SortedPreds.end());
278 // Loop over the predecessors, looking for adjacent BB's that are equal.
279 BasicBlock *LastOne = 0;
280 for (unsigned i = 0; i < Preds.size(); ++i) {
281 if (SortedPreds[i] == LastOne) { // Found a duplicate.
282 RefactorPredecessor(BB, SortedPreds[i]);
285 LastOne = SortedPreds[i];
292 bool CleanupGCCOutput::doFinalization(Module *M) {
293 bool Changed = false;
295 if (M->hasSymbolTable()) {
296 SymbolTable *ST = M->getSymbolTable();
297 const std::set<const Type *> &UsedTypes =
298 getAnalysis<FindUsedTypes>().getTypes();
300 // Check the symbol table for superfluous type entries that aren't used in
303 // Grab the 'type' plane of the module symbol...
304 SymbolTable::iterator STI = ST->find(Type::TypeTy);
305 if (STI != ST->end()) {
306 // Loop over all entries in the type plane...
307 SymbolTable::VarMap &Plane = STI->second;
308 for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
309 if (!UsedTypes.count(cast<Type>(PI->second))) {
310 #if MAP_IS_NOT_BRAINDEAD
311 PI = Plane.erase(PI); // STD C++ Map should support this!
313 Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH*
314 PI = Plane.begin(); // N^2 algorithms are fun. :(
326 //===----------------------------------------------------------------------===//
328 // FunctionResolvingPass - Go over the functions that are in the module and
329 // look for functions that have the same name. More often than not, there will
332 // void "foo"(int, int)
333 // because of the way things are declared in C. If this is the case, patch
336 //===----------------------------------------------------------------------===//
339 struct FunctionResolvingPass : public Pass {
344 // ConvertCallTo - Convert a call to a varargs function with no arg types
345 // specified to a concrete nonvarargs function.
347 static void ConvertCallTo(CallInst *CI, Function *Dest) {
348 const FunctionType::ParamTypes &ParamTys =
349 Dest->getFunctionType()->getParamTypes();
350 BasicBlock *BB = CI->getParent();
352 // Get an iterator to where we want to insert cast instructions if the
353 // argument types don't agree.
355 BasicBlock::iterator BBI = find(BB->begin(), BB->end(), CI);
356 assert(BBI != BB->end() && "CallInst not in parent block?");
358 assert(CI->getNumOperands()-1 == ParamTys.size()&&
359 "Function calls resolved funny somehow, incompatible number of args");
361 vector<Value*> Params;
363 // Convert all of the call arguments over... inserting cast instructions if
364 // the types are not compatible.
365 for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
366 Value *V = CI->getOperand(i);
368 if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
369 Instruction *Cast = new CastInst(V, ParamTys[i-1]);
370 BBI = BB->getInstList().insert(BBI, Cast)+1;
377 // Replace the old call instruction with a new call instruction that calls
378 // the real function.
380 ReplaceInstWithInst(BB->getInstList(), BBI, new CallInst(Dest, Params));
384 bool FunctionResolvingPass::run(Module *M) {
385 SymbolTable *ST = M->getSymbolTable();
386 if (!ST) return false;
388 std::map<string, vector<Function*> > Functions;
390 // Loop over the entries in the symbol table. If an entry is a func pointer,
391 // then add it to the Functions map. We do a two pass algorithm here to avoid
392 // problems with iterators getting invalidated if we did a one pass scheme.
394 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
395 if (const PointerType *PT = dyn_cast<PointerType>(I->first))
396 if (isa<FunctionType>(PT->getElementType())) {
397 SymbolTable::VarMap &Plane = I->second;
398 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
400 const string &Name = PI->first;
401 Functions[Name].push_back(cast<Function>(PI->second));
405 bool Changed = false;
407 // Now we have a list of all functions with a particular name. If there is
408 // more than one entry in a list, merge the functions together.
410 for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
411 E = Functions.end(); I != E; ++I) {
412 vector<Function*> &Functions = I->second;
413 Function *Implementation = 0; // Find the implementation
414 Function *Concrete = 0;
415 for (unsigned i = 0; i < Functions.size(); ) {
416 if (!Functions[i]->isExternal()) { // Found an implementation
417 assert(Implementation == 0 && "Multiple definitions of the same"
418 " function. Case not handled yet!");
419 Implementation = Functions[i];
421 // Ignore functions that are never used so they don't cause spurious
422 // warnings... here we will actually DCE the function so that it isn't
425 if (Functions[i]->use_size() == 0) {
426 M->getFunctionList().remove(Functions[i]);
428 Functions.erase(Functions.begin()+i);
434 if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
435 if (Concrete) { // Found two different functions types. Can't choose
439 Concrete = Functions[i];
444 if (Functions.size() > 1) { // Found a multiply defined function...
445 // We should find exactly one non-vararg function definition, which is
446 // probably the implementation. Change all of the function definitions
447 // and uses to use it instead.
450 cerr << "Warning: Found functions types that are not compatible:\n";
451 for (unsigned i = 0; i < Functions.size(); ++i) {
452 cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
453 << Functions[i]->getName() << "\n";
455 cerr << " No linkage of functions named '" << Functions[0]->getName()
458 for (unsigned i = 0; i < Functions.size(); ++i)
459 if (Functions[i] != Concrete) {
460 Function *Old = Functions[i];
461 const FunctionType *OldMT = Old->getFunctionType();
462 const FunctionType *ConcreteMT = Concrete->getFunctionType();
465 assert(Old->getReturnType() == Concrete->getReturnType() &&
466 "Differing return types not handled yet!");
467 assert(OldMT->getParamTypes().size() <=
468 ConcreteMT->getParamTypes().size() &&
469 "Concrete type must have more specified parameters!");
471 // Check to make sure that if there are specified types, that they
474 for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
475 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
476 cerr << "Parameter types conflict for" << OldMT
477 << " and " << ConcreteMT;
480 if (Broken) break; // Can't process this one!
483 // Attempt to convert all of the uses of the old function to the
484 // concrete form of the function. If there is a use of the fn
485 // that we don't understand here we punt to avoid making a bad
488 // At this point, we know that the return values are the same for
489 // our two functions and that the Old function has no varargs fns
490 // specified. In otherwords it's just <retty> (...)
492 for (unsigned i = 0; i < Old->use_size(); ) {
493 User *U = *(Old->use_begin()+i);
494 if (CastInst *CI = dyn_cast<CastInst>(U)) {
495 // Convert casts directly
496 assert(CI->getOperand(0) == Old);
497 CI->setOperand(0, Concrete);
499 } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
500 // Can only fix up calls TO the argument, not args passed in.
501 if (CI->getCalledValue() == Old) {
502 ConvertCallTo(CI, Concrete);
505 cerr << "Couldn't cleanup this function call, must be an"
506 << " argument or something!" << CI;
510 cerr << "Cannot convert use of function: " << U << "\n";
522 Pass *createFunctionResolvingPass() {
523 return new FunctionResolvingPass();