-//===- CleanupGCCOutput.cpp - Cleanup GCC Output ----------------------------=//
+//===- CleanupGCCOutput.cpp - Cleanup GCC Output --------------------------===//
//
// 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
+// * Fix various problems that we might have in PHI nodes and casts
+// * Link uses of 'void %foo(...)' to 'void %foo(sometypes)'
+//
// Note: This code produces dead declarations, it is a good idea to run DCE
// after this pass.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/CleanupGCCOutput.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 <algorithm>
+#include <iostream>
+using std::vector;
+using std::string;
+using std::cerr;
+
+static const Type *PtrSByte = 0; // 'sbyte*' type
-static inline bool ShouldNukeSymtabEntry(const pair<string, Value*> &E) {
+namespace {
+ struct CleanupGCCOutput : public MethodPass {
+ // 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);
+
+ // runOnFunction - This method simplifies the specified function hopefully.
+ //
+ bool runOnMethod(Function *F);
+
+ // doPassFinalization - Strip out type names that are unused by the program
+ bool doFinalization(Module *M);
+
+ // getAnalysisUsageInfo - 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);
+ }
+ };
+}
+
+Pass *createCleanupGCCOutputPass() {
+ return new CleanupGCCOutput();
+}
+
+
+
+// ShouldNukSymtabEntry - Return true if this module level symbol table entry
+// should be eliminated.
+//
+static inline bool ShouldNukeSymtabEntry(const std::pair<string, Value*> &E) {
// Nuke all names for primitive types!
if (cast<Type>(E.second)->isPrimitiveType()) return true;
+ // Nuke all pointers to primitive types as well...
+ if (const PointerType *PT = dyn_cast<PointerType>(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;
}
-
-// doPassInitialization - For this pass, it removes global symbol table
+// 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.
//
-bool CleanupGCCOutput::doPassInitialization(Module *M) {
+bool CleanupGCCOutput::doInitialization(Module *M) {
bool Changed = false;
+ if (PtrSByte == 0)
+ PtrSByte = PointerType::get(Type::SByteTy);
+
if (M->hasSymbolTable()) {
- // Grab the type plane of the module...
SymbolTable *ST = M->getSymbolTable();
+
+ // 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...
++PI;
}
}
-
}
return Changed;
}
-// doPerMethodWork - This method simplifies the specified method hopefully.
+// 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...
+ std::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);
+ }
+ } 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 function until there is at
+// most a single instance of a basic block in any predecessor list.
+//
+static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
+ Function *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 function.
+ 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);
+ }
+}
+
+
+// runOnMethod - Loop through the function and fix problems with the PHI nodes
+// in the current function. The problem is that PHI nodes might exist 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 ]
+//
+//
+bool CleanupGCCOutput::runOnMethod(Function *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(pred_begin(BB), pred_end(BB));
+
+ // Handle the problem. 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];
+ }
+ }
+ }
+ return Changed;
+}
+
+bool CleanupGCCOutput::doFinalization(Module *M) {
+ bool Changed = false;
+
+ if (M->hasSymbolTable()) {
+ SymbolTable *ST = M->getSymbolTable();
+ const std::set<const Type *> &UsedTypes =
+ getAnalysis<FindUsedTypes>().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<Type>(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;
+}
+
+
+//===----------------------------------------------------------------------===//
+//
+// FunctionResolvingPass - Go over the functions that are in the module and
+// look for functions 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.
+//
+//===----------------------------------------------------------------------===//
+
+namespace {
+ struct FunctionResolvingPass : public Pass {
+ bool run(Module *M);
+ };
+}
+
+// ConvertCallTo - Convert a call to a varargs function with no arg types
+// specified to a concrete nonvarargs function.
//
-bool CleanupGCCOutput::doPerMethodWork(Method *M) {
+static void ConvertCallTo(CallInst *CI, Function *Dest) {
+ const FunctionType::ParamTypes &ParamTys =
+ Dest->getFunctionType()->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()&&
+ "Function calls resolved funny somehow, incompatible number of args");
+
+ vector<Value*> 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 function.
+ //
+ ReplaceInstWithInst(BB->getInstList(), BBI, new CallInst(Dest, Params));
+}
+
+
+bool FunctionResolvingPass::run(Module *M) {
+ SymbolTable *ST = M->getSymbolTable();
+ if (!ST) return false;
+
+ std::map<string, vector<Function*> > Functions;
+
+ // Loop over the entries in the symbol table. If an entry is a func pointer,
+ // then add it to the Functions 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 (isa<FunctionType>(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;
+ Functions[Name].push_back(cast<Function>(PI->second));
+ }
+ }
+
bool Changed = false;
+ // Now we have a list of all functions with a particular name. If there is
+ // more than one entry in a list, merge the functions together.
+ //
+ for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
+ E = Functions.end(); I != E; ++I) {
+ vector<Function*> &Functions = I->second;
+ Function *Implementation = 0; // Find the implementation
+ Function *Concrete = 0;
+ for (unsigned i = 0; i < Functions.size(); ) {
+ if (!Functions[i]->isExternal()) { // Found an implementation
+ assert(Implementation == 0 && "Multiple definitions of the same"
+ " function. Case not handled yet!");
+ Implementation = Functions[i];
+ } else {
+ // Ignore functions 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 (Functions[i]->use_size() == 0) {
+ M->getFunctionList().remove(Functions[i]);
+ delete Functions[i];
+ Functions.erase(Functions.begin()+i);
+ Changed = true;
+ continue;
+ }
+ }
+
+ if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
+ if (Concrete) { // Found two different functions types. Can't choose
+ Concrete = 0;
+ break;
+ }
+ Concrete = Functions[i];
+ }
+ ++i;
+ }
+
+ if (Functions.size() > 1) { // Found a multiply defined function...
+ // We should find exactly one non-vararg function definition, which is
+ // probably the implementation. Change all of the function definitions
+ // and uses to use it instead.
+ //
+ if (!Concrete) {
+ cerr << "Warning: Found functions types that are not compatible:\n";
+ for (unsigned i = 0; i < Functions.size(); ++i) {
+ cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
+ << Functions[i]->getName() << "\n";
+ }
+ cerr << " No linkage of functions named '" << Functions[0]->getName()
+ << "' performed!\n";
+ } else {
+ for (unsigned i = 0; i < Functions.size(); ++i)
+ if (Functions[i] != Concrete) {
+ Function *Old = Functions[i];
+ const FunctionType *OldMT = Old->getFunctionType();
+ const FunctionType *ConcreteMT = Concrete->getFunctionType();
+ 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 function to the
+ // concrete form of the function. If there is a use of the fn
+ // 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 function has no varargs fns
+ // 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 function: " << U << "\n";
+ ++i;
+ }
+ }
+ }
+ }
+ }
+ }
+
return Changed;
}
+
+Pass *createFunctionResolvingPass() {
+ return new FunctionResolvingPass();
+}
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