mirror of
https://github.com/c64scene-ar/llvm-6502.git
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fd79ab5088
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1273 91177308-0d34-0410-b5e6-96231b3b80d8
552 lines
21 KiB
C++
552 lines
21 KiB
C++
//===- CleanupGCCOutput.cpp - Cleanup GCC Output ----------------------------=//
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//
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// This pass is used to cleanup the output of GCC. GCC's output is
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// unneccessarily gross for a couple of reasons. This pass does the following
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// things to try to clean it up:
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//
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// * Eliminate names for GCC types that we know can't be needed by the user.
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// - Eliminate names for types that are unused in the entire translation unit
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// but only if they do not name a structure type!
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// - Replace calls to 'sbyte *%malloc(uint)' and 'void %free(sbyte *)' with
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// malloc and free instructions.
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//
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// Note: This code produces dead declarations, it is a good idea to run DCE
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// after this pass.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/CleanupGCCOutput.h"
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#include "TransformInternals.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/iOther.h"
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#include "llvm/iMemory.h"
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#include "llvm/iTerminators.h"
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#include <algorithm>
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static const Type *PtrArrSByte = 0; // '[sbyte]*' type
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static const Type *PtrSByte = 0; // 'sbyte*' type
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// ConvertCallTo - Convert a call to a varargs function with no arg types
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// specified to a concrete nonvarargs method.
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//
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static void ConvertCallTo(CallInst *CI, Method *Dest) {
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const MethodType::ParamTypes &ParamTys =
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Dest->getMethodType()->getParamTypes();
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BasicBlock *BB = CI->getParent();
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// Get an iterator to where we want to insert cast instructions if the
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// argument types don't agree.
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//
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BasicBlock::iterator BBI = find(BB->begin(), BB->end(), CI);
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assert(BBI != BB->end() && "CallInst not in parent block?");
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assert(CI->getNumOperands()-1 == ParamTys.size()&&
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"Method calls resolved funny somehow, incompatible number of args");
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vector<Value*> Params;
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// Convert all of the call arguments over... inserting cast instructions if
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// the types are not compatible.
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for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
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Value *V = CI->getOperand(i);
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if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
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Instruction *Cast = new CastInst(V, ParamTys[i-1]);
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BBI = BB->getInstList().insert(BBI, Cast)+1;
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V = Cast;
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}
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Params.push_back(V);
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}
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// Replace the old call instruction with a new call instruction that calls
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// the real method.
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//
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ReplaceInstWithInst(BB->getInstList(), BBI, new CallInst(Dest, Params));
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}
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// PatchUpMethodReferences - Go over the methods that are in the module and
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// look for methods that have the same name. More often than not, there will
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// be things like:
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// void "foo"(...)
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// void "foo"(int, int)
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// because of the way things are declared in C. If this is the case, patch
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// things up.
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//
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bool CleanupGCCOutput::PatchUpMethodReferences(Module *M) {
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SymbolTable *ST = M->getSymbolTable();
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if (!ST) return false;
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map<string, vector<Method*> > Methods;
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// Loop over the entries in the symbol table. If an entry is a method pointer,
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// then add it to the Methods map. We do a two pass algorithm here to avoid
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// problems with iterators getting invalidated if we did a one pass scheme.
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//
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for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
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if (const PointerType *PT = dyn_cast<PointerType>(I->first))
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if (const MethodType *MT = dyn_cast<MethodType>(PT->getValueType())) {
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SymbolTable::VarMap &Plane = I->second;
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for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
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PI != PE; ++PI) {
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const string &Name = PI->first;
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Method *M = cast<Method>(PI->second);
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Methods[Name].push_back(M);
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}
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}
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bool Changed = false;
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// Now we have a list of all methods with a particular name. If there is more
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// than one entry in a list, merge the methods together.
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//
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for (map<string, vector<Method*> >::iterator I = Methods.begin(),
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E = Methods.end(); I != E; ++I) {
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vector<Method*> &Methods = I->second;
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Method *Implementation = 0; // Find the implementation
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Method *Concrete = 0;
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for (unsigned i = 0; i < Methods.size(); ) {
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if (!Methods[i]->isExternal()) { // Found an implementation
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assert(Implementation == 0 && "Multiple definitions of the same"
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" method. Case not handled yet!");
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Implementation = Methods[i];
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} else {
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// Ignore methods that are never used so they don't cause spurious
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// warnings... here we will actually DCE the function so that it isn't
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// used later.
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//
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if (Methods[i]->use_size() == 0) {
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M->getMethodList().remove(Methods[i]);
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delete Methods[i];
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Methods.erase(Methods.begin()+i);
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Changed = true;
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continue;
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}
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}
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if (Methods[i] && (!Methods[i]->getMethodType()->isVarArg() ||
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Methods[i]->getMethodType()->getParamTypes().size())) {
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if (Concrete) { // Found two different methods types. Can't choose
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Concrete = 0;
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break;
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}
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Concrete = Methods[i];
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}
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++i;
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}
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if (Methods.size() > 1) { // Found a multiply defined method.
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// We should find exactly one non-vararg method definition, which is
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// probably the implementation. Change all of the method definitions
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// and uses to use it instead.
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//
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if (!Concrete) {
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cerr << "Warning: Found methods types that are not compatible:\n";
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for (unsigned i = 0; i < Methods.size(); ++i) {
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cerr << "\t" << Methods[i]->getType()->getDescription() << " %"
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<< Methods[i]->getName() << endl;
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}
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cerr << " No linkage of methods named '" << Methods[0]->getName()
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<< "' performed!\n";
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} else {
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for (unsigned i = 0; i < Methods.size(); ++i)
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if (Methods[i] != Concrete) {
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Method *Old = Methods[i];
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assert(Old->getReturnType() == Concrete->getReturnType() &&
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"Differing return types not handled yet!");
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assert(Old->getMethodType()->getParamTypes().size() == 0 &&
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"Cannot handle varargs fn's with specified element types!");
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// Attempt to convert all of the uses of the old method to the
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// concrete form of the method. If there is a use of the method
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// that we don't understand here we punt to avoid making a bad
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// transformation.
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//
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// At this point, we know that the return values are the same for
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// our two functions and that the Old method has no varargs methods
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// specified. In otherwords it's just <retty> (...)
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//
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for (unsigned i = 0; i < Old->use_size(); ) {
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User *U = *(Old->use_begin()+i);
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if (CastInst *CI = dyn_cast<CastInst>(U)) {
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// Convert casts directly
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assert(CI->getOperand(0) == Old);
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CI->setOperand(0, Concrete);
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Changed = true;
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} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// Can only fix up calls TO the argument, not args passed in.
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if (CI->getCalledValue() == Old) {
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ConvertCallTo(CI, Concrete);
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Changed = true;
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} else {
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cerr << "Couldn't cleanup this function call, must be an"
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<< " argument or something!" << CI;
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++i;
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}
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} else {
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cerr << "Cannot convert use of method: " << U << endl;
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++i;
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}
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}
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}
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}
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}
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}
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return Changed;
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}
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// ShouldNukSymtabEntry - Return true if this module level symbol table entry
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// should be eliminated.
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//
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static inline bool ShouldNukeSymtabEntry(const pair<string, Value*> &E) {
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// Nuke all names for primitive types!
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if (cast<Type>(E.second)->isPrimitiveType()) return true;
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// The only types that could contain .'s in the program are things generated
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// by GCC itself, including "complex.float" and friends. Nuke them too.
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if (E.first.find('.') != string::npos) return true;
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return false;
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}
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// doPassInitialization - For this pass, it removes global symbol table
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// entries for primitive types. These are never used for linking in GCC and
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// they make the output uglier to look at, so we nuke them.
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//
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bool CleanupGCCOutput::doPassInitialization(Module *M) {
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bool Changed = false;
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if (PtrArrSByte == 0) {
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PtrArrSByte = PointerType::get(ArrayType::get(Type::SByteTy));
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PtrSByte = PointerType::get(Type::SByteTy);
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}
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if (M->hasSymbolTable()) {
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SymbolTable *ST = M->getSymbolTable();
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// Go over the methods that are in the module and look for methods that have
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// the same name. More often than not, there will be things like:
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// void "foo"(...) and void "foo"(int, int) because of the way things are
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// declared in C. If this is the case, patch things up.
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//
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Changed |= PatchUpMethodReferences(M);
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// If the module has a symbol table, they might be referring to the malloc
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// and free functions. If this is the case, grab the method pointers that
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// the module is using.
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//
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// Lookup %malloc and %free in the symbol table, for later use. If they
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// don't exist, or are not external, we do not worry about converting calls
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// to that function into the appropriate instruction.
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//
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const PointerType *MallocType = // Get the type for malloc
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PointerType::get(MethodType::get(PointerType::get(Type::SByteTy),
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vector<const Type*>(1, Type::UIntTy), false));
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Malloc = cast_or_null<Method>(ST->lookup(MallocType, "malloc"));
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if (Malloc && !Malloc->isExternal())
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Malloc = 0; // Don't mess with locally defined versions of the fn
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const PointerType *FreeType = // Get the type for free
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PointerType::get(MethodType::get(Type::VoidTy,
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vector<const Type*>(1, PointerType::get(Type::SByteTy)), false));
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Free = cast_or_null<Method>(ST->lookup(FreeType, "free"));
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if (Free && !Free->isExternal())
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Free = 0; // Don't mess with locally defined versions of the fn
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// Check the symbol table for superfluous type entries...
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//
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// Grab the 'type' plane of the module symbol...
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SymbolTable::iterator STI = ST->find(Type::TypeTy);
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if (STI != ST->end()) {
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// Loop over all entries in the type plane...
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SymbolTable::VarMap &Plane = STI->second;
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for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
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if (ShouldNukeSymtabEntry(*PI)) { // Should we remove this entry?
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#if MAP_IS_NOT_BRAINDEAD
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PI = Plane.erase(PI); // STD C++ Map should support this!
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#else
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Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH*
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PI = Plane.begin();
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#endif
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Changed = true;
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} else {
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++PI;
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}
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}
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}
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return Changed;
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}
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// doOneCleanupPass - Do one pass over the input method, fixing stuff up.
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//
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bool CleanupGCCOutput::doOneCleanupPass(Method *M) {
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bool Changed = false;
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for (Method::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) {
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BasicBlock *BB = *MI;
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BasicBlock::InstListType &BIL = BB->getInstList();
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for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
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Instruction *I = *BI;
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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if (CI->getCalledValue() == Malloc) { // Replace call to malloc?
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MallocInst *MallocI = new MallocInst(PtrArrSByte, CI->getOperand(1),
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CI->getName());
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CI->setName("");
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BI = BIL.insert(BI, MallocI)+1;
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ReplaceInstWithInst(BIL, BI, new CastInst(MallocI, PtrSByte));
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Changed = true;
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continue; // Skip the ++BI
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} else if (CI->getCalledValue() == Free) { // Replace call to free?
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ReplaceInstWithInst(BIL, BI, new FreeInst(CI->getOperand(1)));
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Changed = true;
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continue; // Skip the ++BI
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}
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}
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++BI;
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}
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}
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return Changed;
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}
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// FixCastsAndPHIs - The LLVM GCC has a tendancy to intermix Cast instructions
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// in with the PHI nodes. These cast instructions are potentially there for two
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// different reasons:
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//
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// 1. The cast could be for an early PHI, and be accidentally inserted before
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// another PHI node. In this case, the PHI node should be moved to the end
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// of the PHI nodes in the basic block. We know that it is this case if
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// the source for the cast is a PHI node in this basic block.
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//
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// 2. If not #1, the cast must be a source argument for one of the PHI nodes
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// in the current basic block. If this is the case, the cast should be
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// lifted into the basic block for the appropriate predecessor.
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//
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static inline bool FixCastsAndPHIs(BasicBlock *BB) {
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bool Changed = false;
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BasicBlock::iterator InsertPos = BB->begin();
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// Find the end of the interesting instructions...
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while (isa<PHINode>(*InsertPos) || isa<CastInst>(*InsertPos)) ++InsertPos;
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// Back the InsertPos up to right after the last PHI node.
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while (InsertPos != BB->begin() && isa<CastInst>(*(InsertPos-1))) --InsertPos;
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// No PHI nodes, quick exit.
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if (InsertPos == BB->begin()) return false;
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// Loop over all casts trapped between the PHI's...
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BasicBlock::iterator I = BB->begin();
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while (I != InsertPos) {
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if (CastInst *CI = dyn_cast<CastInst>(*I)) { // Fix all cast instructions
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Value *Src = CI->getOperand(0);
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// Move the cast instruction to the current insert position...
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--InsertPos; // New position for cast to go...
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swap(*InsertPos, *I); // Cast goes down, PHI goes up
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if (isa<PHINode>(Src) && // Handle case #1
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cast<PHINode>(Src)->getParent() == BB) {
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// We're done for case #1
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} else { // Handle case #2
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// In case #2, we have to do a few things:
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// 1. Remove the cast from the current basic block.
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// 2. Identify the PHI node that the cast is for.
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// 3. Find out which predecessor the value is for.
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// 4. Move the cast to the end of the basic block that it SHOULD be
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//
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// Remove the cast instruction from the basic block. The remove only
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// invalidates iterators in the basic block that are AFTER the removed
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// element. Because we just moved the CastInst to the InsertPos, no
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// iterators get invalidated.
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//
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BB->getInstList().remove(InsertPos);
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// Find the PHI node. Since this cast was generated specifically for a
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// PHI node, there can only be a single PHI node using it.
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//
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assert(CI->use_size() == 1 && "Exactly one PHI node should use cast!");
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PHINode *PN = cast<PHINode>(*CI->use_begin());
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// Find out which operand of the PHI it is...
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unsigned i;
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for (i = 0; i < PN->getNumIncomingValues(); ++i)
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if (PN->getIncomingValue(i) == CI)
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break;
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assert(i != PN->getNumIncomingValues() && "PHI doesn't use cast!");
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// Get the predecessor the value is for...
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BasicBlock *Pred = PN->getIncomingBlock(i);
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// Reinsert the cast right before the terminator in Pred.
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Pred->getInstList().insert(Pred->end()-1, CI);
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}
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} else {
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++I;
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}
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}
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return Changed;
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}
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// RefactorPredecessor - When we find out that a basic block is a repeated
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// predecessor in a PHI node, we have to refactor the method until there is at
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// most a single instance of a basic block in any predecessor list.
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//
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static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
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Method *M = BB->getParent();
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assert(find(BB->pred_begin(), BB->pred_end(), Pred) != BB->pred_end() &&
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"Pred is not a predecessor of BB!");
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// Create a new basic block, adding it to the end of the method.
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BasicBlock *NewBB = new BasicBlock("", M);
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// Add an unconditional branch to BB to the new block.
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NewBB->getInstList().push_back(new BranchInst(BB));
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// Get the terminator that causes a branch to BB from Pred.
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TerminatorInst *TI = Pred->getTerminator();
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// Find the first use of BB in the terminator...
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User::op_iterator OI = find(TI->op_begin(), TI->op_end(), BB);
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assert(OI != TI->op_end() && "Pred does not branch to BB!!!");
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// Change the use of BB to point to the new stub basic block
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*OI = NewBB;
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// Now we need to loop through all of the PHI nodes in BB and convert their
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// first incoming value for Pred to reference the new basic block instead.
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//
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for (BasicBlock::iterator I = BB->begin();
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PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
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int BBIdx = PN->getBasicBlockIndex(Pred);
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assert(BBIdx != -1 && "PHI node doesn't have an entry for Pred!");
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// The value that used to look like it came from Pred now comes from NewBB
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PN->setIncomingBlock((unsigned)BBIdx, NewBB);
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}
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}
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// CheckIncomingValueFor - Make sure that the specified PHI node has an entry
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// for the provided basic block. If it doesn't, add one and return true.
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//
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static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
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if (PN->getBasicBlockIndex(BB) != -1) return; // Already has value
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Value *NewVal = 0;
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const Type *Ty = PN->getType();
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if (const PointerType *PT = dyn_cast<PointerType>(Ty))
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NewVal = ConstPoolPointerNull::get(PT);
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else if (Ty == Type::BoolTy)
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NewVal = ConstPoolBool::True;
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else if (Ty == Type::FloatTy || Ty == Type::DoubleTy)
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NewVal = ConstPoolFP::get(Ty, 42);
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else if (Ty->isIntegral())
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NewVal = ConstPoolInt::get(Ty, 42);
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assert(NewVal && "Unknown PHI node type!");
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PN->addIncoming(NewVal, BB);
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}
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// fixLocalProblems - Loop through the method and fix problems with the PHI
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// nodes in the current method. The two problems that are handled are:
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//
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// 1. PHI nodes with multiple entries for the same predecessor. GCC sometimes
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// generates code that looks like this:
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//
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// bb7: br bool %cond1004, label %bb8, label %bb8
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// bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
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//
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// which is completely illegal LLVM code. To compensate for this, we insert
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// an extra basic block, and convert the code to look like this:
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//
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// bb7: br bool %cond1004, label %bbX, label %bb8
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// bbX: br label bb8
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// bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
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//
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//
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// 2. PHI nodes with fewer arguments than predecessors.
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// These can be generated by GCC if a variable is uninitalized over a path
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// in the CFG. We fix this by adding an entry for the missing predecessors
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// that is initialized to either 42 for a numeric/FP value, or null if it's
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// a pointer value. This problem can be generated by code that looks like
|
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// this:
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// int foo(int y) {
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// int X;
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// if (y) X = 1;
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// return X;
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|
// }
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//
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static bool fixLocalProblems(Method *M) {
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bool Changed = false;
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|
// Don't use iterators because invalidation gets messy...
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|
for (unsigned MI = 0; MI < M->size(); ++MI) {
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BasicBlock *BB = M->getBasicBlocks()[MI];
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|
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Changed |= FixCastsAndPHIs(BB);
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|
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|
if (isa<PHINode>(BB->front())) {
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|
const vector<BasicBlock*> Preds(BB->pred_begin(), BB->pred_end());
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|
|
|
// Handle Problem #1. Sort the list of predecessors so that it is easy to
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|
// decide whether or not duplicate predecessors exist.
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|
vector<BasicBlock*> SortedPreds(Preds);
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sort(SortedPreds.begin(), SortedPreds.end());
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|
|
|
// Loop over the predecessors, looking for adjacent BB's that are equal.
|
|
BasicBlock *LastOne = 0;
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|
for (unsigned i = 0; i < Preds.size(); ++i) {
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if (SortedPreds[i] == LastOne) { // Found a duplicate.
|
|
RefactorPredecessor(BB, SortedPreds[i]);
|
|
Changed = true;
|
|
}
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|
LastOne = SortedPreds[i];
|
|
}
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|
|
|
// 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) {
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|
|
|
// 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;
|
|
}
|