1 //===- SimpleStructMutation.cpp - Swap structure elements around -*- C++ -*--=//
3 // This pass does a simple transformation that swaps all of the elements of the
4 // struct types in the program around.
6 //===----------------------------------------------------------------------===//
9 #include "llvm/Transforms/IPO/SimpleStructMutation.h"
10 #include "llvm/Transforms/IPO/MutateStructTypes.h"
11 #include "llvm/Analysis/FindUsedTypes.h"
12 #include "llvm/Analysis/FindUnsafePointerTypes.h"
13 #include "../TransformInternals.h"
21 class SimpleStructMutation : public MutateStructTypes {
23 enum Transform { SwapElements, SortElements } CurrentXForm;
25 SimpleStructMutation(enum Transform XForm) : CurrentXForm(XForm) {}
27 virtual bool run(Module *M) {
28 setTransforms(getTransforms(M, CurrentXForm));
29 bool Changed = MutateStructTypes::run(M);
34 // getAnalysisUsage - This function needs the results of the
35 // FindUsedTypes and FindUnsafePointerTypes analysis passes...
37 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
38 AU.addRequired(FindUsedTypes::ID);
39 AU.addRequired(FindUnsafePointerTypes::ID);
40 MutateStructTypes::getAnalysisUsage(AU);
44 TransformsType getTransforms(Module *M, enum Transform);
46 } // end anonymous namespace
50 // PruneTypes - Given a type Ty, make sure that neither it, or one of its
51 // subtypes, occur in TypesToModify.
53 static void PruneTypes(const Type *Ty, set<const StructType*> &TypesToModify,
54 set<const Type*> &ProcessedTypes) {
55 if (ProcessedTypes.count(Ty)) return; // Already been checked
56 ProcessedTypes.insert(Ty);
58 // If the element is in TypesToModify, remove it now...
59 if (const StructType *ST = dyn_cast<StructType>(Ty)) {
60 TypesToModify.erase(ST); // This doesn't fail if the element isn't present
61 std::cerr << "Unable to swap type: " << ST << "\n";
64 // Remove all types that this type contains as well... do not remove types
65 // that are referenced only through pointers, because we depend on the size of
66 // the pointer, not on what the structure points to.
68 for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
70 if (!isa<PointerType>(*I))
71 PruneTypes(*I, TypesToModify, ProcessedTypes);
75 static bool FirstLess(const pair<unsigned, unsigned> &LHS,
76 const pair<unsigned, unsigned> &RHS) {
77 return LHS.second < RHS.second;
80 static unsigned getIndex(const vector<pair<unsigned, unsigned> > &Vec,
82 for (unsigned i = 0; ; ++i)
83 if (Vec[i].first == Field) return i;
86 static inline void GetTransformation(const StructType *ST,
87 vector<int> &Transform,
88 enum SimpleStructMutation::Transform XForm) {
89 unsigned NumElements = ST->getElementTypes().size();
90 Transform.reserve(NumElements);
93 case SimpleStructMutation::SwapElements:
94 // The transformation to do is: just simply swap the elements
95 for (unsigned i = 0; i < NumElements; ++i)
96 Transform.push_back(NumElements-i-1);
99 case SimpleStructMutation::SortElements: {
100 vector<pair<unsigned, unsigned> > ElList;
102 // Build mapping from index to size
103 for (unsigned i = 0; i < NumElements; ++i)
105 std::make_pair(i, TD.getTypeSize(ST->getElementTypes()[i])));
107 sort(ElList.begin(), ElList.end(), ptr_fun(FirstLess));
109 for (unsigned i = 0; i < NumElements; ++i)
110 Transform.push_back(getIndex(ElList, i));
118 SimpleStructMutation::TransformsType
119 SimpleStructMutation::getTransforms(Module *M, enum Transform XForm) {
120 // We need to know which types to modify, and which types we CAN'T modify
121 // TODO: Do symbol tables as well
123 // Get the results out of the analyzers...
124 FindUsedTypes &FUT = getAnalysis<FindUsedTypes>();
125 const set<const Type *> &UsedTypes = FUT.getTypes();
127 FindUnsafePointerTypes &FUPT = getAnalysis<FindUnsafePointerTypes>();
128 const set<PointerType*> &UnsafePTys = FUPT.getUnsafeTypes();
132 // Combine the two sets, weeding out non structure types. Closures in C++
133 // sure would be nice.
134 set<const StructType*> TypesToModify;
135 for (set<const Type *>::const_iterator I = UsedTypes.begin(),
136 E = UsedTypes.end(); I != E; ++I)
137 if (const StructType *ST = dyn_cast<StructType>(*I))
138 TypesToModify.insert(ST);
141 // Go through the Unsafe types and remove all types from TypesToModify that we
142 // are not allowed to modify, because that would be unsafe.
144 set<const Type*> ProcessedTypes;
145 for (set<PointerType*>::const_iterator I = UnsafePTys.begin(),
146 E = UnsafePTys.end(); I != E; ++I) {
147 //cerr << "Pruning type: " << *I << "\n";
148 PruneTypes(*I, TypesToModify, ProcessedTypes);
152 // Build up a set of structure types that we are going to modify, and
153 // information describing how to modify them.
154 std::map<const StructType*, vector<int> > Transforms;
156 for (set<const StructType*>::iterator I = TypesToModify.begin(),
157 E = TypesToModify.end(); I != E; ++I) {
158 const StructType *ST = *I;
160 vector<int> &Transform = Transforms[ST]; // Fill in the map directly
161 GetTransformation(ST, Transform, XForm);
168 Pass *createSwapElementsPass() {
169 return new SimpleStructMutation(SimpleStructMutation::SwapElements);
171 Pass *createSortElementsPass() {
172 return new SimpleStructMutation(SimpleStructMutation::SortElements);