#include "llvm/Instructions.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
+#include "llvm/Operator.h"
#include "llvm/Pass.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
STATISTIC(NumAliasesWritten, "Number of aliases generated");
STATISTIC(NumDoubleWeak, "Number of new functions created");
-/// ProfileFunction - Creates a hash-code for the function which is the same
-/// for any two functions that will compare equal, without looking at the
-/// instructions inside the function.
-static unsigned ProfileFunction(const Function *F) {
+/// Creates a hash-code for the function which is the same for any two
+/// functions that will compare equal, without looking at the instructions
+/// inside the function.
+static unsigned profileFunction(const Function *F) {
const FunctionType *FTy = F->getFunctionType();
FoldingSetNodeID ID;
namespace {
+/// ComparableFunction - A struct that pairs together functions with a
+/// TargetData so that we can keep them together as elements in the DenseSet.
class ComparableFunction {
public:
static const ComparableFunction EmptyKey;
static const ComparableFunction TombstoneKey;
+ static TargetData * const LookupOnly;
ComparableFunction(Function *Func, TargetData *TD)
- : Func(Func), Hash(ProfileFunction(Func)), TD(TD) {}
+ : Func(Func), Hash(profileFunction(Func)), TD(TD) {}
Function *getFunc() const { return Func; }
unsigned getHash() const { return Hash; }
Func = NULL;
}
- bool &getOrInsertCachedComparison(const ComparableFunction &Other,
- bool &inserted) const {
- typedef DenseMap<Function *, bool>::iterator iterator;
- std::pair<iterator, bool> p =
- CompareResultCache.insert(std::make_pair(Other.getFunc(), false));
- inserted = p.second;
- return p.first->second;
- }
-
private:
explicit ComparableFunction(unsigned Hash)
: Func(NULL), Hash(Hash), TD(NULL) {}
- // DenseMap::grow() triggers a recomparison of all keys in the map, which is
- // wildly expensive. This cache tries to preserve known results.
- mutable DenseMap<Function *, bool> CompareResultCache;
-
AssertingVH<Function> Func;
unsigned Hash;
TargetData *TD;
const ComparableFunction ComparableFunction::EmptyKey = ComparableFunction(0);
const ComparableFunction ComparableFunction::TombstoneKey =
ComparableFunction(1);
+TargetData *const ComparableFunction::LookupOnly = (TargetData*)(-1);
}
namespace {
-/// MergeFunctions finds functions which will generate identical machine code,
-/// by considering all pointer types to be equivalent. Once identified,
-/// MergeFunctions will fold them by replacing a call to one to a call to a
-/// bitcast of the other.
-///
-class MergeFunctions : public ModulePass {
-public:
- static char ID;
- MergeFunctions()
- : ModulePass(ID), HasGlobalAliases(false) {
- initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
- }
-
- bool runOnModule(Module &M);
-
-private:
- typedef DenseSet<ComparableFunction> FnSetType;
-
- /// A work queue of functions that may have been modified and should be
- /// analyzed again.
- std::vector<WeakVH> Deferred;
-
- /// Insert a ComparableFunction into the FnSet, or merge it away if it's
- /// equal to one that's already present.
- bool Insert(ComparableFunction &NewF);
-
- /// Remove a Function from the FnSet and queue it up for a second sweep of
- /// analysis.
- void Remove(Function *F);
-
- /// Find the functions that use this Value and remove them from FnSet and
- /// queue the functions.
- void RemoveUsers(Value *V);
-
- /// Replace all direct calls of Old with calls of New. Will bitcast New if
- /// necessary to make types match.
- void replaceDirectCallers(Function *Old, Function *New);
-
- /// MergeTwoFunctions - Merge two equivalent functions. Upon completion, G
- /// may be deleted, or may be converted into a thunk. In either case, it
- /// should never be visited again.
- void MergeTwoFunctions(Function *F, Function *G);
-
- /// WriteThunkOrAlias - Replace G with a thunk or an alias to F. Deletes G.
- void WriteThunkOrAlias(Function *F, Function *G);
-
- /// WriteThunk - Replace G with a simple tail call to bitcast(F). Also
- /// replace direct uses of G with bitcast(F). Deletes G.
- void WriteThunk(Function *F, Function *G);
-
- /// WriteAlias - Replace G with an alias to F. Deletes G.
- void WriteAlias(Function *F, Function *G);
-
- /// The set of all distinct functions. Use the Insert and Remove methods to
- /// modify it.
- FnSetType FnSet;
-
- /// TargetData for more accurate GEP comparisons. May be NULL.
- TargetData *TD;
-
- /// Whether or not the target supports global aliases.
- bool HasGlobalAliases;
-};
-
-} // end anonymous namespace
-
-char MergeFunctions::ID = 0;
-INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
-
-ModulePass *llvm::createMergeFunctionsPass() {
- return new MergeFunctions();
-}
-
-namespace {
/// FunctionComparator - Compares two functions to determine whether or not
/// they will generate machine code with the same behaviour. TargetData is
/// used if available. The comparator always fails conservatively (erring on the
public:
FunctionComparator(const TargetData *TD, const Function *F1,
const Function *F2)
- : F1(F1), F2(F2), TD(TD), IDMap1Count(0), IDMap2Count(0) {}
+ : F1(F1), F2(F2), TD(TD) {}
- /// Compare - test whether the two functions have equivalent behaviour.
- bool Compare();
+ /// Test whether the two functions have equivalent behaviour.
+ bool compare();
private:
- /// Compare - test whether two basic blocks have equivalent behaviour.
- bool Compare(const BasicBlock *BB1, const BasicBlock *BB2);
+ /// Test whether two basic blocks have equivalent behaviour.
+ bool compare(const BasicBlock *BB1, const BasicBlock *BB2);
- /// Enumerate - Assign or look up previously assigned numbers for the two
- /// values, and return whether the numbers are equal. Numbers are assigned in
- /// the order visited.
- bool Enumerate(const Value *V1, const Value *V2);
+ /// Assign or look up previously assigned numbers for the two values, and
+ /// return whether the numbers are equal. Numbers are assigned in the order
+ /// visited.
+ bool enumerate(const Value *V1, const Value *V2);
- /// isEquivalentOperation - Compare two Instructions for equivalence, similar
- /// to Instruction::isSameOperationAs but with modifications to the type
+ /// Compare two Instructions for equivalence, similar to
+ /// Instruction::isSameOperationAs but with modifications to the type
/// comparison.
bool isEquivalentOperation(const Instruction *I1,
const Instruction *I2) const;
- /// isEquivalentGEP - Compare two GEPs for equivalent pointer arithmetic.
+ /// Compare two GEPs for equivalent pointer arithmetic.
bool isEquivalentGEP(const GEPOperator *GEP1, const GEPOperator *GEP2);
bool isEquivalentGEP(const GetElementPtrInst *GEP1,
const GetElementPtrInst *GEP2) {
return isEquivalentGEP(cast<GEPOperator>(GEP1), cast<GEPOperator>(GEP2));
}
- /// isEquivalentType - Compare two Types, treating all pointer types as equal.
+ /// Compare two Types, treating all pointer types as equal.
bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
// The two functions undergoing comparison.
const TargetData *TD;
- typedef DenseMap<const Value *, unsigned long> IDMap;
- IDMap Map1, Map2;
- unsigned long IDMap1Count, IDMap2Count;
+ DenseMap<const Value *, const Value *> id_map;
+ DenseSet<const Value *> seen_values;
};
+
}
-/// isEquivalentType - any two pointers in the same address space are
-/// equivalent. Otherwise, standard type equivalence rules apply.
+// Any two pointers in the same address space are equivalent, intptr_t and
+// pointers are equivalent. Otherwise, standard type equivalence rules apply.
bool FunctionComparator::isEquivalentType(const Type *Ty1,
const Type *Ty2) const {
if (Ty1 == Ty2)
return true;
- if (Ty1->getTypeID() != Ty2->getTypeID())
+ if (Ty1->getTypeID() != Ty2->getTypeID()) {
+ if (TD) {
+ LLVMContext &Ctx = Ty1->getContext();
+ if (isa<PointerType>(Ty1) && Ty2 == TD->getIntPtrType(Ctx)) return true;
+ if (isa<PointerType>(Ty2) && Ty1 == TD->getIntPtrType(Ctx)) return true;
+ }
return false;
+ }
- switch(Ty1->getTypeID()) {
+ switch (Ty1->getTypeID()) {
default:
llvm_unreachable("Unknown type!");
// Fall through in Release mode.
case Type::IntegerTyID:
case Type::OpaqueTyID:
+ case Type::VectorTyID:
// Ty1 == Ty2 would have returned true earlier.
return false;
return ATy1->getNumElements() == ATy2->getNumElements() &&
isEquivalentType(ATy1->getElementType(), ATy2->getElementType());
}
-
- case Type::VectorTyID: {
- const VectorType *VTy1 = cast<VectorType>(Ty1);
- const VectorType *VTy2 = cast<VectorType>(Ty2);
- return VTy1->getNumElements() == VTy2->getNumElements() &&
- isEquivalentType(VTy1->getElementType(), VTy2->getElementType());
- }
}
}
-/// isEquivalentOperation - determine whether the two operations are the same
-/// except that pointer-to-A and pointer-to-B are equivalent. This should be
-/// kept in sync with Instruction::isSameOperationAs.
+// Determine whether the two operations are the same except that pointer-to-A
+// and pointer-to-B are equivalent. This should be kept in sync with
+// Instruction::isSameOperationAs.
bool FunctionComparator::isEquivalentOperation(const Instruction *I1,
const Instruction *I2) const {
+ // Differences from Instruction::isSameOperationAs:
+ // * replace type comparison with calls to isEquivalentType.
+ // * we test for I->hasSameSubclassOptionalData (nuw/nsw/tail) at the top
+ // * because of the above, we don't test for the tail bit on calls later on
if (I1->getOpcode() != I2->getOpcode() ||
I1->getNumOperands() != I2->getNumOperands() ||
!isEquivalentType(I1->getType(), I2->getType()) ||
if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
if (const CallInst *CI = dyn_cast<CallInst>(I1))
- return CI->isTailCall() == cast<CallInst>(I2)->isTailCall() &&
- CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
- CI->getAttributes().getRawPointer() ==
- cast<CallInst>(I2)->getAttributes().getRawPointer();
+ return CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
+ CI->getAttributes() == cast<CallInst>(I2)->getAttributes();
if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
- CI->getAttributes().getRawPointer() ==
- cast<InvokeInst>(I2)->getAttributes().getRawPointer();
+ CI->getAttributes() == cast<InvokeInst>(I2)->getAttributes();
if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
return false;
return true;
}
-/// isEquivalentGEP - determine whether two GEP operations perform the same
-/// underlying arithmetic.
+// Determine whether two GEP operations perform the same underlying arithmetic.
bool FunctionComparator::isEquivalentGEP(const GEPOperator *GEP1,
const GEPOperator *GEP2) {
// When we have target data, we can reduce the GEP down to the value in bytes
return false;
for (unsigned i = 0, e = GEP1->getNumOperands(); i != e; ++i) {
- if (!Enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
+ if (!enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
return false;
}
return true;
}
-/// Enumerate - Compare two values used by the two functions under pair-wise
-/// comparison. If this is the first time the values are seen, they're added to
-/// the mapping so that we will detect mismatches on next use.
-bool FunctionComparator::Enumerate(const Value *V1, const Value *V2) {
+// Compare two values used by the two functions under pair-wise comparison. If
+// this is the first time the values are seen, they're added to the mapping so
+// that we will detect mismatches on next use.
+bool FunctionComparator::enumerate(const Value *V1, const Value *V2) {
// Check for function @f1 referring to itself and function @f2 referring to
// itself, or referring to each other, or both referring to either of them.
// They're all equivalent if the two functions are otherwise equivalent.
if (V1 == F2 && V2 == F1)
return true;
- // TODO: constant expressions with GEP or references to F1 or F2.
- if (isa<Constant>(V1))
- return V1 == V2;
-
- if (isa<InlineAsm>(V1) && isa<InlineAsm>(V2)) {
- const InlineAsm *IA1 = cast<InlineAsm>(V1);
- const InlineAsm *IA2 = cast<InlineAsm>(V2);
- return IA1->getAsmString() == IA2->getAsmString() &&
- IA1->getConstraintString() == IA2->getConstraintString();
+ if (const Constant *C1 = dyn_cast<Constant>(V1)) {
+ if (V1 == V2) return true;
+ const Constant *C2 = dyn_cast<Constant>(V2);
+ if (!C2) return false;
+ // TODO: constant expressions with GEP or references to F1 or F2.
+ if (C1->isNullValue() && C2->isNullValue() &&
+ isEquivalentType(C1->getType(), C2->getType()))
+ return true;
+ // Try bitcasting C2 to C1's type. If the bitcast is legal and returns C1
+ // then they must have equal bit patterns.
+ return C1->getType()->canLosslesslyBitCastTo(C2->getType()) &&
+ C1 == ConstantExpr::getBitCast(const_cast<Constant*>(C2), C1->getType());
}
- unsigned long &ID1 = Map1[V1];
- if (!ID1)
- ID1 = ++IDMap1Count;
+ if (isa<InlineAsm>(V1) || isa<InlineAsm>(V2))
+ return V1 == V2;
- unsigned long &ID2 = Map2[V2];
- if (!ID2)
- ID2 = ++IDMap2Count;
+ // Check that V1 maps to V2. If we find a value that V1 maps to then we simply
+ // check whether it's equal to V2. When there is no mapping then we need to
+ // ensure that V2 isn't already equivalent to something else. For this
+ // purpose, we track the V2 values in a set.
- return ID1 == ID2;
+ const Value *&map_elem = id_map[V1];
+ if (map_elem)
+ return map_elem == V2;
+ if (!seen_values.insert(V2).second)
+ return false;
+ map_elem = V2;
+ return true;
}
-/// Compare - test whether two basic blocks have equivalent behaviour.
-bool FunctionComparator::Compare(const BasicBlock *BB1, const BasicBlock *BB2) {
+// Test whether two basic blocks have equivalent behaviour.
+bool FunctionComparator::compare(const BasicBlock *BB1, const BasicBlock *BB2) {
BasicBlock::const_iterator F1I = BB1->begin(), F1E = BB1->end();
BasicBlock::const_iterator F2I = BB2->begin(), F2E = BB2->end();
do {
- if (!Enumerate(F1I, F2I))
+ if (!enumerate(F1I, F2I))
return false;
if (const GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(F1I)) {
if (!GEP2)
return false;
- if (!Enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
+ if (!enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
return false;
if (!isEquivalentGEP(GEP1, GEP2))
Value *OpF1 = F1I->getOperand(i);
Value *OpF2 = F2I->getOperand(i);
- if (!Enumerate(OpF1, OpF2))
+ if (!enumerate(OpF1, OpF2))
return false;
if (OpF1->getValueID() != OpF2->getValueID() ||
return F1I == F1E && F2I == F2E;
}
-/// Compare - test whether the two functions have equivalent behaviour.
-bool FunctionComparator::Compare() {
+// Test whether the two functions have equivalent behaviour.
+bool FunctionComparator::compare() {
// We need to recheck everything, but check the things that weren't included
// in the hash first.
// passed in.
for (Function::const_arg_iterator f1i = F1->arg_begin(),
f2i = F2->arg_begin(), f1e = F1->arg_end(); f1i != f1e; ++f1i, ++f2i) {
- if (!Enumerate(f1i, f2i))
+ if (!enumerate(f1i, f2i))
llvm_unreachable("Arguments repeat!");
}
const BasicBlock *F1BB = F1BBs.pop_back_val();
const BasicBlock *F2BB = F2BBs.pop_back_val();
- if (!Enumerate(F1BB, F2BB) || !Compare(F1BB, F2BB))
+ if (!enumerate(F1BB, F2BB) || !compare(F1BB, F2BB))
return false;
const TerminatorInst *F1TI = F1BB->getTerminator();
return true;
}
-/// Replace direct callers of Old with New.
+namespace {
+
+/// MergeFunctions finds functions which will generate identical machine code,
+/// by considering all pointer types to be equivalent. Once identified,
+/// MergeFunctions will fold them by replacing a call to one to a call to a
+/// bitcast of the other.
+///
+class MergeFunctions : public ModulePass {
+public:
+ static char ID;
+ MergeFunctions()
+ : ModulePass(ID), HasGlobalAliases(false) {
+ initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnModule(Module &M);
+
+private:
+ typedef DenseSet<ComparableFunction> FnSetType;
+
+ /// A work queue of functions that may have been modified and should be
+ /// analyzed again.
+ std::vector<WeakVH> Deferred;
+
+ /// Insert a ComparableFunction into the FnSet, or merge it away if it's
+ /// equal to one that's already present.
+ bool insert(ComparableFunction &NewF);
+
+ /// Remove a Function from the FnSet and queue it up for a second sweep of
+ /// analysis.
+ void remove(Function *F);
+
+ /// Find the functions that use this Value and remove them from FnSet and
+ /// queue the functions.
+ void removeUsers(Value *V);
+
+ /// Replace all direct calls of Old with calls of New. Will bitcast New if
+ /// necessary to make types match.
+ void replaceDirectCallers(Function *Old, Function *New);
+
+ /// Merge two equivalent functions. Upon completion, G may be deleted, or may
+ /// be converted into a thunk. In either case, it should never be visited
+ /// again.
+ void mergeTwoFunctions(Function *F, Function *G);
+
+ /// Replace G with a thunk or an alias to F. Deletes G.
+ void writeThunkOrAlias(Function *F, Function *G);
+
+ /// Replace G with a simple tail call to bitcast(F). Also replace direct uses
+ /// of G with bitcast(F). Deletes G.
+ void writeThunk(Function *F, Function *G);
+
+ /// Replace G with an alias to F. Deletes G.
+ void writeAlias(Function *F, Function *G);
+
+ /// The set of all distinct functions. Use the insert() and remove() methods
+ /// to modify it.
+ FnSetType FnSet;
+
+ /// TargetData for more accurate GEP comparisons. May be NULL.
+ TargetData *TD;
+
+ /// Whether or not the target supports global aliases.
+ bool HasGlobalAliases;
+};
+
+} // end anonymous namespace
+
+char MergeFunctions::ID = 0;
+INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
+
+ModulePass *llvm::createMergeFunctionsPass() {
+ return new MergeFunctions();
+}
+
+bool MergeFunctions::runOnModule(Module &M) {
+ bool Changed = false;
+ TD = getAnalysisIfAvailable<TargetData>();
+
+ for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
+ if (!I->isDeclaration() && !I->hasAvailableExternallyLinkage())
+ Deferred.push_back(WeakVH(I));
+ }
+ FnSet.resize(Deferred.size());
+
+ do {
+ std::vector<WeakVH> Worklist;
+ Deferred.swap(Worklist);
+
+ DEBUG(dbgs() << "size of module: " << M.size() << '\n');
+ DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
+
+ // Insert only strong functions and merge them. Strong function merging
+ // always deletes one of them.
+ for (std::vector<WeakVH>::iterator I = Worklist.begin(),
+ E = Worklist.end(); I != E; ++I) {
+ if (!*I) continue;
+ Function *F = cast<Function>(*I);
+ if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
+ !F->mayBeOverridden()) {
+ ComparableFunction CF = ComparableFunction(F, TD);
+ Changed |= insert(CF);
+ }
+ }
+
+ // Insert only weak functions and merge them. By doing these second we
+ // create thunks to the strong function when possible. When two weak
+ // functions are identical, we create a new strong function with two weak
+ // weak thunks to it which are identical but not mergable.
+ for (std::vector<WeakVH>::iterator I = Worklist.begin(),
+ E = Worklist.end(); I != E; ++I) {
+ if (!*I) continue;
+ Function *F = cast<Function>(*I);
+ if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
+ F->mayBeOverridden()) {
+ ComparableFunction CF = ComparableFunction(F, TD);
+ Changed |= insert(CF);
+ }
+ }
+ DEBUG(dbgs() << "size of FnSet: " << FnSet.size() << '\n');
+ } while (!Deferred.empty());
+
+ FnSet.clear();
+
+ return Changed;
+}
+
+bool DenseMapInfo<ComparableFunction>::isEqual(const ComparableFunction &LHS,
+ const ComparableFunction &RHS) {
+ if (LHS.getFunc() == RHS.getFunc() &&
+ LHS.getHash() == RHS.getHash())
+ return true;
+ if (!LHS.getFunc() || !RHS.getFunc())
+ return false;
+
+ // One of these is a special "underlying pointer comparison only" object.
+ if (LHS.getTD() == ComparableFunction::LookupOnly ||
+ RHS.getTD() == ComparableFunction::LookupOnly)
+ return false;
+
+ assert(LHS.getTD() == RHS.getTD() &&
+ "Comparing functions for different targets");
+
+ return FunctionComparator(LHS.getTD(), LHS.getFunc(),
+ RHS.getFunc()).compare();
+}
+
+// Replace direct callers of Old with New.
void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
++UI;
CallSite CS(*TheIter);
if (CS && CS.isCallee(TheIter)) {
- Remove(CS.getInstruction()->getParent()->getParent());
+ remove(CS.getInstruction()->getParent()->getParent());
TheIter.getUse().set(BitcastNew);
}
}
}
-void MergeFunctions::WriteThunkOrAlias(Function *F, Function *G) {
+// Replace G with an alias to F if possible, or else a thunk to F. Deletes G.
+void MergeFunctions::writeThunkOrAlias(Function *F, Function *G) {
if (HasGlobalAliases && G->hasUnnamedAddr()) {
if (G->hasExternalLinkage() || G->hasLocalLinkage() ||
G->hasWeakLinkage()) {
- WriteAlias(F, G);
+ writeAlias(F, G);
return;
}
}
- WriteThunk(F, G);
+ writeThunk(F, G);
}
-/// WriteThunk - Replace G with a simple tail call to bitcast(F). Also replace
-/// direct uses of G with bitcast(F). Deletes G.
-void MergeFunctions::WriteThunk(Function *F, Function *G) {
+// Replace G with a simple tail call to bitcast(F). Also replace direct uses
+// of G with bitcast(F). Deletes G.
+void MergeFunctions::writeThunk(Function *F, Function *G) {
if (!G->mayBeOverridden()) {
// Redirect direct callers of G to F.
replaceDirectCallers(G, F);
NewG->copyAttributesFrom(G);
NewG->takeName(G);
- RemoveUsers(G);
+ removeUsers(G);
G->replaceAllUsesWith(NewG);
G->eraseFromParent();
- DEBUG(dbgs() << "WriteThunk: " << NewG->getName() << '\n');
+ DEBUG(dbgs() << "writeThunk: " << NewG->getName() << '\n');
++NumThunksWritten;
}
-/// WriteAlias - Replace G with an alias to F and delete G.
-void MergeFunctions::WriteAlias(Function *F, Function *G) {
+// Replace G with an alias to F and delete G.
+void MergeFunctions::writeAlias(Function *F, Function *G) {
Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
GlobalAlias *GA = new GlobalAlias(G->getType(), G->getLinkage(), "",
BitcastF, G->getParent());
F->setAlignment(std::max(F->getAlignment(), G->getAlignment()));
GA->takeName(G);
GA->setVisibility(G->getVisibility());
- RemoveUsers(G);
+ removeUsers(G);
G->replaceAllUsesWith(GA);
G->eraseFromParent();
- DEBUG(dbgs() << "WriteAlias: " << GA->getName() << '\n');
+ DEBUG(dbgs() << "writeAlias: " << GA->getName() << '\n');
++NumAliasesWritten;
}
-/// MergeTwoFunctions - Merge two equivalent functions. Upon completion,
-/// Function G is deleted.
-void MergeFunctions::MergeTwoFunctions(Function *F, Function *G) {
+// Merge two equivalent functions. Upon completion, Function G is deleted.
+void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
if (F->mayBeOverridden()) {
assert(G->mayBeOverridden());
F->getParent());
H->copyAttributesFrom(F);
H->takeName(F);
- RemoveUsers(F);
+ removeUsers(F);
F->replaceAllUsesWith(H);
unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
- WriteAlias(F, G);
- WriteAlias(F, H);
+ writeAlias(F, G);
+ writeAlias(F, H);
F->setAlignment(MaxAlignment);
F->setLinkage(GlobalValue::PrivateLinkage);
++NumDoubleWeak;
} else {
- WriteThunkOrAlias(F, G);
+ writeThunkOrAlias(F, G);
}
++NumFunctionsMerged;
}
-// Insert - Insert a ComparableFunction into the FnSet, or merge it away if
-// equal to one that's already inserted.
-bool MergeFunctions::Insert(ComparableFunction &NewF) {
+// Insert a ComparableFunction into the FnSet, or merge it away if equal to one
+// that was already inserted.
+bool MergeFunctions::insert(ComparableFunction &NewF) {
std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
- if (Result.second)
+ if (Result.second) {
+ DEBUG(dbgs() << "Inserting as unique: " << NewF.getFunc()->getName() << '\n');
return false;
+ }
const ComparableFunction &OldF = *Result.first;
Function *DeleteF = NewF.getFunc();
NewF.release();
- MergeTwoFunctions(OldF.getFunc(), DeleteF);
+ mergeTwoFunctions(OldF.getFunc(), DeleteF);
return true;
}
-// Remove - Remove a function from FnSet. If it was already in FnSet, add it to
-// Deferred so that we'll look at it in the next round.
-void MergeFunctions::Remove(Function *F) {
- ComparableFunction CF = ComparableFunction(F, TD);
+// Remove a function from FnSet. If it was already in FnSet, add it to Deferred
+// so that we'll look at it in the next round.
+void MergeFunctions::remove(Function *F) {
+ // We need to make sure we remove F, not a function "equal" to F per the
+ // function equality comparator.
+ //
+ // The special "lookup only" ComparableFunction bypasses the expensive
+ // function comparison in favour of a pointer comparison on the underlying
+ // Function*'s.
+ ComparableFunction CF = ComparableFunction(F, ComparableFunction::LookupOnly);
if (FnSet.erase(CF)) {
+ DEBUG(dbgs() << "Removed " << F->getName() << " from set and deferred it.\n");
Deferred.push_back(F);
}
}
-// RemoveUsers - For each instruction used by the value, Remove() the function
-// that contains the instruction. This should happen right before a call to RAUW.
-void MergeFunctions::RemoveUsers(Value *V) {
+// For each instruction used by the value, remove() the function that contains
+// the instruction. This should happen right before a call to RAUW.
+void MergeFunctions::removeUsers(Value *V) {
std::vector<Value *> Worklist;
Worklist.push_back(V);
while (!Worklist.empty()) {
UI != UE; ++UI) {
Use &U = UI.getUse();
if (Instruction *I = dyn_cast<Instruction>(U.getUser())) {
- Remove(I->getParent()->getParent());
+ remove(I->getParent()->getParent());
} else if (isa<GlobalValue>(U.getUser())) {
// do nothing
} else if (Constant *C = dyn_cast<Constant>(U.getUser())) {
}
}
}
-
-bool MergeFunctions::runOnModule(Module &M) {
- bool Changed = false;
- TD = getAnalysisIfAvailable<TargetData>();
-
- for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
- Deferred.push_back(WeakVH(I));
- }
-
- do {
- std::vector<WeakVH> Worklist;
- Deferred.swap(Worklist);
-
- DEBUG(dbgs() << "size of module: " << M.size() << '\n');
- DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
-
- // Insert only strong functions and merge them. Strong function merging
- // always deletes one of them.
- for (std::vector<WeakVH>::iterator I = Worklist.begin(),
- E = Worklist.end(); I != E; ++I) {
- if (!*I) continue;
- Function *F = cast<Function>(*I);
- if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
- !F->mayBeOverridden()) {
- ComparableFunction CF = ComparableFunction(F, TD);
- Changed |= Insert(CF);
- }
- }
-
- // Insert only weak functions and merge them. By doing these second we
- // create thunks to the strong function when possible. When two weak
- // functions are identical, we create a new strong function with two weak
- // weak thunks to it which are identical but not mergable.
- for (std::vector<WeakVH>::iterator I = Worklist.begin(),
- E = Worklist.end(); I != E; ++I) {
- if (!*I) continue;
- Function *F = cast<Function>(*I);
- if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
- F->mayBeOverridden()) {
- ComparableFunction CF = ComparableFunction(F, TD);
- Changed |= Insert(CF);
- }
- }
- DEBUG(dbgs() << "size of FnSet: " << FnSet.size() << '\n');
- } while (!Deferred.empty());
-
- FnSet.clear();
-
- return Changed;
-}
-
-bool DenseMapInfo<ComparableFunction>::isEqual(const ComparableFunction &LHS,
- const ComparableFunction &RHS) {
- if (LHS.getFunc() == RHS.getFunc() &&
- LHS.getHash() == RHS.getHash())
- return true;
- if (!LHS.getFunc() || !RHS.getFunc())
- return false;
- assert(LHS.getTD() == RHS.getTD() &&
- "Comparing functions for different targets");
-
- bool inserted;
- bool &result1 = LHS.getOrInsertCachedComparison(RHS, inserted);
- if (!inserted)
- return result1;
- bool &result2 = RHS.getOrInsertCachedComparison(LHS, inserted);
- if (!inserted)
- return result1 = result2;
-
- return result1 = result2 = FunctionComparator(LHS.getTD(), LHS.getFunc(),
- RHS.getFunc()).Compare();
-}
projects / oota-llvm.git / blobdiff