//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "mergefunc"
#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Constants.h"
-#include "llvm/InlineAsm.h"
-#include "llvm/Instructions.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
-#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
#include <vector>
using namespace llvm;
+#define DEBUG_TYPE "mergefunc"
+
STATISTIC(NumFunctionsMerged, "Number of functions merged");
STATISTIC(NumThunksWritten, "Number of thunks generated");
+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) {
- const FunctionType *FTy = F->getFunctionType();
+/// Returns the type id for a type to be hashed. We turn pointer types into
+/// integers here because the actual compare logic below considers pointers and
+/// integers of the same size as equal.
+static Type::TypeID getTypeIDForHash(Type *Ty) {
+ if (Ty->isPointerTy())
+ return Type::IntegerTyID;
+ return Ty->getTypeID();
+}
+
+/// 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) {
+ FunctionType *FTy = F->getFunctionType();
FoldingSetNodeID ID;
ID.AddInteger(F->size());
ID.AddInteger(F->getCallingConv());
ID.AddBoolean(F->hasGC());
ID.AddBoolean(FTy->isVarArg());
- ID.AddInteger(FTy->getReturnType()->getTypeID());
+ ID.AddInteger(getTypeIDForHash(FTy->getReturnType()));
for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
- ID.AddInteger(FTy->getParamType(i)->getTypeID());
+ ID.AddInteger(getTypeIDForHash(FTy->getParamType(i)));
return ID.ComputeHash();
}
namespace {
+/// ComparableFunction - A struct that pairs together functions with a
+/// DataLayout so that we can keep them together as elements in the DenseSet.
class ComparableFunction {
public:
static const ComparableFunction EmptyKey;
static const ComparableFunction TombstoneKey;
+ static DataLayout * const LookupOnly;
- ComparableFunction(Function *Func, TargetData *TD)
- : Func(Func), Hash(ProfileFunction(Func)), TD(TD) {}
+ ComparableFunction(Function *Func, const DataLayout *DL)
+ : Func(Func), Hash(profileFunction(Func)), DL(DL) {}
Function *getFunc() const { return Func; }
unsigned getHash() const { return Hash; }
- TargetData *getTD() const { return TD; }
+ const DataLayout *getDataLayout() const { return DL; }
// Drops AssertingVH reference to the function. Outside of debug mode, this
// does nothing.
private:
explicit ComparableFunction(unsigned Hash)
- : Func(NULL), Hash(Hash), TD(NULL) {}
+ : Func(NULL), Hash(Hash), DL(NULL) {}
AssertingVH<Function> Func;
unsigned Hash;
- TargetData *TD;
+ const DataLayout *DL;
};
const ComparableFunction ComparableFunction::EmptyKey = ComparableFunction(0);
const ComparableFunction ComparableFunction::TombstoneKey =
ComparableFunction(1);
+DataLayout *const ComparableFunction::LookupOnly = (DataLayout*)(-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) {
- initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
- }
-
- bool runOnModule(Module &M);
-
-private:
- typedef DenseSet<ComparableFunction> FnSetType;
-
-
- /// Insert a ComparableFunction into the FnSet, or merge it away if it's
- /// equal to one that's already present.
- bool Insert(FnSetType &FnSet, ComparableFunction &NewF);
-
- /// 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) const;
-
- /// 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) const;
-
- TargetData *TD;
-};
-
-} // 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
+/// they will generate machine code with the same behaviour. DataLayout is
/// used if available. The comparator always fails conservatively (erring on the
/// side of claiming that two functions are different).
class FunctionComparator {
public:
- FunctionComparator(const TargetData *TD, const Function *F1,
+ FunctionComparator(const DataLayout *DL, const Function *F1,
const Function *F2)
- : F1(F1), F2(F2), TD(TD), IDMap1Count(0), IDMap2Count(0) {}
+ : F1(F1), F2(F2), DL(DL) {}
- /// 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.
- bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
+ /// cmpType - compares two types,
+ /// defines total ordering among the types set.
+ ///
+ /// Return values:
+ /// 0 if types are equal,
+ /// -1 if Left is less than Right,
+ /// +1 if Left is greater than Right.
+ ///
+ /// Description:
+ /// Comparison is broken onto stages. Like in lexicographical comparison
+ /// stage coming first has higher priority.
+ /// On each explanation stage keep in mind total ordering properties.
+ ///
+ /// 0. Before comparison we coerce pointer types of 0 address space to
+ /// integer.
+ /// We also don't bother with same type at left and right, so
+ /// just return 0 in this case.
+ ///
+ /// 1. If types are of different kind (different type IDs).
+ /// Return result of type IDs comparison, treating them as numbers.
+ /// 2. If types are vectors or integers, compare Type* values as numbers.
+ /// 3. Types has same ID, so check whether they belongs to the next group:
+ /// * Void
+ /// * Float
+ /// * Double
+ /// * X86_FP80
+ /// * FP128
+ /// * PPC_FP128
+ /// * Label
+ /// * Metadata
+ /// If so - return 0, yes - we can treat these types as equal only because
+ /// their IDs are same.
+ /// 4. If Left and Right are pointers, return result of address space
+ /// comparison (numbers comparison). We can treat pointer types of same
+ /// address space as equal.
+ /// 5. If types are complex.
+ /// Then both Left and Right are to be expanded and their element types will
+ /// be checked with the same way. If we get Res != 0 on some stage, return it.
+ /// Otherwise return 0.
+ /// 6. For all other cases put llvm_unreachable.
+ int cmpType(Type *TyL, Type *TyR) const;
+
+ bool isEquivalentType(Type *Ty1, Type *Ty2) const {
+ return cmpType(Ty1, Ty2) == 0;
+ }
+
+ int cmpNumbers(uint64_t L, uint64_t R) const;
// The two functions undergoing comparison.
const Function *F1, *F2;
- const TargetData *TD;
+ const DataLayout *DL;
- 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.
-bool FunctionComparator::isEquivalentType(const Type *Ty1,
- const Type *Ty2) const {
- if (Ty1 == Ty2)
- return true;
- if (Ty1->getTypeID() != Ty2->getTypeID())
- return false;
+int FunctionComparator::cmpNumbers(uint64_t L, uint64_t R) const {
+ if (L < R) return -1;
+ if (L > R) return 1;
+ return 0;
+}
+
+/// cmpType - compares two types,
+/// defines total ordering among the types set.
+/// See method declaration comments for more details.
+int FunctionComparator::cmpType(Type *TyL, Type *TyR) const {
+
+ PointerType *PTyL = dyn_cast<PointerType>(TyL);
+ PointerType *PTyR = dyn_cast<PointerType>(TyR);
+
+ if (DL) {
+ if (PTyL && PTyL->getAddressSpace() == 0) TyL = DL->getIntPtrType(TyL);
+ if (PTyR && PTyR->getAddressSpace() == 0) TyR = DL->getIntPtrType(TyR);
+ }
- switch(Ty1->getTypeID()) {
+ if (TyL == TyR)
+ return 0;
+
+ if (int Res = cmpNumbers(TyL->getTypeID(), TyR->getTypeID()))
+ return Res;
+
+ switch (TyL->getTypeID()) {
default:
llvm_unreachable("Unknown type!");
// Fall through in Release mode.
case Type::IntegerTyID:
- case Type::OpaqueTyID:
- // Ty1 == Ty2 would have returned true earlier.
- return false;
+ case Type::VectorTyID:
+ // TyL == TyR would have returned true earlier.
+ return cmpNumbers((uint64_t)TyL, (uint64_t)TyR);
case Type::VoidTyID:
case Type::FloatTyID:
case Type::PPC_FP128TyID:
case Type::LabelTyID:
case Type::MetadataTyID:
- return true;
+ return 0;
case Type::PointerTyID: {
- const PointerType *PTy1 = cast<PointerType>(Ty1);
- const PointerType *PTy2 = cast<PointerType>(Ty2);
- return PTy1->getAddressSpace() == PTy2->getAddressSpace();
+ assert(PTyL && PTyR && "Both types must be pointers here.");
+ return cmpNumbers(PTyL->getAddressSpace(), PTyR->getAddressSpace());
}
case Type::StructTyID: {
- const StructType *STy1 = cast<StructType>(Ty1);
- const StructType *STy2 = cast<StructType>(Ty2);
- if (STy1->getNumElements() != STy2->getNumElements())
- return false;
-
- if (STy1->isPacked() != STy2->isPacked())
- return false;
-
- for (unsigned i = 0, e = STy1->getNumElements(); i != e; ++i) {
- if (!isEquivalentType(STy1->getElementType(i), STy2->getElementType(i)))
- return false;
+ StructType *STyL = cast<StructType>(TyL);
+ StructType *STyR = cast<StructType>(TyR);
+ if (STyL->getNumElements() != STyR->getNumElements())
+ return cmpNumbers(STyL->getNumElements(), STyR->getNumElements());
+
+ if (STyL->isPacked() != STyR->isPacked())
+ return cmpNumbers(STyL->isPacked(), STyR->isPacked());
+
+ for (unsigned i = 0, e = STyL->getNumElements(); i != e; ++i) {
+ if (int Res = cmpType(STyL->getElementType(i),
+ STyR->getElementType(i)))
+ return Res;
}
- return true;
+ return 0;
}
case Type::FunctionTyID: {
- const FunctionType *FTy1 = cast<FunctionType>(Ty1);
- const FunctionType *FTy2 = cast<FunctionType>(Ty2);
- if (FTy1->getNumParams() != FTy2->getNumParams() ||
- FTy1->isVarArg() != FTy2->isVarArg())
- return false;
+ FunctionType *FTyL = cast<FunctionType>(TyL);
+ FunctionType *FTyR = cast<FunctionType>(TyR);
+ if (FTyL->getNumParams() != FTyR->getNumParams())
+ return cmpNumbers(FTyL->getNumParams(), FTyR->getNumParams());
- if (!isEquivalentType(FTy1->getReturnType(), FTy2->getReturnType()))
- return false;
+ if (FTyL->isVarArg() != FTyR->isVarArg())
+ return cmpNumbers(FTyL->isVarArg(), FTyR->isVarArg());
- for (unsigned i = 0, e = FTy1->getNumParams(); i != e; ++i) {
- if (!isEquivalentType(FTy1->getParamType(i), FTy2->getParamType(i)))
- return false;
+ if (int Res = cmpType(FTyL->getReturnType(), FTyR->getReturnType()))
+ return Res;
+
+ for (unsigned i = 0, e = FTyL->getNumParams(); i != e; ++i) {
+ if (int Res = cmpType(FTyL->getParamType(i), FTyR->getParamType(i)))
+ return Res;
}
- return true;
+ return 0;
}
case Type::ArrayTyID: {
- const ArrayType *ATy1 = cast<ArrayType>(Ty1);
- const ArrayType *ATy2 = cast<ArrayType>(Ty2);
- 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());
+ ArrayType *ATyL = cast<ArrayType>(TyL);
+ ArrayType *ATyR = cast<ArrayType>(TyR);
+ if (ATyL->getNumElements() != ATyR->getNumElements())
+ return cmpNumbers(ATyL->getNumElements(), ATyR->getNumElements());
+ return cmpType(ATyL->getElementType(), ATyR->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()) ||
// Check special state that is a part of some instructions.
if (const LoadInst *LI = dyn_cast<LoadInst>(I1))
return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
- LI->getAlignment() == cast<LoadInst>(I2)->getAlignment();
+ LI->getAlignment() == cast<LoadInst>(I2)->getAlignment() &&
+ LI->getOrdering() == cast<LoadInst>(I2)->getOrdering() &&
+ LI->getSynchScope() == cast<LoadInst>(I2)->getSynchScope();
if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
- SI->getAlignment() == cast<StoreInst>(I2)->getAlignment();
+ SI->getAlignment() == cast<StoreInst>(I2)->getAlignment() &&
+ SI->getOrdering() == cast<StoreInst>(I2)->getOrdering() &&
+ SI->getSynchScope() == cast<StoreInst>(I2)->getSynchScope();
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();
- if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
- if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
- return false;
- for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
- if (IVI->idx_begin()[i] != cast<InsertValueInst>(I2)->idx_begin()[i])
- return false;
- return true;
- }
- if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1)) {
- if (EVI->getNumIndices() != cast<ExtractValueInst>(I2)->getNumIndices())
- return false;
- for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
- if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I2)->idx_begin()[i])
- return false;
- return true;
- }
+ CI->getAttributes() == cast<InvokeInst>(I2)->getAttributes();
+ if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1))
+ return IVI->getIndices() == cast<InsertValueInst>(I2)->getIndices();
+ if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1))
+ return EVI->getIndices() == cast<ExtractValueInst>(I2)->getIndices();
+ if (const FenceInst *FI = dyn_cast<FenceInst>(I1))
+ return FI->getOrdering() == cast<FenceInst>(I2)->getOrdering() &&
+ FI->getSynchScope() == cast<FenceInst>(I2)->getSynchScope();
+ if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(I1))
+ return CXI->isVolatile() == cast<AtomicCmpXchgInst>(I2)->isVolatile() &&
+ CXI->getSuccessOrdering() ==
+ cast<AtomicCmpXchgInst>(I2)->getSuccessOrdering() &&
+ CXI->getFailureOrdering() ==
+ cast<AtomicCmpXchgInst>(I2)->getFailureOrdering() &&
+ CXI->getSynchScope() == cast<AtomicCmpXchgInst>(I2)->getSynchScope();
+ if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I1))
+ return RMWI->getOperation() == cast<AtomicRMWInst>(I2)->getOperation() &&
+ RMWI->isVolatile() == cast<AtomicRMWInst>(I2)->isVolatile() &&
+ RMWI->getOrdering() == cast<AtomicRMWInst>(I2)->getOrdering() &&
+ RMWI->getSynchScope() == cast<AtomicRMWInst>(I2)->getSynchScope();
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
- // added to the address.
- if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) {
- SmallVector<Value *, 8> Indices1(GEP1->idx_begin(), GEP1->idx_end());
- SmallVector<Value *, 8> Indices2(GEP2->idx_begin(), GEP2->idx_end());
- uint64_t Offset1 = TD->getIndexedOffset(GEP1->getPointerOperandType(),
- Indices1.data(), Indices1.size());
- uint64_t Offset2 = TD->getIndexedOffset(GEP2->getPointerOperandType(),
- Indices2.data(), Indices2.size());
- return Offset1 == Offset2;
+ unsigned AS = GEP1->getPointerAddressSpace();
+ if (AS != GEP2->getPointerAddressSpace())
+ return false;
+
+ if (DL) {
+ // When we have target data, we can reduce the GEP down to the value in bytes
+ // added to the address.
+ unsigned BitWidth = DL ? DL->getPointerSizeInBits(AS) : 1;
+ APInt Offset1(BitWidth, 0), Offset2(BitWidth, 0);
+ if (GEP1->accumulateConstantOffset(*DL, Offset1) &&
+ GEP2->accumulateConstantOffset(*DL, Offset2)) {
+ return Offset1 == Offset2;
+ }
}
if (GEP1->getPointerOperand()->getType() !=
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;
}
-/// 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) const {
+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) override;
+
+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;
+
+ /// DataLayout for more accurate GEP comparisons. May be NULL.
+ const DataLayout *DL;
+
+ /// 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;
+ DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : 0;
+
+ 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, DL);
+ 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, DL);
+ 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.getDataLayout() == ComparableFunction::LookupOnly ||
+ RHS.getDataLayout() == ComparableFunction::LookupOnly)
+ return false;
+
+ assert(LHS.getDataLayout() == RHS.getDataLayout() &&
+ "Comparing functions for different targets");
+
+ return FunctionComparator(LHS.getDataLayout(), 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 (auto UI = Old->use_begin(), UE = Old->use_end(); UI != UE;) {
+ Use *U = &*UI;
+ ++UI;
+ CallSite CS(U->getUser());
+ if (CS && CS.isCallee(U)) {
+ remove(CS.getInstruction()->getParent()->getParent());
+ U->set(BitcastNew);
+ }
+ }
+}
+
+// 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);
+ return;
+ }
+ }
+
+ writeThunk(F, G);
+}
+
+// Helper for writeThunk,
+// Selects proper bitcast operation,
+// but a bit simpler then CastInst::getCastOpcode.
+static Value* createCast(IRBuilder<false> &Builder, Value *V, Type *DestTy) {
+ Type *SrcTy = V->getType();
+ if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
+ return Builder.CreateIntToPtr(V, DestTy);
+ else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
+ return Builder.CreatePtrToInt(V, DestTy);
+ else
+ return Builder.CreateBitCast(V, DestTy);
+}
+
+// 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.
- Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
- for (Value::use_iterator UI = G->use_begin(), UE = G->use_end();
- UI != UE;) {
- Value::use_iterator TheIter = UI;
- ++UI;
- CallSite CS(*TheIter);
- if (CS && CS.isCallee(TheIter))
- TheIter.getUse().set(BitcastF);
- }
+ replaceDirectCallers(G, F);
}
// If G was internal then we may have replaced all uses of G with F. If so,
SmallVector<Value *, 16> Args;
unsigned i = 0;
- const FunctionType *FFTy = F->getFunctionType();
+ FunctionType *FFTy = F->getFunctionType();
for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
AI != AE; ++AI) {
- Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
+ Args.push_back(createCast(Builder, (Value*)AI, FFTy->getParamType(i)));
++i;
}
- CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
+ CallInst *CI = Builder.CreateCall(F, Args);
CI->setTailCall();
CI->setCallingConv(F->getCallingConv());
if (NewG->getReturnType()->isVoidTy()) {
Builder.CreateRetVoid();
} else {
- Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
+ Builder.CreateRet(createCast(Builder, CI, NewG->getReturnType()));
}
NewG->copyAttributesFrom(G);
NewG->takeName(G);
+ removeUsers(G);
G->replaceAllUsesWith(NewG);
G->eraseFromParent();
- DEBUG(dbgs() << "WriteThunk: " << NewG->getName() << '\n');
+ DEBUG(dbgs() << "writeThunk: " << NewG->getName() << '\n');
++NumThunksWritten;
}
-/// MergeTwoFunctions - Merge two equivalent functions. Upon completion,
-/// Function G is deleted.
-void MergeFunctions::MergeTwoFunctions(Function *F, Function *G) const {
+// 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);
+ G->replaceAllUsesWith(GA);
+ G->eraseFromParent();
+
+ DEBUG(dbgs() << "writeAlias: " << GA->getName() << '\n');
+ ++NumAliasesWritten;
+}
+
+// Merge two equivalent functions. Upon completion, Function G is deleted.
+void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
if (F->mayBeOverridden()) {
assert(G->mayBeOverridden());
- // Make them both thunks to the same internal function.
- Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
- F->getParent());
- H->copyAttributesFrom(F);
- H->takeName(F);
- F->replaceAllUsesWith(H);
+ if (HasGlobalAliases) {
+ // Make them both thunks to the same internal function.
+ Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
+ F->getParent());
+ H->copyAttributesFrom(F);
+ H->takeName(F);
+ removeUsers(F);
+ F->replaceAllUsesWith(H);
- unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
+ unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
- WriteThunk(F, G);
- WriteThunk(F, H);
+ writeAlias(F, G);
+ writeAlias(F, H);
- F->setAlignment(MaxAlignment);
- F->setLinkage(GlobalValue::InternalLinkage);
+ F->setAlignment(MaxAlignment);
+ F->setLinkage(GlobalValue::PrivateLinkage);
+ } else {
+ // We can't merge them. Instead, pick one and update all direct callers
+ // to call it and hope that we improve the instruction cache hit rate.
+ replaceDirectCallers(G, F);
+ }
++NumDoubleWeak;
} else {
- WriteThunk(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(FnSetType &FnSet, 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;
+ // Don't merge tiny functions, since it can just end up making the function
+ // larger.
+ // FIXME: Should still merge them if they are unnamed_addr and produce an
+ // alias.
+ if (NewF.getFunc()->size() == 1) {
+ if (NewF.getFunc()->front().size() <= 2) {
+ DEBUG(dbgs() << NewF.getFunc()->getName()
+ << " is to small to bother merging\n");
+ return false;
+ }
+ }
+
// Never thunk a strong function to a weak function.
assert(!OldF.getFunc()->mayBeOverridden() ||
NewF.getFunc()->mayBeOverridden());
Function *DeleteF = NewF.getFunc();
NewF.release();
- MergeTwoFunctions(OldF.getFunc(), DeleteF);
+ mergeTwoFunctions(OldF.getFunc(), DeleteF);
return true;
}
-// IsThunk - This method determines whether or not a given Function is a thunk\// like the ones emitted by this pass and therefore not subject to further
-// merging.
-static bool IsThunk(const Function *F) {
- // The safe direction to fail is to return true. In that case, the function
- // will be removed from merging analysis. If we failed to including functions
- // then we may try to merge unmergable thing (ie., identical weak functions)
- // which will push us into an infinite loop.
-
- assert(!F->isDeclaration() && "Expected a function definition.");
-
- const BasicBlock *BB = &F->front();
- // A thunk is:
- // bitcast-inst*
- // optional-reg tail call @thunkee(args...*)
- // ret void|optional-reg
- // where the args are in the same order as the arguments.
-
- // Put this at the top since it triggers most often.
- const ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
- if (!RI) return false;
-
- // Verify that the sequence of bitcast-inst's are all casts of arguments and
- // that there aren't any extras (ie. no repeated casts).
- int LastArgNo = -1;
- BasicBlock::const_iterator I = BB->begin();
- while (const BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
- const Argument *A = dyn_cast<Argument>(BCI->getOperand(0));
- if (!A) return false;
- if ((int)A->getArgNo() <= LastArgNo) return false;
- LastArgNo = A->getArgNo();
- ++I;
- }
-
- // Verify that we have a direct tail call and that the calling conventions
- // and number of arguments match.
- const CallInst *CI = dyn_cast<CallInst>(I++);
- if (!CI || !CI->isTailCall() || !CI->getCalledFunction() ||
- CI->getCallingConv() != CI->getCalledFunction()->getCallingConv() ||
- CI->getNumArgOperands() != F->arg_size())
- return false;
-
- // Verify that the call instruction has the same arguments as this function
- // and that they're all either the incoming argument or a cast of the right
- // argument.
- for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) {
- const Value *V = CI->getArgOperand(i);
- const Argument *A = dyn_cast<Argument>(V);
- if (!A) {
- const BitCastInst *BCI = dyn_cast<BitCastInst>(V);
- if (!BCI) return false;
- A = cast<Argument>(BCI->getOperand(0));
- }
- if (A->getArgNo() != i) return false;
- }
-
- // Verify that the terminator is a ret void (if we're void) or a ret of the
- // call's return, or a ret of a bitcast of the call's return.
- if (const BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
- ++I;
- if (BCI->getOperand(0) != CI) return false;
+// 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);
}
- if (RI != I) return false;
- if (RI->getNumOperands() == 0)
- return CI->getType()->isVoidTy();
- return RI->getReturnValue() == CI;
}
-bool MergeFunctions::runOnModule(Module &M) {
- bool Changed = false;
- TD = getAnalysisIfAvailable<TargetData>();
-
- bool LocalChanged;
- do {
- DEBUG(dbgs() << "size of module: " << M.size() << '\n');
- LocalChanged = false;
- FnSetType FnSet;
-
- // Insert only strong functions and merge them. Strong function merging
- // always deletes one of them.
- for (Module::iterator I = M.begin(), E = M.end(); I != E;) {
- Function *F = I++;
- if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
- !F->mayBeOverridden() && !IsThunk(F)) {
- ComparableFunction CF = ComparableFunction(F, TD);
- LocalChanged |= Insert(FnSet, 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 (Module::iterator I = M.begin(), E = M.end(); I != E;) {
- Function *F = I++;
- if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
- F->mayBeOverridden() && !IsThunk(F)) {
- ComparableFunction CF = ComparableFunction(F, TD);
- LocalChanged |= Insert(FnSet, CF);
+// 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()) {
+ Value *V = Worklist.back();
+ Worklist.pop_back();
+
+ for (User *U : V->users()) {
+ if (Instruction *I = dyn_cast<Instruction>(U)) {
+ remove(I->getParent()->getParent());
+ } else if (isa<GlobalValue>(U)) {
+ // do nothing
+ } else if (Constant *C = dyn_cast<Constant>(U)) {
+ for (User *UU : C->users())
+ Worklist.push_back(UU);
}
}
- DEBUG(dbgs() << "size of FnSet: " << FnSet.size() << '\n');
- Changed |= LocalChanged;
- } while (LocalChanged);
-
- 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");
- return FunctionComparator(LHS.getTD(),
- LHS.getFunc(), RHS.getFunc()).Compare();
+ }
}
projects / oota-llvm.git / blobdiff