#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/IRBuilder.h"
+#include "llvm/Support/PatternMatch.h"
using namespace llvm;
+using namespace PatternMatch;
STATISTIC(NumGVNInstr, "Number of instructions deleted");
STATISTIC(NumGVNLoad, "Number of loads deleted");
STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
STATISTIC(NumGVNBlocks, "Number of blocks merged");
+STATISTIC(NumGVNSimpl, "Number of instructions simplified");
+STATISTIC(NumGVNEqProp, "Number of equalities propagated");
STATISTIC(NumPRELoad, "Number of loads PRE'd");
static cl::opt<bool> EnablePRE("enable-pre",
namespace {
struct Expression {
uint32_t opcode;
- const Type* type;
+ Type *type;
SmallVector<uint32_t, 4> varargs;
- Expression() { }
- Expression(uint32_t o) : opcode(o) { }
+ Expression(uint32_t o = ~2U) : opcode(o) { }
bool operator==(const Expression &other) const {
if (opcode != other.opcode)
return false;
- else if (opcode == ~0U || opcode == ~1U)
+ if (opcode == ~0U || opcode == ~1U)
return true;
- else if (type != other.type)
+ if (type != other.type)
return false;
- else if (varargs != other.varargs)
+ if (varargs != other.varargs)
return false;
return true;
}
};
class ValueTable {
- private:
- DenseMap<Value*, uint32_t> valueNumbering;
- DenseMap<Expression, uint32_t> expressionNumbering;
- AliasAnalysis* AA;
- MemoryDependenceAnalysis* MD;
- DominatorTree* DT;
-
- uint32_t nextValueNumber;
-
- Expression create_expression(Instruction* I);
- uint32_t lookup_or_add_call(CallInst* C);
- public:
- ValueTable() : nextValueNumber(1) { }
- uint32_t lookup_or_add(Value *V);
- uint32_t lookup(Value *V) const;
- void add(Value *V, uint32_t num);
- void clear();
- void erase(Value *v);
- void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
- AliasAnalysis *getAliasAnalysis() const { return AA; }
- void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
- void setDomTree(DominatorTree* D) { DT = D; }
- uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
- void verifyRemoved(const Value *) const;
+ DenseMap<Value*, uint32_t> valueNumbering;
+ DenseMap<Expression, uint32_t> expressionNumbering;
+ AliasAnalysis *AA;
+ MemoryDependenceAnalysis *MD;
+ DominatorTree *DT;
+
+ uint32_t nextValueNumber;
+
+ Expression create_expression(Instruction* I);
+ Expression create_extractvalue_expression(ExtractValueInst* EI);
+ uint32_t lookup_or_add_call(CallInst* C);
+ public:
+ ValueTable() : nextValueNumber(1) { }
+ uint32_t lookup_or_add(Value *V);
+ uint32_t lookup(Value *V) const;
+ void add(Value *V, uint32_t num);
+ void clear();
+ void erase(Value *v);
+ void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
+ AliasAnalysis *getAliasAnalysis() const { return AA; }
+ void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
+ void setDomTree(DominatorTree* D) { DT = D; }
+ uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
+ void verifyRemoved(const Value *) const;
};
}
// ValueTable Internal Functions
//===----------------------------------------------------------------------===//
-
Expression ValueTable::create_expression(Instruction *I) {
Expression e;
e.type = I->getType();
OI != OE; ++OI)
e.varargs.push_back(lookup_or_add(*OI));
- if (CmpInst *C = dyn_cast<CmpInst>(I))
+ if (CmpInst *C = dyn_cast<CmpInst>(I)) {
e.opcode = (C->getOpcode() << 8) | C->getPredicate();
- else if (ExtractValueInst *E = dyn_cast<ExtractValueInst>(I)) {
- for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
- II != IE; ++II)
- e.varargs.push_back(*II);
} else if (InsertValueInst *E = dyn_cast<InsertValueInst>(I)) {
for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
II != IE; ++II)
return e;
}
+Expression ValueTable::create_extractvalue_expression(ExtractValueInst *EI) {
+ assert(EI != 0 && "Not an ExtractValueInst?");
+ Expression e;
+ e.type = EI->getType();
+ e.opcode = 0;
+
+ IntrinsicInst *I = dyn_cast<IntrinsicInst>(EI->getAggregateOperand());
+ if (I != 0 && EI->getNumIndices() == 1 && *EI->idx_begin() == 0 ) {
+ // EI might be an extract from one of our recognised intrinsics. If it
+ // is we'll synthesize a semantically equivalent expression instead on
+ // an extract value expression.
+ switch (I->getIntrinsicID()) {
+ case Intrinsic::sadd_with_overflow:
+ case Intrinsic::uadd_with_overflow:
+ e.opcode = Instruction::Add;
+ break;
+ case Intrinsic::ssub_with_overflow:
+ case Intrinsic::usub_with_overflow:
+ e.opcode = Instruction::Sub;
+ break;
+ case Intrinsic::smul_with_overflow:
+ case Intrinsic::umul_with_overflow:
+ e.opcode = Instruction::Mul;
+ break;
+ default:
+ break;
+ }
+
+ if (e.opcode != 0) {
+ // Intrinsic recognized. Grab its args to finish building the expression.
+ assert(I->getNumArgOperands() == 2 &&
+ "Expect two args for recognised intrinsics.");
+ e.varargs.push_back(lookup_or_add(I->getArgOperand(0)));
+ e.varargs.push_back(lookup_or_add(I->getArgOperand(1)));
+ return e;
+ }
+ }
+
+ // Not a recognised intrinsic. Fall back to producing an extract value
+ // expression.
+ e.opcode = EI->getOpcode();
+ for (Instruction::op_iterator OI = EI->op_begin(), OE = EI->op_end();
+ OI != OE; ++OI)
+ e.varargs.push_back(lookup_or_add(*OI));
+
+ for (ExtractValueInst::idx_iterator II = EI->idx_begin(), IE = EI->idx_end();
+ II != IE; ++II)
+ e.varargs.push_back(*II);
+
+ return e;
+}
+
//===----------------------------------------------------------------------===//
// ValueTable External Functions
//===----------------------------------------------------------------------===//
// Non-local case.
const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
MD->getNonLocalCallDependency(CallSite(C));
- // FIXME: call/call dependencies for readonly calls should return def, not
- // clobber! Move the checking logic to MemDep!
+ // FIXME: Move the checking logic to MemDep!
CallInst* cdep = 0;
// Check to see if we have a single dominating call instruction that is
// identical to C.
for (unsigned i = 0, e = deps.size(); i != e; ++i) {
const NonLocalDepEntry *I = &deps[i];
- // Ignore non-local dependencies.
if (I->getResult().isNonLocal())
continue;
- // We don't handle non-depedencies. If we already have a call, reject
+ // We don't handle non-definitions. If we already have a call, reject
// instruction dependencies.
- if (I->getResult().isClobber() || cdep != 0) {
+ if (!I->getResult().isDef() || cdep != 0) {
cdep = 0;
break;
}
case Instruction::ExtractElement:
case Instruction::InsertElement:
case Instruction::ShuffleVector:
- case Instruction::ExtractValue:
case Instruction::InsertValue:
case Instruction::GetElementPtr:
exp = create_expression(I);
break;
+ case Instruction::ExtractValue:
+ exp = create_extractvalue_expression(cast<ExtractValueInst>(I));
+ break;
default:
valueNumbering[V] = nextValueNumber;
return nextValueNumber++;
return VI->second;
}
-/// clear - Remove all entries from the ValueTable
+/// clear - Remove all entries from the ValueTable.
void ValueTable::clear() {
valueNumbering.clear();
expressionNumbering.clear();
nextValueNumber = 1;
}
-/// erase - Remove a value from the value numbering
+/// erase - Remove a value from the value numbering.
void ValueTable::erase(Value *V) {
valueNumbering.erase(V);
}
namespace {
class GVN : public FunctionPass {
- bool runOnFunction(Function &F);
- public:
- static char ID; // Pass identification, replacement for typeid
- explicit GVN(bool noloads = false)
- : FunctionPass(ID), NoLoads(noloads), MD(0) {
- initializeGVNPass(*PassRegistry::getPassRegistry());
- }
-
- private:
bool NoLoads;
MemoryDependenceAnalysis *MD;
DominatorTree *DT;
- const TargetData* TD;
+ const TargetData *TD;
+ const TargetLibraryInfo *TLI;
ValueTable VN;
DenseMap<uint32_t, LeaderTableEntry> LeaderTable;
BumpPtrAllocator TableAllocator;
+ SmallVector<Instruction*, 8> InstrsToErase;
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ explicit GVN(bool noloads = false)
+ : FunctionPass(ID), NoLoads(noloads), MD(0) {
+ initializeGVNPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F);
+
+ /// markInstructionForDeletion - This removes the specified instruction from
+ /// our various maps and marks it for deletion.
+ void markInstructionForDeletion(Instruction *I) {
+ VN.erase(I);
+ InstrsToErase.push_back(I);
+ }
+
+ const TargetData *getTargetData() const { return TD; }
+ DominatorTree &getDominatorTree() const { return *DT; }
+ AliasAnalysis *getAliasAnalysis() const { return VN.getAliasAnalysis(); }
+ MemoryDependenceAnalysis &getMemDep() const { return *MD; }
+ private:
/// addToLeaderTable - Push a new Value to the LeaderTable onto the list for
/// its value number.
void addToLeaderTable(uint32_t N, Value *V, BasicBlock *BB) {
- LeaderTableEntry& Curr = LeaderTable[N];
+ LeaderTableEntry &Curr = LeaderTable[N];
if (!Curr.Val) {
Curr.Val = V;
Curr.BB = BB;
return;
}
- LeaderTableEntry* Node = TableAllocator.Allocate<LeaderTableEntry>();
+ LeaderTableEntry *Node = TableAllocator.Allocate<LeaderTableEntry>();
Node->Val = V;
Node->BB = BB;
Node->Next = Curr.Next;
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
+ AU.addRequired<TargetLibraryInfo>();
if (!NoLoads)
AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<AliasAnalysis>();
}
+
// Helper fuctions
// FIXME: eliminate or document these better
- bool processLoad(LoadInst* L,
- SmallVectorImpl<Instruction*> &toErase);
- bool processInstruction(Instruction *I,
- SmallVectorImpl<Instruction*> &toErase);
- bool processNonLocalLoad(LoadInst* L,
- SmallVectorImpl<Instruction*> &toErase);
+ bool processLoad(LoadInst *L);
+ bool processInstruction(Instruction *I);
+ bool processNonLocalLoad(LoadInst *L);
bool processBlock(BasicBlock *BB);
- void dump(DenseMap<uint32_t, Value*>& d);
+ void dump(DenseMap<uint32_t, Value*> &d);
bool iterateOnFunction(Function &F);
- bool performPRE(Function& F);
+ bool performPRE(Function &F);
Value *findLeader(BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
void verifyRemoved(const Instruction *I) const;
bool splitCriticalEdges();
+ unsigned replaceAllDominatedUsesWith(Value *From, Value *To,
+ BasicBlock *Root);
+ bool propagateEquality(Value *LHS, Value *RHS, BasicBlock *Root);
};
char GVN::ID = 0;
INITIALIZE_PASS_BEGIN(GVN, "gvn", "Global Value Numbering", false, false)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(GVN, "gvn", "Global Value Numbering", false, false)
/// CanCoerceMustAliasedValueToLoad - Return true if
/// CoerceAvailableValueToLoadType will succeed.
static bool CanCoerceMustAliasedValueToLoad(Value *StoredVal,
- const Type *LoadTy,
+ Type *LoadTy,
const TargetData &TD) {
// If the loaded or stored value is an first class array or struct, don't try
// to transform them. We need to be able to bitcast to integer.
///
/// If we can't do it, return null.
static Value *CoerceAvailableValueToLoadType(Value *StoredVal,
- const Type *LoadedTy,
+ Type *LoadedTy,
Instruction *InsertPt,
const TargetData &TD) {
if (!CanCoerceMustAliasedValueToLoad(StoredVal, LoadedTy, TD))
return 0;
- const Type *StoredValTy = StoredVal->getType();
+ // If this is already the right type, just return it.
+ Type *StoredValTy = StoredVal->getType();
- uint64_t StoreSize = TD.getTypeStoreSizeInBits(StoredValTy);
+ uint64_t StoreSize = TD.getTypeSizeInBits(StoredValTy);
uint64_t LoadSize = TD.getTypeSizeInBits(LoadedTy);
// If the store and reload are the same size, we can always reuse it.
if (StoreSize == LoadSize) {
- if (StoredValTy->isPointerTy() && LoadedTy->isPointerTy()) {
- // Pointer to Pointer -> use bitcast.
+ // Pointer to Pointer -> use bitcast.
+ if (StoredValTy->isPointerTy() && LoadedTy->isPointerTy())
return new BitCastInst(StoredVal, LoadedTy, "", InsertPt);
- }
// Convert source pointers to integers, which can be bitcast.
if (StoredValTy->isPointerTy()) {
StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
}
- const Type *TypeToCastTo = LoadedTy;
+ Type *TypeToCastTo = LoadedTy;
if (TypeToCastTo->isPointerTy())
TypeToCastTo = TD.getIntPtrType(StoredValTy->getContext());
}
// Truncate the integer to the right size now.
- const Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadSize);
+ Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadSize);
StoredVal = new TruncInst(StoredVal, NewIntTy, "trunc", InsertPt);
if (LoadedTy == NewIntTy)
/// Check this case to see if there is anything more we can do before we give
/// up. This returns -1 if we have to give up, or a byte number in the stored
/// value of the piece that feeds the load.
-static int AnalyzeLoadFromClobberingWrite(const Type *LoadTy, Value *LoadPtr,
+static int AnalyzeLoadFromClobberingWrite(Type *LoadTy, Value *LoadPtr,
Value *WritePtr,
uint64_t WriteSizeInBits,
const TargetData &TD) {
- // If the loaded or stored value is an first class array or struct, don't try
+ // If the loaded or stored value is a first class array or struct, don't try
// to transform them. We need to be able to bitcast to integer.
if (LoadTy->isStructTy() || LoadTy->isArrayTy())
return -1;
/// AnalyzeLoadFromClobberingStore - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store.
-static int AnalyzeLoadFromClobberingStore(const Type *LoadTy, Value *LoadPtr,
+static int AnalyzeLoadFromClobberingStore(Type *LoadTy, Value *LoadPtr,
StoreInst *DepSI,
const TargetData &TD) {
// Cannot handle reading from store of first-class aggregate yet.
StorePtr, StoreSize, TD);
}
-static int AnalyzeLoadFromClobberingMemInst(const Type *LoadTy, Value *LoadPtr,
+/// AnalyzeLoadFromClobberingLoad - This function is called when we have a
+/// memdep query of a load that ends up being clobbered by another load. See if
+/// the other load can feed into the second load.
+static int AnalyzeLoadFromClobberingLoad(Type *LoadTy, Value *LoadPtr,
+ LoadInst *DepLI, const TargetData &TD){
+ // Cannot handle reading from store of first-class aggregate yet.
+ if (DepLI->getType()->isStructTy() || DepLI->getType()->isArrayTy())
+ return -1;
+
+ Value *DepPtr = DepLI->getPointerOperand();
+ uint64_t DepSize = TD.getTypeSizeInBits(DepLI->getType());
+ int R = AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr, DepPtr, DepSize, TD);
+ if (R != -1) return R;
+
+ // If we have a load/load clobber an DepLI can be widened to cover this load,
+ // then we should widen it!
+ int64_t LoadOffs = 0;
+ const Value *LoadBase =
+ GetPointerBaseWithConstantOffset(LoadPtr, LoadOffs, TD);
+ unsigned LoadSize = TD.getTypeStoreSize(LoadTy);
+
+ unsigned Size = MemoryDependenceAnalysis::
+ getLoadLoadClobberFullWidthSize(LoadBase, LoadOffs, LoadSize, DepLI, TD);
+ if (Size == 0) return -1;
+
+ return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr, DepPtr, Size*8, TD);
+}
+
+
+
+static int AnalyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
MemIntrinsic *MI,
const TargetData &TD) {
// If the mem operation is a non-constant size, we can't handle it.
Constant *Src = dyn_cast<Constant>(MTI->getSource());
if (Src == 0) return -1;
- GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Src));
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Src, &TD));
if (GV == 0 || !GV->isConstant()) return -1;
// See if the access is within the bounds of the transfer.
llvm::Type::getInt8PtrTy(Src->getContext()));
Constant *OffsetCst =
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
- Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
+ Src = ConstantExpr::getGetElementPtr(Src, OffsetCst);
Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
if (ConstantFoldLoadFromConstPtr(Src, &TD))
return Offset;
/// GetStoreValueForLoad - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
-/// that the store *may* provide bits used by the load but we can't be sure
-/// because the pointers don't mustalias. Check this case to see if there is
-/// anything more we can do before we give up.
+/// that the store provides bits used by the load but we the pointers don't
+/// mustalias. Check this case to see if there is anything more we can do
+/// before we give up.
static Value *GetStoreValueForLoad(Value *SrcVal, unsigned Offset,
- const Type *LoadTy,
+ Type *LoadTy,
Instruction *InsertPt, const TargetData &TD){
LLVMContext &Ctx = SrcVal->getType()->getContext();
// Compute which bits of the stored value are being used by the load. Convert
// to an integer type to start with.
if (SrcVal->getType()->isPointerTy())
- SrcVal = Builder.CreatePtrToInt(SrcVal, TD.getIntPtrType(Ctx), "tmp");
+ SrcVal = Builder.CreatePtrToInt(SrcVal, TD.getIntPtrType(Ctx));
if (!SrcVal->getType()->isIntegerTy())
- SrcVal = Builder.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize*8),
- "tmp");
+ SrcVal = Builder.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize*8));
// Shift the bits to the least significant depending on endianness.
unsigned ShiftAmt;
ShiftAmt = (StoreSize-LoadSize-Offset)*8;
if (ShiftAmt)
- SrcVal = Builder.CreateLShr(SrcVal, ShiftAmt, "tmp");
+ SrcVal = Builder.CreateLShr(SrcVal, ShiftAmt);
if (LoadSize != StoreSize)
- SrcVal = Builder.CreateTrunc(SrcVal, IntegerType::get(Ctx, LoadSize*8),
- "tmp");
+ SrcVal = Builder.CreateTrunc(SrcVal, IntegerType::get(Ctx, LoadSize*8));
return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, TD);
}
+/// GetLoadValueForLoad - This function is called when we have a
+/// memdep query of a load that ends up being a clobbering load. This means
+/// that the load *may* provide bits used by the load but we can't be sure
+/// because the pointers don't mustalias. Check this case to see if there is
+/// anything more we can do before we give up.
+static Value *GetLoadValueForLoad(LoadInst *SrcVal, unsigned Offset,
+ Type *LoadTy, Instruction *InsertPt,
+ GVN &gvn) {
+ const TargetData &TD = *gvn.getTargetData();
+ // If Offset+LoadTy exceeds the size of SrcVal, then we must be wanting to
+ // widen SrcVal out to a larger load.
+ unsigned SrcValSize = TD.getTypeStoreSize(SrcVal->getType());
+ unsigned LoadSize = TD.getTypeStoreSize(LoadTy);
+ if (Offset+LoadSize > SrcValSize) {
+ assert(SrcVal->isSimple() && "Cannot widen volatile/atomic load!");
+ assert(SrcVal->getType()->isIntegerTy() && "Can't widen non-integer load");
+ // If we have a load/load clobber an DepLI can be widened to cover this
+ // load, then we should widen it to the next power of 2 size big enough!
+ unsigned NewLoadSize = Offset+LoadSize;
+ if (!isPowerOf2_32(NewLoadSize))
+ NewLoadSize = NextPowerOf2(NewLoadSize);
+
+ Value *PtrVal = SrcVal->getPointerOperand();
+
+ // Insert the new load after the old load. This ensures that subsequent
+ // memdep queries will find the new load. We can't easily remove the old
+ // load completely because it is already in the value numbering table.
+ IRBuilder<> Builder(SrcVal->getParent(), ++BasicBlock::iterator(SrcVal));
+ Type *DestPTy =
+ IntegerType::get(LoadTy->getContext(), NewLoadSize*8);
+ DestPTy = PointerType::get(DestPTy,
+ cast<PointerType>(PtrVal->getType())->getAddressSpace());
+ Builder.SetCurrentDebugLocation(SrcVal->getDebugLoc());
+ PtrVal = Builder.CreateBitCast(PtrVal, DestPTy);
+ LoadInst *NewLoad = Builder.CreateLoad(PtrVal);
+ NewLoad->takeName(SrcVal);
+ NewLoad->setAlignment(SrcVal->getAlignment());
+
+ DEBUG(dbgs() << "GVN WIDENED LOAD: " << *SrcVal << "\n");
+ DEBUG(dbgs() << "TO: " << *NewLoad << "\n");
+
+ // Replace uses of the original load with the wider load. On a big endian
+ // system, we need to shift down to get the relevant bits.
+ Value *RV = NewLoad;
+ if (TD.isBigEndian())
+ RV = Builder.CreateLShr(RV,
+ NewLoadSize*8-SrcVal->getType()->getPrimitiveSizeInBits());
+ RV = Builder.CreateTrunc(RV, SrcVal->getType());
+ SrcVal->replaceAllUsesWith(RV);
+
+ // We would like to use gvn.markInstructionForDeletion here, but we can't
+ // because the load is already memoized into the leader map table that GVN
+ // tracks. It is potentially possible to remove the load from the table,
+ // but then there all of the operations based on it would need to be
+ // rehashed. Just leave the dead load around.
+ gvn.getMemDep().removeInstruction(SrcVal);
+ SrcVal = NewLoad;
+ }
+
+ return GetStoreValueForLoad(SrcVal, Offset, LoadTy, InsertPt, TD);
+}
+
+
/// GetMemInstValueForLoad - This function is called when we have a
/// memdep query of a load that ends up being a clobbering mem intrinsic.
static Value *GetMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
- const Type *LoadTy, Instruction *InsertPt,
+ Type *LoadTy, Instruction *InsertPt,
const TargetData &TD){
LLVMContext &Ctx = LoadTy->getContext();
uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
llvm::Type::getInt8PtrTy(Src->getContext()));
Constant *OffsetCst =
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
- Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
+ Src = ConstantExpr::getGetElementPtr(Src, OffsetCst);
Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
return ConstantFoldLoadFromConstPtr(Src, &TD);
}
BasicBlock *BB;
enum ValType {
SimpleVal, // A simple offsetted value that is accessed.
+ LoadVal, // A value produced by a load.
MemIntrin // A memory intrinsic which is loaded from.
};
/// V - The value that is live out of the block.
- PointerIntPair<Value *, 1, ValType> Val;
+ PointerIntPair<Value *, 2, ValType> Val;
/// Offset - The byte offset in Val that is interesting for the load query.
unsigned Offset;
return Res;
}
+ static AvailableValueInBlock getLoad(BasicBlock *BB, LoadInst *LI,
+ unsigned Offset = 0) {
+ AvailableValueInBlock Res;
+ Res.BB = BB;
+ Res.Val.setPointer(LI);
+ Res.Val.setInt(LoadVal);
+ Res.Offset = Offset;
+ return Res;
+ }
+
bool isSimpleValue() const { return Val.getInt() == SimpleVal; }
+ bool isCoercedLoadValue() const { return Val.getInt() == LoadVal; }
+ bool isMemIntrinValue() const { return Val.getInt() == MemIntrin; }
+
Value *getSimpleValue() const {
assert(isSimpleValue() && "Wrong accessor");
return Val.getPointer();
}
+ LoadInst *getCoercedLoadValue() const {
+ assert(isCoercedLoadValue() && "Wrong accessor");
+ return cast<LoadInst>(Val.getPointer());
+ }
+
MemIntrinsic *getMemIntrinValue() const {
- assert(!isSimpleValue() && "Wrong accessor");
+ assert(isMemIntrinValue() && "Wrong accessor");
return cast<MemIntrinsic>(Val.getPointer());
}
/// MaterializeAdjustedValue - Emit code into this block to adjust the value
/// defined here to the specified type. This handles various coercion cases.
- Value *MaterializeAdjustedValue(const Type *LoadTy,
- const TargetData *TD) const {
+ Value *MaterializeAdjustedValue(Type *LoadTy, GVN &gvn) const {
Value *Res;
if (isSimpleValue()) {
Res = getSimpleValue();
if (Res->getType() != LoadTy) {
+ const TargetData *TD = gvn.getTargetData();
assert(TD && "Need target data to handle type mismatch case");
Res = GetStoreValueForLoad(Res, Offset, LoadTy, BB->getTerminator(),
*TD);
- DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\nOffset: " << Offset << " "
+ DEBUG(dbgs() << "GVN COERCED NONLOCAL VAL:\nOffset: " << Offset << " "
<< *getSimpleValue() << '\n'
<< *Res << '\n' << "\n\n\n");
}
+ } else if (isCoercedLoadValue()) {
+ LoadInst *Load = getCoercedLoadValue();
+ if (Load->getType() == LoadTy && Offset == 0) {
+ Res = Load;
+ } else {
+ Res = GetLoadValueForLoad(Load, Offset, LoadTy, BB->getTerminator(),
+ gvn);
+
+ DEBUG(dbgs() << "GVN COERCED NONLOCAL LOAD:\nOffset: " << Offset << " "
+ << *getCoercedLoadValue() << '\n'
+ << *Res << '\n' << "\n\n\n");
+ }
} else {
+ const TargetData *TD = gvn.getTargetData();
+ assert(TD && "Need target data to handle type mismatch case");
Res = GetMemInstValueForLoad(getMemIntrinValue(), Offset,
LoadTy, BB->getTerminator(), *TD);
- DEBUG(errs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
+ DEBUG(dbgs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
<< " " << *getMemIntrinValue() << '\n'
<< *Res << '\n' << "\n\n\n");
}
}
};
-}
+} // end anonymous namespace
/// ConstructSSAForLoadSet - Given a set of loads specified by ValuesPerBlock,
/// construct SSA form, allowing us to eliminate LI. This returns the value
/// that should be used at LI's definition site.
static Value *ConstructSSAForLoadSet(LoadInst *LI,
SmallVectorImpl<AvailableValueInBlock> &ValuesPerBlock,
- const TargetData *TD,
- const DominatorTree &DT,
- AliasAnalysis *AA) {
+ GVN &gvn) {
// Check for the fully redundant, dominating load case. In this case, we can
// just use the dominating value directly.
if (ValuesPerBlock.size() == 1 &&
- DT.properlyDominates(ValuesPerBlock[0].BB, LI->getParent()))
- return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), TD);
+ gvn.getDominatorTree().properlyDominates(ValuesPerBlock[0].BB,
+ LI->getParent()))
+ return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), gvn);
// Otherwise, we have to construct SSA form.
SmallVector<PHINode*, 8> NewPHIs;
SSAUpdater SSAUpdate(&NewPHIs);
SSAUpdate.Initialize(LI->getType(), LI->getName());
- const Type *LoadTy = LI->getType();
+ Type *LoadTy = LI->getType();
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
const AvailableValueInBlock &AV = ValuesPerBlock[i];
if (SSAUpdate.HasValueForBlock(BB))
continue;
- SSAUpdate.AddAvailableValue(BB, AV.MaterializeAdjustedValue(LoadTy, TD));
+ SSAUpdate.AddAvailableValue(BB, AV.MaterializeAdjustedValue(LoadTy, gvn));
}
// Perform PHI construction.
Value *V = SSAUpdate.GetValueInMiddleOfBlock(LI->getParent());
// If new PHI nodes were created, notify alias analysis.
- if (V->getType()->isPointerTy())
+ if (V->getType()->isPointerTy()) {
+ AliasAnalysis *AA = gvn.getAliasAnalysis();
+
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
AA->copyValue(LI, NewPHIs[i]);
// escaping uses to any values that are operands to these PHIs.
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i) {
PHINode *P = NewPHIs[i];
- for (unsigned ii = 0, ee = P->getNumIncomingValues(); ii != ee; ++ii)
- AA->addEscapingUse(P->getOperandUse(2*ii));
+ for (unsigned ii = 0, ee = P->getNumIncomingValues(); ii != ee; ++ii) {
+ unsigned jj = PHINode::getOperandNumForIncomingValue(ii);
+ AA->addEscapingUse(P->getOperandUse(jj));
+ }
}
+ }
return V;
}
/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
/// non-local by performing PHI construction.
-bool GVN::processNonLocalLoad(LoadInst *LI,
- SmallVectorImpl<Instruction*> &toErase) {
+bool GVN::processNonLocalLoad(LoadInst *LI) {
// Find the non-local dependencies of the load.
SmallVector<NonLocalDepResult, 64> Deps;
AliasAnalysis::Location Loc = VN.getAliasAnalysis()->getLocation(LI);
// If we had to process more than one hundred blocks to find the
// dependencies, this load isn't worth worrying about. Optimizing
// it will be too expensive.
- if (Deps.size() > 100)
+ unsigned NumDeps = Deps.size();
+ if (NumDeps > 100)
return false;
// If we had a phi translation failure, we'll have a single entry which is a
// clobber in the current block. Reject this early.
- if (Deps.size() == 1 && Deps[0].getResult().isClobber()) {
+ if (NumDeps == 1 &&
+ !Deps[0].getResult().isDef() && !Deps[0].getResult().isClobber()) {
DEBUG(
dbgs() << "GVN: non-local load ";
WriteAsOperand(dbgs(), LI);
- dbgs() << " is clobbered by " << *Deps[0].getResult().getInst() << '\n';
+ dbgs() << " has unknown dependencies\n";
);
return false;
}
// where we have a value available in repl, also keep track of whether we see
// dependencies that produce an unknown value for the load (such as a call
// that could potentially clobber the load).
- SmallVector<AvailableValueInBlock, 16> ValuesPerBlock;
- SmallVector<BasicBlock*, 16> UnavailableBlocks;
+ SmallVector<AvailableValueInBlock, 64> ValuesPerBlock;
+ SmallVector<BasicBlock*, 64> UnavailableBlocks;
- for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
+ for (unsigned i = 0, e = NumDeps; i != e; ++i) {
BasicBlock *DepBB = Deps[i].getBB();
MemDepResult DepInfo = Deps[i].getResult();
+ if (!DepInfo.isDef() && !DepInfo.isClobber()) {
+ UnavailableBlocks.push_back(DepBB);
+ continue;
+ }
+
if (DepInfo.isClobber()) {
// The address being loaded in this non-local block may not be the same as
// the pointer operand of the load if PHI translation occurs. Make sure
}
}
}
+
+ // Check to see if we have something like this:
+ // load i32* P
+ // load i8* (P+1)
+ // if we have this, replace the later with an extraction from the former.
+ if (LoadInst *DepLI = dyn_cast<LoadInst>(DepInfo.getInst())) {
+ // If this is a clobber and L is the first instruction in its block, then
+ // we have the first instruction in the entry block.
+ if (DepLI != LI && Address && TD) {
+ int Offset = AnalyzeLoadFromClobberingLoad(LI->getType(),
+ LI->getPointerOperand(),
+ DepLI, *TD);
+
+ if (Offset != -1) {
+ ValuesPerBlock.push_back(AvailableValueInBlock::getLoad(DepBB,DepLI,
+ Offset));
+ continue;
+ }
+ }
+ }
// If the clobbering value is a memset/memcpy/memmove, see if we can
// forward a value on from it.
continue;
}
+ // DepInfo.isDef() here
+
Instruction *DepInst = DepInfo.getInst();
// Loading the allocation -> undef.
continue;
}
}
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB, LD));
+ ValuesPerBlock.push_back(AvailableValueInBlock::getLoad(DepBB, LD));
continue;
}
DEBUG(dbgs() << "GVN REMOVING NONLOCAL LOAD: " << *LI << '\n');
// Perform PHI construction.
- Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
- VN.getAliasAnalysis());
+ Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, *this);
LI->replaceAllUsesWith(V);
if (isa<PHINode>(V))
V->takeName(LI);
if (V->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
- VN.erase(LI);
- toErase.push_back(LI);
+ markInstructionForDeletion(LI);
++NumGVNLoad;
return true;
}
for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
Blockers.insert(UnavailableBlocks[i]);
- // Lets find first basic block with more than one predecessor. Walk backwards
- // through predecessors if needed.
+ // Let's find the first basic block with more than one predecessor. Walk
+ // backwards through predecessors if needed.
BasicBlock *LoadBB = LI->getParent();
BasicBlock *TmpBB = LoadBB;
<< Pred->getName() << "': " << *LI << '\n');
return false;
}
+
+ if (LoadBB->isLandingPad()) {
+ DEBUG(dbgs()
+ << "COULD NOT PRE LOAD BECAUSE OF LANDING PAD CRITICAL EDGE '"
+ << Pred->getName() << "': " << *LI << '\n');
+ return false;
+ }
+
unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
NeedToSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
}
}
+
if (!NeedToSplit.empty()) {
toSplit.append(NeedToSplit.begin(), NeedToSplit.end());
return false;
if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa))
NewLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+ // Transfer DebugLoc.
+ NewLoad->setDebugLoc(LI->getDebugLoc());
+
// Add the newly created load.
ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,
NewLoad));
}
// Perform PHI construction.
- Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
- VN.getAliasAnalysis());
+ Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, *this);
LI->replaceAllUsesWith(V);
if (isa<PHINode>(V))
V->takeName(LI);
if (V->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
- VN.erase(LI);
- toErase.push_back(LI);
+ markInstructionForDeletion(LI);
++NumPRELoad;
return true;
}
/// processLoad - Attempt to eliminate a load, first by eliminating it
/// locally, and then attempting non-local elimination if that fails.
-bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {
+bool GVN::processLoad(LoadInst *L) {
if (!MD)
return false;
- if (L->isVolatile())
+ if (!L->isSimple())
return false;
+ if (L->use_empty()) {
+ markInstructionForDeletion(L);
+ return true;
+ }
+
// ... to a pointer that has been loaded from before...
MemDepResult Dep = MD->getDependency(L);
- // If the value isn't available, don't do anything!
- if (Dep.isClobber()) {
+ // If we have a clobber and target data is around, see if this is a clobber
+ // that we can fix up through code synthesis.
+ if (Dep.isClobber() && TD) {
// Check to see if we have something like this:
// store i32 123, i32* %P
// %A = bitcast i32* %P to i8*
// completely covers this load. This sort of thing can happen in bitfield
// access code.
Value *AvailVal = 0;
- if (StoreInst *DepSI = dyn_cast<StoreInst>(Dep.getInst()))
- if (TD) {
- int Offset = AnalyzeLoadFromClobberingStore(L->getType(),
- L->getPointerOperand(),
- DepSI, *TD);
- if (Offset != -1)
- AvailVal = GetStoreValueForLoad(DepSI->getValueOperand(), Offset,
- L->getType(), L, *TD);
- }
+ if (StoreInst *DepSI = dyn_cast<StoreInst>(Dep.getInst())) {
+ int Offset = AnalyzeLoadFromClobberingStore(L->getType(),
+ L->getPointerOperand(),
+ DepSI, *TD);
+ if (Offset != -1)
+ AvailVal = GetStoreValueForLoad(DepSI->getValueOperand(), Offset,
+ L->getType(), L, *TD);
+ }
+
+ // Check to see if we have something like this:
+ // load i32* P
+ // load i8* (P+1)
+ // if we have this, replace the later with an extraction from the former.
+ if (LoadInst *DepLI = dyn_cast<LoadInst>(Dep.getInst())) {
+ // If this is a clobber and L is the first instruction in its block, then
+ // we have the first instruction in the entry block.
+ if (DepLI == L)
+ return false;
+
+ int Offset = AnalyzeLoadFromClobberingLoad(L->getType(),
+ L->getPointerOperand(),
+ DepLI, *TD);
+ if (Offset != -1)
+ AvailVal = GetLoadValueForLoad(DepLI, Offset, L->getType(), L, *this);
+ }
// If the clobbering value is a memset/memcpy/memmove, see if we can forward
// a value on from it.
if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(Dep.getInst())) {
- if (TD) {
- int Offset = AnalyzeLoadFromClobberingMemInst(L->getType(),
- L->getPointerOperand(),
- DepMI, *TD);
- if (Offset != -1)
- AvailVal = GetMemInstValueForLoad(DepMI, Offset, L->getType(), L,*TD);
- }
+ int Offset = AnalyzeLoadFromClobberingMemInst(L->getType(),
+ L->getPointerOperand(),
+ DepMI, *TD);
+ if (Offset != -1)
+ AvailVal = GetMemInstValueForLoad(DepMI, Offset, L->getType(), L, *TD);
}
if (AvailVal) {
L->replaceAllUsesWith(AvailVal);
if (AvailVal->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(AvailVal);
- VN.erase(L);
- toErase.push_back(L);
+ markInstructionForDeletion(L);
++NumGVNLoad;
return true;
}
-
+ }
+
+ // If the value isn't available, don't do anything!
+ if (Dep.isClobber()) {
DEBUG(
- // fast print dep, using operator<< on instruction would be too slow
+ // fast print dep, using operator<< on instruction is too slow.
dbgs() << "GVN: load ";
WriteAsOperand(dbgs(), L);
Instruction *I = Dep.getInst();
// If it is defined in another block, try harder.
if (Dep.isNonLocal())
- return processNonLocalLoad(L, toErase);
+ return processNonLocalLoad(L);
+
+ if (!Dep.isDef()) {
+ DEBUG(
+ // fast print dep, using operator<< on instruction is too slow.
+ dbgs() << "GVN: load ";
+ WriteAsOperand(dbgs(), L);
+ dbgs() << " has unknown dependence\n";
+ );
+ return false;
+ }
Instruction *DepInst = Dep.getInst();
if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInst)) {
L->replaceAllUsesWith(StoredVal);
if (StoredVal->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(StoredVal);
- VN.erase(L);
- toErase.push_back(L);
+ markInstructionForDeletion(L);
++NumGVNLoad;
return true;
}
// (depending on its type).
if (DepLI->getType() != L->getType()) {
if (TD) {
- AvailableVal = CoerceAvailableValueToLoadType(DepLI, L->getType(), L,*TD);
+ AvailableVal = CoerceAvailableValueToLoadType(DepLI, L->getType(),
+ L, *TD);
if (AvailableVal == 0)
return false;
L->replaceAllUsesWith(AvailableVal);
if (DepLI->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(DepLI);
- VN.erase(L);
- toErase.push_back(L);
+ markInstructionForDeletion(L);
++NumGVNLoad;
return true;
}
// intervening stores, for example.
if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
- VN.erase(L);
- toErase.push_back(L);
+ markInstructionForDeletion(L);
++NumGVNLoad;
return true;
}
// If this load occurs either right after a lifetime begin,
// then the loaded value is undefined.
- if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(DepInst)) {
if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
- VN.erase(L);
- toErase.push_back(L);
+ markInstructionForDeletion(L);
++NumGVNLoad;
return true;
}
return Val;
}
+/// replaceAllDominatedUsesWith - Replace all uses of 'From' with 'To' if the
+/// use is dominated by the given basic block. Returns the number of uses that
+/// were replaced.
+unsigned GVN::replaceAllDominatedUsesWith(Value *From, Value *To,
+ BasicBlock *Root) {
+ unsigned Count = 0;
+ for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
+ UI != UE; ) {
+ Use &U = (UI++).getUse();
+ if (DT->dominates(Root, cast<Instruction>(U.getUser())->getParent())) {
+ U.set(To);
+ ++Count;
+ }
+ }
+ return Count;
+}
+
+/// propagateEquality - The given values are known to be equal in every block
+/// dominated by 'Root'. Exploit this, for example by replacing 'LHS' with
+/// 'RHS' everywhere in the scope. Returns whether a change was made.
+bool GVN::propagateEquality(Value *LHS, Value *RHS, BasicBlock *Root) {
+ if (LHS == RHS) return false;
+ assert(LHS->getType() == RHS->getType() && "Equal but types differ!");
+
+ // Don't try to propagate equalities between constants.
+ if (isa<Constant>(LHS) && isa<Constant>(RHS))
+ return false;
+
+ // Make sure that any constants are on the right-hand side. In general the
+ // best results are obtained by placing the longest lived value on the RHS.
+ if (isa<Constant>(LHS))
+ std::swap(LHS, RHS);
+
+ // If neither term is constant then bail out. This is not for correctness,
+ // it's just that the non-constant case is much less useful: it occurs just
+ // as often as the constant case but handling it hardly ever results in an
+ // improvement.
+ if (!isa<Constant>(RHS))
+ return false;
+
+ // If value numbering later deduces that an instruction in the scope is equal
+ // to 'LHS' then ensure it will be turned into 'RHS'.
+ addToLeaderTable(VN.lookup_or_add(LHS), RHS, Root);
+
+ // Replace all occurrences of 'LHS' with 'RHS' everywhere in the scope. As
+ // LHS always has at least one use that is not dominated by Root, this will
+ // never do anything if LHS has only one use.
+ bool Changed = false;
+ if (!LHS->hasOneUse()) {
+ unsigned NumReplacements = replaceAllDominatedUsesWith(LHS, RHS, Root);
+ Changed |= NumReplacements > 0;
+ NumGVNEqProp += NumReplacements;
+ }
+
+ // Now try to deduce additional equalities from this one. For example, if the
+ // known equality was "(A != B)" == "false" then it follows that A and B are
+ // equal in the scope. Only boolean equalities with an explicit true or false
+ // RHS are currently supported.
+ if (!RHS->getType()->isIntegerTy(1))
+ // Not a boolean equality - bail out.
+ return Changed;
+ ConstantInt *CI = dyn_cast<ConstantInt>(RHS);
+ if (!CI)
+ // RHS neither 'true' nor 'false' - bail out.
+ return Changed;
+ // Whether RHS equals 'true'. Otherwise it equals 'false'.
+ bool isKnownTrue = CI->isAllOnesValue();
+ bool isKnownFalse = !isKnownTrue;
+
+ // If "A && B" is known true then both A and B are known true. If "A || B"
+ // is known false then both A and B are known false.
+ Value *A, *B;
+ if ((isKnownTrue && match(LHS, m_And(m_Value(A), m_Value(B)))) ||
+ (isKnownFalse && match(LHS, m_Or(m_Value(A), m_Value(B))))) {
+ Changed |= propagateEquality(A, RHS, Root);
+ Changed |= propagateEquality(B, RHS, Root);
+ return Changed;
+ }
+
+ // If we are propagating an equality like "(A == B)" == "true" then also
+ // propagate the equality A == B.
+ if (ICmpInst *Cmp = dyn_cast<ICmpInst>(LHS)) {
+ // Only equality comparisons are supported.
+ if ((isKnownTrue && Cmp->getPredicate() == CmpInst::ICMP_EQ) ||
+ (isKnownFalse && Cmp->getPredicate() == CmpInst::ICMP_NE)) {
+ Value *Op0 = Cmp->getOperand(0), *Op1 = Cmp->getOperand(1);
+ Changed |= propagateEquality(Op0, Op1, Root);
+ }
+ return Changed;
+ }
+
+ return Changed;
+}
+
+/// isOnlyReachableViaThisEdge - There is an edge from 'Src' to 'Dst'. Return
+/// true if every path from the entry block to 'Dst' passes via this edge. In
+/// particular 'Dst' must not be reachable via another edge from 'Src'.
+static bool isOnlyReachableViaThisEdge(BasicBlock *Src, BasicBlock *Dst,
+ DominatorTree *DT) {
+ // While in theory it is interesting to consider the case in which Dst has
+ // more than one predecessor, because Dst might be part of a loop which is
+ // only reachable from Src, in practice it is pointless since at the time
+ // GVN runs all such loops have preheaders, which means that Dst will have
+ // been changed to have only one predecessor, namely Src.
+ BasicBlock *Pred = Dst->getSinglePredecessor();
+ assert((!Pred || Pred == Src) && "No edge between these basic blocks!");
+ (void)Src;
+ return Pred != 0;
+}
/// processInstruction - When calculating availability, handle an instruction
/// by inserting it into the appropriate sets
-bool GVN::processInstruction(Instruction *I,
- SmallVectorImpl<Instruction*> &toErase) {
+bool GVN::processInstruction(Instruction *I) {
// Ignore dbg info intrinsics.
if (isa<DbgInfoIntrinsic>(I))
return false;
// to value numbering it. Value numbering often exposes redundancies, for
// example if it determines that %y is equal to %x then the instruction
// "%z = and i32 %x, %y" becomes "%z = and i32 %x, %x" which we now simplify.
- if (Value *V = SimplifyInstruction(I, TD, DT)) {
+ if (Value *V = SimplifyInstruction(I, TD, TLI, DT)) {
I->replaceAllUsesWith(V);
if (MD && V->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
- VN.erase(I);
- toErase.push_back(I);
+ markInstructionForDeletion(I);
+ ++NumGVNSimpl;
return true;
}
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
- bool Changed = processLoad(LI, toErase);
-
- if (!Changed) {
- unsigned Num = VN.lookup_or_add(LI);
- addToLeaderTable(Num, LI, LI->getParent());
- }
+ if (processLoad(LI))
+ return true;
- return Changed;
+ unsigned Num = VN.lookup_or_add(LI);
+ addToLeaderTable(Num, LI, LI->getParent());
+ return false;
}
- // For conditions branches, we can perform simple conditional propagation on
+ // For conditional branches, we can perform simple conditional propagation on
// the condition value itself.
if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
return false;
-
+
Value *BranchCond = BI->getCondition();
- uint32_t CondVN = VN.lookup_or_add(BranchCond);
-
+
BasicBlock *TrueSucc = BI->getSuccessor(0);
BasicBlock *FalseSucc = BI->getSuccessor(1);
-
- if (TrueSucc->getSinglePredecessor())
- addToLeaderTable(CondVN,
- ConstantInt::getTrue(TrueSucc->getContext()),
- TrueSucc);
- if (FalseSucc->getSinglePredecessor())
- addToLeaderTable(CondVN,
- ConstantInt::getFalse(TrueSucc->getContext()),
- FalseSucc);
-
- return false;
+ BasicBlock *Parent = BI->getParent();
+ bool Changed = false;
+
+ if (isOnlyReachableViaThisEdge(Parent, TrueSucc, DT))
+ Changed |= propagateEquality(BranchCond,
+ ConstantInt::getTrue(TrueSucc->getContext()),
+ TrueSucc);
+
+ if (isOnlyReachableViaThisEdge(Parent, FalseSucc, DT))
+ Changed |= propagateEquality(BranchCond,
+ ConstantInt::getFalse(FalseSucc->getContext()),
+ FalseSucc);
+
+ return Changed;
}
-
+
+ // For switches, propagate the case values into the case destinations.
+ if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
+ Value *SwitchCond = SI->getCondition();
+ BasicBlock *Parent = SI->getParent();
+ bool Changed = false;
+ for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
+ BasicBlock *Dst = SI->getCaseSuccessor(i);
+ if (isOnlyReachableViaThisEdge(Parent, Dst, DT))
+ Changed |= propagateEquality(SwitchCond, SI->getCaseValue(i), Dst);
+ }
+ return Changed;
+ }
+
// Instructions with void type don't return a value, so there's
// no point in trying to find redudancies in them.
if (I->getType()->isVoidTy()) return false;
}
// Remove it!
- VN.erase(I);
I->replaceAllUsesWith(repl);
if (MD && repl->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(repl);
- toErase.push_back(I);
+ markInstructionForDeletion(I);
return true;
}
MD = &getAnalysis<MemoryDependenceAnalysis>();
DT = &getAnalysis<DominatorTree>();
TD = getAnalysisIfAvailable<TargetData>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
VN.setMemDep(MD);
VN.setDomTree(DT);
}
unsigned Iteration = 0;
-
- // FIXME: Remove this when PR8954 is fixed.
- DT->DT->recalculate(F);
-
while (ShouldContinue) {
DEBUG(dbgs() << "GVN iteration: " << Iteration << "\n");
ShouldContinue = iterateOnFunction(F);
bool GVN::processBlock(BasicBlock *BB) {
- // FIXME: Kill off toErase by doing erasing eagerly in a helper function (and
- // incrementing BI before processing an instruction).
- SmallVector<Instruction*, 8> toErase;
+ // FIXME: Kill off InstrsToErase by doing erasing eagerly in a helper function
+ // (and incrementing BI before processing an instruction).
+ assert(InstrsToErase.empty() &&
+ "We expect InstrsToErase to be empty across iterations");
bool ChangedFunction = false;
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE;) {
- ChangedFunction |= processInstruction(BI, toErase);
- if (toErase.empty()) {
+ ChangedFunction |= processInstruction(BI);
+ if (InstrsToErase.empty()) {
++BI;
continue;
}
// If we need some instructions deleted, do it now.
- NumGVNInstr += toErase.size();
+ NumGVNInstr += InstrsToErase.size();
// Avoid iterator invalidation.
bool AtStart = BI == BB->begin();
if (!AtStart)
--BI;
- for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I) {
+ for (SmallVector<Instruction*, 4>::iterator I = InstrsToErase.begin(),
+ E = InstrsToErase.end(); I != E; ++I) {
DEBUG(dbgs() << "GVN removed: " << **I << '\n');
if (MD) MD->removeInstruction(*I);
(*I)->eraseFromParent();
DEBUG(verifyRemoved(*I));
}
- toErase.clear();
+ InstrsToErase.clear();
if (AtStart)
BI = BB->begin();
// Nothing to PRE in the entry block.
if (CurrentBlock == &F.getEntryBlock()) continue;
+ // Don't perform PRE on a landing pad.
+ if (CurrentBlock->isLandingPad()) continue;
+
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
Instruction *CurInst = BI++;
PREInstr->insertBefore(PREPred->getTerminator());
PREInstr->setName(CurInst->getName() + ".pre");
+ PREInstr->setDebugLoc(CurInst->getDebugLoc());
predMap[PREPred] = PREInstr;
VN.add(PREInstr, ValNo);
++NumGVNPRE;
addToLeaderTable(ValNo, PREInstr, PREPred);
// Create a PHI to make the value available in this block.
- PHINode* Phi = PHINode::Create(CurInst->getType(),
+ pred_iterator PB = pred_begin(CurrentBlock), PE = pred_end(CurrentBlock);
+ PHINode* Phi = PHINode::Create(CurInst->getType(), std::distance(PB, PE),
CurInst->getName() + ".pre-phi",
CurrentBlock->begin());
- for (pred_iterator PI = pred_begin(CurrentBlock),
- PE = pred_end(CurrentBlock); PI != PE; ++PI) {
+ for (pred_iterator PI = PB; PI != PE; ++PI) {
BasicBlock *P = *PI;
Phi->addIncoming(predMap[P], P);
}
VN.add(Phi, ValNo);
addToLeaderTable(ValNo, Phi, CurrentBlock);
-
+ Phi->setDebugLoc(CurInst->getDebugLoc());
CurInst->replaceAllUsesWith(Phi);
if (Phi->getType()->isPointerTy()) {
// Because we have added a PHI-use of the pointer value, it has now
// "escaped" from alias analysis' perspective. We need to inform
// AA of this.
- for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee; ++ii)
- VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(2*ii));
+ for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee;
+ ++ii) {
+ unsigned jj = PHINode::getOperandNumForIncomingValue(ii);
+ VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(jj));
+ }
if (MD)
MD->invalidateCachedPointerInfo(Phi);
projects / oota-llvm.git / blobdiff