#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/Analysis/PHITransAddr.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
-#include <cstdio>
using namespace llvm;
STATISTIC(NumGVNInstr, "Number of instructions deleted");
static bool isEqual(const Expression &LHS, const Expression &RHS) {
return LHS == RHS;
}
- static bool isPod() { return true; }
};
+
+template <>
+struct isPodLike<Expression> { static const bool value = true; };
+
}
//===----------------------------------------------------------------------===//
valueNumbering[C] = e;
return e;
}
+ if (!MD) {
+ e = nextValueNumber++;
+ valueNumbering[C] = e;
+ return e;
+ }
MemDepResult local_dep = MD->getDependency(C);
// 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 MemoryDependenceAnalysis::NonLocalDepEntry *I = &deps[i];
+ const NonLocalDepEntry *I = &deps[i];
// Ignore non-local dependencies.
- if (I->second.isNonLocal())
+ if (I->getResult().isNonLocal())
continue;
// We don't handle non-depedencies. If we already have a call, reject
// instruction dependencies.
- if (I->second.isClobber() || cdep != 0) {
+ if (I->getResult().isClobber() || cdep != 0) {
cdep = 0;
break;
}
- CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->second.getInst());
+ CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->getResult().getInst());
// FIXME: All duplicated with non-local case.
- if (NonLocalDepCall && DT->properlyDominates(I->first, C->getParent())){
+ if (NonLocalDepCall && DT->properlyDominates(I->getBB(), C->getParent())){
cdep = NonLocalDepCall;
continue;
}
/// lookup - Returns the value number of the specified value. Fails if
/// the value has not yet been numbered.
uint32_t ValueTable::lookup(Value *V) const {
- DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+ DenseMap<Value*, uint32_t>::const_iterator VI = valueNumbering.find(V);
assert(VI != valueNumbering.end() && "Value not numbered?");
return VI->second;
}
/// verifyRemoved - Verify that the value is removed from all internal data
/// structures.
void ValueTable::verifyRemoved(const Value *V) const {
- for (DenseMap<Value*, uint32_t>::iterator
+ for (DenseMap<Value*, uint32_t>::const_iterator
I = valueNumbering.begin(), E = valueNumbering.end(); I != E; ++I) {
assert(I->first != V && "Inst still occurs in value numbering map!");
}
bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
- GVN(bool nopre = false) : FunctionPass(&ID), NoPRE(nopre) { }
+ explicit GVN(bool nopre = false, bool noloads = false)
+ : FunctionPass(&ID), NoPRE(nopre), NoLoads(noloads), MD(0) { }
private:
bool NoPRE;
+ bool NoLoads;
MemoryDependenceAnalysis *MD;
DominatorTree *DT;
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
- AU.addRequired<MemoryDependenceAnalysis>();
+ if (!NoLoads)
+ AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<DominatorTree>();
}
// createGVNPass - The public interface to this file...
-FunctionPass *llvm::createGVNPass(bool NoPRE) { return new GVN(NoPRE); }
+FunctionPass *llvm::createGVNPass(bool NoPRE, bool NoLoads) {
+ return new GVN(NoPRE, NoLoads);
+}
static RegisterPass<GVN> X("gvn",
"Global Value Numbering");
void GVN::dump(DenseMap<uint32_t, Value*>& d) {
- printf("{\n");
+ errs() << "{\n";
for (DenseMap<uint32_t, Value*>::iterator I = d.begin(),
E = d.end(); I != E; ++I) {
- printf("%d\n", I->first);
+ errs() << I->first << "\n";
I->second->dump();
}
- printf("}\n");
+ errs() << "}\n";
}
static bool isSafeReplacement(PHINode* p, Instruction *inst) {
}
-/// AnalyzeLoadFromClobberingStore - 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. 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 AnalyzeLoadFromClobberingStore(LoadInst *L, StoreInst *DepSI,
+/// AnalyzeLoadFromClobberingWrite - This function is called when we have a
+/// memdep query of a load that ends up being a clobbering memory write (store,
+/// memset, memcpy, memmove). This means that the write *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. 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,
+ Value *WritePtr,
+ uint64_t WriteSizeInBits,
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 (isa<StructType>(L->getType()) || isa<ArrayType>(L->getType()) ||
- isa<StructType>(DepSI->getOperand(0)->getType()) ||
- isa<ArrayType>(DepSI->getOperand(0)->getType()))
+ if (isa<StructType>(LoadTy) || isa<ArrayType>(LoadTy))
return -1;
int64_t StoreOffset = 0, LoadOffset = 0;
- Value *StoreBase =
- GetBaseWithConstantOffset(DepSI->getPointerOperand(), StoreOffset, TD);
+ Value *StoreBase = GetBaseWithConstantOffset(WritePtr, StoreOffset, TD);
Value *LoadBase =
- GetBaseWithConstantOffset(L->getPointerOperand(), LoadOffset, TD);
+ GetBaseWithConstantOffset(LoadPtr, LoadOffset, TD);
if (StoreBase != LoadBase)
return -1;
#if 0
errs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
<< "Base = " << *StoreBase << "\n"
- << "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
- << "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
- << "Load Ptr = " << *L->getPointerOperand() << "\n"
- << "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
- errs() << "'" << L->getParent()->getParent()->getName() << "'"
- << *L->getParent();
+ << "Store Ptr = " << *WritePtr << "\n"
+ << "Store Offs = " << StoreOffset << "\n"
+ << "Load Ptr = " << *LoadPtr << "\n";
+ abort();
#endif
return -1;
}
// must have gotten confused.
// FIXME: Investigate cases where this bails out, e.g. rdar://7238614. Then
// remove this check, as it is duplicated with what we have below.
- uint64_t StoreSize = TD.getTypeSizeInBits(DepSI->getOperand(0)->getType());
- uint64_t LoadSize = TD.getTypeSizeInBits(L->getType());
+ uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy);
- if ((StoreSize & 7) | (LoadSize & 7))
+ if ((WriteSizeInBits & 7) | (LoadSize & 7))
return -1;
- StoreSize >>= 3; // Convert to bytes.
+ uint64_t StoreSize = WriteSizeInBits >> 3; // Convert to bytes.
LoadSize >>= 3;
#if 0
errs() << "STORE LOAD DEP WITH COMMON BASE:\n"
<< "Base = " << *StoreBase << "\n"
- << "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
- << "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
- << "Load Ptr = " << *L->getPointerOperand() << "\n"
- << "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
- errs() << "'" << L->getParent()->getParent()->getName() << "'"
- << *L->getParent();
+ << "Store Ptr = " << *WritePtr << "\n"
+ << "Store Offs = " << StoreOffset << "\n"
+ << "Load Ptr = " << *LoadPtr << "\n";
+ abort();
#endif
return -1;
}
return LoadOffset-StoreOffset;
}
+/// 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,
+ StoreInst *DepSI,
+ const TargetData &TD) {
+ // Cannot handle reading from store of first-class aggregate yet.
+ if (isa<StructType>(DepSI->getOperand(0)->getType()) ||
+ isa<ArrayType>(DepSI->getOperand(0)->getType()))
+ return -1;
+
+ Value *StorePtr = DepSI->getPointerOperand();
+ uint64_t StoreSize = TD.getTypeSizeInBits(DepSI->getOperand(0)->getType());
+ return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
+ StorePtr, StoreSize, TD);
+}
+
+static int AnalyzeLoadFromClobberingMemInst(const Type *LoadTy, Value *LoadPtr,
+ MemIntrinsic *MI,
+ const TargetData &TD) {
+ // If the mem operation is a non-constant size, we can't handle it.
+ ConstantInt *SizeCst = dyn_cast<ConstantInt>(MI->getLength());
+ if (SizeCst == 0) return -1;
+ uint64_t MemSizeInBits = SizeCst->getZExtValue()*8;
+
+ // If this is memset, we just need to see if the offset is valid in the size
+ // of the memset..
+ if (MI->getIntrinsicID() == Intrinsic::memset)
+ return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr, MI->getDest(),
+ MemSizeInBits, TD);
+
+ // If we have a memcpy/memmove, the only case we can handle is if this is a
+ // copy from constant memory. In that case, we can read directly from the
+ // constant memory.
+ MemTransferInst *MTI = cast<MemTransferInst>(MI);
+
+ Constant *Src = dyn_cast<Constant>(MTI->getSource());
+ if (Src == 0) return -1;
+
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(Src->getUnderlyingObject());
+ if (GV == 0 || !GV->isConstant()) return -1;
+
+ // See if the access is within the bounds of the transfer.
+ int Offset = AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
+ MI->getDest(), MemSizeInBits, TD);
+ if (Offset == -1)
+ return Offset;
+
+ // Otherwise, see if we can constant fold a load from the constant with the
+ // offset applied as appropriate.
+ Src = ConstantExpr::getBitCast(Src,
+ llvm::Type::getInt8PtrTy(Src->getContext()));
+ Constant *OffsetCst =
+ ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
+ Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
+ Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
+ if (ConstantFoldLoadFromConstPtr(Src, &TD))
+ return Offset;
+ return -1;
+}
+
/// GetStoreValueForLoad - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
uint64_t StoreSize = TD.getTypeSizeInBits(SrcVal->getType())/8;
uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
+ IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
// Compute which bits of the stored value are being used by the load. Convert
// to an integer type to start with.
if (isa<PointerType>(SrcVal->getType()))
- SrcVal = new PtrToIntInst(SrcVal, TD.getIntPtrType(Ctx), "tmp", InsertPt);
+ SrcVal = Builder.CreatePtrToInt(SrcVal, TD.getIntPtrType(Ctx), "tmp");
if (!isa<IntegerType>(SrcVal->getType()))
- SrcVal = new BitCastInst(SrcVal, IntegerType::get(Ctx, StoreSize*8),
- "tmp", InsertPt);
+ SrcVal = Builder.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize*8),
+ "tmp");
// Shift the bits to the least significant depending on endianness.
unsigned ShiftAmt;
- if (TD.isLittleEndian()) {
+ if (TD.isLittleEndian())
ShiftAmt = Offset*8;
- } else {
+ else
ShiftAmt = (StoreSize-LoadSize-Offset)*8;
- }
if (ShiftAmt)
- SrcVal = BinaryOperator::CreateLShr(SrcVal,
- ConstantInt::get(SrcVal->getType(), ShiftAmt), "tmp", InsertPt);
+ SrcVal = Builder.CreateLShr(SrcVal, ShiftAmt, "tmp");
if (LoadSize != StoreSize)
- SrcVal = new TruncInst(SrcVal, IntegerType::get(Ctx, LoadSize*8),
- "tmp", InsertPt);
+ SrcVal = Builder.CreateTrunc(SrcVal, IntegerType::get(Ctx, LoadSize*8),
+ "tmp");
return CoerceAvailableValueToLoadType(SrcVal, 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,
+ const TargetData &TD){
+ LLVMContext &Ctx = LoadTy->getContext();
+ uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
+
+ IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
+
+ // We know that this method is only called when the mem transfer fully
+ // provides the bits for the load.
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(SrcInst)) {
+ // memset(P, 'x', 1234) -> splat('x'), even if x is a variable, and
+ // independently of what the offset is.
+ Value *Val = MSI->getValue();
+ if (LoadSize != 1)
+ Val = Builder.CreateZExt(Val, IntegerType::get(Ctx, LoadSize*8));
+
+ Value *OneElt = Val;
+
+ // Splat the value out to the right number of bits.
+ for (unsigned NumBytesSet = 1; NumBytesSet != LoadSize; ) {
+ // If we can double the number of bytes set, do it.
+ if (NumBytesSet*2 <= LoadSize) {
+ Value *ShVal = Builder.CreateShl(Val, NumBytesSet*8);
+ Val = Builder.CreateOr(Val, ShVal);
+ NumBytesSet <<= 1;
+ continue;
+ }
+
+ // Otherwise insert one byte at a time.
+ Value *ShVal = Builder.CreateShl(Val, 1*8);
+ Val = Builder.CreateOr(OneElt, ShVal);
+ ++NumBytesSet;
+ }
+
+ return CoerceAvailableValueToLoadType(Val, LoadTy, InsertPt, TD);
+ }
+
+ // Otherwise, this is a memcpy/memmove from a constant global.
+ MemTransferInst *MTI = cast<MemTransferInst>(SrcInst);
+ Constant *Src = cast<Constant>(MTI->getSource());
+
+ // Otherwise, see if we can constant fold a load from the constant with the
+ // offset applied as appropriate.
+ Src = ConstantExpr::getBitCast(Src,
+ llvm::Type::getInt8PtrTy(Src->getContext()));
+ Constant *OffsetCst =
+ ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
+ Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
+ Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
+ return ConstantFoldLoadFromConstPtr(Src, &TD);
+}
+
+
+
struct AvailableValueInBlock {
/// BB - The basic block in question.
BasicBlock *BB;
+ enum ValType {
+ SimpleVal, // A simple offsetted value that is accessed.
+ MemIntrin // A memory intrinsic which is loaded from.
+ };
+
/// V - The value that is live out of the block.
- Value *V;
- /// Offset - The byte offset in V that is interesting for the load query.
+ PointerIntPair<Value *, 1, ValType> Val;
+
+ /// Offset - The byte offset in Val that is interesting for the load query.
unsigned Offset;
static AvailableValueInBlock get(BasicBlock *BB, Value *V,
unsigned Offset = 0) {
AvailableValueInBlock Res;
Res.BB = BB;
- Res.V = V;
+ Res.Val.setPointer(V);
+ Res.Val.setInt(SimpleVal);
Res.Offset = Offset;
return Res;
}
+
+ static AvailableValueInBlock getMI(BasicBlock *BB, MemIntrinsic *MI,
+ unsigned Offset = 0) {
+ AvailableValueInBlock Res;
+ Res.BB = BB;
+ Res.Val.setPointer(MI);
+ Res.Val.setInt(MemIntrin);
+ Res.Offset = Offset;
+ return Res;
+ }
+
+ bool isSimpleValue() const { return Val.getInt() == SimpleVal; }
+ Value *getSimpleValue() const {
+ assert(isSimpleValue() && "Wrong accessor");
+ return Val.getPointer();
+ }
+
+ MemIntrinsic *getMemIntrinValue() const {
+ assert(!isSimpleValue() && "Wrong accessor");
+ return cast<MemIntrinsic>(Val.getPointer());
+ }
};
/// ConstructSSAForLoadSet - Given a set of loads specified by ValuesPerBlock,
const Type *LoadTy = LI->getType();
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
- BasicBlock *BB = ValuesPerBlock[i].BB;
- Value *AvailableVal = ValuesPerBlock[i].V;
- unsigned Offset = ValuesPerBlock[i].Offset;
+ const AvailableValueInBlock &AV = ValuesPerBlock[i];
+ BasicBlock *BB = AV.BB;
if (SSAUpdate.HasValueForBlock(BB))
continue;
-
- if (AvailableVal->getType() != LoadTy) {
- assert(TD && "Need target data to handle type mismatch case");
- AvailableVal = GetStoreValueForLoad(AvailableVal, Offset, LoadTy,
- BB->getTerminator(), *TD);
-
- if (Offset) {
- DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\n"
- << *ValuesPerBlock[i].V << '\n'
+
+ unsigned Offset = AV.Offset;
+
+ Value *AvailableVal;
+ if (AV.isSimpleValue()) {
+ AvailableVal = AV.getSimpleValue();
+ if (AvailableVal->getType() != LoadTy) {
+ assert(TD && "Need target data to handle type mismatch case");
+ AvailableVal = GetStoreValueForLoad(AvailableVal, Offset, LoadTy,
+ BB->getTerminator(), *TD);
+
+ DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\nOffset: " << Offset << " "
+ << *AV.getSimpleValue() << '\n'
<< *AvailableVal << '\n' << "\n\n\n");
}
-
-
- DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\n"
- << *ValuesPerBlock[i].V << '\n'
+ } else {
+ AvailableVal = GetMemInstValueForLoad(AV.getMemIntrinValue(), Offset,
+ LoadTy, BB->getTerminator(), *TD);
+ DEBUG(errs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
+ << " " << *AV.getMemIntrinValue() << '\n'
<< *AvailableVal << '\n' << "\n\n\n");
}
-
SSAUpdate.AddAvailableValue(BB, AvailableVal);
}
return V;
}
+static bool isLifetimeStart(Instruction *Inst) {
+ if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst))
+ return II->getIntrinsicID() == Intrinsic::lifetime_start;
+ return false;
+}
+
/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
/// non-local by performing PHI construction.
bool GVN::processNonLocalLoad(LoadInst *LI,
SmallVectorImpl<Instruction*> &toErase) {
// Find the non-local dependencies of the load.
- SmallVector<MemoryDependenceAnalysis::NonLocalDepEntry, 64> Deps;
+ SmallVector<NonLocalDepEntry, 64> Deps;
MD->getNonLocalPointerDependency(LI->getOperand(0), true, LI->getParent(),
Deps);
//DEBUG(errs() << "INVESTIGATING NONLOCAL LOAD: "
// 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].second.isClobber()) {
+ if (Deps.size() == 1 && Deps[0].getResult().isClobber()) {
DEBUG(
errs() << "GVN: non-local load ";
WriteAsOperand(errs(), LI);
- errs() << " is clobbered by " << *Deps[0].second.getInst() << '\n';
+ errs() << " is clobbered by " << *Deps[0].getResult().getInst() << '\n';
);
return false;
}
const TargetData *TD = 0;
for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
- BasicBlock *DepBB = Deps[i].first;
- MemDepResult DepInfo = Deps[i].second;
+ BasicBlock *DepBB = Deps[i].getBB();
+ MemDepResult DepInfo = Deps[i].getResult();
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
+ // to consider the right address.
+ Value *Address = Deps[i].getAddress();
+
// If the dependence is to a store that writes to a superset of the bits
// read by the load, we can extract the bits we need for the load from the
// stored value.
if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
if (TD == 0)
TD = getAnalysisIfAvailable<TargetData>();
- if (TD) {
- int Offset = AnalyzeLoadFromClobberingStore(LI, DepSI, *TD);
+ if (TD && Address) {
+ int Offset = AnalyzeLoadFromClobberingStore(LI->getType(), Address,
+ DepSI, *TD);
if (Offset != -1) {
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
DepSI->getOperand(0),
}
}
}
+
+ // 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>(DepInfo.getInst())) {
+ if (TD == 0)
+ TD = getAnalysisIfAvailable<TargetData>();
+ if (TD && Address) {
+ int Offset = AnalyzeLoadFromClobberingMemInst(LI->getType(), Address,
+ DepMI, *TD);
+ if (Offset != -1) {
+ ValuesPerBlock.push_back(AvailableValueInBlock::getMI(DepBB, DepMI,
+ Offset));
+ continue;
+ }
+ }
+ }
- // FIXME: Handle memset/memcpy.
UnavailableBlocks.push_back(DepBB);
continue;
}
Instruction *DepInst = DepInfo.getInst();
// Loading the allocation -> undef.
- if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
+ if (isa<AllocaInst>(DepInst) || isMalloc(DepInst) ||
+ // Loading immediately after lifetime begin -> undef.
+ isLifetimeStart(DepInst)) {
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
UndefValue::get(LI->getType())));
continue;
}
- // Loading immediately after lifetime begin or end -> undef.
- if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end) {
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
- UndefValue::get(LI->getType())));
- }
- }
-
if (StoreInst *S = dyn_cast<StoreInst>(DepInst)) {
// Reject loads and stores that are to the same address but are of
// different types if we have to.
// to eliminate LI even if we insert uses in the other predecessors, we will
// end up increasing code size. Reject this by scanning for LI.
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
- if (ValuesPerBlock[i].V == LI)
+ if (ValuesPerBlock[i].isSimpleValue() &&
+ ValuesPerBlock[i].getSimpleValue() == LI)
return false;
+ // FIXME: It is extremely unclear what this loop is doing, other than
+ // artificially restricting loadpre.
if (isSinglePred) {
bool isHot = false;
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
- if (Instruction *I = dyn_cast<Instruction>(ValuesPerBlock[i].V))
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
+ const AvailableValueInBlock &AV = ValuesPerBlock[i];
+ if (AV.isSimpleValue())
// "Hot" Instruction is in some loop (because it dominates its dep.
// instruction).
- if (DT->dominates(LI, I)) {
- isHot = true;
- break;
- }
+ if (Instruction *I = dyn_cast<Instruction>(AV.getSimpleValue()))
+ if (DT->dominates(LI, I)) {
+ isHot = true;
+ break;
+ }
+ }
// We are interested only in "hot" instructions. We don't want to do any
// mis-optimizations here.
assert(UnavailablePred != 0 &&
"Fully available value should be eliminated above!");
- // If the loaded pointer is PHI node defined in this block, do PHI translation
- // to get its value in the predecessor.
- Value *LoadPtr = LI->getOperand(0)->DoPHITranslation(LoadBB, UnavailablePred);
-
- // Make sure the value is live in the predecessor. If it was defined by a
- // non-PHI instruction in this block, we don't know how to recompute it above.
- if (Instruction *LPInst = dyn_cast<Instruction>(LoadPtr))
- if (!DT->dominates(LPInst->getParent(), UnavailablePred)) {
- DEBUG(errs() << "COULDN'T PRE LOAD BECAUSE PTR IS UNAVAILABLE IN PRED: "
- << *LPInst << '\n' << *LI << "\n");
- return false;
- }
-
// We don't currently handle critical edges :(
if (UnavailablePred->getTerminator()->getNumSuccessors() != 1) {
DEBUG(errs() << "COULD NOT PRE LOAD BECAUSE OF CRITICAL EDGE '"
<< UnavailablePred->getName() << "': " << *LI << '\n');
return false;
}
+
+ // Do PHI translation to get its value in the predecessor if necessary. The
+ // returned pointer (if non-null) is guaranteed to dominate UnavailablePred.
+ //
+ SmallVector<Instruction*, 8> NewInsts;
+
+ // If all preds have a single successor, then we know it is safe to insert the
+ // load on the pred (?!?), so we can insert code to materialize the pointer if
+ // it is not available.
+ PHITransAddr Address(LI->getOperand(0), TD);
+ Value *LoadPtr = 0;
+ if (allSingleSucc) {
+ LoadPtr = Address.PHITranslateWithInsertion(LoadBB, UnavailablePred,
+ *DT, NewInsts);
+ } else {
+ Address.PHITranslateValue(LoadBB, UnavailablePred);
+ LoadPtr = Address.getAddr();
+
+ // Make sure the value is live in the predecessor.
+ if (Instruction *Inst = dyn_cast_or_null<Instruction>(LoadPtr))
+ if (!DT->dominates(Inst->getParent(), UnavailablePred))
+ LoadPtr = 0;
+ }
+ // If we couldn't find or insert a computation of this phi translated value,
+ // we fail PRE.
+ if (LoadPtr == 0) {
+ assert(NewInsts.empty() && "Shouldn't insert insts on failure");
+ DEBUG(errs() << "COULDN'T INSERT PHI TRANSLATED VALUE OF: "
+ << *LI->getOperand(0) << "\n");
+ return false;
+ }
+
+ // Assign value numbers to these new instructions.
+ for (unsigned i = 0, e = NewInsts.size(); i != e; ++i) {
+ // FIXME: We really _ought_ to insert these value numbers into their
+ // parent's availability map. However, in doing so, we risk getting into
+ // ordering issues. If a block hasn't been processed yet, we would be
+ // marking a value as AVAIL-IN, which isn't what we intend.
+ VN.lookup_or_add(NewInsts[i]);
+ }
+
// Make sure it is valid to move this load here. We have to watch out for:
// @1 = getelementptr (i8* p, ...
// test p and branch if == 0
// we do not have this case. Otherwise, check that the load is safe to
// put anywhere; this can be improved, but should be conservatively safe.
if (!allSingleSucc &&
- !isSafeToLoadUnconditionally(LoadPtr, UnavailablePred->getTerminator()))
+ // FIXME: REEVALUTE THIS.
+ !isSafeToLoadUnconditionally(LoadPtr, UnavailablePred->getTerminator())) {
+ assert(NewInsts.empty() && "Should not have inserted instructions");
return false;
+ }
// Okay, we can eliminate this load by inserting a reload in the predecessor
// and using PHI construction to get the value in the other predecessors, do
// it.
DEBUG(errs() << "GVN REMOVING PRE LOAD: " << *LI << '\n');
-
+ DEBUG(if (!NewInsts.empty())
+ errs() << "INSERTED " << NewInsts.size() << " INSTS: "
+ << *NewInsts.back() << '\n');
+
Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
LI->getAlignment(),
UnavailablePred->getTerminator());
/// 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) {
+ if (!MD)
+ return false;
+
if (L->isVolatile())
return false;
// If the value isn't available, don't do anything!
if (Dep.isClobber()) {
- // FIXME: We should handle memset/memcpy/memmove as dependent instructions
- // to forward the value if available.
- //if (isa<MemIntrinsic>(Dep.getInst()))
- //errs() << "LOAD DEPENDS ON MEM: " << *L << "\n" << *Dep.getInst()<<"\n\n";
-
// Check to see if we have something like this:
// store i32 123, i32* %P
// %A = bitcast i32* %P to i8*
// a common base + constant offset, and if the previous store (or memset)
// 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 (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
- int Offset = AnalyzeLoadFromClobberingStore(L, DepSI, *TD);
- if (Offset != -1) {
- Value *AvailVal = GetStoreValueForLoad(DepSI->getOperand(0), Offset,
- L->getType(), L, *TD);
- DEBUG(errs() << "GVN COERCED STORE BITS:\n" << *DepSI << '\n'
- << *AvailVal << '\n' << *L << "\n\n\n");
-
- // Replace the load!
- L->replaceAllUsesWith(AvailVal);
- if (isa<PointerType>(AvailVal->getType()))
- MD->invalidateCachedPointerInfo(AvailVal);
- toErase.push_back(L);
- NumGVNLoad++;
- return true;
- }
+ int Offset = AnalyzeLoadFromClobberingStore(L->getType(),
+ L->getPointerOperand(),
+ DepSI, *TD);
+ if (Offset != -1)
+ AvailVal = GetStoreValueForLoad(DepSI->getOperand(0), Offset,
+ L->getType(), L, *TD);
}
+ // 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 (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
+ int Offset = AnalyzeLoadFromClobberingMemInst(L->getType(),
+ L->getPointerOperand(),
+ DepMI, *TD);
+ if (Offset != -1)
+ AvailVal = GetMemInstValueForLoad(DepMI, Offset, L->getType(), L,*TD);
+ }
+ }
+
+ if (AvailVal) {
+ DEBUG(errs() << "GVN COERCED INST:\n" << *Dep.getInst() << '\n'
+ << *AvailVal << '\n' << *L << "\n\n\n");
+
+ // Replace the load!
+ L->replaceAllUsesWith(AvailVal);
+ if (isa<PointerType>(AvailVal->getType()))
+ MD->invalidateCachedPointerInfo(AvailVal);
+ toErase.push_back(L);
+ NumGVNLoad++;
+ return true;
+ }
+
DEBUG(
// fast print dep, using operator<< on instruction would be too slow
errs() << "GVN: load ";
return true;
}
- // If this load occurs either right after a lifetime begin or a lifetime end,
+ // If this load occurs either right after a lifetime begin,
// then the loaded value is undefined.
if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end) {
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
toErase.push_back(L);
NumGVNLoad++;
if (constVal) {
p->replaceAllUsesWith(constVal);
- if (isa<PointerType>(constVal->getType()))
+ if (
MD && isa<PointerType>(constVal->getType()))
MD->invalidateCachedPointerInfo(constVal);
VN.erase(p);
// Remove it!
VN.erase(I);
I->replaceAllUsesWith(repl);
- if (isa<PointerType>(repl->getType()))
+ if (
MD && isa<PointerType>(repl->getType()))
MD->invalidateCachedPointerInfo(repl);
toErase.push_back(I);
return true;
/// runOnFunction - This is the main transformation entry point for a function.
bool GVN::runOnFunction(Function& F) {
- MD = &getAnalysis<MemoryDependenceAnalysis>();
+ if (!NoLoads)
+ MD = &getAnalysis<MemoryDependenceAnalysis>();
DT = &getAnalysis<DominatorTree>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
VN.setMemDep(MD);
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
E = toErase.end(); I != E; ++I) {
DEBUG(errs() << "GVN removed: " << **I << '\n');
- MD->removeInstruction(*I);
+ if (MD) MD->removeInstruction(*I);
(*I)->eraseFromParent();
DEBUG(verifyRemoved(*I));
}
localAvail[CurrentBlock]->table[ValNo] = Phi;
CurInst->replaceAllUsesWith(Phi);
- if (isa<PointerType>(Phi->getType()))
+ if (
MD && isa<PointerType>(Phi->getType()))
MD->invalidateCachedPointerInfo(Phi);
VN.erase(CurInst);
DEBUG(errs() << "GVN PRE removed: " << *CurInst << '\n');
- MD->removeInstruction(CurInst);
+ if (MD) MD->removeInstruction(CurInst);
CurInst->eraseFromParent();
DEBUG(verifyRemoved(CurInst));
Changed = true;
// Walk through the value number scope to make sure the instruction isn't
// ferreted away in it.
- for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
+ for (DenseMap<BasicBlock*, ValueNumberScope*>::const_iterator
I = localAvail.begin(), E = localAvail.end(); I != E; ++I) {
const ValueNumberScope *VNS = I->second;
while (VNS) {
- for (DenseMap<uint32_t, Value*>::iterator
+ for (DenseMap<uint32_t, Value*>::const_iterator
II = VNS->table.begin(), IE = VNS->table.end(); II != IE; ++II) {
assert(II->second != Inst && "Inst still in value numbering scope!");
}
projects / oota-llvm.git / blobdiff