#define DEBUG_TYPE "gvn"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
-#include "llvm/Function.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
-#include "llvm/Operator.h"
-#include "llvm/Value.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/PostOrderIterator.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.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/Analysis/ValueTracking.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Allocator.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 <list>
using namespace llvm;
STATISTIC(NumGVNInstr, "Number of instructions deleted");
/// two values.
namespace {
struct Expression {
- enum ExpressionOpcode {
- ADD = Instruction::Add,
- FADD = Instruction::FAdd,
- SUB = Instruction::Sub,
- FSUB = Instruction::FSub,
- MUL = Instruction::Mul,
- FMUL = Instruction::FMul,
- UDIV = Instruction::UDiv,
- SDIV = Instruction::SDiv,
- FDIV = Instruction::FDiv,
- UREM = Instruction::URem,
- SREM = Instruction::SRem,
- FREM = Instruction::FRem,
- SHL = Instruction::Shl,
- LSHR = Instruction::LShr,
- ASHR = Instruction::AShr,
- AND = Instruction::And,
- OR = Instruction::Or,
- XOR = Instruction::Xor,
- TRUNC = Instruction::Trunc,
- ZEXT = Instruction::ZExt,
- SEXT = Instruction::SExt,
- FPTOUI = Instruction::FPToUI,
- FPTOSI = Instruction::FPToSI,
- UITOFP = Instruction::UIToFP,
- SITOFP = Instruction::SIToFP,
- FPTRUNC = Instruction::FPTrunc,
- FPEXT = Instruction::FPExt,
- PTRTOINT = Instruction::PtrToInt,
- INTTOPTR = Instruction::IntToPtr,
- BITCAST = Instruction::BitCast,
- ICMPEQ, ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
- ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
- FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
- FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
- FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
- SHUFFLE, SELECT, GEP, CALL, CONSTANT,
- INSERTVALUE, EXTRACTVALUE, EMPTY, TOMBSTONE };
-
- ExpressionOpcode opcode;
+ uint32_t opcode;
const Type* type;
SmallVector<uint32_t, 4> varargs;
- Value *function;
Expression() { }
- Expression(ExpressionOpcode o) : opcode(o) { }
+ Expression(uint32_t o) : opcode(o) { }
bool operator==(const Expression &other) const {
if (opcode != other.opcode)
return false;
- else if (opcode == EMPTY || opcode == TOMBSTONE)
+ else if (opcode == ~0U || opcode == ~1U)
return true;
else if (type != other.type)
return false;
- else if (function != other.function)
+ else if (varargs != other.varargs)
return false;
- else {
- if (varargs.size() != other.varargs.size())
- return false;
-
- for (size_t i = 0; i < varargs.size(); ++i)
- if (varargs[i] != other.varargs[i])
- return false;
-
- return true;
- }
+ return true;
}
-
- /*bool operator!=(const Expression &other) const {
- return !(*this == other);
- }*/
};
class ValueTable {
uint32_t nextValueNumber;
- Expression::ExpressionOpcode getOpcode(CmpInst* C);
- Expression create_expression(BinaryOperator* BO);
- Expression create_expression(CmpInst* C);
- Expression create_expression(ShuffleVectorInst* V);
- Expression create_expression(ExtractElementInst* C);
- Expression create_expression(InsertElementInst* V);
- Expression create_expression(SelectInst* V);
- Expression create_expression(CastInst* C);
- Expression create_expression(GetElementPtrInst* G);
- Expression create_expression(CallInst* C);
- Expression create_expression(ExtractValueInst* C);
- Expression create_expression(InsertValueInst* C);
-
+ Expression create_expression(Instruction* I);
uint32_t lookup_or_add_call(CallInst* C);
public:
ValueTable() : nextValueNumber(1) { }
namespace llvm {
template <> struct DenseMapInfo<Expression> {
static inline Expression getEmptyKey() {
- return Expression(Expression::EMPTY);
+ return ~0U;
}
static inline Expression getTombstoneKey() {
- return Expression(Expression::TOMBSTONE);
+ return ~1U;
}
static unsigned getHashValue(const Expression e) {
for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
E = e.varargs.end(); I != E; ++I)
hash = *I + hash * 37;
-
- hash = ((unsigned)((uintptr_t)e.function >> 4) ^
- (unsigned)((uintptr_t)e.function >> 9)) +
- hash * 37;
-
+
return hash;
}
static bool isEqual(const Expression &LHS, const Expression &RHS) {
return LHS == RHS;
}
};
-
-template <>
-struct isPodLike<Expression> { static const bool value = true; };
}
// ValueTable Internal Functions
//===----------------------------------------------------------------------===//
-Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
- if (isa<ICmpInst>(C)) {
- switch (C->getPredicate()) {
- default: // THIS SHOULD NEVER HAPPEN
- llvm_unreachable("Comparison with unknown predicate?");
- case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
- case ICmpInst::ICMP_NE: return Expression::ICMPNE;
- case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
- case ICmpInst::ICMP_UGE: return Expression::ICMPUGE;
- case ICmpInst::ICMP_ULT: return Expression::ICMPULT;
- case ICmpInst::ICMP_ULE: return Expression::ICMPULE;
- case ICmpInst::ICMP_SGT: return Expression::ICMPSGT;
- case ICmpInst::ICMP_SGE: return Expression::ICMPSGE;
- case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
- case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
- }
- } else {
- switch (C->getPredicate()) {
- default: // THIS SHOULD NEVER HAPPEN
- llvm_unreachable("Comparison with unknown predicate?");
- case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
- case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
- case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
- case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
- case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
- case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
- case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
- case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
- case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
- case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
- case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
- case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
- case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
- case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
- }
- }
-}
-
-Expression ValueTable::create_expression(CallInst* C) {
- Expression e;
-
- e.type = C->getType();
- e.function = C->getCalledFunction();
- e.opcode = Expression::CALL;
-
- CallSite CS(C);
- for (CallInst::op_iterator I = CS.arg_begin(), E = CS.arg_end();
- I != E; ++I)
- e.varargs.push_back(lookup_or_add(*I));
- return e;
-}
-
-Expression ValueTable::create_expression(BinaryOperator* BO) {
+Expression ValueTable::create_expression(Instruction *I) {
Expression e;
- e.varargs.push_back(lookup_or_add(BO->getOperand(0)));
- e.varargs.push_back(lookup_or_add(BO->getOperand(1)));
- e.function = 0;
- e.type = BO->getType();
- e.opcode = static_cast<Expression::ExpressionOpcode>(BO->getOpcode());
-
- return e;
-}
-
-Expression ValueTable::create_expression(CmpInst* C) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(C->getOperand(0)));
- e.varargs.push_back(lookup_or_add(C->getOperand(1)));
- e.function = 0;
- e.type = C->getType();
- e.opcode = getOpcode(C);
-
- return e;
-}
-
-Expression ValueTable::create_expression(CastInst* C) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(C->getOperand(0)));
- e.function = 0;
- e.type = C->getType();
- e.opcode = static_cast<Expression::ExpressionOpcode>(C->getOpcode());
-
- return e;
-}
-
-Expression ValueTable::create_expression(ShuffleVectorInst* S) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(S->getOperand(0)));
- e.varargs.push_back(lookup_or_add(S->getOperand(1)));
- e.varargs.push_back(lookup_or_add(S->getOperand(2)));
- e.function = 0;
- e.type = S->getType();
- e.opcode = Expression::SHUFFLE;
-
- return e;
-}
-
-Expression ValueTable::create_expression(ExtractElementInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getOperand(0)));
- e.varargs.push_back(lookup_or_add(E->getOperand(1)));
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::EXTRACT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(InsertElementInst* I) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(I->getOperand(0)));
- e.varargs.push_back(lookup_or_add(I->getOperand(1)));
- e.varargs.push_back(lookup_or_add(I->getOperand(2)));
- e.function = 0;
e.type = I->getType();
- e.opcode = Expression::INSERT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(SelectInst* I) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(I->getCondition()));
- e.varargs.push_back(lookup_or_add(I->getTrueValue()));
- e.varargs.push_back(lookup_or_add(I->getFalseValue()));
- e.function = 0;
- e.type = I->getType();
- e.opcode = Expression::SELECT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(GetElementPtrInst* G) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(G->getPointerOperand()));
- e.function = 0;
- e.type = G->getType();
- e.opcode = Expression::GEP;
-
- for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
- I != E; ++I)
- e.varargs.push_back(lookup_or_add(*I));
-
- return e;
-}
-
-Expression ValueTable::create_expression(ExtractValueInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
- for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
- II != IE; ++II)
- e.varargs.push_back(*II);
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::EXTRACTVALUE;
-
- return e;
-}
-
-Expression ValueTable::create_expression(InsertValueInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
- e.varargs.push_back(lookup_or_add(E->getInsertedValueOperand()));
- for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
- II != IE; ++II)
- e.varargs.push_back(*II);
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::INSERTVALUE;
-
+ e.opcode = I->getOpcode();
+ for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
+ OI != OE; ++OI)
+ e.varargs.push_back(lookup_or_add(*OI));
+
+ 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)
+ e.varargs.push_back(*II);
+ }
+
return e;
}
case Instruction::And:
case Instruction::Or :
case Instruction::Xor:
- exp = create_expression(cast<BinaryOperator>(I));
- break;
case Instruction::ICmp:
case Instruction::FCmp:
- exp = create_expression(cast<CmpInst>(I));
- break;
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::BitCast:
- exp = create_expression(cast<CastInst>(I));
- break;
case Instruction::Select:
- exp = create_expression(cast<SelectInst>(I));
- break;
case Instruction::ExtractElement:
- exp = create_expression(cast<ExtractElementInst>(I));
- break;
case Instruction::InsertElement:
- exp = create_expression(cast<InsertElementInst>(I));
- break;
case Instruction::ShuffleVector:
- exp = create_expression(cast<ShuffleVectorInst>(I));
- break;
case Instruction::ExtractValue:
- exp = create_expression(cast<ExtractValueInst>(I));
- break;
case Instruction::InsertValue:
- exp = create_expression(cast<InsertValueInst>(I));
- break;
case Instruction::GetElementPtr:
- exp = create_expression(cast<GetElementPtrInst>(I));
+ exp = create_expression(I);
break;
default:
valueNumbering[V] = nextValueNumber;
// GVN Pass
//===----------------------------------------------------------------------===//
-namespace {
- struct ValueNumberScope {
- ValueNumberScope* parent;
- DenseMap<uint32_t, Value*> table;
-
- ValueNumberScope(ValueNumberScope* p) : parent(p) { }
- };
-}
-
namespace {
class GVN : public FunctionPass {
ValueTable VN;
- /// NumberTable - A mapping from value numers to lists of Value*'s that
- /// have that value number. Use lookupNumber to query it.
- DenseMap<uint32_t, std::pair<Value*, void*> > NumberTable;
+ /// LeaderTable - A mapping from value numbers to lists of Value*'s that
+ /// have that value number. Use findLeader to query it.
+ struct LeaderTableEntry {
+ Value *Val;
+ BasicBlock *BB;
+ LeaderTableEntry *Next;
+ };
+ DenseMap<uint32_t, LeaderTableEntry> LeaderTable;
BumpPtrAllocator TableAllocator;
- /// insert_table - Push a new Value to the NumberTable onto the list for
+ /// addToLeaderTable - Push a new Value to the LeaderTable onto the list for
/// its value number.
- void insert_table(uint32_t N, Value *V) {
- std::pair<Value*, void*>& Curr = NumberTable[N];
- if (!Curr.first) {
- Curr.first = V;
+ void addToLeaderTable(uint32_t N, Value *V, BasicBlock *BB) {
+ LeaderTableEntry& Curr = LeaderTable[N];
+ if (!Curr.Val) {
+ Curr.Val = V;
+ Curr.BB = BB;
return;
}
- std::pair<Value*, void*>* Node =
- TableAllocator.Allocate<std::pair<Value*, void*> >();
- Node->first = V;
- Node->second = Curr.second;
- Curr.second = Node;
+ LeaderTableEntry* Node = TableAllocator.Allocate<LeaderTableEntry>();
+ Node->Val = V;
+ Node->BB = BB;
+ Node->Next = Curr.Next;
+ Curr.Next = Node;
}
- /// erase_table - Scan the list of values corresponding to a given value
- /// number, and remove the given value if encountered.
- void erase_table(uint32_t N, Value *V) {
- std::pair<Value*, void*>* Prev = 0;
- std::pair<Value*, void*>* Curr = &NumberTable[N];
+ /// removeFromLeaderTable - Scan the list of values corresponding to a given
+ /// value number, and remove the given value if encountered.
+ void removeFromLeaderTable(uint32_t N, Value *V, BasicBlock *BB) {
+ LeaderTableEntry* Prev = 0;
+ LeaderTableEntry* Curr = &LeaderTable[N];
- while (Curr->first != V) {
+ while (Curr->Val != V || Curr->BB != BB) {
Prev = Curr;
- Curr = static_cast<std::pair<Value*, void*>*>(Curr->second);
+ Curr = Curr->Next;
}
if (Prev) {
- Prev->second = Curr->second;
+ Prev->Next = Curr->Next;
} else {
- if (!Curr->second) {
- Curr->first = 0;
+ if (!Curr->Next) {
+ Curr->Val = 0;
+ Curr->BB = 0;
} else {
- std::pair<Value*, void*>* Next =
- static_cast<std::pair<Value*, void*>*>(Curr->second);
- Curr->first = Next->first;
- Curr->second = Next->second;
+ LeaderTableEntry* Next = Curr->Next;
+ Curr->Val = Next->Val;
+ Curr->BB = Next->BB;
+ Curr->Next = Next->Next;
}
}
}
void dump(DenseMap<uint32_t, Value*>& d);
bool iterateOnFunction(Function &F);
bool performPRE(Function& F);
- Value *lookupNumber(BasicBlock *BB, uint32_t num);
+ Value *findLeader(BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
void verifyRemoved(const Instruction *I) const;
bool splitCriticalEdges();
return new BitCastInst(StoredVal, LoadedTy, "bitcast", InsertPt);
}
-/// GetBaseWithConstantOffset - Analyze the specified pointer to see if it can
-/// be expressed as a base pointer plus a constant offset. Return the base and
-/// offset to the caller.
-static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
- const TargetData &TD) {
- Operator *PtrOp = dyn_cast<Operator>(Ptr);
- if (PtrOp == 0) return Ptr;
-
- // Just look through bitcasts.
- if (PtrOp->getOpcode() == Instruction::BitCast)
- return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
-
- // If this is a GEP with constant indices, we can look through it.
- GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
- if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
-
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
- ++I, ++GTI) {
- ConstantInt *OpC = cast<ConstantInt>(*I);
- if (OpC->isZero()) continue;
-
- // Handle a struct and array indices which add their offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += OpC->getSExtValue()*Size;
- }
- }
-
- // Re-sign extend from the pointer size if needed to get overflow edge cases
- // right.
- unsigned PtrSize = TD.getPointerSizeInBits();
- if (PtrSize < 64)
- Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
-
- return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
-}
-
-
/// 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
return -1;
int64_t StoreOffset = 0, LoadOffset = 0;
- Value *StoreBase = GetBaseWithConstantOffset(WritePtr, StoreOffset, TD);
- Value *LoadBase =
- GetBaseWithConstantOffset(LoadPtr, LoadOffset, TD);
+ Value *StoreBase = GetPointerBaseWithConstantOffset(WritePtr, StoreOffset,TD);
+ Value *LoadBase = GetPointerBaseWithConstantOffset(LoadPtr, LoadOffset, TD);
if (StoreBase != LoadBase)
return -1;
// If the load and store don't overlap at all, the store doesn't provide
// anything to the load. In this case, they really don't alias at all, AA
// 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 LoadSize = TD.getTypeSizeInBits(LoadTy);
if ((WriteSizeInBits & 7) | (LoadSize & 7))
Constant *Src = dyn_cast<Constant>(MTI->getSource());
if (Src == 0) return -1;
- GlobalVariable *GV = dyn_cast<GlobalVariable>(Src->getUnderlyingObject());
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Src));
if (GV == 0 || !GV->isConstant()) return -1;
// See if the access is within the bounds of the transfer.
if (V->getType()->isPointerTy())
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
AA->copyValue(LI, NewPHIs[i]);
+
+ // Now that we've copied information to the new PHIs, scan through
+ // them again and inform alias analysis that we've added potentially
+ // 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));
+ }
return V;
}
// @1 = getelementptr (i8* p, ...
// test p and branch if == 0
// load @1
- // It is valid to have the getelementptr before the test, even if p can be 0,
- // as getelementptr only does address arithmetic.
+ // It is valid to have the getelementptr before the test, even if p can
+ // be 0, as getelementptr only does address arithmetic.
// If we are not pushing the value through any multiple-successor blocks
// 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.
BasicBlock *UnavailablePred = I->first;
Value *LoadPtr = I->second;
- Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
- LI->getAlignment(),
- UnavailablePred->getTerminator());
+ Instruction *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
+ LI->getAlignment(),
+ UnavailablePred->getTerminator());
+
+ // Transfer the old load's TBAA tag to the new load.
+ if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa))
+ NewLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
// Add the newly created load.
ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,
return false;
}
-// lookupNumber - In order to find a leader for a given value number at a
+// findLeader - In order to find a leader for a given value number at a
// specific basic block, we first obtain the list of all Values for that number,
// and then scan the list to find one whose block dominates the block in
// question. This is fast because dominator tree queries consist of only
// a few comparisons of DFS numbers.
-Value *GVN::lookupNumber(BasicBlock *BB, uint32_t num) {
- std::pair<Value*, void*> Vals = NumberTable[num];
- if (!Vals.first) return 0;
- Instruction *Inst = dyn_cast<Instruction>(Vals.first);
- if (!Inst) return Vals.first;
- BasicBlock *Parent = Inst->getParent();
- if (DT->dominates(Parent, BB))
- return Inst;
+Value *GVN::findLeader(BasicBlock *BB, uint32_t num) {
+ LeaderTableEntry Vals = LeaderTable[num];
+ if (!Vals.Val) return 0;
+
+ Value *Val = 0;
+ if (DT->dominates(Vals.BB, BB)) {
+ Val = Vals.Val;
+ if (isa<Constant>(Val)) return Val;
+ }
- std::pair<Value*, void*>* Next =
- static_cast<std::pair<Value*, void*>*>(Vals.second);
+ LeaderTableEntry* Next = Vals.Next;
while (Next) {
- Instruction *CurrInst = dyn_cast<Instruction>(Next->first);
- if (!CurrInst) return Next->first;
-
- BasicBlock *Parent = CurrInst->getParent();
- if (DT->dominates(Parent, BB))
- return CurrInst;
+ if (DT->dominates(Next->BB, BB)) {
+ if (isa<Constant>(Next->Val)) return Next->Val;
+ if (!Val) Val = Next->Val;
+ }
- Next = static_cast<std::pair<Value*, void*>*>(Next->second);
+ Next = Next->Next;
}
- return 0;
+ return Val;
}
if (!Changed) {
unsigned Num = VN.lookup_or_add(LI);
- insert_table(Num, LI);
+ addToLeaderTable(Num, LI, LI->getParent());
}
return Changed;
}
+ // For conditions 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;
+ }
+
+ // 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;
+
uint32_t NextNum = VN.getNextUnusedValueNumber();
unsigned Num = VN.lookup_or_add(I);
// Allocations are always uniquely numbered, so we can save time and memory
// by fast failing them.
- if (isa<AllocaInst>(I) || isa<TerminatorInst>(I)) {
- insert_table(Num, I);
+ if (isa<AllocaInst>(I) || isa<TerminatorInst>(I) || isa<PHINode>(I)) {
+ addToLeaderTable(Num, I, I->getParent());
return false;
}
- if (isa<PHINode>(I)) {
- insert_table(Num, I);
-
// If the number we were assigned was a brand new VN, then we don't
// need to do a lookup to see if the number already exists
// somewhere in the domtree: it can't!
- } else if (Num == NextNum) {
- insert_table(Num, I);
-
+ if (Num == NextNum) {
+ addToLeaderTable(Num, I, I->getParent());
+ return false;
+ }
+
// Perform fast-path value-number based elimination of values inherited from
// dominators.
- } else if (Value *repl = lookupNumber(I->getParent(), Num)) {
- // Remove it!
- VN.erase(I);
- I->replaceAllUsesWith(repl);
- if (MD && repl->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(repl);
- toErase.push_back(I);
- return true;
-
- } else {
- insert_table(Num, I);
+ Value *repl = findLeader(I->getParent(), Num);
+ if (repl == 0) {
+ // Failure, just remember this instance for future use.
+ addToLeaderTable(Num, I, I->getParent());
+ return false;
}
-
- return false;
+
+ // Remove it!
+ VN.erase(I);
+ I->replaceAllUsesWith(repl);
+ if (MD && repl->getType()->isPointerTy())
+ MD->invalidateCachedPointerInfo(repl);
+ toErase.push_back(I);
+ return true;
}
/// runOnFunction - This is the main transformation entry point for a function.
break;
}
- Value* predV = lookupNumber(P, ValNo);
+ Value* predV = findLeader(P, ValNo);
if (predV == 0) {
PREPred = P;
++NumWithout;
if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
continue;
- if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
+ if (Value *V = findLeader(PREPred, VN.lookup(Op))) {
PREInstr->setOperand(i, V);
} else {
success = false;
++NumGVNPRE;
// Update the availability map to include the new instruction.
- insert_table(ValNo, PREInstr);
+ addToLeaderTable(ValNo, PREInstr, PREPred);
// Create a PHI to make the value available in this block.
PHINode* Phi = PHINode::Create(CurInst->getType(),
}
VN.add(Phi, ValNo);
- insert_table(ValNo, Phi);
+ addToLeaderTable(ValNo, Phi, CurrentBlock);
CurInst->replaceAllUsesWith(Phi);
- if (MD && Phi->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(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));
+
+ if (MD)
+ MD->invalidateCachedPointerInfo(Phi);
+ }
VN.erase(CurInst);
- erase_table(ValNo, CurInst);
+ removeFromLeaderTable(ValNo, CurInst, CurrentBlock);
DEBUG(dbgs() << "GVN PRE removed: " << *CurInst << '\n');
if (MD) MD->removeInstruction(CurInst);
void GVN::cleanupGlobalSets() {
VN.clear();
- NumberTable.clear();
+ LeaderTable.clear();
TableAllocator.Reset();
}
// Walk through the value number scope to make sure the instruction isn't
// ferreted away in it.
- for (DenseMap<uint32_t, std::pair<Value*, void*> >::const_iterator
- I = NumberTable.begin(), E = NumberTable.end(); I != E; ++I) {
- std::pair<Value*, void*> const * Node = &I->second;
- assert(Node->first != Inst && "Inst still in value numbering scope!");
+ for (DenseMap<uint32_t, LeaderTableEntry>::const_iterator
+ I = LeaderTable.begin(), E = LeaderTable.end(); I != E; ++I) {
+ const LeaderTableEntry *Node = &I->second;
+ assert(Node->Val != Inst && "Inst still in value numbering scope!");
- while (Node->second) {
- Node = static_cast<std::pair<Value*, void*>*>(Node->second);
- assert(Node->first != Inst && "Inst still in value numbering scope!");
+ while (Node->Next) {
+ Node = Node->Next;
+ assert(Node->Val != Inst && "Inst still in value numbering scope!");
}
}
}
projects / oota-llvm.git / blobdiff