#define DEBUG_TYPE "lazy-value-info"
#include "llvm/Analysis/LazyValueInfo.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/ValueHandle.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetLibraryInfo.h"
#include <map>
#include <stack>
using namespace llvm;
+using namespace PatternMatch;
char LazyValueInfo::ID = 0;
INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info",
if (NewR.isEmptySet())
return markOverdefined();
- bool changed = Range == NewR;
+ bool changed = Range != NewR;
Range = NewR;
return changed;
}
// Unless we can prove that the two Constants are different, we must
// move to overdefined.
- // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding.
+ // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding.
if (ConstantInt *Res = dyn_cast<ConstantInt>(
ConstantFoldCompareInstOperands(CmpInst::ICMP_NE,
getConstant(),
// Unless we can prove that the two Constants are different, we must
// move to overdefined.
- // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding.
+ // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding.
if (ConstantInt *Res = dyn_cast<ConstantInt>(
ConstantFoldCompareInstOperands(CmpInst::ICMP_NE,
getNotConstant(),
//===----------------------------------------------------------------------===//
namespace {
- /// LVIValueHandle - A callback value handle update the cache when
+ /// LVIValueHandle - A callback value handle updates the cache when
/// values are erased.
class LazyValueInfoCache;
struct LVIValueHandle : public CallbackVH {
};
}
-namespace llvm {
- template<>
- struct DenseMapInfo<LVIValueHandle> {
- typedef DenseMapInfo<Value*> PointerInfo;
- static inline LVIValueHandle getEmptyKey() {
- return LVIValueHandle(PointerInfo::getEmptyKey(),
- static_cast<LazyValueInfoCache*>(0));
- }
- static inline LVIValueHandle getTombstoneKey() {
- return LVIValueHandle(PointerInfo::getTombstoneKey(),
- static_cast<LazyValueInfoCache*>(0));
- }
- static unsigned getHashValue(const LVIValueHandle &Val) {
- return PointerInfo::getHashValue(Val);
- }
- static bool isEqual(const LVIValueHandle &LHS, const LVIValueHandle &RHS) {
- return LHS == RHS;
- }
- };
-
- template<>
- struct DenseMapInfo<std::pair<AssertingVH<BasicBlock>, Value*> > {
- typedef std::pair<AssertingVH<BasicBlock>, Value*> PairTy;
- typedef DenseMapInfo<AssertingVH<BasicBlock> > APointerInfo;
- typedef DenseMapInfo<Value*> BPointerInfo;
- static inline PairTy getEmptyKey() {
- return std::make_pair(APointerInfo::getEmptyKey(),
- BPointerInfo::getEmptyKey());
- }
- static inline PairTy getTombstoneKey() {
- return std::make_pair(APointerInfo::getTombstoneKey(),
- BPointerInfo::getTombstoneKey());
- }
- static unsigned getHashValue( const PairTy &Val) {
- return APointerInfo::getHashValue(Val.first) ^
- BPointerInfo::getHashValue(Val.second);
- }
- static bool isEqual(const PairTy &LHS, const PairTy &RHS) {
- return APointerInfo::isEqual(LHS.first, RHS.first) &&
- BPointerInfo::isEqual(LHS.second, RHS.second);
- }
- };
-}
-
namespace {
/// LazyValueInfoCache - This is the cache kept by LazyValueInfo which
/// maintains information about queries across the clients' queries.
/// ValueCache - This is all of the cached information for all values,
/// mapped from Value* to key information.
- DenseMap<LVIValueHandle, ValueCacheEntryTy> ValueCache;
+ std::map<LVIValueHandle, ValueCacheEntryTy> ValueCache;
/// OverDefinedCache - This tracks, on a per-block basis, the set of
/// values that are over-defined at the end of that block. This is required
E = ToErase.end(); I != E; ++I)
OverDefinedCache.erase(*I);
- for (DenseMap<LVIValueHandle, ValueCacheEntryTy>::iterator
+ for (std::map<LVIValueHandle, ValueCacheEntryTy>::iterator
I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
I->second.erase(BB);
}
void LazyValueInfoCache::solve() {
while (!BlockValueStack.empty()) {
std::pair<BasicBlock*, Value*> &e = BlockValueStack.top();
- if (solveBlockValue(e.second, e.first))
+ if (solveBlockValue(e.second, e.first)) {
+ assert(BlockValueStack.top() == e);
BlockValueStack.pop();
+ }
}
}
return true;
LVIValueHandle ValHandle(Val, this);
- if (!ValueCache.count(ValHandle)) return false;
- return ValueCache[ValHandle].count(BB);
+ std::map<LVIValueHandle, ValueCacheEntryTy>::iterator I =
+ ValueCache.find(ValHandle);
+ if (I == ValueCache.end()) return false;
+ return I->second.count(BB);
}
LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) {
static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) {
if (LoadInst *L = dyn_cast<LoadInst>(I)) {
return L->getPointerAddressSpace() == 0 &&
- GetUnderlyingObject(L->getPointerOperand()) ==
- GetUnderlyingObject(Ptr);
+ GetUnderlyingObject(L->getPointerOperand()) == Ptr;
}
if (StoreInst *S = dyn_cast<StoreInst>(I)) {
return S->getPointerAddressSpace() == 0 &&
- GetUnderlyingObject(S->getPointerOperand()) ==
- GetUnderlyingObject(Ptr);
+ GetUnderlyingObject(S->getPointerOperand()) == Ptr;
}
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
if (MI->isVolatile()) return false;
if (!Len || Len->isZero()) return false;
if (MI->getDestAddressSpace() == 0)
- if (MI->getRawDest() == Ptr || MI->getDest() == Ptr)
+ if (GetUnderlyingObject(MI->getRawDest()) == Ptr)
return true;
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
if (MTI->getSourceAddressSpace() == 0)
- if (MTI->getRawSource() == Ptr || MTI->getSource() == Ptr)
+ if (GetUnderlyingObject(MTI->getRawSource()) == Ptr)
return true;
}
return false;
// then we know that the pointer can't be NULL.
bool NotNull = false;
if (Val->getType()->isPointerTy()) {
- if (isa<AllocaInst>(Val)) {
+ if (isKnownNonNull(Val)) {
NotNull = true;
} else {
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){
- if (InstructionDereferencesPointer(BI, Val)) {
- NotNull = true;
- break;
+ Value *UnderlyingVal = GetUnderlyingObject(Val);
+ // If 'GetUnderlyingObject' didn't converge, skip it. It won't converge
+ // inside InstructionDereferencesPointer either.
+ if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, NULL, 1)) {
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+ BI != BE; ++BI) {
+ if (InstructionDereferencesPointer(BI, UnderlyingVal)) {
+ NotNull = true;
+ break;
+ }
}
}
}
return true;
}
-/// getEdgeValue - This method attempts to infer more complex
-bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom,
- BasicBlock *BBTo, LVILatticeVal &Result) {
- // If already a constant, there is nothing to compute.
- if (Constant *VC = dyn_cast<Constant>(Val)) {
- Result = LVILatticeVal::get(VC);
- return true;
- }
-
+/// \brief Compute the value of Val on the edge BBFrom -> BBTo. Returns false if
+/// Val is not constrained on the edge.
+static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
+ BasicBlock *BBTo, LVILatticeVal &Result) {
// TODO: Handle more complex conditionals. If (v == 0 || v2 < 1) is false, we
// know that v != 0.
if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) {
// If the condition of the branch is an equality comparison, we may be
// able to infer the value.
ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition());
- if (ICI && ICI->getOperand(0) == Val &&
- isa<Constant>(ICI->getOperand(1))) {
- if (ICI->isEquality()) {
+ if (ICI && isa<Constant>(ICI->getOperand(1))) {
+ if (ICI->isEquality() && ICI->getOperand(0) == Val) {
// We know that V has the RHS constant if this is a true SETEQ or
// false SETNE.
if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
return true;
}
- if (ConstantInt *CI = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+ // Recognize the range checking idiom that InstCombine produces.
+ // (X-C1) u< C2 --> [C1, C1+C2)
+ ConstantInt *NegOffset = 0;
+ if (ICI->getPredicate() == ICmpInst::ICMP_ULT)
+ match(ICI->getOperand(0), m_Add(m_Specific(Val),
+ m_ConstantInt(NegOffset)));
+
+ ConstantInt *CI = dyn_cast<ConstantInt>(ICI->getOperand(1));
+ if (CI && (ICI->getOperand(0) == Val || NegOffset)) {
// Calculate the range of values that would satisfy the comparison.
- ConstantRange CmpRange(CI->getValue(), CI->getValue()+1);
+ ConstantRange CmpRange(CI->getValue());
ConstantRange TrueValues =
ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange);
+ if (NegOffset) // Apply the offset from above.
+ TrueValues = TrueValues.subtract(NegOffset->getValue());
+
// If we're interested in the false dest, invert the condition.
if (!isTrueDest) TrueValues = TrueValues.inverse();
-
- // Figure out the possible values of the query BEFORE this branch.
- if (!hasBlockValue(Val, BBFrom)) {
- BlockValueStack.push(std::make_pair(BBFrom, Val));
- return false;
- }
-
- LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
- if (!InBlock.isConstantRange()) {
- Result = LVILatticeVal::getRange(TrueValues);
- return true;
- }
-
- // Find all potential values that satisfy both the input and output
- // conditions.
- ConstantRange PossibleValues =
- TrueValues.intersectWith(InBlock.getConstantRange());
- Result = LVILatticeVal::getRange(PossibleValues);
+ Result = LVILatticeVal::getRange(TrueValues);
return true;
}
}
// If the edge was formed by a switch on the value, then we may know exactly
// what it is.
if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) {
- if (SI->getCondition() == Val) {
- // We don't know anything in the default case.
- if (SI->getDefaultDest() == BBTo) {
- Result.markOverdefined();
- return true;
- }
-
- // We only know something if there is exactly one value that goes from
- // BBFrom to BBTo.
- unsigned NumEdges = 0;
- ConstantInt *EdgeVal = 0;
- for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
- if (SI->getSuccessor(i) != BBTo) continue;
- if (NumEdges++) break;
- EdgeVal = SI->getCaseValue(i);
- }
- assert(EdgeVal && "Missing successor?");
- if (NumEdges == 1) {
- Result = LVILatticeVal::get(EdgeVal);
- return true;
- }
+ if (SI->getCondition() != Val)
+ return false;
+
+ bool DefaultCase = SI->getDefaultDest() == BBTo;
+ unsigned BitWidth = Val->getType()->getIntegerBitWidth();
+ ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/);
+
+ for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
+ i != e; ++i) {
+ ConstantRange EdgeVal(i.getCaseValue()->getValue());
+ if (DefaultCase) {
+ // It is possible that the default destination is the destination of
+ // some cases. There is no need to perform difference for those cases.
+ if (i.getCaseSuccessor() != BBTo)
+ EdgesVals = EdgesVals.difference(EdgeVal);
+ } else if (i.getCaseSuccessor() == BBTo)
+ EdgesVals = EdgesVals.unionWith(EdgeVal);
}
- }
-
- // Otherwise see if the value is known in the block.
- if (hasBlockValue(Val, BBFrom)) {
- Result = getBlockValue(Val, BBFrom);
+ Result = LVILatticeVal::getRange(EdgesVals);
return true;
}
- BlockValueStack.push(std::make_pair(BBFrom, Val));
return false;
}
+/// \brief Compute the value of Val on the edge BBFrom -> BBTo, or the value at
+/// the basic block if the edge does not constraint Val.
+bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom,
+ BasicBlock *BBTo, LVILatticeVal &Result) {
+ // If already a constant, there is nothing to compute.
+ if (Constant *VC = dyn_cast<Constant>(Val)) {
+ Result = LVILatticeVal::get(VC);
+ return true;
+ }
+
+ if (getEdgeValueLocal(Val, BBFrom, BBTo, Result)) {
+ if (!Result.isConstantRange() ||
+ Result.getConstantRange().getSingleElement())
+ return true;
+
+ // FIXME: this check should be moved to the beginning of the function when
+ // LVI better supports recursive values. Even for the single value case, we
+ // can intersect to detect dead code (an empty range).
+ if (!hasBlockValue(Val, BBFrom)) {
+ BlockValueStack.push(std::make_pair(BBFrom, Val));
+ return false;
+ }
+
+ // Try to intersect ranges of the BB and the constraint on the edge.
+ LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
+ if (!InBlock.isConstantRange())
+ return true;
+
+ ConstantRange Range =
+ Result.getConstantRange().intersectWith(InBlock.getConstantRange());
+ Result = LVILatticeVal::getRange(Range);
+ return true;
+ }
+
+ if (!hasBlockValue(Val, BBFrom)) {
+ BlockValueStack.push(std::make_pair(BBFrom, Val));
+ return false;
+ }
+
+ // if we couldn't compute the value on the edge, use the value from the BB
+ Result = getBlockValue(Val, BBFrom);
+ return true;
+}
+
LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
if (PImpl)
getCache(PImpl).clear();
- TD = getAnalysisIfAvailable<TargetData>();
+ TD = getAnalysisIfAvailable<DataLayout>();
TLI = &getAnalysis<TargetLibraryInfo>();
// Fully lazy.
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