#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetLibraryInfo.h"
#include <map>
#include <stack>
using namespace llvm;
INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info",
"Lazy Value Information Analysis", false, true)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(LazyValueInfo, "lazy-value-info",
"Lazy Value Information Analysis", false, true)
// LVILatticeVal
//===----------------------------------------------------------------------===//
-/// LVILatticeVal - This is the information tracked by LazyValueInfo for each
-/// value.
+/// This is the information tracked by LazyValueInfo for each value.
///
/// FIXME: This is basically just for bringup, this can be made a lot more rich
/// in the future.
namespace {
class LVILatticeVal {
enum LatticeValueTy {
- /// undefined - This Value has no known value yet.
+ /// This Value has no known value yet.
undefined,
-
- /// constant - This Value has a specific constant value.
+
+ /// This Value has a specific constant value.
constant,
- /// notconstant - This Value is known to not have the specified value.
+
+ /// This Value is known to not have the specified value.
notconstant,
- /// constantrange - The Value falls within this range.
+ /// The Value falls within this range.
constantrange,
- /// overdefined - This value is not known to be constant, and we know that
- /// it has a value.
+ /// This value is not known to be constant, and we know that it has a value.
overdefined
};
-
+
/// Val: This stores the current lattice value along with the Constant* for
/// the constant if this is a 'constant' or 'notconstant' value.
LatticeValueTy Tag;
Constant *Val;
ConstantRange Range;
-
+
public:
LVILatticeVal() : Tag(undefined), Val(nullptr), Range(1, true) {}
Res.markConstantRange(CR);
return Res;
}
+ static LVILatticeVal getOverdefined() {
+ LVILatticeVal Res;
+ Res.markOverdefined();
+ return Res;
+ }
bool isUndefined() const { return Tag == undefined; }
bool isConstant() const { return Tag == constant; }
bool isNotConstant() const { return Tag == notconstant; }
bool isConstantRange() const { return Tag == constantrange; }
bool isOverdefined() const { return Tag == overdefined; }
-
+
Constant *getConstant() const {
assert(isConstant() && "Cannot get the constant of a non-constant!");
return Val;
}
-
+
Constant *getNotConstant() const {
assert(isNotConstant() && "Cannot get the constant of a non-notconstant!");
return Val;
}
-
+
ConstantRange getConstantRange() const {
assert(isConstantRange() &&
"Cannot get the constant-range of a non-constant-range!");
return Range;
}
-
- /// markOverdefined - Return true if this is a change in status.
+
+ /// Return true if this is a change in status.
bool markOverdefined() {
if (isOverdefined())
return false;
return true;
}
- /// markConstant - Return true if this is a change in status.
+ /// Return true if this is a change in status.
bool markConstant(Constant *V) {
assert(V && "Marking constant with NULL");
if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
Val = V;
return true;
}
-
- /// markNotConstant - Return true if this is a change in status.
+
+ /// Return true if this is a change in status.
bool markNotConstant(Constant *V) {
assert(V && "Marking constant with NULL");
if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
Val = V;
return true;
}
-
- /// markConstantRange - Return true if this is a change in status.
+
+ /// Return true if this is a change in status.
bool markConstantRange(const ConstantRange NewR) {
if (isConstantRange()) {
if (NewR.isEmptySet())
return markOverdefined();
-
+
bool changed = Range != NewR;
Range = NewR;
return changed;
}
-
+
assert(isUndefined());
if (NewR.isEmptySet())
return markOverdefined();
-
+
Tag = constantrange;
Range = NewR;
return true;
}
-
- /// mergeIn - Merge the specified lattice value into this one, updating this
+
+ /// Merge the specified lattice value into this one, updating this
/// one and returning true if anything changed.
- bool mergeIn(const LVILatticeVal &RHS) {
+ bool mergeIn(const LVILatticeVal &RHS, const DataLayout &DL) {
if (RHS.isUndefined() || isOverdefined()) return false;
if (RHS.isOverdefined()) return markOverdefined();
// Unless we can prove that the two Constants are different, we must
// move to overdefined.
- // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding.
- if (ConstantInt *Res = dyn_cast<ConstantInt>(
- ConstantFoldCompareInstOperands(CmpInst::ICMP_NE,
- getConstant(),
- RHS.getNotConstant())))
+ if (ConstantInt *Res =
+ dyn_cast<ConstantInt>(ConstantFoldCompareInstOperands(
+ CmpInst::ICMP_NE, getConstant(), RHS.getNotConstant(), DL)))
if (Res->isOne())
return markNotConstant(RHS.getNotConstant());
// Unless we can prove that the two Constants are different, we must
// move to overdefined.
- // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding.
- if (ConstantInt *Res = dyn_cast<ConstantInt>(
- ConstantFoldCompareInstOperands(CmpInst::ICMP_NE,
- getNotConstant(),
- RHS.getConstant())))
+ if (ConstantInt *Res =
+ dyn_cast<ConstantInt>(ConstantFoldCompareInstOperands(
+ CmpInst::ICMP_NE, getNotConstant(), RHS.getConstant(), DL)))
if (Res->isOne())
return false;
return markConstantRange(NewR);
}
};
-
+
} // end anonymous namespace.
namespace llvm {
//===----------------------------------------------------------------------===//
namespace {
- /// LVIValueHandle - A callback value handle updates the cache when
- /// values are erased.
+ /// A callback value handle updates the cache when values are erased.
class LazyValueInfoCache;
- struct LVIValueHandle : public CallbackVH {
+ struct LVIValueHandle final : public CallbackVH {
LazyValueInfoCache *Parent;
-
+
LVIValueHandle(Value *V, LazyValueInfoCache *P)
: CallbackVH(V), Parent(P) { }
};
}
-namespace {
- /// LazyValueInfoCache - This is the cache kept by LazyValueInfo which
+namespace {
+ /// This is the cache kept by LazyValueInfo which
/// maintains information about queries across the clients' queries.
class LazyValueInfoCache {
- /// ValueCacheEntryTy - This is all of the cached block information for
- /// exactly one Value*. The entries are sorted by the BasicBlock* of the
+ /// This is all of the cached block information for exactly one Value*.
+ /// The entries are sorted by the BasicBlock* of the
/// entries, allowing us to do a lookup with a binary search.
- typedef std::map<AssertingVH<BasicBlock>, LVILatticeVal> ValueCacheEntryTy;
+ /// Over-defined lattice values are recorded in OverDefinedCache to reduce
+ /// memory overhead.
+ typedef SmallDenseMap<AssertingVH<BasicBlock>, LVILatticeVal, 4>
+ ValueCacheEntryTy;
- /// ValueCache - This is all of the cached information for all values,
+ /// This is all of the cached information for all values,
/// mapped from Value* to key information.
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
- /// for cache updating.
- typedef std::pair<AssertingVH<BasicBlock>, Value*> OverDefinedPairTy;
- DenseSet<OverDefinedPairTy> OverDefinedCache;
- /// SeenBlocks - Keep track of all blocks that we have ever seen, so we
+ /// This tracks, on a per-block basis, the set of values that are
+ /// over-defined at the end of that block.
+ typedef DenseMap<AssertingVH<BasicBlock>, SmallPtrSet<Value *, 4>>
+ OverDefinedCacheTy;
+ OverDefinedCacheTy OverDefinedCache;
+
+ /// Keep track of all blocks that we have ever seen, so we
/// don't spend time removing unused blocks from our caches.
DenseSet<AssertingVH<BasicBlock> > SeenBlocks;
- /// BlockValueStack - This stack holds the state of the value solver
- /// during a query. It basically emulates the callstack of the naive
+ /// This stack holds the state of the value solver during a query.
+ /// It basically emulates the callstack of the naive
/// recursive value lookup process.
std::stack<std::pair<BasicBlock*, Value*> > BlockValueStack;
- /// BlockValueSet - Keeps track of which block-value pairs are in
- /// BlockValueStack.
+ /// Keeps track of which block-value pairs are in BlockValueStack.
DenseSet<std::pair<BasicBlock*, Value*> > BlockValueSet;
- /// pushBlockValue - Push BV onto BlockValueStack unless it's already in
- /// there. Returns true on success.
+ /// Push BV onto BlockValueStack unless it's already in there.
+ /// Returns true on success.
bool pushBlockValue(const std::pair<BasicBlock *, Value *> &BV) {
- if (BlockValueSet.count(BV))
+ if (!BlockValueSet.insert(BV).second)
return false; // It's already in the stack.
BlockValueStack.push(BV);
- BlockValueSet.insert(BV);
return true;
}
- /// A pointer to the cache of @llvm.assume calls.
- AssumptionCache *AC;
- /// An optional DL pointer.
- const DataLayout *DL;
- /// An optional DT pointer.
- DominatorTree *DT;
-
+ AssumptionCache *AC; ///< A pointer to the cache of @llvm.assume calls.
+ const DataLayout &DL; ///< A mandatory DataLayout
+ DominatorTree *DT; ///< An optional DT pointer.
+
friend struct LVIValueHandle;
void insertResult(Value *Val, BasicBlock *BB, const LVILatticeVal &Result) {
SeenBlocks.insert(BB);
- lookup(Val)[BB] = Result;
+
+ // Insert over-defined values into their own cache to reduce memory
+ // overhead.
if (Result.isOverdefined())
- OverDefinedCache.insert(std::make_pair(BB, Val));
+ OverDefinedCache[BB].insert(Val);
+ else
+ lookup(Val)[BB] = Result;
}
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
Instruction *BBI);
void solve();
-
+
ValueCacheEntryTy &lookup(Value *V) {
return ValueCache[LVIValueHandle(V, this)];
}
+ bool isOverdefined(Value *V, BasicBlock *BB) const {
+ auto ODI = OverDefinedCache.find(BB);
+
+ if (ODI == OverDefinedCache.end())
+ return false;
+
+ return ODI->second.count(V);
+ }
+
+ bool hasCachedValueInfo(Value *V, BasicBlock *BB) {
+ if (isOverdefined(V, BB))
+ return true;
+
+ LVIValueHandle ValHandle(V, this);
+ auto I = ValueCache.find(ValHandle);
+ if (I == ValueCache.end())
+ return false;
+
+ return I->second.count(BB);
+ }
+
+ LVILatticeVal getCachedValueInfo(Value *V, BasicBlock *BB) {
+ if (isOverdefined(V, BB))
+ return LVILatticeVal::getOverdefined();
+
+ return lookup(V)[BB];
+ }
+
public:
- /// getValueInBlock - This is the query interface to determine the lattice
+ /// This is the query interface to determine the lattice
/// value for the specified Value* at the end of the specified block.
LVILatticeVal getValueInBlock(Value *V, BasicBlock *BB,
Instruction *CxtI = nullptr);
- /// getValueAt - This is the query interface to determine the lattice
+ /// This is the query interface to determine the lattice
/// value for the specified Value* at the specified instruction (generally
/// from an assume intrinsic).
LVILatticeVal getValueAt(Value *V, Instruction *CxtI);
- /// getValueOnEdge - This is the query interface to determine the lattice
+ /// This is the query interface to determine the lattice
/// value for the specified Value* that is true on the specified edge.
LVILatticeVal getValueOnEdge(Value *V, BasicBlock *FromBB,BasicBlock *ToBB,
Instruction *CxtI = nullptr);
-
- /// threadEdge - This is the update interface to inform the cache that an
- /// edge from PredBB to OldSucc has been threaded to be from PredBB to
- /// NewSucc.
+
+ /// This is the update interface to inform the cache that an edge from
+ /// PredBB to OldSucc has been threaded to be from PredBB to NewSucc.
void threadEdge(BasicBlock *PredBB,BasicBlock *OldSucc,BasicBlock *NewSucc);
-
- /// eraseBlock - This is part of the update interface to inform the cache
+
+ /// This is part of the update interface to inform the cache
/// that a block has been deleted.
void eraseBlock(BasicBlock *BB);
-
+
/// clear - Empty the cache.
void clear() {
SeenBlocks.clear();
OverDefinedCache.clear();
}
- LazyValueInfoCache(AssumptionCache *AC, const DataLayout *DL = nullptr,
+ LazyValueInfoCache(AssumptionCache *AC, const DataLayout &DL,
DominatorTree *DT = nullptr)
: AC(AC), DL(DL), DT(DT) {}
};
} // end anonymous namespace
void LVIValueHandle::deleted() {
- typedef std::pair<AssertingVH<BasicBlock>, Value*> OverDefinedPairTy;
-
- SmallVector<OverDefinedPairTy, 4> ToErase;
- for (const OverDefinedPairTy &P : Parent->OverDefinedCache)
- if (P.second == getValPtr())
- ToErase.push_back(P);
- for (const OverDefinedPairTy &P : ToErase)
- Parent->OverDefinedCache.erase(P);
-
+ SmallVector<AssertingVH<BasicBlock>, 4> ToErase;
+ for (auto &I : Parent->OverDefinedCache) {
+ SmallPtrSetImpl<Value *> &ValueSet = I.second;
+ if (ValueSet.count(getValPtr()))
+ ValueSet.erase(getValPtr());
+ if (ValueSet.empty())
+ ToErase.push_back(I.first);
+ }
+ for (auto &BB : ToErase)
+ Parent->OverDefinedCache.erase(BB);
+
// This erasure deallocates *this, so it MUST happen after we're done
// using any and all members of *this.
Parent->ValueCache.erase(*this);
return;
SeenBlocks.erase(I);
- SmallVector<OverDefinedPairTy, 4> ToErase;
- for (const OverDefinedPairTy& P : OverDefinedCache)
- if (P.first == BB)
- ToErase.push_back(P);
- for (const OverDefinedPairTy &P : ToErase)
- OverDefinedCache.erase(P);
+ auto ODI = OverDefinedCache.find(BB);
+ if (ODI != OverDefinedCache.end())
+ OverDefinedCache.erase(ODI);
- for (std::map<LVIValueHandle, ValueCacheEntryTy>::iterator
- I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
+ for (auto I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
I->second.erase(BB);
}
if (solveBlockValue(e.second, e.first)) {
// The work item was completely processed.
assert(BlockValueStack.top() == e && "Nothing should have been pushed!");
- assert(lookup(e.second).count(e.first) && "Result should be in cache!");
+ assert(hasCachedValueInfo(e.second, e.first) &&
+ "Result should be in cache!");
BlockValueStack.pop();
BlockValueSet.erase(e);
if (isa<Constant>(Val))
return true;
- LVIValueHandle ValHandle(Val, this);
- std::map<LVIValueHandle, ValueCacheEntryTy>::iterator I =
- ValueCache.find(ValHandle);
- if (I == ValueCache.end()) return false;
- return I->second.count(BB);
+ return hasCachedValueInfo(Val, BB);
}
LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) {
return LVILatticeVal::get(VC);
SeenBlocks.insert(BB);
- return lookup(Val)[BB];
+ return getCachedValueInfo(Val, BB);
+}
+
+static LVILatticeVal getFromRangeMetadata(Instruction *BBI) {
+ switch (BBI->getOpcode()) {
+ default: break;
+ case Instruction::Load:
+ case Instruction::Call:
+ case Instruction::Invoke:
+ if (MDNode *Ranges = BBI->getMetadata(LLVMContext::MD_range))
+ if (isa<IntegerType>(BBI->getType())) {
+ ConstantRange Result = getConstantRangeFromMetadata(*Ranges);
+ return LVILatticeVal::getRange(Result);
+ }
+ break;
+ };
+ // Nothing known - Note that we do not want overdefined here. We may know
+ // something else about the value and not having range metadata shouldn't
+ // cause us to throw away those facts.
+ return LVILatticeVal();
}
bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
if (isa<Constant>(Val))
return true;
- if (lookup(Val).count(BB)) {
+ if (hasCachedValueInfo(Val, BB)) {
// If we have a cached value, use that.
DEBUG(dbgs() << " reuse BB '" << BB->getName()
- << "' val=" << lookup(Val)[BB] << '\n');
+ << "' val=" << getCachedValueInfo(Val, BB) << '\n');
// Since we're reusing a cached value, we don't need to update the
// OverDefinedCache. The cache will have been properly updated whenever the
// Hold off inserting this value into the Cache in case we have to return
// false and come back later.
LVILatticeVal Res;
-
+
Instruction *BBI = dyn_cast<Instruction>(Val);
if (!BBI || BBI->getParent() != BB) {
if (!solveBlockValueNonLocal(Res, Val, BB))
return true;
}
- if (AllocaInst *AI = dyn_cast<AllocaInst>(BBI)) {
- Res = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType()));
+ // If this value is a nonnull pointer, record it's range and bailout.
+ PointerType *PT = dyn_cast<PointerType>(BBI->getType());
+ if (PT && isKnownNonNull(BBI)) {
+ Res = LVILatticeVal::getNot(ConstantPointerNull::get(PT));
insertResult(Val, BB, Res);
return true;
}
+ // If this is an instruction which supports range metadata, return the
+ // implied range. TODO: This should be an intersection, not a union.
+ Res.mergeIn(getFromRangeMetadata(BBI), DL);
+
// We can only analyze the definitions of certain classes of instructions
// (integral binops and casts at the moment), so bail if this isn't one.
LVILatticeVal Result;
static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) {
if (LoadInst *L = dyn_cast<LoadInst>(I)) {
return L->getPointerAddressSpace() == 0 &&
- GetUnderlyingObject(L->getPointerOperand()) == Ptr;
+ GetUnderlyingObject(L->getPointerOperand(),
+ L->getModule()->getDataLayout()) == Ptr;
}
if (StoreInst *S = dyn_cast<StoreInst>(I)) {
return S->getPointerAddressSpace() == 0 &&
- GetUnderlyingObject(S->getPointerOperand()) == Ptr;
+ GetUnderlyingObject(S->getPointerOperand(),
+ S->getModule()->getDataLayout()) == Ptr;
}
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
if (MI->isVolatile()) return false;
if (!Len || Len->isZero()) return false;
if (MI->getDestAddressSpace() == 0)
- if (GetUnderlyingObject(MI->getRawDest()) == Ptr)
+ if (GetUnderlyingObject(MI->getRawDest(),
+ MI->getModule()->getDataLayout()) == Ptr)
return true;
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
if (MTI->getSourceAddressSpace() == 0)
- if (GetUnderlyingObject(MTI->getRawSource()) == Ptr)
+ if (GetUnderlyingObject(MTI->getRawSource(),
+ MTI->getModule()->getDataLayout()) == Ptr)
return true;
}
return false;
if (isKnownNonNull(Val)) {
NotNull = true;
} else {
- Value *UnderlyingVal = GetUnderlyingObject(Val);
+ const DataLayout &DL = BB->getModule()->getDataLayout();
+ Value *UnderlyingVal = GetUnderlyingObject(Val, DL);
// If 'GetUnderlyingObject' didn't converge, skip it. It won't converge
// inside InstructionDereferencesPointer either.
- if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, nullptr, 1)) {
+ if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, DL, 1)) {
for (Instruction &I : *BB) {
if (InstructionDereferencesPointer(&I, UnderlyingVal)) {
NotNull = true;
if (EdgesMissing)
continue;
- Result.mergeIn(EdgeResult);
+ Result.mergeIn(EdgeResult, DL);
// If we hit overdefined, exit early. The BlockVals entry is already set
// to overdefined.
PointerType *PTy = cast<PointerType>(Val->getType());
Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
}
-
+
BBLV = Result;
return true;
}
BBLV = Result;
return true;
}
-
+
bool LazyValueInfoCache::solveBlockValuePHINode(LVILatticeVal &BBLV,
PHINode *PN, BasicBlock *BB) {
LVILatticeVal Result; // Start Undefined.
if (EdgesMissing)
continue;
- Result.mergeIn(EdgeResult);
+ Result.mergeIn(EdgeResult, DL);
// If we hit overdefined, exit early. The BlockVals entry is already set
// to overdefined.
if (Result.isOverdefined()) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because of pred.\n");
-
+
BBLV = Result;
return true;
}
if (!AssumeVH)
continue;
auto *I = cast<CallInst>(AssumeVH);
- if (!isValidAssumeForContext(I, BBI, DL, DT))
+ if (!isValidAssumeForContext(I, BBI, DT))
continue;
Value *C = I->getArgOperand(0);
if (BBLV.isOverdefined())
BBLV = Result;
else
- BBLV.mergeIn(Result);
+ BBLV.mergeIn(Result, DL);
}
}
}
BBLV.markOverdefined();
return true;
}
-
+
ConstantRange LHSRange = LHSVal.getConstantRange();
ConstantRange RHSRange(1);
IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
case Instruction::Or:
Result.markConstantRange(LHSRange.binaryOr(RHSRange));
break;
-
+
// Unhandled instructions are overdefined.
default:
DEBUG(dbgs() << " compute BB '" << BB->getName()
Result.markOverdefined();
break;
}
-
+
BBLV = Result;
return true;
}
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.
+ // Calculate the range of values that are allowed by the comparison
ConstantRange CmpRange(CI->getValue());
ConstantRange TrueValues =
- ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange);
+ ConstantRange::makeAllowedICmpRegion(ICI->getPredicate(), CmpRange);
if (NegOffset) // Apply the offset from above.
TrueValues = TrueValues.subtract(NegOffset->getValue());
/// 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
+ // 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 this is a conditional branch and only one successor goes to BBTo, then
- // we maybe able to infer something from the condition.
+ // we may be able to infer something from the condition.
if (BI->isConditional() &&
BI->getSuccessor(0) != BI->getSuccessor(1)) {
bool isTrueDest = BI->getSuccessor(0) == BBTo;
assert(BI->getSuccessor(!isTrueDest) == BBTo &&
"BBTo isn't a successor of BBFrom");
-
+
// If V is the condition of the branch itself, then we know exactly what
// it is.
if (BI->getCondition() == Val) {
Type::getInt1Ty(Val->getContext()), isTrueDest));
return true;
}
-
+
// 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 (getValueFromFromCondition(Val, ICI, Result, isTrueDest))
- return true;
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
+ if (getValueFromFromCondition(Val, ICI, Result, isTrueDest))
+ return true;
}
}
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.
+/// \brief Compute the value of Val on the edge BBFrom -> BBTo or the value at
+/// the basic block if the edge does not constrain Val.
bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom,
BasicBlock *BBTo, LVILatticeVal &Result,
Instruction *CxtI) {
Instruction *CxtI) {
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
-
+
assert(BlockValueStack.empty() && BlockValueSet.empty());
pushBlockValue(std::make_pair(BB, V));
<< CxtI->getName() << "'\n");
LVILatticeVal Result;
+ if (auto *I = dyn_cast<Instruction>(V))
+ Result = getFromRangeMetadata(I);
mergeAssumeBlockValueConstantRange(V, Result, CxtI);
DEBUG(dbgs() << " Result = " << Result << "\n");
Instruction *CxtI) {
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
-
+
LVILatticeVal Result;
if (!getEdgeValue(V, FromBB, ToBB, Result, CxtI)) {
solve();
void LazyValueInfoCache::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
BasicBlock *NewSucc) {
- // When an edge in the graph has been threaded, values that we could not
- // determine a value for before (i.e. were marked overdefined) may be possible
- // to solve now. We do NOT try to proactively update these values. Instead,
- // we clear their entries from the cache, and allow lazy updating to recompute
- // them when needed.
-
+ // When an edge in the graph has been threaded, values that we could not
+ // determine a value for before (i.e. were marked overdefined) may be
+ // possible to solve now. We do NOT try to proactively update these values.
+ // Instead, we clear their entries from the cache, and allow lazy updating to
+ // recompute them when needed.
+
// The updating process is fairly simple: we need to drop cached info
// for all values that were marked overdefined in OldSucc, and for those same
// values in any successor of OldSucc (except NewSucc) in which they were
// also marked overdefined.
std::vector<BasicBlock*> worklist;
worklist.push_back(OldSucc);
-
- DenseSet<Value*> ClearSet;
- for (OverDefinedPairTy &P : OverDefinedCache)
- if (P.first == OldSucc)
- ClearSet.insert(P.second);
-
+
+ auto I = OverDefinedCache.find(OldSucc);
+ if (I == OverDefinedCache.end())
+ return; // Nothing to process here.
+ SmallVector<Value *, 4> ValsToClear(I->second.begin(), I->second.end());
+
// Use a worklist to perform a depth-first search of OldSucc's successors.
// NOTE: We do not need a visited list since any blocks we have already
// visited will have had their overdefined markers cleared already, and we
while (!worklist.empty()) {
BasicBlock *ToUpdate = worklist.back();
worklist.pop_back();
-
+
// Skip blocks only accessible through NewSucc.
if (ToUpdate == NewSucc) continue;
-
+
bool changed = false;
- for (Value *V : ClearSet) {
+ for (Value *V : ValsToClear) {
// If a value was marked overdefined in OldSucc, and is here too...
- DenseSet<OverDefinedPairTy>::iterator OI =
- OverDefinedCache.find(std::make_pair(ToUpdate, V));
- if (OI == OverDefinedCache.end()) continue;
-
- // Remove it from the caches.
- ValueCacheEntryTy &Entry = ValueCache[LVIValueHandle(V, this)];
- ValueCacheEntryTy::iterator CI = Entry.find(ToUpdate);
-
- assert(CI != Entry.end() && "Couldn't find entry to update?");
- Entry.erase(CI);
- OverDefinedCache.erase(OI);
-
- // If we removed anything, then we potentially need to update
+ auto OI = OverDefinedCache.find(ToUpdate);
+ if (OI == OverDefinedCache.end())
+ continue;
+ SmallPtrSetImpl<Value *> &ValueSet = OI->second;
+ if (!ValueSet.count(V))
+ continue;
+
+ ValueSet.erase(V);
+ if (ValueSet.empty())
+ OverDefinedCache.erase(OI);
+
+ // If we removed anything, then we potentially need to update
// blocks successors too.
changed = true;
}
if (!changed) continue;
-
+
worklist.insert(worklist.end(), succ_begin(ToUpdate), succ_end(ToUpdate));
}
}
// LazyValueInfo Impl
//===----------------------------------------------------------------------===//
-/// getCache - This lazily constructs the LazyValueInfoCache.
+/// This lazily constructs the LazyValueInfoCache.
static LazyValueInfoCache &getCache(void *&PImpl, AssumptionCache *AC,
- const DataLayout *DL = nullptr,
+ const DataLayout *DL,
DominatorTree *DT = nullptr) {
- if (!PImpl)
- PImpl = new LazyValueInfoCache(AC, DL, DT);
+ if (!PImpl) {
+ assert(DL && "getCache() called with a null DataLayout");
+ PImpl = new LazyValueInfoCache(AC, *DL, DT);
+ }
return *static_cast<LazyValueInfoCache*>(PImpl);
}
bool LazyValueInfo::runOnFunction(Function &F) {
AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+ const DataLayout &DL = F.getParent()->getDataLayout();
DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DT = DTWP ? &DTWP->getDomTree() : nullptr;
- DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
- DL = DLP ? &DLP->getDataLayout() : nullptr;
-
- TLI = &getAnalysis<TargetLibraryInfo>();
+ TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
if (PImpl)
- getCache(PImpl, AC, DL, DT).clear();
+ getCache(PImpl, AC, &DL, DT).clear();
// Fully lazy.
return false;
void LazyValueInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<AssumptionCacheTracker>();
- AU.addRequired<TargetLibraryInfo>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
}
void LazyValueInfo::releaseMemory() {
// If the cache was allocated, free it.
if (PImpl) {
- delete &getCache(PImpl, AC);
+ delete &getCache(PImpl, AC, nullptr);
PImpl = nullptr;
}
}
Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB,
Instruction *CxtI) {
+ const DataLayout &DL = BB->getModule()->getDataLayout();
LVILatticeVal Result =
- getCache(PImpl, AC, DL, DT).getValueInBlock(V, BB, CxtI);
+ getCache(PImpl, AC, &DL, DT).getValueInBlock(V, BB, CxtI);
if (Result.isConstant())
return Result.getConstant();
return nullptr;
}
-/// getConstantOnEdge - Determine whether the specified value is known to be a
-/// constant on the specified edge. Return null if not.
+/// Determine whether the specified value is known to be a
+/// constant on the specified edge. Return null if not.
Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
BasicBlock *ToBB,
Instruction *CxtI) {
+ const DataLayout &DL = FromBB->getModule()->getDataLayout();
LVILatticeVal Result =
- getCache(PImpl, AC, DL, DT).getValueOnEdge(V, FromBB, ToBB, CxtI);
+ getCache(PImpl, AC, &DL, DT).getValueOnEdge(V, FromBB, ToBB, CxtI);
if (Result.isConstant())
return Result.getConstant();
return nullptr;
}
-static LazyValueInfo::Tristate
-getPredicateResult(unsigned Pred, Constant *C, LVILatticeVal &Result,
- const DataLayout *DL, TargetLibraryInfo *TLI) {
+static LazyValueInfo::Tristate getPredicateResult(unsigned Pred, Constant *C,
+ LVILatticeVal &Result,
+ const DataLayout &DL,
+ TargetLibraryInfo *TLI) {
// If we know the value is a constant, evaluate the conditional.
Constant *Res = nullptr;
return ResCI->isZero() ? LazyValueInfo::False : LazyValueInfo::True;
return LazyValueInfo::Unknown;
}
-
+
if (Result.isConstantRange()) {
ConstantInt *CI = dyn_cast<ConstantInt>(C);
if (!CI) return LazyValueInfo::Unknown;
-
+
ConstantRange CR = Result.getConstantRange();
if (Pred == ICmpInst::ICMP_EQ) {
if (!CR.contains(CI->getValue()))
return LazyValueInfo::False;
-
+
if (CR.isSingleElement() && CR.contains(CI->getValue()))
return LazyValueInfo::True;
} else if (Pred == ICmpInst::ICMP_NE) {
if (!CR.contains(CI->getValue()))
return LazyValueInfo::True;
-
+
if (CR.isSingleElement() && CR.contains(CI->getValue()))
return LazyValueInfo::False;
}
-
+
// Handle more complex predicates.
ConstantRange TrueValues =
ICmpInst::makeConstantRange((ICmpInst::Predicate)Pred, CI->getValue());
return LazyValueInfo::False;
return LazyValueInfo::Unknown;
}
-
+
if (Result.isNotConstant()) {
// If this is an equality comparison, we can try to fold it knowing that
// "V != C1".
}
return LazyValueInfo::Unknown;
}
-
+
return LazyValueInfo::Unknown;
}
-/// getPredicateOnEdge - Determine whether the specified value comparison
-/// with a constant is known to be true or false on the specified CFG edge.
-/// Pred is a CmpInst predicate.
+/// Determine whether the specified value comparison with a constant is known to
+/// be true or false on the specified CFG edge. Pred is a CmpInst predicate.
LazyValueInfo::Tristate
LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
BasicBlock *FromBB, BasicBlock *ToBB,
Instruction *CxtI) {
+ const DataLayout &DL = FromBB->getModule()->getDataLayout();
LVILatticeVal Result =
- getCache(PImpl, AC, DL, DT).getValueOnEdge(V, FromBB, ToBB, CxtI);
+ getCache(PImpl, AC, &DL, DT).getValueOnEdge(V, FromBB, ToBB, CxtI);
return getPredicateResult(Pred, C, Result, DL, TLI);
}
LazyValueInfo::Tristate
LazyValueInfo::getPredicateAt(unsigned Pred, Value *V, Constant *C,
Instruction *CxtI) {
- LVILatticeVal Result = getCache(PImpl, AC, DL, DT).getValueAt(V, CxtI);
-
- return getPredicateResult(Pred, C, Result, DL, TLI);
+ const DataLayout &DL = CxtI->getModule()->getDataLayout();
+ LVILatticeVal Result = getCache(PImpl, AC, &DL, DT).getValueAt(V, CxtI);
+ Tristate Ret = getPredicateResult(Pred, C, Result, DL, TLI);
+ if (Ret != Unknown)
+ return Ret;
+
+ // Note: The following bit of code is somewhat distinct from the rest of LVI;
+ // LVI as a whole tries to compute a lattice value which is conservatively
+ // correct at a given location. In this case, we have a predicate which we
+ // weren't able to prove about the merged result, and we're pushing that
+ // predicate back along each incoming edge to see if we can prove it
+ // separately for each input. As a motivating example, consider:
+ // bb1:
+ // %v1 = ... ; constantrange<1, 5>
+ // br label %merge
+ // bb2:
+ // %v2 = ... ; constantrange<10, 20>
+ // br label %merge
+ // merge:
+ // %phi = phi [%v1, %v2] ; constantrange<1,20>
+ // %pred = icmp eq i32 %phi, 8
+ // We can't tell from the lattice value for '%phi' that '%pred' is false
+ // along each path, but by checking the predicate over each input separately,
+ // we can.
+ // We limit the search to one step backwards from the current BB and value.
+ // We could consider extending this to search further backwards through the
+ // CFG and/or value graph, but there are non-obvious compile time vs quality
+ // tradeoffs.
+ if (CxtI) {
+ BasicBlock *BB = CxtI->getParent();
+
+ // Function entry or an unreachable block. Bail to avoid confusing
+ // analysis below.
+ pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+ if (PI == PE)
+ return Unknown;
+
+ // If V is a PHI node in the same block as the context, we need to ask
+ // questions about the predicate as applied to the incoming value along
+ // each edge. This is useful for eliminating cases where the predicate is
+ // known along all incoming edges.
+ if (auto *PHI = dyn_cast<PHINode>(V))
+ if (PHI->getParent() == BB) {
+ Tristate Baseline = Unknown;
+ for (unsigned i = 0, e = PHI->getNumIncomingValues(); i < e; i++) {
+ Value *Incoming = PHI->getIncomingValue(i);
+ BasicBlock *PredBB = PHI->getIncomingBlock(i);
+ // Note that PredBB may be BB itself.
+ Tristate Result = getPredicateOnEdge(Pred, Incoming, C, PredBB, BB,
+ CxtI);
+
+ // Keep going as long as we've seen a consistent known result for
+ // all inputs.
+ Baseline = (i == 0) ? Result /* First iteration */
+ : (Baseline == Result ? Baseline : Unknown); /* All others */
+ if (Baseline == Unknown)
+ break;
+ }
+ if (Baseline != Unknown)
+ return Baseline;
+ }
+
+ // For a comparison where the V is outside this block, it's possible
+ // that we've branched on it before. Look to see if the value is known
+ // on all incoming edges.
+ if (!isa<Instruction>(V) ||
+ cast<Instruction>(V)->getParent() != BB) {
+ // For predecessor edge, determine if the comparison is true or false
+ // on that edge. If they're all true or all false, we can conclude
+ // the value of the comparison in this block.
+ Tristate Baseline = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI);
+ if (Baseline != Unknown) {
+ // Check that all remaining incoming values match the first one.
+ while (++PI != PE) {
+ Tristate Ret = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI);
+ if (Ret != Baseline) break;
+ }
+ // If we terminated early, then one of the values didn't match.
+ if (PI == PE) {
+ return Baseline;
+ }
+ }
+ }
+ }
+ return Unknown;
}
void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
BasicBlock *NewSucc) {
- if (PImpl)
- getCache(PImpl, AC, DL, DT).threadEdge(PredBB, OldSucc, NewSucc);
+ if (PImpl) {
+ const DataLayout &DL = PredBB->getModule()->getDataLayout();
+ getCache(PImpl, AC, &DL, DT).threadEdge(PredBB, OldSucc, NewSucc);
+ }
}
void LazyValueInfo::eraseBlock(BasicBlock *BB) {
- if (PImpl)
- getCache(PImpl, AC, DL, DT).eraseBlock(BB);
+ if (PImpl) {
+ const DataLayout &DL = BB->getModule()->getDataLayout();
+ getCache(PImpl, AC, &DL, DT).eraseBlock(BB);
+ }
}
projects / oota-llvm.git / blobdiff