-//===- LazyValueInfo.cpp - Value constraint analysis ----------------------===//
+//===- LazyValueInfo.cpp - Value constraint analysis ------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/AssumptionTracker.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
char LazyValueInfo::ID = 0;
INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info",
"Lazy Value Information Analysis", false, true)
+INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
INITIALIZE_PASS_END(LazyValueInfo, "lazy-value-info",
"Lazy Value Information Analysis", false, true)
/// during a query. It basically emulates the callstack of the naive
/// recursive value lookup process.
std::stack<std::pair<BasicBlock*, Value*> > BlockValueStack;
+
+ /// A pointer to the cache of @llvm.assume calls.
+ AssumptionTracker *AT;
+ /// An optional DL pointer.
+ const DataLayout *DL;
+ /// An optional DT pointer.
+ DominatorTree *DT;
friend struct LVIValueHandle;
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
bool getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T,
- LVILatticeVal &Result);
+ LVILatticeVal &Result,
+ Instruction *CxtI = nullptr);
bool hasBlockValue(Value *Val, BasicBlock *BB);
// These methods process one work item and may add more. A false value
PHINode *PN, BasicBlock *BB);
bool solveBlockValueConstantRange(LVILatticeVal &BBLV,
Instruction *BBI, BasicBlock *BB);
+ void mergeAssumeBlockValueConstantRange(Value *Val, LVILatticeVal &BBLV,
+ Instruction *BBI);
void solve();
public:
/// getValueInBlock - 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);
+ LVILatticeVal getValueInBlock(Value *V, BasicBlock *BB,
+ Instruction *CxtI = nullptr);
+
+ /// getValueAt - 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
/// value for the specified Value* that is true on the specified edge.
- LVILatticeVal getValueOnEdge(Value *V, BasicBlock *FromBB,BasicBlock *ToBB);
+ 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
ValueCache.clear();
OverDefinedCache.clear();
}
+
+ LazyValueInfoCache(AssumptionTracker *AT,
+ const DataLayout *DL = nullptr,
+ DominatorTree *DT = nullptr) : AT(AT), DL(DL), DT(DT) {}
};
} // end anonymous namespace
// OverDefinedCacheUpdater is a helper object that will update
// the OverDefinedCache for us when this method exits. Make sure to
- // call markResult on it as we exist, passing a bool to indicate if the
- // cache needs updating, i.e. if we have solve a new value or not.
+ // call markResult on it as we exit, passing a bool to indicate if the
+ // cache needs updating, i.e. if we have solved a new value or not.
OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
- // Once this BB is encountered, Val's value for this BB will not be Undefined
- // any longer. When we encounter this BB again, if Val's value is Overdefined,
- // we need to compute its value again.
- //
- // For example, considering this control flow,
- // BB1->BB2, BB1->BB3, BB2->BB3, BB2->BB4
- //
- // Suppose we have "icmp slt %v, 0" in BB1, and "icmp sgt %v, 0" in BB3. At
- // the very beginning, when analyzing edge BB2->BB3, we don't know %v's value
- // in BB2, and the data flow algorithm tries to compute BB2's predecessors, so
- // then we know %v has negative value on edge BB1->BB2. And then we return to
- // check BB2 again, and at this moment BB2 has Overdefined value for %v in
- // BB2. So we should have to follow data flow propagation algorithm to get the
- // value on edge BB1->BB2 propagated to BB2, and finally %v on BB2 has a
- // constant range describing a negative value.
-
- if (!BBLV.isUndefined() && !BBLV.isOverdefined()) {
+ if (!BBLV.isUndefined()) {
DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
// Since we're reusing a cached value here, we don't need to update the
- // OverDefinedCahce. The cache will have been properly updated
+ // OverDefinedCache. The cache will have been properly updated
// whenever the cached value was inserted.
ODCacheUpdater.markResult(false);
return true;
BasicBlock *PhiBB = PN->getIncomingBlock(i);
Value *PhiVal = PN->getIncomingValue(i);
LVILatticeVal EdgeResult;
- EdgesMissing |= !getEdgeValue(PhiVal, PhiBB, BB, EdgeResult);
+ // Note that we can provide PN as the context value to getEdgeValue, even
+ // though the results will be cached, because PN is the value being used as
+ // the cache key in the caller.
+ EdgesMissing |= !getEdgeValue(PhiVal, PhiBB, BB, EdgeResult, PN);
if (EdgesMissing)
continue;
return true;
}
+static bool getValueFromFromCondition(Value *Val, ICmpInst *ICI,
+ LVILatticeVal &Result,
+ bool isTrueDest = true);
+
+// If we can determine a constant range for the value Val in the context
+// provided by the instruction BBI, then merge it into BBLV. If we did find a
+// constant range, return true.
+void LazyValueInfoCache::mergeAssumeBlockValueConstantRange(Value *Val,
+ LVILatticeVal &BBLV,
+ Instruction *BBI) {
+ BBI = BBI ? BBI : dyn_cast<Instruction>(Val);
+ if (!BBI)
+ return;
+
+ for (auto &I : AT->assumptions(BBI->getParent()->getParent())) {
+ if (!isValidAssumeForContext(I, BBI, DL, DT))
+ continue;
+
+ Value *C = I->getArgOperand(0);
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(C)) {
+ LVILatticeVal Result;
+ if (getValueFromFromCondition(Val, ICI, Result)) {
+ if (BBLV.isOverdefined())
+ BBLV = Result;
+ else
+ BBLV.mergeIn(Result);
+ }
+ }
+ }
+}
+
bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV,
Instruction *BBI,
BasicBlock *BB) {
}
LVILatticeVal LHSVal = getBlockValue(BBI->getOperand(0), BB);
+ mergeAssumeBlockValueConstantRange(BBI->getOperand(0), LHSVal, BBI);
if (!LHSVal.isConstantRange()) {
BBLV.markOverdefined();
return true;
return true;
}
+bool getValueFromFromCondition(Value *Val, ICmpInst *ICI,
+ LVILatticeVal &Result, bool isTrueDest) {
+ 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))
+ Result = LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
+ else
+ Result = LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
+ return true;
+ }
+
+ // Recognize the range checking idiom that InstCombine produces.
+ // (X-C1) u< C2 --> [C1, C1+C2)
+ ConstantInt *NegOffset = nullptr;
+ 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());
+ 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();
+
+ Result = LVILatticeVal::getRange(TrueValues);
+ return true;
+ }
+ }
+
+ return false;
+}
+
/// \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,
// 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 && 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))
- Result = LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
- else
- Result = LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
- return true;
- }
-
- // Recognize the range checking idiom that InstCombine produces.
- // (X-C1) u< C2 --> [C1, C1+C2)
- ConstantInt *NegOffset = nullptr;
- 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());
- 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();
-
- Result = LVILatticeVal::getRange(TrueValues);
- return true;
- }
- }
+ if (getValueFromFromCondition(Val, ICI, Result, isTrueDest))
+ return true;
}
}
/// \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) {
+ BasicBlock *BBTo, LVILatticeVal &Result,
+ Instruction *CxtI) {
// If already a constant, there is nothing to compute.
if (Constant *VC = dyn_cast<Constant>(Val)) {
Result = LVILatticeVal::get(VC);
if (getEdgeValueLocal(Val, BBFrom, BBTo, Result)) {
if (!Result.isConstantRange() ||
- Result.getConstantRange().getSingleElement())
+ Result.getConstantRange().getSingleElement())
return true;
// FIXME: this check should be moved to the beginning of the function when
// Try to intersect ranges of the BB and the constraint on the edge.
LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
+ mergeAssumeBlockValueConstantRange(Val, InBlock, BBFrom->getTerminator());
+ // See note on the use of the CxtI with mergeAssumeBlockValueConstantRange,
+ // and caching, below.
+ mergeAssumeBlockValueConstantRange(Val, InBlock, CxtI);
if (!InBlock.isConstantRange())
return true;
return false;
}
- // if we couldn't compute the value on the edge, use the value from the BB
+ // If we couldn't compute the value on the edge, use the value from the BB.
Result = getBlockValue(Val, BBFrom);
+ mergeAssumeBlockValueConstantRange(Val, Result, BBFrom->getTerminator());
+ // We can use the context instruction (generically the ultimate instruction
+ // the calling pass is trying to simplify) here, even though the result of
+ // this function is generally cached when called from the solve* functions
+ // (and that cached result might be used with queries using a different
+ // context instruction), because when this function is called from the solve*
+ // functions, the context instruction is not provided. When called from
+ // LazyValueInfoCache::getValueOnEdge, the context instruction is provided,
+ // but then the result is not cached.
+ mergeAssumeBlockValueConstantRange(Val, Result, CxtI);
return true;
}
-LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
+LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB,
+ Instruction *CxtI) {
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
BlockValueStack.push(std::make_pair(BB, V));
solve();
LVILatticeVal Result = getBlockValue(V, BB);
+ mergeAssumeBlockValueConstantRange(V, Result, CxtI);
+
+ DEBUG(dbgs() << " Result = " << Result << "\n");
+ return Result;
+}
+
+LVILatticeVal LazyValueInfoCache::getValueAt(Value *V, Instruction *CxtI) {
+ DEBUG(dbgs() << "LVI Getting value " << *V << " at '"
+ << CxtI->getName() << "'\n");
+
+ LVILatticeVal Result;
+ mergeAssumeBlockValueConstantRange(V, Result, CxtI);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
}
LVILatticeVal LazyValueInfoCache::
-getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB) {
+getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB,
+ Instruction *CxtI) {
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
LVILatticeVal Result;
- if (!getEdgeValue(V, FromBB, ToBB, Result)) {
+ if (!getEdgeValue(V, FromBB, ToBB, Result, CxtI)) {
solve();
- bool WasFastQuery = getEdgeValue(V, FromBB, ToBB, Result);
+ bool WasFastQuery = getEdgeValue(V, FromBB, ToBB, Result, CxtI);
(void)WasFastQuery;
assert(WasFastQuery && "More work to do after problem solved?");
}
// 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 dropped cached info
+ // 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.
//===----------------------------------------------------------------------===//
/// getCache - This lazily constructs the LazyValueInfoCache.
-static LazyValueInfoCache &getCache(void *&PImpl) {
+static LazyValueInfoCache &getCache(void *&PImpl,
+ AssumptionTracker *AT,
+ const DataLayout *DL = nullptr,
+ DominatorTree *DT = nullptr) {
if (!PImpl)
- PImpl = new LazyValueInfoCache();
+ PImpl = new LazyValueInfoCache(AT, DL, DT);
return *static_cast<LazyValueInfoCache*>(PImpl);
}
bool LazyValueInfo::runOnFunction(Function &F) {
- if (PImpl)
- getCache(PImpl).clear();
+ AT = &getAnalysis<AssumptionTracker>();
+
+ DominatorTreeWrapperPass *DTWP =
+ getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ DT = DTWP ? &DTWP->getDomTree() : nullptr;
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
DL = DLP ? &DLP->getDataLayout() : nullptr;
+
TLI = &getAnalysis<TargetLibraryInfo>();
+ if (PImpl)
+ getCache(PImpl, AT, DL, DT).clear();
+
// Fully lazy.
return false;
}
void LazyValueInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
+ AU.addRequired<AssumptionTracker>();
AU.addRequired<TargetLibraryInfo>();
}
void LazyValueInfo::releaseMemory() {
// If the cache was allocated, free it.
if (PImpl) {
- delete &getCache(PImpl);
+ delete &getCache(PImpl, AT);
PImpl = nullptr;
}
}
-Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB) {
- LVILatticeVal Result = getCache(PImpl).getValueInBlock(V, BB);
+Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB,
+ Instruction *CxtI) {
+ LVILatticeVal Result =
+ getCache(PImpl, AT, DL, DT).getValueInBlock(V, BB, CxtI);
if (Result.isConstant())
return Result.getConstant();
/// getConstantOnEdge - 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) {
- LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
+ BasicBlock *ToBB,
+ Instruction *CxtI) {
+ LVILatticeVal Result =
+ getCache(PImpl, AT, DL, DT).getValueOnEdge(V, FromBB, ToBB, CxtI);
if (Result.isConstant())
return Result.getConstant();
return nullptr;
}
-/// 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.
-LazyValueInfo::Tristate
-LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
- BasicBlock *FromBB, BasicBlock *ToBB) {
- LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
-
+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;
if (Result.isConstant()) {
Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, DL,
TLI);
if (ConstantInt *ResCI = dyn_cast<ConstantInt>(Res))
- return ResCI->isZero() ? False : True;
- return Unknown;
+ return ResCI->isZero() ? LazyValueInfo::False : LazyValueInfo::True;
+ return LazyValueInfo::Unknown;
}
if (Result.isConstantRange()) {
ConstantInt *CI = dyn_cast<ConstantInt>(C);
- if (!CI) return Unknown;
+ if (!CI) return LazyValueInfo::Unknown;
ConstantRange CR = Result.getConstantRange();
if (Pred == ICmpInst::ICMP_EQ) {
if (!CR.contains(CI->getValue()))
- return False;
+ return LazyValueInfo::False;
if (CR.isSingleElement() && CR.contains(CI->getValue()))
- return True;
+ return LazyValueInfo::True;
} else if (Pred == ICmpInst::ICMP_NE) {
if (!CR.contains(CI->getValue()))
- return True;
+ return LazyValueInfo::True;
if (CR.isSingleElement() && CR.contains(CI->getValue()))
- return False;
+ return LazyValueInfo::False;
}
// Handle more complex predicates.
ConstantRange TrueValues =
ICmpInst::makeConstantRange((ICmpInst::Predicate)Pred, CI->getValue());
if (TrueValues.contains(CR))
- return True;
+ return LazyValueInfo::True;
if (TrueValues.inverse().contains(CR))
- return False;
- return Unknown;
+ return LazyValueInfo::False;
+ return LazyValueInfo::Unknown;
}
if (Result.isNotConstant()) {
Result.getNotConstant(), C, DL,
TLI);
if (Res->isNullValue())
- return False;
+ return LazyValueInfo::False;
} else if (Pred == ICmpInst::ICMP_NE) {
// !C1 != C -> true iff C1 == C.
Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
Result.getNotConstant(), C, DL,
TLI);
if (Res->isNullValue())
- return True;
+ return LazyValueInfo::True;
}
- return Unknown;
+ return LazyValueInfo::Unknown;
}
- return 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.
+LazyValueInfo::Tristate
+LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
+ BasicBlock *FromBB, BasicBlock *ToBB,
+ Instruction *CxtI) {
+ LVILatticeVal Result =
+ getCache(PImpl, AT, 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, AT, DL, DT).getValueAt(V, CxtI);
+
+ return getPredicateResult(Pred, C, Result, DL, TLI);
}
void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
BasicBlock *NewSucc) {
- if (PImpl) getCache(PImpl).threadEdge(PredBB, OldSucc, NewSucc);
+ if (PImpl) getCache(PImpl, AT, DL, DT).threadEdge(PredBB, OldSucc, NewSucc);
}
void LazyValueInfo::eraseBlock(BasicBlock *BB) {
- if (PImpl) getCache(PImpl).eraseBlock(BB);
+ if (PImpl) getCache(PImpl, AT, DL, DT).eraseBlock(BB);
}
projects / oota-llvm.git / blobdiff