#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/ValueHandle.h"
-#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include <map>
-#include <set>
#include <stack>
using namespace llvm;
+using namespace PatternMatch;
char LazyValueInfo::ID = 0;
-INITIALIZE_PASS(LazyValueInfo, "lazy-value-info",
+INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info",
+ "Lazy Value Information Analysis", false, true)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_END(LazyValueInfo, "lazy-value-info",
"Lazy Value Information Analysis", false, true)
namespace llvm {
constant,
/// notconstant - This Value is known to not have the specified value.
notconstant,
-
+
/// constantrange - The Value falls within this range.
constantrange,
-
+
/// overdefined - This value is not known to be constant, and we know that
/// it has a value.
overdefined
// Unless we can prove that the two Constants are different, we must
// move to overdefined.
- // FIXME: use TargetData for smarter constant folding.
+ // FIXME: use TargetData/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 for smarter constant folding.
+ // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding.
if (ConstantInt *Res = dyn_cast<ConstantInt>(
ConstantFoldCompareInstOperands(CmpInst::ICMP_NE,
getNotConstant(),
} // end anonymous namespace.
namespace llvm {
+raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val)
+ LLVM_ATTRIBUTE_USED;
raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) {
if (Val.isUndefined())
return OS << "undefined";
//===----------------------------------------------------------------------===//
namespace {
+ /// LVIValueHandle - A callback value handle update the cache when
+ /// values are erased.
+ class LazyValueInfoCache;
+ struct LVIValueHandle : public CallbackVH {
+ LazyValueInfoCache *Parent;
+
+ LVIValueHandle(Value *V, LazyValueInfoCache *P)
+ : CallbackVH(V), Parent(P) { }
+
+ void deleted();
+ void allUsesReplacedWith(Value *V) {
+ deleted();
+ }
+ };
+}
+
+namespace {
/// LazyValueInfoCache - This is the cache kept by LazyValueInfo which
/// maintains information about queries across the clients' queries.
class LazyValueInfoCache {
- public:
/// ValueCacheEntryTy - 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;
- private:
- /// LVIValueHandle - A callback value handle update the cache when
- /// values are erased.
- struct LVIValueHandle : public CallbackVH {
- LazyValueInfoCache *Parent;
-
- LVIValueHandle(Value *V, LazyValueInfoCache *P)
- : CallbackVH(V), Parent(P) { }
-
- void deleted();
- void allUsesReplacedWith(Value *V) {
- deleted();
- }
- };
+ /// ValueCache - 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
+ /// 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
+ /// recursive value lookup process.
+ std::stack<std::pair<BasicBlock*, Value*> > BlockValueStack;
+
+ friend struct LVIValueHandle;
/// OverDefinedCacheUpdater - A helper object that ensures that the
/// OverDefinedCache is updated whenever solveBlockValue returns.
return changed;
}
};
-
- /// ValueCache - 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.
- std::set<std::pair<AssertingVH<BasicBlock>, Value*> > OverDefinedCache;
+
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
bool getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T,
ValueCacheEntryTy &lookup(Value *V) {
return ValueCache[LVIValueHandle(V, this)];
}
-
- std::stack<std::pair<BasicBlock*, Value*> > block_value_stack;
public:
/// getValueInBlock - This is the query interface to determine the lattice
/// clear - Empty the cache.
void clear() {
+ SeenBlocks.clear();
ValueCache.clear();
OverDefinedCache.clear();
}
};
} // end anonymous namespace
-void LazyValueInfoCache::LVIValueHandle::deleted() {
- for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
+void LVIValueHandle::deleted() {
+ typedef std::pair<AssertingVH<BasicBlock>, Value*> OverDefinedPairTy;
+
+ SmallVector<OverDefinedPairTy, 4> ToErase;
+ for (DenseSet<OverDefinedPairTy>::iterator
I = Parent->OverDefinedCache.begin(),
E = Parent->OverDefinedCache.end();
- I != E; ) {
- std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator tmp = I;
- ++I;
- if (tmp->second == getValPtr())
- Parent->OverDefinedCache.erase(tmp);
+ I != E; ++I) {
+ if (I->second == getValPtr())
+ ToErase.push_back(*I);
}
+ for (SmallVector<OverDefinedPairTy, 4>::iterator I = ToErase.begin(),
+ E = ToErase.end(); I != E; ++I)
+ Parent->OverDefinedCache.erase(*I);
+
// This erasure deallocates *this, so it MUST happen after we're done
// using any and all members of *this.
Parent->ValueCache.erase(*this);
}
void LazyValueInfoCache::eraseBlock(BasicBlock *BB) {
- for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
- I = OverDefinedCache.begin(), E = OverDefinedCache.end(); I != E; ) {
- std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator tmp = I;
- ++I;
- if (tmp->first == BB)
- OverDefinedCache.erase(tmp);
+ // Shortcut if we have never seen this block.
+ DenseSet<AssertingVH<BasicBlock> >::iterator I = SeenBlocks.find(BB);
+ if (I == SeenBlocks.end())
+ return;
+ SeenBlocks.erase(I);
+
+ SmallVector<OverDefinedPairTy, 4> ToErase;
+ for (DenseSet<OverDefinedPairTy>::iterator I = OverDefinedCache.begin(),
+ E = OverDefinedCache.end(); I != E; ++I) {
+ if (I->first == BB)
+ ToErase.push_back(*I);
}
+
+ for (SmallVector<OverDefinedPairTy, 4>::iterator I = ToErase.begin(),
+ E = ToErase.end(); I != E; ++I)
+ OverDefinedCache.erase(*I);
for (std::map<LVIValueHandle, ValueCacheEntryTy>::iterator
I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
}
void LazyValueInfoCache::solve() {
- while (!block_value_stack.empty()) {
- std::pair<BasicBlock*, Value*> &e = block_value_stack.top();
+ while (!BlockValueStack.empty()) {
+ std::pair<BasicBlock*, Value*> &e = BlockValueStack.top();
if (solveBlockValue(e.second, e.first))
- block_value_stack.pop();
+ BlockValueStack.pop();
}
}
if (isa<Constant>(Val))
return true;
- return lookup(Val).count(BB);
+ LVIValueHandle ValHandle(Val, this);
+ if (!ValueCache.count(ValHandle)) return false;
+ return ValueCache[ValHandle].count(BB);
}
LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) {
if (Constant *VC = dyn_cast<Constant>(Val))
return LVILatticeVal::get(VC);
+ SeenBlocks.insert(BB);
return lookup(Val)[BB];
}
return true;
ValueCacheEntryTy &Cache = lookup(Val);
+ SeenBlocks.insert(BB);
LVILatticeVal &BBLV = Cache[BB];
// OverDefinedCacheUpdater is a helper object that will update
return ODCacheUpdater.markResult(solveBlockValuePHINode(BBLV, PN, BB));
}
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(BBI)) {
+ BBLV = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType()));
+ return ODCacheUpdater.markResult(true);
+ }
+
// 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;
GetUnderlyingObject(S->getPointerOperand()) ==
GetUnderlyingObject(Ptr);
}
- // FIXME: llvm.memset, etc.
+ if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
+ if (MI->isVolatile()) return false;
+
+ // FIXME: check whether it has a valuerange that excludes zero?
+ ConstantInt *Len = dyn_cast<ConstantInt>(MI->getLength());
+ if (!Len || Len->isZero()) return false;
+
+ if (MI->getDestAddressSpace() == 0)
+ if (MI->getRawDest() == Ptr || MI->getDest() == Ptr)
+ return true;
+ if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
+ if (MTI->getSourceAddressSpace() == 0)
+ if (MTI->getRawSource() == Ptr || MTI->getSource() == Ptr)
+ return true;
+ }
return false;
}
// then we know that the pointer can't be NULL.
bool NotNull = false;
if (Val->getType()->isPointerTy()) {
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){
- if (InstructionDereferencesPointer(BI, Val)) {
- NotNull = true;
- break;
+ if (isa<AllocaInst>(Val)) {
+ NotNull = true;
+ } else {
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){
+ if (InstructionDereferencesPointer(BI, Val)) {
+ NotNull = true;
+ break;
+ }
}
}
}
if (BB == &BB->getParent()->getEntryBlock()) {
assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
if (NotNull) {
-
const PointerType *PTy = cast<PointerType>(Val->getType());
+ PointerType *PTy = cast<PointerType>(Val->getType());
Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
} else {
Result.markOverdefined();
// If we previously determined that this is a pointer that can't be null
// then return that rather than giving up entirely.
if (NotNull) {
-
const PointerType *PTy = cast<PointerType>(Val->getType());
+ PointerType *PTy = cast<PointerType>(Val->getType());
Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
}
BasicBlock *BB) {
// Figure out the range of the LHS. If that fails, bail.
if (!hasBlockValue(BBI->getOperand(0), BB)) {
- block_value_stack.push(std::make_pair(BB, BBI->getOperand(0)));
+ BlockValueStack.push(std::make_pair(BB, BBI->getOperand(0)));
return false;
}
ConstantRange LHSRange = LHSVal.getConstantRange();
ConstantRange RHSRange(1);
- const IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
+ IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
if (isa<BinaryOperator>(BBI)) {
if (ConstantInt *RHS = dyn_cast<ConstantInt>(BBI->getOperand(1))) {
RHSRange = ConstantRange(RHS->getValue());
// 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 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);
// 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;
+ for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+ i != e; ++i) {
+ if (i.getCaseSuccessor() != BBTo) continue;
if (NumEdges++) break;
- EdgeVal = SI->getCaseValue(i);
+ EdgeVal = i.getCaseValue();
}
assert(EdgeVal && "Missing successor?");
if (NumEdges == 1) {
Result = getBlockValue(Val, BBFrom);
return true;
}
- block_value_stack.push(std::make_pair(BBFrom, Val));
+ BlockValueStack.push(std::make_pair(BBFrom, Val));
return false;
}
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
- block_value_stack.push(std::make_pair(BB, V));
+ BlockValueStack.push(std::make_pair(BB, V));
solve();
LVILatticeVal Result = getBlockValue(V, BB);
worklist.push_back(OldSucc);
DenseSet<Value*> ClearSet;
- for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
- I = OverDefinedCache.begin(), E = OverDefinedCache.end(); I != E; ++I) {
+ for (DenseSet<OverDefinedPairTy>::iterator I = OverDefinedCache.begin(),
+ E = OverDefinedCache.end(); I != E; ++I) {
if (I->first == OldSucc)
ClearSet.insert(I->second);
}
for (DenseSet<Value*>::iterator I = ClearSet.begin(), E = ClearSet.end();
I != E; ++I) {
// If a value was marked overdefined in OldSucc, and is here too...
- std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator OI =
+ DenseSet<OverDefinedPairTy>::iterator OI =
OverDefinedCache.find(std::make_pair(ToUpdate, *I));
if (OI == OverDefinedCache.end()) continue;
bool LazyValueInfo::runOnFunction(Function &F) {
if (PImpl)
getCache(PImpl).clear();
-
+
TD = getAnalysisIfAvailable<TargetData>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
+
// Fully lazy.
return false;
}
+void LazyValueInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<TargetLibraryInfo>();
+}
+
void LazyValueInfo::releaseMemory() {
// If the cache was allocated, free it.
if (PImpl) {
// If we know the value is a constant, evaluate the conditional.
Constant *Res = 0;
if (Result.isConstant()) {
- Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, TD);
+ Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, TD,
+ TLI);
if (ConstantInt *ResCI = dyn_cast<ConstantInt>(Res))
return ResCI->isZero() ? False : True;
return Unknown;
if (Pred == ICmpInst::ICMP_EQ) {
// !C1 == C -> false iff C1 == C.
Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
- Result.getNotConstant(), C, TD);
+ Result.getNotConstant(), C, TD,
+ TLI);
if (Res->isNullValue())
return False;
} else if (Pred == ICmpInst::ICMP_NE) {
// !C1 != C -> true iff C1 == C.
Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
- Result.getNotConstant(), C, TD);
+ Result.getNotConstant(), C, TD,
+ TLI);
if (Res->isNullValue())
return True;
}
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