#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/ADT/DenseSet.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Target/TargetData.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 <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
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 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 for smarter constant folding.
+ // FIXME: use DataLayout/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 updates 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.
- std::set<std::pair<AssertingVH<BasicBlock>, Value*> > OverDefinedCache;
+ 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.
+ struct OverDefinedCacheUpdater {
+ LazyValueInfoCache *Parent;
+ Value *Val;
+ BasicBlock *BB;
+ LVILatticeVal &BBLV;
+
+ OverDefinedCacheUpdater(Value *V, BasicBlock *B, LVILatticeVal &LV,
+ LazyValueInfoCache *P)
+ : Parent(P), Val(V), BB(B), BBLV(LV) { }
+
+ bool markResult(bool changed) {
+ if (changed && BBLV.isOverdefined())
+ Parent->OverDefinedCache.insert(std::make_pair(BB, Val));
+ return changed;
+ }
+ };
+
+
- LVILatticeVal &getCachedEntryForBlock(Value *Val, BasicBlock *BB);
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
- LVILatticeVal getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T);
+ bool getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T,
+ LVILatticeVal &Result);
+ bool hasBlockValue(Value *Val, BasicBlock *BB);
+
+ // These methods process one work item and may add more. A false value
+ // returned means that the work item was not completely processed and must
+ // be revisited after going through the new items.
+ bool solveBlockValue(Value *Val, BasicBlock *BB);
+ bool solveBlockValueNonLocal(LVILatticeVal &BBLV,
+ Value *Val, BasicBlock *BB);
+ bool solveBlockValuePHINode(LVILatticeVal &BBLV,
+ PHINode *PN, BasicBlock *BB);
+ bool solveBlockValueConstantRange(LVILatticeVal &BBLV,
+ Instruction *BBI, BasicBlock *BB);
+
+ void solve();
ValueCacheEntryTy &lookup(Value *V) {
return ValueCache[LVIValueHandle(V, this)];
}
-
- LVILatticeVal setBlockValue(Value *V, BasicBlock *BB, LVILatticeVal L,
- ValueCacheEntryTy &Cache) {
- if (L.isOverdefined()) OverDefinedCache.insert(std::make_pair(BB, V));
- return Cache[BB] = L;
- }
-
+
public:
/// getValueInBlock - This is the query interface to determine the lattice
/// value for the specified Value* at the end of the specified block.
/// 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)
I->second.erase(BB);
}
+void LazyValueInfoCache::solve() {
+ while (!BlockValueStack.empty()) {
+ std::pair<BasicBlock*, Value*> &e = BlockValueStack.top();
+ if (solveBlockValue(e.second, e.first)) {
+ assert(BlockValueStack.top() == e);
+ BlockValueStack.pop();
+ }
+ }
+}
+
+bool LazyValueInfoCache::hasBlockValue(Value *Val, BasicBlock *BB) {
+ // If already a constant, there is nothing to compute.
+ 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);
+}
+
LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) {
+ // If already a constant, there is nothing to compute.
+ if (Constant *VC = dyn_cast<Constant>(Val))
+ return LVILatticeVal::get(VC);
+
+ SeenBlocks.insert(BB);
+ return lookup(Val)[BB];
+}
+
+bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
+ if (isa<Constant>(Val))
+ return true;
+
ValueCacheEntryTy &Cache = lookup(Val);
+ SeenBlocks.insert(BB);
LVILatticeVal &BBLV = Cache[BB];
+ // 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.
+ OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
+
// If we've already computed this block's value, return it.
if (!BBLV.isUndefined()) {
DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
- return BBLV;
+
+ // Since we're reusing a cached value here, we don't need to update the
+ // OverDefinedCahce. The cache will have been properly updated
+ // whenever the cached value was inserted.
+ ODCacheUpdater.markResult(false);
+ return true;
}
// Otherwise, this is the first time we're seeing this block. Reset the
Instruction *BBI = dyn_cast<Instruction>(Val);
if (BBI == 0 || BBI->getParent() != BB) {
- LVILatticeVal Result; // Start Undefined.
-
- // If this is a pointer, and there's a load from that pointer in this BB,
- // 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){
- LoadInst *L = dyn_cast<LoadInst>(BI);
- if (L && L->getPointerAddressSpace() == 0 &&
- GetUnderlyingObject(L->getPointerOperand()) ==
- GetUnderlyingObject(Val)) {
- NotNull = true;
- break;
- }
- }
- }
-
- unsigned NumPreds = 0;
- // Loop over all of our predecessors, merging what we know from them into
- // result.
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
- Result.mergeIn(getEdgeValue(Val, *PI, BB));
-
- // 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");
- // 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());
- Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
- }
-
- return setBlockValue(Val, BB, Result, Cache);
- }
- ++NumPreds;
- }
-
-
- // If this is the entry block, we must be asking about an argument. The
- // value is overdefined.
- if (NumPreds == 0 && BB == &BB->getParent()->front()) {
- assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
- Result.markOverdefined();
- return setBlockValue(Val, BB, Result, Cache);
- }
-
- // Return the merged value, which is more precise than 'overdefined'.
- assert(!Result.isOverdefined());
- return setBlockValue(Val, BB, Result, Cache);
+ return ODCacheUpdater.markResult(solveBlockValueNonLocal(BBLV, Val, BB));
}
-
- // If this value is defined by an instruction in this block, we have to
- // process it here somehow or return overdefined.
+
if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
- LVILatticeVal Result; // Start Undefined.
-
- // Loop over all of our predecessors, merging what we know from them into
- // result.
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
- Value *PhiVal = PN->getIncomingValueForBlock(*PI);
- Result.mergeIn(getValueOnEdge(PhiVal, *PI, BB));
-
- // 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");
- return setBlockValue(Val, BB, Result, Cache);
- }
- }
-
- // Return the merged value, which is more precise than 'overdefined'.
- assert(!Result.isOverdefined());
- return setBlockValue(Val, BB, Result, Cache);
+ return ODCacheUpdater.markResult(solveBlockValuePHINode(BBLV, PN, BB));
}
- assert(Cache[BB].isOverdefined() &&
- "Recursive query changed our cache?");
+ 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.
!BBI->getType()->isIntegerTy()) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
- Result.markOverdefined();
- return setBlockValue(Val, BB, Result, Cache);
+ BBLV.markOverdefined();
+ return ODCacheUpdater.markResult(true);
}
-
+
// FIXME: We're currently limited to binops with a constant RHS. This should
// be improved.
BinaryOperator *BO = dyn_cast<BinaryOperator>(BBI);
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
- Result.markOverdefined();
- return setBlockValue(Val, BB, Result, Cache);
- }
+ BBLV.markOverdefined();
+ return ODCacheUpdater.markResult(true);
+ }
+
+ return ODCacheUpdater.markResult(solveBlockValueConstantRange(BBLV, BBI, BB));
+}
+
+static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) {
+ if (LoadInst *L = dyn_cast<LoadInst>(I)) {
+ return L->getPointerAddressSpace() == 0 &&
+ GetUnderlyingObject(L->getPointerOperand()) == Ptr;
+ }
+ if (StoreInst *S = dyn_cast<StoreInst>(I)) {
+ return S->getPointerAddressSpace() == 0 &&
+ GetUnderlyingObject(S->getPointerOperand()) == Ptr;
+ }
+ 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 (GetUnderlyingObject(MI->getRawDest()) == Ptr)
+ return true;
+ if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
+ if (MTI->getSourceAddressSpace() == 0)
+ if (GetUnderlyingObject(MTI->getRawSource()) == Ptr)
+ return true;
+ }
+ return false;
+}
+
+bool LazyValueInfoCache::solveBlockValueNonLocal(LVILatticeVal &BBLV,
+ Value *Val, BasicBlock *BB) {
+ LVILatticeVal Result; // Start Undefined.
+
+ // If this is a pointer, and there's a load from that pointer in this BB,
+ // then we know that the pointer can't be NULL.
+ bool NotNull = false;
+ if (Val->getType()->isPointerTy()) {
+ if (isKnownNonNull(Val)) {
+ NotNull = true;
+ } else {
+ 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;
+ }
+ }
+ }
+ }
+ }
+
+ // If this is the entry block, we must be asking about an argument. The
+ // value is overdefined.
+ if (BB == &BB->getParent()->getEntryBlock()) {
+ assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
+ if (NotNull) {
+ PointerType *PTy = cast<PointerType>(Val->getType());
+ Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
+ } else {
+ Result.markOverdefined();
+ }
+ BBLV = Result;
+ return true;
+ }
+
+ // Loop over all of our predecessors, merging what we know from them into
+ // result.
+ bool EdgesMissing = false;
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
+ LVILatticeVal EdgeResult;
+ EdgesMissing |= !getEdgeValue(Val, *PI, BB, EdgeResult);
+ if (EdgesMissing)
+ continue;
+
+ Result.mergeIn(EdgeResult);
+
+ // 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");
+ // If we previously determined that this is a pointer that can't be null
+ // then return that rather than giving up entirely.
+ if (NotNull) {
+ PointerType *PTy = cast<PointerType>(Val->getType());
+ Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
+ }
+
+ BBLV = Result;
+ return true;
+ }
+ }
+ if (EdgesMissing)
+ return false;
+
+ // Return the merged value, which is more precise than 'overdefined'.
+ assert(!Result.isOverdefined());
+ BBLV = Result;
+ return true;
+}
+
+bool LazyValueInfoCache::solveBlockValuePHINode(LVILatticeVal &BBLV,
+ PHINode *PN, BasicBlock *BB) {
+ LVILatticeVal Result; // Start Undefined.
+
+ // Loop over all of our predecessors, merging what we know from them into
+ // result.
+ bool EdgesMissing = false;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *PhiBB = PN->getIncomingBlock(i);
+ Value *PhiVal = PN->getIncomingValue(i);
+ LVILatticeVal EdgeResult;
+ EdgesMissing |= !getEdgeValue(PhiVal, PhiBB, BB, EdgeResult);
+ if (EdgesMissing)
+ continue;
+
+ Result.mergeIn(EdgeResult);
+
+ // 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 (EdgesMissing)
+ return false;
+
+ // Return the merged value, which is more precise than 'overdefined'.
+ assert(!Result.isOverdefined() && "Possible PHI in entry block?");
+ BBLV = Result;
+ return true;
+}
+
+bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV,
+ Instruction *BBI,
+ BasicBlock *BB) {
// Figure out the range of the LHS. If that fails, bail.
- LVILatticeVal LHSVal = getValueInBlock(BBI->getOperand(0), BB);
+ if (!hasBlockValue(BBI->getOperand(0), BB)) {
+ BlockValueStack.push(std::make_pair(BB, BBI->getOperand(0)));
+ return false;
+ }
+
+ LVILatticeVal LHSVal = getBlockValue(BBI->getOperand(0), BB);
if (!LHSVal.isConstantRange()) {
- Result.markOverdefined();
- return setBlockValue(Val, BB, Result, Cache);
+ BBLV.markOverdefined();
+ return true;
}
- ConstantInt *RHS = 0;
ConstantRange LHSRange = LHSVal.getConstantRange();
ConstantRange RHSRange(1);
- const IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
+ IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
if (isa<BinaryOperator>(BBI)) {
- RHS = dyn_cast<ConstantInt>(BBI->getOperand(1));
- if (!RHS) {
- Result.markOverdefined();
- return setBlockValue(Val, BB, Result, Cache);
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(BBI->getOperand(1))) {
+ RHSRange = ConstantRange(RHS->getValue());
+ } else {
+ BBLV.markOverdefined();
+ return true;
}
-
- RHSRange = ConstantRange(RHS->getValue(), RHS->getValue()+1);
}
-
+
// NOTE: We're currently limited by the set of operations that ConstantRange
// can evaluate symbolically. Enhancing that set will allows us to analyze
// more definitions.
+ LVILatticeVal Result;
switch (BBI->getOpcode()) {
case Instruction::Add:
Result.markConstantRange(LHSRange.add(RHSRange));
break;
}
- return setBlockValue(Val, BB, Result, Cache);
+ BBLV = Result;
+ return true;
}
-
-/// getEdgeValue - This method attempts to infer more complex
-LVILatticeVal LazyValueInfoCache::getEdgeValue(Value *Val,
- BasicBlock *BBFrom,
- BasicBlock *BBTo) {
+/// \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 V is the condition of the branch itself, then we know exactly what
// it is.
- if (BI->getCondition() == Val)
- return LVILatticeVal::get(ConstantInt::get(
+ if (BI->getCondition() == Val) {
+ Result = LVILatticeVal::get(ConstantInt::get(
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 (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 LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
- return LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
+ Result = LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
+ else
+ Result = LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
+ 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.
- LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
- if (!InBlock.isConstantRange())
- return LVILatticeVal::getRange(TrueValues);
-
- // Find all potential values that satisfy both the input and output
- // conditions.
- ConstantRange PossibleValues =
- TrueValues.intersectWith(InBlock.getConstantRange());
-
- return 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) {
- LVILatticeVal Result;
- Result.markOverdefined();
- return Result;
- }
-
- // 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)
- return LVILatticeVal::get(EdgeVal);
+ 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);
}
+ Result = LVILatticeVal::getRange(EdgesVals);
+ return true;
}
-
- // Otherwise see if the value is known in the block.
- return getBlockValue(Val, BBFrom);
+ return false;
}
-LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
+/// \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>(V))
- return LVILatticeVal::get(VC);
-
+ 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");
+ BlockValueStack.push(std::make_pair(BB, V));
+ solve();
LVILatticeVal Result = getBlockValue(V, BB);
-
+
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
}
LVILatticeVal LazyValueInfoCache::
getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB) {
- // If already a constant, there is nothing to compute.
- if (Constant *VC = dyn_cast<Constant>(V))
- return LVILatticeVal::get(VC);
-
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
- LVILatticeVal Result = getEdgeValue(V, FromBB, ToBB);
-
+ LVILatticeVal Result;
+ if (!getEdgeValue(V, FromBB, ToBB, Result)) {
+ solve();
+ bool WasFastQuery = getEdgeValue(V, FromBB, ToBB, Result);
+ (void)WasFastQuery;
+ assert(WasFastQuery && "More work to do after problem solved?");
+ }
+
DEBUG(dbgs() << " Result = " << Result << "\n");
-
return Result;
}
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;
// Remove it from the caches.
ValueCacheEntryTy &Entry = ValueCache[LVIValueHandle(*I, this)];
ValueCacheEntryTy::iterator CI = Entry.find(ToUpdate);
-
+
assert(CI != Entry.end() && "Couldn't find entry to update?");
Entry.erase(CI);
OverDefinedCache.erase(OI);
// blocks successors too.
changed = true;
}
-
+
if (!changed) continue;
worklist.insert(worklist.end(), succ_begin(ToUpdate), succ_end(ToUpdate));
bool LazyValueInfo::runOnFunction(Function &F) {
if (PImpl)
getCache(PImpl).clear();
-
- TD = getAnalysisIfAvailable<TargetData>();
+
+ TD = getAnalysisIfAvailable<DataLayout>();
+ 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;
}