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Take the first step towards making LVI non-recursive: get rid of the LVIQuery abstraction.

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llvm-svn: 121357
This commit is contained in:
Owen Anderson 2010-12-09 06:14:58 +00:00
parent ebd7ab9857
commit a882a78d4b
1 changed files with 39 additions and 101 deletions
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140
lib/Analysis/LazyValueInfo.cpp
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@ -277,10 +277,6 @@ namespace {
/// maintains information about queries across the clients' queries.
class LazyValueInfoCache {
public:
/// BlockCacheEntryTy - This is a computed lattice value at the end of the
/// specified basic block for a Value* that depends on context.
typedef std::pair<AssertingVH<BasicBlock>, LVILatticeVal> BlockCacheEntryTy;
/// 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.
@ -310,6 +306,20 @@ namespace {
/// for cache updating.
std::set<std::pair<AssertingVH<BasicBlock>, Value*> > OverDefinedCache;
LVILatticeVal &getCachedEntryForBlock(Value *Val, BasicBlock *BB);
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
LVILatticeVal getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T);
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
@ -337,64 +347,6 @@ namespace {
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// LVIQuery Impl
//===----------------------------------------------------------------------===//
namespace {
/// LVIQuery - This is a transient object that exists while a query is
/// being performed.
///
/// TODO: Reuse LVIQuery instead of recreating it for every query, this avoids
/// reallocation of the densemap on every query.
class LVIQuery {
typedef LazyValueInfoCache::BlockCacheEntryTy BlockCacheEntryTy;
typedef LazyValueInfoCache::ValueCacheEntryTy ValueCacheEntryTy;
/// This is the current value being queried for.
Value *Val;
/// This is a pointer to the owning cache, for recursive queries.
LazyValueInfoCache &Parent;
/// This is all of the cached information about this value.
ValueCacheEntryTy &Cache;
/// This tracks, for each block, what values are overdefined.
std::set<std::pair<AssertingVH<BasicBlock>, Value*> > &OverDefinedCache;
/// NewBlocks - This is a mapping of the new BasicBlocks which have been
/// added to cache but that are not in sorted order.
DenseSet<BasicBlock*> NewBlockInfo;
public:
LVIQuery(Value *V, LazyValueInfoCache &P,
ValueCacheEntryTy &VC,
std::set<std::pair<AssertingVH<BasicBlock>, Value*> > &ODC)
: Val(V), Parent(P), Cache(VC), OverDefinedCache(ODC) {
}
~LVIQuery() {
// When the query is done, insert the newly discovered facts into the
// cache in sorted order.
if (NewBlockInfo.empty()) return;
for (DenseSet<BasicBlock*>::iterator I = NewBlockInfo.begin(),
E = NewBlockInfo.end(); I != E; ++I) {
if (Cache[*I].isOverdefined())
OverDefinedCache.insert(std::make_pair(*I, Val));
}
}
LVILatticeVal getBlockValue(BasicBlock *BB);
LVILatticeVal getEdgeValue(BasicBlock *FromBB, BasicBlock *ToBB);
private:
LVILatticeVal getCachedEntryForBlock(BasicBlock *BB);
};
} // end anonymous namespace
void LazyValueInfoCache::LVIValueHandle::deleted() {
for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
I = Parent->OverDefinedCache.begin(),
@ -425,16 +377,9 @@ void LazyValueInfoCache::eraseBlock(BasicBlock *BB) {
I->second.erase(BB);
}
/// getCachedEntryForBlock - See if we already have a value for this block. If
/// so, return it, otherwise create a new entry in the Cache map to use.
LVILatticeVal LVIQuery::getCachedEntryForBlock(BasicBlock *BB) {
NewBlockInfo.insert(BB);
return Cache[BB];
}
LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// See if we already have a value for this block.
LVILatticeVal BBLV = getCachedEntryForBlock(BB);
LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) {
ValueCacheEntryTy &Cache = lookup(Val);
LVILatticeVal &BBLV = Cache[BB];
// If we've already computed this block's value, return it.
if (!BBLV.isUndefined()) {
@ -446,7 +391,6 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// lattice value to overdefined, so that cycles will terminate and be
// conservatively correct.
BBLV.markOverdefined();
Cache[BB] = BBLV;
Instruction *BBI = dyn_cast<Instruction>(Val);
if (BBI == 0 || BBI->getParent() != BB) {
@ -471,7 +415,7 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// 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(*PI, BB));
Result.mergeIn(getEdgeValue(Val, *PI, BB));
// If we hit overdefined, exit early. The BlockVals entry is already set
// to overdefined.
@ -485,7 +429,7 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
}
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
++NumPreds;
}
@ -496,12 +440,12 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
if (NumPreds == 0 && BB == &BB->getParent()->front()) {
assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
Result.markOverdefined();
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
return Cache[BB] = Result;
return setBlockValue(Val, BB, Result, Cache);
}
// If this value is defined by an instruction in this block, we have to
@ -513,23 +457,24 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// result.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
Value* PhiVal = PN->getIncomingValueForBlock(*PI);
Result.mergeIn(Parent.getValueOnEdge(PhiVal, *PI, BB));
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 Result;
return setBlockValue(Val, BB, Result, Cache);
}
}
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
return Cache[BB] = Result;
return setBlockValue(Val, BB, Result, Cache);
}
assert(Cache[BB].isOverdefined() && "Recursive query changed our cache?");
assert(Cache[BB].isOverdefined() &&
"Recursive query changed our cache?");
// 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.
@ -539,7 +484,7 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
Result.markOverdefined();
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
// FIXME: We're currently limited to binops with a constant RHS. This should
@ -550,14 +495,14 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
<< "' - overdefined because inst def found.\n");
Result.markOverdefined();
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
// Figure out the range of the LHS. If that fails, bail.
LVILatticeVal LHSVal = Parent.getValueInBlock(BBI->getOperand(0), BB);
LVILatticeVal LHSVal = getValueInBlock(BBI->getOperand(0), BB);
if (!LHSVal.isConstantRange()) {
Result.markOverdefined();
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
ConstantInt *RHS = 0;
@ -568,7 +513,7 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
RHS = dyn_cast<ConstantInt>(BBI->getOperand(1));
if (!RHS) {
Result.markOverdefined();
return Result;
return setBlockValue(Val, BB, Result, Cache);
}
RHSRange = ConstantRange(RHS->getValue(), RHS->getValue()+1);
@ -623,12 +568,14 @@ LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
break;
}
return Cache[BB] = Result;
return setBlockValue(Val, BB, Result, Cache);
}
/// getEdgeValue - This method attempts to infer more complex
LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
LVILatticeVal LazyValueInfoCache::getEdgeValue(Value *Val,
BasicBlock *BBFrom,
BasicBlock *BBTo) {
// 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())) {
@ -669,7 +616,7 @@ LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
if (!isTrueDest) TrueValues = TrueValues.inverse();
// Figure out the possible values of the query BEFORE this branch.
LVILatticeVal InBlock = getBlockValue(BBFrom);
LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
if (!InBlock.isConstantRange())
return LVILatticeVal::getRange(TrueValues);
@ -711,14 +658,9 @@ LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
}
// Otherwise see if the value is known in the block.
return getBlockValue(BBFrom);
return getBlockValue(Val, BBFrom);
}
//===----------------------------------------------------------------------===//
// LazyValueInfoCache Impl
//===----------------------------------------------------------------------===//
LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
// If already a constant, there is nothing to compute.
if (Constant *VC = dyn_cast<Constant>(V))
@ -727,9 +669,7 @@ LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
LVILatticeVal Result = LVIQuery(V, *this,
ValueCache[LVIValueHandle(V, this)],
OverDefinedCache).getBlockValue(BB);
LVILatticeVal Result = getBlockValue(V, BB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
@ -744,9 +684,7 @@ getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB) {
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
LVILatticeVal Result =
LVIQuery(V, *this, ValueCache[LVIValueHandle(V, this)],
OverDefinedCache).getEdgeValue(FromBB, ToBB);
LVILatticeVal Result = getEdgeValue(V, FromBB, ToBB);
DEBUG(dbgs() << " Result = " << Result << "\n");