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Simplify UninitializedValues.cpp by removing logic to handle the previous (imprecise) representation 

of '&&' and '||' in the CFG.  This is no longer needed, and greatly simplifies the code.

llvm-svn: 160494
This commit is contained in:
Ted Kremenek 2012-07-19 04:59:05 +00:00
parent aaf9735951
commit 6080d32194
1 changed files with 25 additions and 142 deletions
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167
clang/lib/Analysis/UninitializedValues.cpp
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@ -98,38 +98,32 @@ static bool isAlwaysUninit(const Value v) {
namespace {
typedef llvm::PackedVector<Value, 2> ValueVector;
typedef std::pair<ValueVector *, ValueVector *> BVPair;
class CFGBlockValues {
const CFG &cfg;
BVPair *vals;
std::vector<ValueVector*> vals;
ValueVector scratch;
DeclToIndex declToIndex;
ValueVector &lazyCreate(ValueVector *&bv);
public:
CFGBlockValues(const CFG &cfg);
~CFGBlockValues();
unsigned getNumEntries() const { return declToIndex.size(); }
void computeSetOfDeclarations(const DeclContext &dc);
ValueVector &getValueVector(const CFGBlock *block,
const CFGBlock *dstBlock);
BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate);
ValueVector &getValueVector(const CFGBlock *block) {
return *vals[block->getBlockID()];
}
void setAllScratchValues(Value V);
void mergeIntoScratch(ValueVector const &source, bool isFirst);
bool updateValueVectorWithScratch(const CFGBlock *block);
bool updateValueVectors(const CFGBlock *block, const BVPair &newVals);
bool hasNoDeclarations() const {
return declToIndex.size() == 0;
}
void resetScratch();
ValueVector &getScratch() { return scratch; }
ValueVector::reference operator[](const VarDecl *vd);
@ -137,91 +131,29 @@ public:
const VarDecl *vd) {
const llvm::Optional<unsigned> &idx = declToIndex.getValueIndex(vd);
assert(idx.hasValue());
return getValueVector(block, dstBlock)[idx.getValue()];
return getValueVector(block)[idx.getValue()];
}
};
} // end anonymous namespace
CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) {
unsigned n = cfg.getNumBlockIDs();
if (!n)
return;
vals = new std::pair<ValueVector*, ValueVector*>[n];
memset((void*)vals, 0, sizeof(*vals) * n);
}
CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) {}
CFGBlockValues::~CFGBlockValues() {
unsigned n = cfg.getNumBlockIDs();
if (n == 0)
return;
for (unsigned i = 0; i < n; ++i) {
delete vals[i].first;
delete vals[i].second;
}
delete [] vals;
for (std::vector<ValueVector*>::iterator I = vals.begin(), E = vals.end();
I != E; ++I)
delete *I;
}
void CFGBlockValues::computeSetOfDeclarations(const DeclContext &dc) {
declToIndex.computeMap(dc);
scratch.resize(declToIndex.size());
}
ValueVector &CFGBlockValues::lazyCreate(ValueVector *&bv) {
if (!bv)
bv = new ValueVector(declToIndex.size());
return *bv;
}
/// This function pattern matches for a '&&' or '||' that appears at
/// the beginning of a CFGBlock that also (1) has a terminator and
/// (2) has no other elements. If such an expression is found, it is returned.
static const BinaryOperator *getLogicalOperatorInChain(const CFGBlock *block) {
if (block->empty())
return 0;
CFGElement front = block->front();
const CFGStmt *cstmt = front.getAs<CFGStmt>();
if (!cstmt)
return 0;
const BinaryOperator *b = dyn_cast_or_null<BinaryOperator>(cstmt->getStmt());
if (!b || !b->isLogicalOp())
return 0;
if (block->pred_size() == 2) {
if (block->getTerminatorCondition() == b) {
if (block->succ_size() == 2)
return b;
}
else if (block->size() == 1)
return b;
}
return 0;
}
ValueVector &CFGBlockValues::getValueVector(const CFGBlock *block,
const CFGBlock *dstBlock) {
unsigned idx = block->getBlockID();
if (dstBlock && getLogicalOperatorInChain(block)) {
if (*block->succ_begin() == dstBlock)
return lazyCreate(vals[idx].first);
assert(*(block->succ_begin()+1) == dstBlock);
return lazyCreate(vals[idx].second);
}
assert(vals[idx].second == 0);
return lazyCreate(vals[idx].first);
}
BVPair &CFGBlockValues::getValueVectors(const clang::CFGBlock *block,
bool shouldLazyCreate) {
unsigned idx = block->getBlockID();
lazyCreate(vals[idx].first);
if (shouldLazyCreate)
lazyCreate(vals[idx].second);
return vals[idx];
unsigned decls = declToIndex.size();
scratch.resize(decls);
unsigned n = cfg.getNumBlockIDs();
if (!n)
return;
vals.resize(n);
for (unsigned i = 0; i < n; ++i)
vals[i] = new ValueVector(decls);
}
#if DEBUG_LOGGING
@ -249,7 +181,7 @@ void CFGBlockValues::mergeIntoScratch(ValueVector const &source,
}
bool CFGBlockValues::updateValueVectorWithScratch(const CFGBlock *block) {
ValueVector &dst = getValueVector(block, 0);
ValueVector &dst = getValueVector(block);
bool changed = (dst != scratch);
if (changed)
dst = scratch;
@ -259,20 +191,6 @@ bool CFGBlockValues::updateValueVectorWithScratch(const CFGBlock *block) {
return changed;
}
bool CFGBlockValues::updateValueVectors(const CFGBlock *block,
const BVPair &newVals) {
BVPair &vals = getValueVectors(block, true);
bool changed = *newVals.first != *vals.first ||
*newVals.second != *vals.second;
*vals.first = *newVals.first;
*vals.second = *newVals.second;
#if DEBUG_LOGGING
printVector(block, *vals.first, 1);
printVector(block, *vals.second, 2);
#endif
return changed;
}
void CFGBlockValues::resetScratch() {
scratch.reset();
}
@ -768,42 +686,15 @@ static bool runOnBlock(const CFGBlock *block, const CFG &cfg,
const ClassifyRefs &classification,
llvm::BitVector &wasAnalyzed,
UninitVariablesHandler *handler = 0) {
wasAnalyzed[block->getBlockID()] = true;
if (const BinaryOperator *b = getLogicalOperatorInChain(block)) {
CFGBlock::const_pred_iterator itr = block->pred_begin();
BVPair vA = vals.getValueVectors(*itr, false);
++itr;
BVPair vB = vals.getValueVectors(*itr, false);
BVPair valsAB;
if (b->getOpcode() == BO_LAnd) {
// Merge the 'F' bits from the first and second.
vals.mergeIntoScratch(*(vA.second ? vA.second : vA.first), true);
vals.mergeIntoScratch(*(vB.second ? vB.second : vB.first), false);
valsAB.first = vA.first;
valsAB.second = &vals.getScratch();
} else {
// Merge the 'T' bits from the first and second.
assert(b->getOpcode() == BO_LOr);
vals.mergeIntoScratch(*vA.first, true);
vals.mergeIntoScratch(*vB.first, false);
valsAB.first = &vals.getScratch();
valsAB.second = vA.second ? vA.second : vA.first;
}
return vals.updateValueVectors(block, valsAB);
}
// Default behavior: merge in values of predecessor blocks.
vals.resetScratch();
// Merge in values of predecessor blocks.
bool isFirst = true;
for (CFGBlock::const_pred_iterator I = block->pred_begin(),
E = block->pred_end(); I != E; ++I) {
const CFGBlock *pred = *I;
if (wasAnalyzed[pred->getBlockID()]) {
vals.mergeIntoScratch(vals.getValueVector(pred, block), isFirst);
vals.mergeIntoScratch(vals.getValueVector(pred), isFirst);
isFirst = false;
}
}
@ -828,9 +719,6 @@ void clang::runUninitializedVariablesAnalysis(
vals.computeSetOfDeclarations(dc);
if (vals.hasNoDeclarations())
return;
#if DEBUG_LOGGING
cfg.dump(dc.getParentASTContext().getLangOpts(), true);
#endif
stats.NumVariablesAnalyzed = vals.getNumEntries();
@ -840,15 +728,10 @@ void clang::runUninitializedVariablesAnalysis(
// Mark all variables uninitialized at the entry.
const CFGBlock &entry = cfg.getEntry();
for (CFGBlock::const_succ_iterator i = entry.succ_begin(),
e = entry.succ_end(); i != e; ++i) {
if (const CFGBlock *succ = *i) {
ValueVector &vec = vals.getValueVector(&entry, succ);
const unsigned n = vals.getNumEntries();
for (unsigned j = 0; j < n ; ++j) {
vec[j] = Uninitialized;
}
}
ValueVector &vec = vals.getValueVector(&entry);
const unsigned n = vals.getNumEntries();
for (unsigned j = 0; j < n ; ++j) {
vec[j] = Uninitialized;
}
// Proceed with the workist.