/// Utility function that checks whether \p VPBlockVec has duplicate
/// VPBlockBases.
static bool hasDuplicates(const SmallVectorImpl<VPBlockBase *> &VPBlockVec) {
SmallDenseSet<const VPBlockBase *, 8> VPBlockSet;
for (const auto *Block : VPBlockVec) {
if (VPBlockSet.count(Block))
return true;
VPBlockSet.insert(Block);
}
return false;
}
/// Sort local variables so that variables appearing inside of helper
/// expressions come first.
static SmallVector<DbgVariable *, 8>
sortLocalVars(SmallVectorImpl<DbgVariable *> &Input) {
SmallVector<DbgVariable *, 8> Result;
SmallVector<PointerIntPair<DbgVariable *, 1>, 8> WorkList;
// Map back from a DIVariable to its containing DbgVariable.
SmallDenseMap<const DILocalVariable *, DbgVariable *> DbgVar;
// Set of DbgVariables in Result.
SmallDenseSet<DbgVariable *, 8> Visited;
// For cycle detection.
SmallDenseSet<DbgVariable *, 8> Visiting;
// Initialize the worklist and the DIVariable lookup table.
for (auto Var : reverse(Input)) {
DbgVar.insert({Var->getVariable(), Var});
WorkList.push_back({Var, 0});
}
// Perform a stable topological sort by doing a DFS.
while (!WorkList.empty()) {
auto Item = WorkList.back();
DbgVariable *Var = Item.getPointer();
bool visitedAllDependencies = Item.getInt();
WorkList.pop_back();
// Dependency is in a different lexical scope or a global.
if (!Var)
continue;
// Already handled.
if (Visited.count(Var))
continue;
// Add to Result if all dependencies are visited.
if (visitedAllDependencies) {
Visited.insert(Var);
Result.push_back(Var);
continue;
}
// Detect cycles.
auto Res = Visiting.insert(Var);
if (!Res.second) {
assert(false && "dependency cycle in local variables");
return Result;
}
// Push dependencies and this node onto the worklist, so that this node is
// visited again after all of its dependencies are handled.
WorkList.push_back({Var, 1});
for (auto *Dependency : dependencies(Var)) {
auto Dep = dyn_cast_or_null<const DILocalVariable>(Dependency);
WorkList.push_back({DbgVar[Dep], 0});
}
}
return Result;
}
unsigned DWARFVerifier::verifyAbbrevSection(const DWARFDebugAbbrev *Abbrev) {
unsigned NumErrors = 0;
if (Abbrev) {
const DWARFAbbreviationDeclarationSet *AbbrDecls =
Abbrev->getAbbreviationDeclarationSet(0);
for (auto AbbrDecl : *AbbrDecls) {
SmallDenseSet<uint16_t> AttributeSet;
for (auto Attribute : AbbrDecl.attributes()) {
auto Result = AttributeSet.insert(Attribute.Attr);
if (!Result.second) {
error() << "Abbreviation declaration contains multiple "
<< AttributeString(Attribute.Attr) << " attributes.\n";
AbbrDecl.dump(OS);
++NumErrors;
}
}
}
}
return NumErrors;
}
bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DominatorTree *DT,
LoopInfo *LI,
MemoryDependenceResults *MemDep) {
// Don't merge away blocks who have their address taken.
if (BB->hasAddressTaken()) return false;
// Can't merge if there are multiple predecessors, or no predecessors.
BasicBlock *PredBB = BB->getUniquePredecessor();
if (!PredBB) return false;
// Don't break self-loops.
if (PredBB == BB) return false;
// Don't break unwinding instructions.
if (PredBB->getTerminator()->isExceptional())
return false;
succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
BasicBlock *OnlySucc = BB;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
OnlySucc = nullptr; // There are multiple distinct successors!
break;
}
// Can't merge if there are multiple successors.
if (!OnlySucc) return false;
// Can't merge if there is PHI loop.
for (PHINode &PN : BB->phis())
for (Value *IncValue : PN.incoming_values())
if (IncValue == &PN)
return false;
// Begin by getting rid of unneeded PHIs.
SmallVector<Value *, 4> IncomingValues;
if (isa<PHINode>(BB->front())) {
for (PHINode &PN : BB->phis())
if (PN.getIncomingValue(0) != &PN)
IncomingValues.push_back(PN.getIncomingValue(0));
FoldSingleEntryPHINodes(BB, MemDep);
}
// Delete the unconditional branch from the predecessor...
PredBB->getInstList().pop_back();
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(PredBB);
// Move all definitions in the successor to the predecessor...
PredBB->getInstList().splice(PredBB->end(), BB->getInstList());
// Eliminate duplicate dbg.values describing the entry PHI node post-splice.
for (auto *Incoming : IncomingValues) {
if (isa<Instruction>(Incoming)) {
SmallVector<DbgValueInst *, 2> DbgValues;
SmallDenseSet<std::pair<DILocalVariable *, DIExpression *>, 2>
DbgValueSet;
llvm::findDbgValues(DbgValues, Incoming);
for (auto &DVI : DbgValues) {
auto R = DbgValueSet.insert({DVI->getVariable(), DVI->getExpression()});
if (!R.second)
DVI->eraseFromParent();
}
}
}
// Inherit predecessors name if it exists.
if (!PredBB->hasName())
PredBB->takeName(BB);
// Finally, erase the old block and update dominator info.
if (DT)
if (DomTreeNode *DTN = DT->getNode(BB)) {
DomTreeNode *PredDTN = DT->getNode(PredBB);
SmallVector<DomTreeNode *, 8> Children(DTN->begin(), DTN->end());
for (DomTreeNode *DI : Children)
DT->changeImmediateDominator(DI, PredDTN);
DT->eraseNode(BB);
}
if (LI)
LI->removeBlock(BB);
if (MemDep)
MemDep->invalidateCachedPredecessors();
BB->eraseFromParent();
return true;
}
