#include "llvm/Analysis/CFG.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/Dominators.h"
using namespace llvm;
void llvm::FindFunctionBackedges(const Function &F,
SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) {
const BasicBlock *BB = &F.getEntryBlock();
if (succ_begin(BB) == succ_end(BB))
return;
SmallPtrSet<const BasicBlock*, 8> Visited;
SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack;
SmallPtrSet<const BasicBlock*, 8> InStack;
Visited.insert(BB);
VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
InStack.insert(BB);
do {
std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back();
const BasicBlock *ParentBB = Top.first;
succ_const_iterator &I = Top.second;
bool FoundNew = false;
while (I != succ_end(ParentBB)) {
BB = *I++;
if (Visited.insert(BB)) {
FoundNew = true;
break;
}
if (InStack.count(BB))
Result.push_back(std::make_pair(ParentBB, BB));
}
if (FoundNew) {
InStack.insert(BB);
VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
} else {
InStack.erase(VisitStack.pop_back_val().first);
}
} while (!VisitStack.empty());
}
unsigned llvm::GetSuccessorNumber(BasicBlock *BB, BasicBlock *Succ) {
TerminatorInst *Term = BB->getTerminator();
#ifndef NDEBUG
unsigned e = Term->getNumSuccessors();
#endif
for (unsigned i = 0; ; ++i) {
assert(i != e && "Didn't find edge?");
if (Term->getSuccessor(i) == Succ)
return i;
}
}
bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
bool AllowIdenticalEdges) {
assert(SuccNum < TI->getNumSuccessors() && "Illegal edge specification!");
if (TI->getNumSuccessors() == 1) return false;
const BasicBlock *Dest = TI->getSuccessor(SuccNum);
const_pred_iterator I = pred_begin(Dest), E = pred_end(Dest);
assert(I != E && "No preds, but we have an edge to the block?");
const BasicBlock *FirstPred = *I;
++I; if (!AllowIdenticalEdges)
return I != E;
while (I != E) {
const BasicBlock *P = *I;
if (P != FirstPred)
return true;
E = pred_end(P);
++I;
}
return false;
}
static const Loop *getOutermostLoop(const LoopInfo *LI, const BasicBlock *BB) {
const Loop *L = LI->getLoopFor(BB);
if (L) {
while (const Loop *Parent = L->getParentLoop())
L = Parent;
}
return L;
}
static bool loopContainsBoth(const LoopInfo *LI,
const BasicBlock *BB1, const BasicBlock *BB2) {
const Loop *L1 = getOutermostLoop(LI, BB1);
const Loop *L2 = getOutermostLoop(LI, BB2);
return L1 != NULL && L1 == L2;
}
static bool isPotentiallyReachableInner(SmallVectorImpl<BasicBlock *> &Worklist,
BasicBlock *StopBB,
const DominatorTree *DT,
const LoopInfo *LI) {
if (DT && !DT->isReachableFromEntry(StopBB))
DT = 0;
unsigned Limit = 32;
SmallSet<const BasicBlock*, 64> Visited;
do {
BasicBlock *BB = Worklist.pop_back_val();
if (!Visited.insert(BB))
continue;
if (BB == StopBB)
return true;
if (DT && DT->dominates(BB, StopBB))
return true;
if (LI && loopContainsBoth(LI, BB, StopBB))
return true;
if (!--Limit) {
return true;
}
if (const Loop *Outer = LI ? getOutermostLoop(LI, BB) : 0) {
Outer->getExitBlocks(Worklist);
} else {
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
Worklist.push_back(*I);
}
} while (!Worklist.empty());
return false;
}
bool llvm::isPotentiallyReachable(const BasicBlock *A, const BasicBlock *B,
const DominatorTree *DT, const LoopInfo *LI) {
assert(A->getParent() == B->getParent() &&
"This analysis is function-local!");
SmallVector<BasicBlock*, 32> Worklist;
Worklist.push_back(const_cast<BasicBlock*>(A));
return isPotentiallyReachableInner(Worklist, const_cast<BasicBlock*>(B),
DT, LI);
}
bool llvm::isPotentiallyReachable(const Instruction *A, const Instruction *B,
const DominatorTree *DT, const LoopInfo *LI) {
assert(A->getParent()->getParent() == B->getParent()->getParent() &&
"This analysis is function-local!");
SmallVector<BasicBlock*, 32> Worklist;
if (A->getParent() == B->getParent()) {
BasicBlock *BB = const_cast<BasicBlock *>(A->getParent());
if (LI && LI->getLoopFor(BB) != 0)
return true;
for (BasicBlock::const_iterator I = A, E = BB->end(); I != E; ++I) {
if (&*I == B)
return true;
}
if (BB == &BB->getParent()->getEntryBlock())
return false;
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
Worklist.push_back(*I);
if (Worklist.empty()) {
return false;
}
} else {
Worklist.push_back(const_cast<BasicBlock*>(A->getParent()));
}
if (A->getParent() == &A->getParent()->getParent()->getEntryBlock())
return true;
if (B->getParent() == &A->getParent()->getParent()->getEntryBlock())
return false;
return isPotentiallyReachableInner(Worklist,
const_cast<BasicBlock*>(B->getParent()),
DT, LI);
}