MachineDominators.cpp [plain text]
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/SmallBitVector.h"
using namespace llvm;
namespace llvm {
template class DomTreeNodeBase<MachineBasicBlock>;
template class DominatorTreeBase<MachineBasicBlock>;
}
char MachineDominatorTree::ID = 0;
INITIALIZE_PASS(MachineDominatorTree, "machinedomtree",
"MachineDominator Tree Construction", true, true)
char &llvm::MachineDominatorsID = MachineDominatorTree::ID;
void MachineDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool MachineDominatorTree::runOnMachineFunction(MachineFunction &F) {
CriticalEdgesToSplit.clear();
NewBBs.clear();
DT->recalculate(F);
return false;
}
MachineDominatorTree::MachineDominatorTree()
: MachineFunctionPass(ID) {
initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
DT = new DominatorTreeBase<MachineBasicBlock>(false);
}
MachineDominatorTree::~MachineDominatorTree() {
delete DT;
}
void MachineDominatorTree::releaseMemory() {
DT->releaseMemory();
}
void MachineDominatorTree::print(raw_ostream &OS, const Module*) const {
DT->print(OS);
}
void MachineDominatorTree::applySplitCriticalEdges() const {
if (CriticalEdgesToSplit.empty())
return;
SmallBitVector IsNewIDom(CriticalEdgesToSplit.size(), true);
size_t Idx = 0;
for (CriticalEdge &Edge : CriticalEdgesToSplit) {
MachineBasicBlock *Succ = Edge.ToBB;
MachineDomTreeNode *SuccDTNode = DT->getNode(Succ);
for (MachineBasicBlock *PredBB : Succ->predecessors()) {
if (PredBB == Edge.NewBB)
continue;
if (NewBBs.count(PredBB)) {
assert(PredBB->pred_size() == 1 && "A basic block resulting from a "
"critical edge split has more "
"than one predecessor!");
PredBB = *PredBB->pred_begin();
}
if (!DT->dominates(SuccDTNode, DT->getNode(PredBB))) {
IsNewIDom[Idx] = false;
break;
}
}
++Idx;
}
Idx = 0;
for (CriticalEdge &Edge : CriticalEdgesToSplit) {
MachineDomTreeNode *NewDTNode = DT->addNewBlock(Edge.NewBB, Edge.FromBB);
if (IsNewIDom[Idx])
DT->changeImmediateDominator(DT->getNode(Edge.ToBB), NewDTNode);
++Idx;
}
NewBBs.clear();
CriticalEdgesToSplit.clear();
}