void DFSSortClusters::dfs(uint32_t cid) {
if (m_visited.test(cid)) return;
m_visited.set(cid);
m_list.push_back(Vlabel(cid));
// find the best successor, which is the one to which cid has the
// highest weight among the ones that haven't been visited yet
int64_t maxWgt = 0;
uint32_t bestSucc = uint32_t(-1);
for (auto& sInfo : m_clusterSuccs[cid]) {
auto succId = sInfo.first;
if (m_visited.test(succId)) continue;
auto wgt = sInfo.second;
if (wgt >= maxWgt) {
maxWgt = wgt;
bestSucc = succId;
}
}
if (bestSucc == uint32_t(-1)) return;
// visit bestSucc first
dfs(bestSucc);
// now visit the remaining ones
for (auto& sInfo : m_clusterSuccs[cid]) {
if (sInfo.first != bestSucc) {
dfs(sInfo.first);
}
}
}
void natural_loop_dfs(jit::vector<Block*>& out, Visited& visited, Block* blk) {
if (visited.test(blk->id())) return;
visited.set(blk->id());
blk->forEachPred([&] (Block* pred) {
natural_loop_dfs(out, visited, pred);
});
out.push_back(blk);
}
void Vgen::emit(jcc& i) {
assertx(i.cc != CC_None);
if (i.targets[1] != i.targets[0]) {
if (next == i.targets[1]) {
// the taken branch is the fall-through block, invert the branch.
i = jcc{ccNegate(i.cc), i.sf, {i.targets[1], i.targets[0]}};
}
jccs.push_back({a->frontier(), i.targets[1]});
// B.cond range is +/- 1MB but this uses BR
backend.emitSmashableJump(*codeBlock, kEndOfTargetChain, i.cc);
}
emit(jmp{i.targets[0]});
}
void Vgen::emit(tbcc& i) {
assertx(i.cc == vixl::ne || i.cc == vixl::eq);
if (i.targets[1] != i.targets[0]) {
if (next == i.targets[1]) {
// the taken branch is the fall-through block, invert the branch.
i = tbcc{i.cc == vixl::ne ? vixl::eq : vixl::ne, i.bit, i.s,
{i.targets[1], i.targets[0]}};
}
bccs.push_back({a->frontier(), i.targets[1]});
// offset range +/- 32KB
if (i.cc == vixl::ne) {
a->tbnz(X(i.s), i.bit, 0);
} else {
a->tbz(X(i.s), i.bit, 0);
}
}
emit(jmp{i.targets[0]});
}
void Vgen::emit(jmp i) {
if (next == i.target) return;
jmps.push_back({a->frontier(), i.target});
// B range is +/- 128MB but this uses BR
backend.emitSmashableJump(*codeBlock, kEndOfTargetChain, CC_None);
}
void Vgen::emit(hcunwind& i) {
catches.push_back({points[i.call], i.targets[1]});
emit(jmp{i.targets[0]});
}