void CSDataRando::findArgNodes(Module &M) {
// Create function equivalence classes from the global equivalence classes.
EquivalenceClasses<const GlobalValue*> &GlobalECs = DSA->getGlobalECs();
EquivalenceClasses<const Function*> FunctionECs;
for (auto ei = GlobalECs.begin(), ee = GlobalECs.end(); ei != ee; ei++) {
// Ignore non-leader values.
if (!ei->isLeader()) { continue; }
const Function *Leader = nullptr;
for (auto mi = GlobalECs.member_begin(ei), me = GlobalECs.member_end();
mi != me;
mi++) {
// Only look at functions.
if (const Function *F = dyn_cast<Function>(*mi)) {
if (Leader) {
FunctionECs.unionSets(Leader, F);
} else {
Leader = FunctionECs.getOrInsertLeaderValue(F);
}
}
}
}
// Make sure all Functions are part of an equivalence class. This is important
// since non-address taken functions may not appear in GlobalECs.
for (Function &F : M) {
if (!F.isDeclaration()) {
FunctionECs.insert(&F);
}
}
// Go through all equivalence classes and determine the additional
// arguments.
for (auto ei = FunctionECs.begin(), ee = FunctionECs.end();ei != ee; ei++) {
if (ei->isLeader()) {
NumFunctionECs++;
std::vector<const Function*> Functions;
Functions.insert(Functions.end(), FunctionECs.member_begin(ei), FunctionECs.member_end());
// If we can't safely replace uses of the function's address with its
// clone's address then we can't safely transform indirect calls to this
// equivalence class. We still find the arg nodes for each function to
// replace direct calls to these functions.
if (!DSA->canReplaceAddress(ei->getData())) {
NumFunECsWithExternal++;
for (const Function *F : Functions) {
if (!F->isDeclaration()) {
findFunctionArgNodes(F);
FunctionInfo[F].CanReplaceAddress = false;
}
}
} else {
findFunctionArgNodes(Functions);
}
}
}
}
ObservationTable::EquivalenceClasses ObservationTable::_getEquivalenceClasses(bool ofK)
{
EquivalenceClasses equivalenceClasses;
StringSet& localK = ofK ? this->K : this->_KK;
// Divide K into equivalence classes according to \equiv F
for (string k : localK) {
ContextSet distribution = this->_getDistributionByK(k);
auto equivalenceClass = equivalenceClasses.find(distribution);
if (equivalenceClass != equivalenceClasses.end()) { // Found
equivalenceClass->second.insert(k);
} else { // Not found
StringSet ks; // set of k strings
ks.insert(k);
equivalenceClasses.insert({ distribution, ks });
}
}
return equivalenceClasses;
}
bool AArch64A57FPLoadBalancing::runOnBasicBlock(MachineBasicBlock &MBB) {
bool Changed = false;
DEBUG(dbgs() << "Running on MBB: " << MBB << " - scanning instructions...\n");
// First, scan the basic block producing a set of chains.
// The currently "active" chains - chains that can be added to and haven't
// been killed yet. This is keyed by register - all chains can only have one
// "link" register between each inst in the chain.
std::map<unsigned, Chain*> ActiveChains;
std::set<Chain*> AllChains;
unsigned Idx = 0;
for (auto &MI : MBB)
scanInstruction(&MI, Idx++, ActiveChains, AllChains);
DEBUG(dbgs() << "Scan complete, "<< AllChains.size() << " chains created.\n");
// Group the chains into disjoint sets based on their liveness range. This is
// a poor-man's version of graph coloring. Ideally we'd create an interference
// graph and perform full-on graph coloring on that, but;
// (a) That's rather heavyweight for only two colors.
// (b) We expect multiple disjoint interference regions - in practice the live
// range of chains is quite small and they are clustered between loads
// and stores.
EquivalenceClasses<Chain*> EC;
for (auto *I : AllChains)
EC.insert(I);
for (auto *I : AllChains) {
for (auto *J : AllChains) {
if (I != J && I->rangeOverlapsWith(J))
EC.unionSets(I, J);
}
}
DEBUG(dbgs() << "Created " << EC.getNumClasses() << " disjoint sets.\n");
// Now we assume that every member of an equivalence class interferes
// with every other member of that class, and with no members of other classes.
// Convert the EquivalenceClasses to a simpler set of sets.
std::vector<std::vector<Chain*> > V;
for (auto I = EC.begin(), E = EC.end(); I != E; ++I) {
std::vector<Chain*> Cs(EC.member_begin(I), EC.member_end());
if (Cs.empty()) continue;
V.push_back(Cs);
}
// Now we have a set of sets, order them by start address so
// we can iterate over them sequentially.
std::sort(V.begin(), V.end(),
[](const std::vector<Chain*> &A,
const std::vector<Chain*> &B) {
return A.front()->startsBefore(B.front());
});
// As we only have two colors, we can track the global (BB-level) balance of
// odds versus evens. We aim to keep this near zero to keep both execution
// units fed.
// Positive means we're even-heavy, negative we're odd-heavy.
//
// FIXME: If chains have interdependencies, for example:
// mul r0, r1, r2
// mul r3, r0, r1
// We do not model this and may color each one differently, assuming we'll
// get ILP when we obviously can't. This hasn't been seen to be a problem
// in practice so far, so we simplify the algorithm by ignoring it.
int Parity = 0;
for (auto &I : V)
Changed |= colorChainSet(I, MBB, Parity);
for (auto *C : AllChains)
delete C;
return Changed;
}
