void
Function::printCFGraph(const char *filePath)
{
FILE *out = fopen(filePath, "a");
if (!out) {
ERROR("failed to open file: %s\n", filePath);
return;
}
INFO("printing control flow graph to: %s\n", filePath);
fprintf(out, "digraph G {\n");
for (IteratorRef it = cfg.iteratorDFS(); !it->end(); it->next()) {
BasicBlock *bb = BasicBlock::get(
reinterpret_cast<Graph::Node *>(it->get()));
int idA = bb->getId();
for (Graph::EdgeIterator ei = bb->cfg.outgoing(); !ei.end(); ei.next()) {
int idB = BasicBlock::get(ei.getNode())->getId();
switch (ei.getType()) {
case Graph::Edge::TREE:
fprintf(out, "\t%i -> %i;\n", idA, idB);
break;
case Graph::Edge::FORWARD:
fprintf(out, "\t%i -> %i [color=green];\n", idA, idB);
break;
case Graph::Edge::CROSS:
fprintf(out, "\t%i -> %i [color=red];\n", idA, idB);
break;
case Graph::Edge::BACK:
fprintf(out, "\t%i -> %i;\n", idA, idB);
break;
case Graph::Edge::DUMMY:
fprintf(out, "\t%i -> %i [style=dotted];\n", idA, idB);
break;
default:
assert(0);
break;
}
}
}
fprintf(out, "}\n");
fclose(out);
}
// Efficiently Computing Static Single Assignment Form and
// the Control Dependence Graph,
// R. Cytron, J. Ferrante, B. K. Rosen, M. N. Wegman, F. K. Zadeck
bool
Function::convertToSSA()
{
// 0. calculate live in variables (for pruned SSA)
buildLiveSets();
// 1. create the dominator tree
domTree = new DominatorTree(&cfg);
reinterpret_cast<DominatorTree *>(domTree)->findDominanceFrontiers();
// 2. insert PHI functions
DLList workList;
LValue *lval;
BasicBlock *bb;
int var;
int iterCount = 0;
int *hasAlready = new int[allBBlocks.getSize() * 2];
int *work = &hasAlready[allBBlocks.getSize()];
memset(hasAlready, 0, allBBlocks.getSize() * 2 * sizeof(int));
// for each variable
for (var = 0; var < allLValues.getSize(); ++var) {
if (!allLValues.get(var))
continue;
lval = reinterpret_cast<Value *>(allLValues.get(var))->asLValue();
if (!lval || lval->defs.empty())
continue;
++iterCount;
// TODO: don't add phi functions for values that aren't used outside
// the BB they're defined in
// gather blocks with assignments to lval in workList
for (Value::DefIterator d = lval->defs.begin();
d != lval->defs.end(); ++d) {
bb = ((*d)->getInsn() ? (*d)->getInsn()->bb : NULL);
if (!bb)
continue; // instruction likely been removed but not XXX deleted
if (work[bb->getId()] == iterCount)
continue;
work[bb->getId()] = iterCount;
workList.insert(bb);
}
// for each block in workList, insert a phi for lval in the block's
// dominance frontier (if we haven't already done so)
for (DLList::Iterator wI = workList.iterator(); !wI.end(); wI.erase()) {
bb = BasicBlock::get(wI);
DLList::Iterator dfIter = bb->getDF().iterator();
for (; !dfIter.end(); dfIter.next()) {
Instruction *phi;
BasicBlock *dfBB = BasicBlock::get(dfIter);
if (hasAlready[dfBB->getId()] >= iterCount)
continue;
hasAlready[dfBB->getId()] = iterCount;
// pruned SSA: don't need a phi if the value is not live-in
if (!dfBB->liveSet.test(lval->id))
continue;
phi = new_Instruction(this, OP_PHI, typeOfSize(lval->reg.size));
dfBB->insertTail(phi);
phi->setDef(0, lval);
for (int s = 0; s < dfBB->cfg.incidentCount(); ++s)
phi->setSrc(s, lval);
if (work[dfBB->getId()] < iterCount) {
work[dfBB->getId()] = iterCount;
wI.insert(dfBB);
}
}
}
}
delete[] hasAlready;
RenamePass rename(this);
return rename.run();
}
