LValue *
RenamePass::mkUndefined(Value *val)
{
LValue *lval = val->asLValue();
assert(lval);
LValue *ud = new_LValue(func, lval);
Instruction *nop = new_Instruction(func, OP_NOP, typeOfSize(lval->reg.size));
nop->setDef(0, ud);
BasicBlock::get(func->cfg.getRoot())->insertHead(nop);
return ud;
}
LValue *
LValue::clone(ClonePolicy<Function>& pol) const
{
LValue *that = new_LValue(pol.context(), reg.file);
pol.set<Value>(this, that);
that->reg.size = this->reg.size;
that->reg.type = this->reg.type;
that->reg.data = this->reg.data;
return that;
}
// Go through BBs in dominance order, create new values for each definition,
// and replace all sources with their current new values.
//
// NOTE: The values generated for function inputs/outputs have no connection
// to their corresponding outputs/inputs in other functions. Only allocation
// of physical registers will establish this connection.
//
void RenamePass::search(BasicBlock *bb)
{
LValue *lval, *ssa;
int d, s;
const Target *targ = prog->getTarget();
// Put current definitions for function inputs values on the stack.
// They can be used before any redefinitions are pushed.
if (bb == BasicBlock::get(func->cfg.getRoot())) {
for (std::deque<ValueDef>::iterator it = func->ins.begin();
it != func->ins.end(); ++it) {
lval = it->get()->asLValue();
assert(lval);
ssa = new_LValue(func, targ->nativeFile(lval->reg.file));
ssa->reg.size = lval->reg.size;
ssa->reg.data.id = lval->reg.data.id;
it->setSSA(ssa);
stack[lval->id].push(ssa);
}
}
for (Instruction *stmt = bb->getFirst(); stmt; stmt = stmt->next) {
// PHI sources get definitions from the passes through the incident BBs,
// so skip them here.
if (stmt->op != OP_PHI) {
for (s = 0; stmt->srcExists(s); ++s) {
lval = stmt->getSrc(s)->asLValue();
if (!lval)
continue;
// Values on the stack created in previously visited blocks, and
// function inputs, will be valid because they dominate this one.
lval = getStackTop(lval);
if (!lval)
lval = mkUndefined(stmt->getSrc(s));
stmt->setSrc(s, lval);
}
}
for (d = 0; stmt->defExists(d); ++d) {
lval = stmt->def(d).get()->asLValue();
assert(lval);
stmt->def(d).setSSA(
new_LValue(func, targ->nativeFile(lval->reg.file)));
stmt->def(d).get()->reg.size = lval->reg.size;
stmt->def(d).get()->reg.data.id = lval->reg.data.id;
stack[lval->id].push(stmt->def(d).get());
}
}
// Update sources of PHI ops corresponding to this BB in outgoing BBs.
for (Graph::EdgeIterator ei = bb->cfg.outgoing(); !ei.end(); ei.next()) {
Instruction *phi;
int p = 0;
BasicBlock *sb = BasicBlock::get(ei.getNode());
// which predecessor of sb is bb ?
for (Graph::EdgeIterator ei = sb->cfg.incident(); !ei.end(); ei.next()) {
if (ei.getNode() == &bb->cfg)
break;
++p;
}
assert(p < sb->cfg.incidentCount());
for (phi = sb->getPhi(); phi && phi->op == OP_PHI; phi = phi->next) {
lval = getStackTop(phi->getSrc(p));
if (!lval)
lval = mkUndefined(phi->getSrc(p));
phi->setSrc(p, lval);
}
}
// Visit the BBs we dominate.
for (Graph::EdgeIterator ei = bb->dom.outgoing(); !ei.end(); ei.next())
search(BasicBlock::get(ei.getNode()));
// Update function outputs to the last definitions of their pre-SSA values.
// I hope they're unique, i.e. that we get PHIs for all of them ...
if (bb == BasicBlock::get(func->cfgExit)) {
for (std::deque<ValueRef>::iterator it = func->outs.begin();
it != func->outs.end(); ++it) {
lval = it->get()->asLValue();
if (!lval)
continue;
lval = getStackTop(lval);
if (!lval)
lval = mkUndefined(it->get());
it->set(lval);
}
}
// Pop the values we created in this block from the stack because we will
// return to blocks that we do not dominate.
for (Instruction *stmt = bb->getFirst(); stmt; stmt = stmt->next) {
if (stmt->op == OP_NOP)
continue;
for (d = 0; stmt->defExists(d); ++d)
stack[stmt->def(d).preSSA()->id].pop();
}
}
