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;
}
Instruction *
Instruction::clone(ClonePolicy<Function>& pol, Instruction *i) const
{
if (!i)
i = new_Instruction(pol.context(), op, dType);
#ifndef NDEBUG // non-conformant assert, so this is required
assert(typeid(*i) == typeid(*this));
#endif
pol.set<Instruction>(this, i);
i->sType = sType;
i->rnd = rnd;
i->cache = cache;
i->subOp = subOp;
i->saturate = saturate;
i->join = join;
i->exit = exit;
i->mask = mask;
i->ftz = ftz;
i->dnz = dnz;
i->ipa = ipa;
i->lanes = lanes;
i->perPatch = perPatch;
i->postFactor = postFactor;
for (int d = 0; defExists(d); ++d)
i->setDef(d, pol.get(getDef(d)));
for (int s = 0; srcExists(s); ++s) {
i->setSrc(s, pol.get(getSrc(s)));
i->src(s).mod = src(s).mod;
}
i->cc = cc;
i->predSrc = predSrc;
i->flagsDef = flagsDef;
i->flagsSrc = flagsSrc;
return i;
}
// 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();
}