void LocationSetTest::testClear()
{
LocationSet set;
set.clear();
QVERIFY(set.empty());
set.insert(Location::regOf(REG_PENT_ESI));
set.clear();
QVERIFY(set.empty());
}
// Helper function for UserProc::propagateStatements()
// Works on basic block n; call from UserProc with n=0 (entry BB)
// If an SSA location is in usedByDomPhi it means it is used in a phi that dominates its assignment
// However, it could turn out that the phi is dead, in which case we don't want to keep the associated entries in
// usedByDomPhi. So we maintain the map defdByPhi which maps locations defined at a phi to the phi statements. Every
// time we see a use of a location in defdByPhi, we remove that map entry. At the end of the procedure we therefore have
// only dead phi statements in the map, so we can delete the associated entries in defdByPhi and also remove the dead
// phi statements.
// We add to the set usedByDomPhi0 whenever we see a location referenced by a phi parameter. When we see a definition
// for such a location, we remove it from the usedByDomPhi0 set (to save memory) and add it to the usedByDomPhi set.
// For locations defined before they are used in a phi parameter, there will be no entry in usedByDomPhi, so we ignore
// it. Remember that each location is defined only once, so that's the time to decide if it is dominated by a phi use or
// not.
void DataFlow::findLiveAtDomPhi(int n, LocationSet& usedByDomPhi, LocationSet& usedByDomPhi0,
std::map<Exp*, PhiAssign*, lessExpStar>& defdByPhi) {
// For each statement this BB
BasicBlock::rtlit rit; StatementList::iterator sit;
PBB bb = BBs[n];
Statement* S;
for (S = bb->getFirstStmt(rit, sit); S; S = bb->getNextStmt(rit, sit)) {
if (S->isPhi()) {
// For each phi parameter, insert an entry into usedByDomPhi0
PhiAssign* pa = (PhiAssign*)S;
PhiAssign::iterator it;
for (it = pa->begin(); it != pa->end(); ++it) {
if (it->e) {
RefExp* re = new RefExp(it->e, it->def);
usedByDomPhi0.insert(re);
}
}
// Insert an entry into the defdByPhi map
RefExp* wrappedLhs = new RefExp(pa->getLeft(), pa);
defdByPhi[wrappedLhs] = pa;
// Fall through to the below, because phi uses are also legitimate uses
}
LocationSet ls;
S->addUsedLocs(ls);
// Consider uses of this statement
LocationSet::iterator it;
for (it = ls.begin(); it != ls.end(); ++it) {
// Remove this entry from the map, since it is not unused
defdByPhi.erase(*it);
}
// Now process any definitions
ls.clear();
S->getDefinitions(ls);
for (it = ls.begin(); it != ls.end(); ++it) {
RefExp* wrappedDef = new RefExp(*it, S);
// If this definition is in the usedByDomPhi0 set, then it is in fact dominated by a phi use, so move it to
// the final usedByDomPhi set
if (usedByDomPhi0.find(wrappedDef) != usedByDomPhi0.end()) {
usedByDomPhi0.remove(wrappedDef);
usedByDomPhi.insert(wrappedDef);
}
}
}
// Visit each child in the dominator graph
// Note: this is a linear search!
// Note also that usedByDomPhi0 may have some irrelevant entries, but this will do no harm, and attempting to erase
// the irrelevant ones would probably cost more than leaving them alone
int sz = idom.size();
for (int c = 0; c < sz; ++c) {
if (idom[c] != n) continue;
// Recurse to the child
findLiveAtDomPhi(c, usedByDomPhi, usedByDomPhi0, defdByPhi);
}
}
