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Classify value numbers into connected components in linear time.

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llvm-svn: 116105
This commit is contained in:
Jakob Stoklund Olesen 2010-10-08 21:19:28 +00:00
parent bfd3c31acf
commit 9d127e625c
1 changed files with 15 additions and 23 deletions
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38
lib/CodeGen/LiveInterval.cpp
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@ -709,47 +709,39 @@ void LiveRange::print(raw_ostream &os) const {
/// multiple LiveIntervals.
void ConnectedVNInfoEqClasses::Connect(unsigned a, unsigned b) {
// Add new eq classes as needed.
for (unsigned i = eqClass_.size(), m = std::max(a, b); i <= m; ++i)
eqClass_.push_back(i);
unsigned eqa = eqClass_[a];
unsigned eqb = eqClass_[b];
if (eqa == eqb)
return;
// Make sure a and b are in the same class while maintaining eqClass_[i] <= i.
if (eqa > eqb)
std::swap(eqa, eqb);
// Now, eqa < eqb. Switch all eqb members over to eqa.
for (unsigned i = eqb, e = eqClass_.size(); i != e; ++i)
if (eqClass_[i] == eqb)
eqClass_[i] = eqa;
eqClass_[a] = eqb;
else
eqClass_[b] = eqa;
}
unsigned ConnectedVNInfoEqClasses::Renumber() {
// No values at all.
if (eqClass_.empty())
return 0;
// Common case: A single connected component.
if (eqClass_.back() == 0)
return 1;
// Renumber classes. We use the fact that eqClass_[i] == i for class leaders.
// Assign final class numbers.
// We use the fact that eqClass_[i] == i for class leaders.
// For others, eqClass_[i] points to an earlier value in the same class.
unsigned count = 0;
for (unsigned i = 0, e = eqClass_.size(); i != e; ++i) {
unsigned q = eqClass_[i];
if (q == i)
eqClass_[i] = count++;
else
eqClass_[i] = eqClass_[q];
assert(q <= i && "Invariant broken");
eqClass_[i] = q == i ? count++ : eqClass_[q];
}
return count;
}
unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
// Determine connections.
// Create initial equivalence classes.
eqClass_.clear();
eqClass_.reserve(LI->getNumValNums());
for (unsigned i = 0, e = LI->getNumValNums(); i != e; ++i)
eqClass_.push_back(i);
// Determine connections.
for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end();
I != E; ++I) {
const VNInfo *VNI = *I;