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Classify value numbers into connected components in linear time.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116105 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-10-08 21:19:28 +00:00
parent ff9dfedd10
commit 54f32e6575
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. /// multiple LiveIntervals.
void ConnectedVNInfoEqClasses::Connect(unsigned a, unsigned b) { 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 eqa = eqClass_[a];
unsigned eqb = eqClass_[b]; unsigned eqb = eqClass_[b];
if (eqa == eqb) if (eqa == eqb)
return; return;
// Make sure a and b are in the same class while maintaining eqClass_[i] <= i.
if (eqa > eqb) if (eqa > eqb)
std::swap(eqa, eqb); eqClass_[a] = eqb;
// Now, eqa < eqb. Switch all eqb members over to eqa. else
for (unsigned i = eqb, e = eqClass_.size(); i != e; ++i) eqClass_[b] = eqa;
if (eqClass_[i] == eqb)
eqClass_[i] = eqa;
} }
unsigned ConnectedVNInfoEqClasses::Renumber() { unsigned ConnectedVNInfoEqClasses::Renumber() {
// No values at all. // Assign final class numbers.
if (eqClass_.empty()) // We use the fact that eqClass_[i] == i for class leaders.
return 0; // For others, eqClass_[i] points to an earlier value in the same class.
// 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.
unsigned count = 0; unsigned count = 0;
for (unsigned i = 0, e = eqClass_.size(); i != e; ++i) { for (unsigned i = 0, e = eqClass_.size(); i != e; ++i) {
unsigned q = eqClass_[i]; unsigned q = eqClass_[i];
if (q == i) assert(q <= i && "Invariant broken");
eqClass_[i] = count++; eqClass_[i] = q == i ? count++ : eqClass_[q];
else
eqClass_[i] = eqClass_[q];
} }
return count; return count;
} }
unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) { unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
// Determine connections. // Create initial equivalence classes.
eqClass_.clear(); 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(); for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end();
I != E; ++I) { I != E; ++I) {
const VNInfo *VNI = *I; const VNInfo *VNI = *I;