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Teach ConnectedVNInfoEqClasses::Classify to deal with unused values.

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We don't want unused values forming their own equivalence classes, so we lump
them all together in one class, and then merge them with the class of the last
used value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117670 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-10-29 17:37:29 +00:00
parent c94fcb1507
commit 6d309059a7
1 changed files with 15 additions and 1 deletions
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16
lib/CodeGen/LiveInterval.cpp
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@ -740,11 +740,20 @@ unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
for (unsigned i = 0, e = LI->getNumValNums(); i != e; ++i)
eqClass_.push_back(i);
const VNInfo *used = 0, *unused = 0;
// Determine connections.
for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end();
I != E; ++I) {
const VNInfo *VNI = *I;
assert(!VNI->isUnused() && "Cannot handle unused values");
// Group all unused values into one class.
if (VNI->isUnused()) {
if (unused)
Connect(unused->id, VNI->id);
unused = VNI;
continue;
}
used = VNI;
if (VNI->isPHIDef()) {
const MachineBasicBlock *MBB = lis_.getMBBFromIndex(VNI->def);
assert(MBB && "Phi-def has no defining MBB");
@ -762,6 +771,11 @@ unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
Connect(VNI->id, UVNI->id);
}
}
// Lump all the unused values in with the last used value.
if (used && unused)
Connect(used->id, unused->id);
return Renumber();
}