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Fix a bug where we incorrectly value numbered the first PHI definition the

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same as the PHI use.  This is not correct as the PHI use value is different
depending on which branch is taken.  This fixes espresso with aggressive
coallescing, and perhaps others.

llvm-svn: 15189
This commit is contained in:
Chris Lattner 2004-07-25 05:45:18 +00:00
parent e3da94e11f
commit 32cab750d4
1 changed files with 26 additions and 3 deletions
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29
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -393,9 +393,32 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock* mbb,
DEBUG(std::cerr << "RESULT: " << interval);
} else {
// Otherwise, this must be because of phi elimination. In this case,
// the defined value will be live until the end of the basic block it
// is defined in.
// Otherwise, this must be because of phi elimination. If this is the
// first redefinition of the vreg that we have seen, go back and change
// the live range in the PHI block to be a different value number.
if (interval.containsOneValue()) {
assert(vi.Kills.size() == 1 &&
"PHI elimination vreg should have one kill, the PHI itself!");
// Remove the old range that we now know has an incorrect number.
MachineInstr *Killer = vi.Kills[0];
unsigned Start = getInstructionIndex(Killer->getParent()->begin());
unsigned End = getUseIndex(getInstructionIndex(Killer))+1;
DEBUG(std::cerr << "Removing [" << Start << "," << End << "] from: "
<< interval << "\n");
interval.removeRange(Start, End);
DEBUG(std::cerr << "RESULT: " << interval);
// Replace the interval with one of a NEW value number.
LiveRange LR(Start, End, interval.getNextValue());
DEBUG(std::cerr << " replace range with " << LR);
interval.addRange(LR);
DEBUG(std::cerr << "RESULT: " << interval);
}
// In the case of PHI elimination, each variable definition is only
// live until the end of the block. We've already taken care of the
// rest of the live range.
unsigned defIndex = getDefIndex(getInstructionIndex(mi));
LiveRange LR(defIndex,
getInstructionIndex(&mbb->back()) + InstrSlots::NUM,