diff options
Diffstat (limited to 'lib/CodeGen/LiveIntervalAnalysis.cpp')
| -rw-r--r-- | lib/CodeGen/LiveIntervalAnalysis.cpp | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index d54eaefb66..361210e106 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -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, |