Hi, guys. sorry if this has already been discussed, but I still feel like clarifying: how should the register allocator handle IMPLICIT_DEF instructions? The LiveIntervalAnalysis class is assigning them zero length intervals. After I removed this, e.g, by removing the lines: if (mi->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) { DOUT << "is a implicit_def\n"; return; } from LiveIntervalAnalysis, it makes it easier for my allocator to pass the LLVM 2.3 tests. I guess that is not really what I was supposed to do, so, what is the way that I should handle IMPLICIT_DEF's in my allocator? All the best, Fernando