#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/RecyclingAllocator.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
// Actually perform the elimination.
if (DoCSE) {
for (unsigned i = 0, e = CSEPairs.size(); i != e; ++i) {
- MRI->replaceRegWith(CSEPairs[i].first, CSEPairs[i].second);
- MRI->clearKillFlags(CSEPairs[i].second);
+ unsigned OldReg = CSEPairs[i].first;
+ unsigned NewReg = CSEPairs[i].second;
+ // OldReg may have been unused but is used now, clear the Dead flag
+ MachineInstr *Def = MRI->getUniqueVRegDef(NewReg);
+ assert(Def != nullptr && "CSEd register has no unique definition?");
+ Def->clearRegisterDeads(NewReg);
+ // Replace with NewReg and clear kill flags which may be wrong now.
+ MRI->replaceRegWith(OldReg, NewReg);
+ MRI->clearKillFlags(NewReg);
}
// Go through implicit defs of CSMI and MI, if a def is not dead at MI,