[LiveVariables] Skip verification of kills inside bundles

[foad]

Summary

LiveVariables does not examine the contents of bundles, so
MachineVerifier should not expect it to know about kill flags on
operands of instructions inside a bundle.

With this fix we can enable machine verification after running the
LiveVariables analysis. Doing this does not show any problems in
check-llvm in an LLVM_ENABLE_EXPENSIVE_CHECKS build.

[MatzeB]

Fine with me. LiveVariables are deprecated anyway. LGTM

llvm/lib/CodeGen/MachineVerifier.cpp

void MachineVerifier::checkLiveness(const MachineOperand *MO, unsigned MONum) {
   const MachineInstr *MI = MO->getParent();
   const Register Reg = MO->getReg();
 
   // Both use and def operands can read a register.
   if (MO->readsReg()) {
     if (MO->isKill())
       addRegWithSubRegs(regsKilled, Reg);
 
-    // Check that LiveVars knows this kill.
-    if (LiveVars && Register::isVirtualRegister(Reg) && MO->isKill()) {
+    // Check that LiveVars knows this kill (unless we are inside a bundle, in
+    // which case we have already checked that LiveVars knows any kills on the
+    // bundle header instead).
+    if (LiveVars && Register::isVirtualRegister(Reg) && MO->isKill() &&
+        !MI->isBundledWithPred()) {
       LiveVariables::VarInfo &VI = LiveVars->getVarInfo(Reg);
       if (!is_contained(VI.Kills, MI))
         report("Kill missing from LiveVariables", MO, MONum);
     }
 
     // Check LiveInts liveness and kill.
     if (LiveInts && !LiveInts->isNotInMIMap(*MI)) {
       SlotIndex UseIdx = LiveInts->getInstructionIndex(*MI);

llvm/lib/CodeGen/TargetPassConfig.cpp

void TargetPassConfig::addOptimizedRegAlloc() {
   // LiveVariables can be removed completely, and LiveIntervals can be directly
   // computed. (We still either need to regenerate kill flags after regalloc, or
   // preferably fix the scavenger to not depend on them).
   // FIXME: UnreachableMachineBlockElim is a dependant pass of LiveVariables.
   // When LiveVariables is removed this has to be removed/moved either.
   // Explicit addition of UnreachableMachineBlockElim allows stopping before or
   // after it with -stop-before/-stop-after.
   addPass(&UnreachableMachineBlockElimID);
-  addPass(&LiveVariablesID, false);
+  addPass(&LiveVariablesID);
 
   // Edge splitting is smarter with machine loop info.
   addPass(&MachineLoopInfoID, false);
   addPass(&PHIEliminationID, false);
 
   // Eventually, we want to run LiveIntervals before PHI elimination.
   if (EarlyLiveIntervals)
     addPass(&LiveIntervalsID, false);