[llvm] [CodeGen] Mark LIFETIME_START and LIFETIME_END as not safe to move (PR #211179)

[Luke Lau via llvm-commits]

================
@@ -1360,7 +1360,7 @@ bool MachineInstr::isSafeToMove(bool &SawStore) const {
   // Don't touch instructions that have non-trivial invariants.  For example,
   // terminators have to be at the end of a basic block.
   if (isPosition() || isDebugInstr() || isTerminator() ||
-      isJumpTableDebugInfo())
+      isJumpTableDebugInfo() || isLifetimeMarker())
----------------
lukel97 wrote:

Yes for wouldBeTriviallyDead, done in 3c543e647862408179c6f05ed86e8449bae0f4e1.

Apparently not for isDead:

```c++
  // FIXME: See issue #105950 for why LIFETIME markers are considered dead here.
  if (isLifetimeMarker())
    return true;
```

Not sure why isDead and wouldBeTriviallyDead diverge here.

https://github.com/llvm/llvm-project/pull/211179