Move Containment Analysis to Lowering

- Ensure that the only changes to child nodes are the specification of srcCandidates
(i.e. the register requirements of the parent/consumer)
- Since this now occurs before redoing dataflow, we don't have complete information on
what lclVars are containable. To mitigate this:
  - In `TreeNodeInfoInit()`, if a lclVar is marked `isRegOptional` but is now untracked,
  change it to be contained.
  - Mark decomposed/promoted fields of long params as `lvDoNotEnregister`
 - Ensure that any new code added after `Lowering` is analyzed as necessary.

- When a value becomes unused, it is no longer contained. (This is needed now because liveness runs after containment analysis)
- Add dumping of nodes deleted as unused.
- Need to set byteable regs, as needed on contained RMW memory ops.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/jit/rationalize.cpp b/src/jit/rationalize.cpp
index 5244c7424d..257e02d491 100644
--- a/src/jit/rationalize.cpp
+++ b/src/jit/rationalize.cpp
@@ -516,6 +516,7 @@ void Rationalizer::RewriteAssignment(LIR::Use& use)
             location->gtType = TYP_BYREF;
 
             assignment->SetOper(GT_STOREIND);
+            assignment->AsStoreInd()->SetRMWStatusDefault();
 
             // TODO: JIT dump
         }