[SR-4353] Use word-size field in native object header for reference counting #46932
Description
| Previous ID | SR-4353 |
| Radar | rdar://problem/29765800 |
| Original Reporter | @bob-wilson |
| Type | Improvement |
| Status | Resolved |
| Resolution | Done |
Additional Detail from JIRA
| Votes | 0 |
| Component/s | Compiler |
| Labels | Improvement, AffectsABI |
| Assignee | @gparker42 |
| Priority | Medium |
md5: acede700f07b312a6e3ed4b7bd66e0e3
Issue Description:
The plan for the stable ABI is to have a word-sized field in the native object header that can be used for reference counting. So far, we have had a fixed-size 64-bit field for that purpose. Greg Parker's work on the new reference counting implementation (#5282 sets the stage for this, but we still need to shrink the size of that field on 32-bit targets.