| ================== |
| LD64 vs LLD-MACHO |
| ================== |
| |
| This doc lists all significant deliberate differences in behavior between LD64 and LLD-MachO. |
| |
| String literal deduplication |
| **************************** |
| LD64 always deduplicates string literals. LLD only does it when the `--icf=` or |
| the `--deduplicate-literals` flag is passed. Omitting deduplication by default |
| ensures that our link is as fast as possible. However, it may also break some |
| programs which have (incorrectly) relied on string deduplication always |
| occurring. In particular, programs which compare string literals via pointer |
| equality must be fixed to use value equality instead. |
| |
| ``-no_deduplicate`` Flag |
| ********************** |
| - LD64: |
| * This turns off ICF (deduplication pass) in the linker. |
| - LLD |
| * This turns off ICF and string merging in the linker. |
| |
| ObjC symbols treatment |
| ********************** |
| There are differences in how LLD and LD64 handle ObjC symbols loaded from archives. |
| |
| - LD64: |
| * Duplicate ObjC symbols from the same archives will not raise an error. LD64 will pick the first one. |
| * Duplicate ObjC symbols from different archives will raise a "duplicate symbol" error. |
| - LLD: |
| * Duplicate symbols, regardless of which archives they are from, will raise errors. |
