This is combination of two patches by Nicholas Wilson:
1. https://reviews.llvm.org/D41954
2. https://reviews.llvm.org/D42495
Along with a few local modifications:
- One change I made was to add the UNDEFINED bit to the binary format
to avoid the extra byte used when writing data symbols. Although this
bit is redundant for other symbols types (i.e. undefined can be
implied if a function or global is a wasm import)
- I prefer to be explicit and consistent and not have derived flags.
- Some field renaming.
- Some reverting of unrelated minor changes.
- No test output differences.
Differential Revision: https://reviews.llvm.org/D43147
llvm-svn: 325860