Commit Graph

4 Commits

Author SHA1 Message Date
Fangrui Song 49279ca160 [ELF] Improve --export-dynamic-symbol performance by checking whether wildcard is really used
A hasWildcard pattern iterates over symVector, which can be slow when there
are many --export-dynamic-symbol. In optimistic cases, most patterns don't use
a wildcard character. hasWildcard: false can avoid a symbol table iteration.

While here, add two tests using `[` and `?`, respectively.
2020-06-17 17:12:10 -07:00
Fangrui Song 751f18e7d4 [ELF] Refine --export-dynamic-symbol semantics to be compatible GNU ld 2.35
GNU ld from binutils 2.35 onwards will likely support
--export-dynamic-symbol but with different semantics.
https://sourceware.org/pipermail/binutils/2020-May/111302.html

Differences:

1. -export-dynamic-symbol is not supported
2. --export-dynamic-symbol takes a glob argument
3. --export-dynamic-symbol can suppress binding the references to the definition within the shared object if (-Bsymbolic or -Bsymbolic-functions)
4. --export-dynamic-symbol does not imply -u

I don't think the first three points can affect any user.
For the fourth point, Not implying -u can lead to some archive members unfetched.
Add -u foo to restore the previous behavior.

Exact semantics:

* -no-pie or -pie: matched non-local defined symbols will be added to the dynamic symbol table.
* -shared: matched non-local STV_DEFAULT symbols will not be bound to definitions within the shared object
  even if they would otherwise be due to -Bsymbolic, -Bsymbolic-functions, or --dynamic-list.

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D80487
2020-06-01 11:30:03 -07:00
Rui Ueyama 5e52022af6 Make --export-dynamic-symbol to add undefined symbols even if --export-dynamic is given.
This patch addresses a minor compatibility issue with GNU linkers.
Previously, --export-dynamic-symbol is completely ignored if you
pass --export-dynamic together.

Differential Revision: https://reviews.llvm.org/D43266

llvm-svn: 325152
2018-02-14 18:38:33 +00:00
Rui Ueyama 90b395e93a Make --export-dynamic-symbol to pull out object files from archives.
This is for compatiblity with GNU gold. GNU gold tries to resolve
symbols specified by --export-dynamic-symbol. So, if a symbol specified
by --export-dynamic-symbol is in an archive file, lld's result is
currently different from gold's.

Interestingly, that behavior is different for --dynamic-list.
I added a new test to ensure that.

Differential Revision: https://reviews.llvm.org/D43103

llvm-svn: 324752
2018-02-09 17:39:06 +00:00