Commit Graph

6 Commits

Author SHA1 Message Date
Jez Ng 7bbdbacd00 [lld-macho] Use export trie instead of symtab when linking against dylibs
Summary:
This allows us to link against stripped dylibs. Moreover, it's simply
more correct: The symbol table includes symbols that the dylib uses but
doesn't export.

This temporarily regresses our ability to do lazy symbol binding because
dyld_stub_binder isn't in libSystem's export trie. Rather, it is in one
of the sub-libraries libSystem re-exports. (This doesn't affect our
tests since we are mocking out dyld_stub_binder there.) A follow-up diff
will address this by adding support for sub-libraries.

Depends on D79114.

Reviewers: ruiu, pcc, MaskRay, smeenai, alexshap, gkm, Ktwu, christylee

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79226
2020-05-09 20:56:22 -07:00
Jez Ng 9854edd817 [lld-macho] Implement basic export trie
Build the trie by performing a three-way radix quicksort: We start by
sorting the strings by their first characters, then sort the strings
with the same first characters by their second characters, and so on
recursively. Each time the prefixes diverge, we add a node to the trie.
Thanks to @ruiu for the idea.

I used llvm-mc's radix quicksort implementation as a starting point. The
trie offset fixpoint code was taken from
MachONormalizedFileBinaryWriter.cpp.

Differential Revision: https://reviews.llvm.org/D76977
2020-04-29 15:44:27 -07:00
Jez Ng 62b8f32f76 [lld-macho][reland] Add support for emitting dylibs with a single symbol
This got reverted due to UBSAN errors in a diff lower in the stack,
which is being fixed in https://reviews.llvm.org/D79050. This diff is
otherwise identical to the original https://reviews.llvm.org/D76908
(which was committed in 9598778bd1 and reverted in b52bc2653b).

Differential Revision: https://reviews.llvm.org/D79051
2020-04-28 17:08:32 -07:00
Shoaib Meenai b52bc2653b Revert "[lld-macho] Add support for emitting dylibs with a single symbol"
This reverts commit 9598778bd1.

Reverting due to UBSan failures:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/40817/steps/check-lld%20ubsan/logs/stdio
2020-04-28 11:34:03 -07:00
Jez Ng 9598778bd1 [lld-macho] Add support for emitting dylibs with a single symbol
Summary:
Add logic for emitting the correct set of load commands and segments
when `-dylib` is passed.

I haven't gotten to implementing a real export trie yet, so we can only
emit a single symbol, but it's enough to replace the YAML test files
introduced in D76252.

Differential Revision: https://reviews.llvm.org/D76908
2020-04-27 13:33:46 -07:00
Jez Ng 060efd24c7 [lld-macho] Add basic support for linking against dylibs
This diff implements:

* dylib loading (much of which is being restored from @pcc and @ruiu's
  original work)
* The GOT_LOAD relocation, which allows us to load non-lazy dylib
  symbols
* Basic bind opcode emission, which tells `dyld` how to populate the GOT

Differential Revision: https://reviews.llvm.org/D76252
2020-04-21 13:43:19 -07:00