commit | e51a6266856843542f11f93f1b7b2ec2caa6bc2b | [log] [tgz] |
---|---|---|
author | Jez Ng <jezng@fb.com> | Tue Feb 23 21:41:54 2021 -0500 |
committer | Copybara-Service <copybara-worker@google.com> | Fri Feb 26 22:03:35 2021 -0800 |
tree | 93f2cf7a179a98b4dc460eba214c131db8b975ad | |
parent | 6148eaf89da3ded93f7067a5e729430381c075a7 [diff] |
[lld-macho] Fix semantics & add tests for ARM64 GOT/TLV relocs I've adjusted the RelocAttrBits to better fit the semantics of the relocations. In particular: 1. *_UNSIGNED relocations are no longer marked with the `TLV` bit, even though they can occur within TLV sections. Instead the `TLV` bit is reserved for relocations that can reference thread-local symbols, and *_UNSIGNED relocations have their own `UNSIGNED` bit. The previous implementation caused TLV and regular UNSIGNED semantics to be conflated, resulting in rebase opcodes being incorrectly emitted for TLV relocations. 2. I've added a new `POINTER` bit to denote non-relaxable GOT relocations. This distinction isn't important on x86 -- the GOT relocations there are either relaxable or non-relaxable loads -- but arm64 has `GOT_LOAD_PAGE21` which loads the page that the referent symbol is in (regardless of whether the symbol ends up in the GOT). This relocation must reference a GOT symbol (so must have the `GOT` bit set) but isn't itself relaxable (so must not have the `LOAD` bit). The `POINTER` bit is used for relocations that *must* reference a GOT slot. 3. A similar situation occurs for TLV relocations. 4. ld64 supports both a pcrel and an absolute version of ARM64_RELOC_POINTER_TO_GOT. But the semantics of the absolute version are pretty weird -- it results in the value of the GOT slot being written, rather than the address. (That means a reference to a dynamically-bound slot will result in zeroes being written.) The programs I've tried linking don't use this form of the relocation, so I've dropped our partial support for it by removing the relevant RelocAttrBits. Reviewed By: alexshap Differential Revision: https://reviews.llvm.org/D97031 GitOrigin-RevId: 5e851733c5b603bec962bb4c5cf9d5cc93d88175
This directory and its subdirectories contain source code for the LLVM Linker, a modular cross platform linker which is built as part of the LLVM compiler infrastructure project.
lld is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.
In order to make sure various developers can evaluate patches over the same tests, we create a collection of self contained programs.
It is hosted at https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz
The current sha256 is 10eec685463d5a8bbf08d77f4ca96282161d396c65bd97dc99dbde644a31610f
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