llvm-project/lld
Shoaib Meenai 1af25a9860 [ELF] Fix wrapping symbols produced during LTO codegen
We were previously not correctly wrapping symbols that were only
produced during LTO codegen and unreferenced before then, or symbols
only referenced from such symbols. The root cause was that we weren't
marking the wrapped symbol as used if we only saw the use after LTO
codegen, leading to the failed wrapping.

Fix this by explicitly tracking whether a symbol will become referenced
after wrapping is done. We can use this property to tell LTO to preserve
such symbols, instead of overload isUsedInRegularObj for this purpose.
Since we're no longer setting isUsedInRegularObj for all symbols which
will be wrapped, its value at the time of performing the wrapping in the
symbol table will accurately reflect whether the symbol was actually
used in an object (including in an LTO-generated object), and we can
propagate that value to the wrapped symbol and thereby ensure we wrap
correctly.

This incorrect wrapping was the only scenario I was aware of where we
produced an invalid PLT relocation, which D123985 started diagnosing,
and with it fixed, we lose the test for that diagnosis. I think it's
worth keeping the diagnosis though, in case we run into other issues in
the future which would be caught by it.

Fixes PR50675.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D124056
2022-04-22 16:45:21 -07:00
..
COFF Force GHashCell to be 8-byte-aligned. 2022-04-18 08:46:03 -07:00
Common Cleanup codegen includes 2022-03-16 08:43:00 +01:00
ELF [ELF] Fix wrapping symbols produced during LTO codegen 2022-04-22 16:45:21 -07:00
MachO [lld-macho] Fix ICF crash when comparing symbol relocs 2022-04-22 15:36:53 -04:00
MinGW [LLD][MinGW] Add --heap argument support 2022-01-30 00:01:45 +02:00
cmake/modules [CMake] Factor out config prefix finding logic 2022-01-07 20:16:18 +00:00
docs [lld/win] Mention in release notes that /winsysroot: currently requires /machine: 2022-04-22 09:40:39 -04:00
include/lld [lld] Make error handling functions opaque 2022-02-17 11:54:57 -08:00
test [ELF] Fix wrapping symbols produced during LTO codegen 2022-04-22 16:45:21 -07:00
tools/lld [LLD] Fix issue in HIP due to unspecified order of evaluation of the function object 2022-02-08 19:12:15 -05:00
utils
wasm [lld] Remove support for legacy pass manager 2022-04-07 10:17:31 +02:00
.clang-format
.clang-tidy NFC: .clang-tidy: Inherit configs from parents to improve maintainability 2021-06-08 08:25:59 -07:00
.gitignore
CMakeLists.txt [lld] Require C++14 in LLD standalone build 2022-02-22 18:15:29 -05:00
CODE_OWNERS.TXT
LICENSE.TXT
README.md [doc] Place sha256 in lld/README.md into backticks 2021-01-12 10:19:40 -08:00

README.md

LLVM Linker (lld)

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.

Benchmarking

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.