This is a result of what I found during my work on https://bugs.llvm.org/show_bug.cgi?id=41679.
Previously LLVM readelf took the information about .dynamic section
from its PT_DYNAMIC segment only. GNU tools have a bit different logic.
They also use the information from the .dynamic section header if it is available.
This patch changes the code to improve the compatibility with the GNU Binutils.
Differential revision: https://reviews.llvm.org/D61937
llvm-svn: 361165
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.
Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.
The design goals were to provide:
- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
environments (MSVC in particular).
Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.
In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:
1. There are no competing defined symbols in a given set of libraries, or
if they exist, the program owner doesn't care which is linked to their
program.
2. There may be circular dependencies between libraries.
The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:
.section ".deplibs","MS",@llvm_dependent_libraries,1
.asciz "foo"
For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.
LLD processes the dependent library specifiers in the following way:
1. Dependent libraries which are found from the specifiers in .deplibs sections
of relocatable object files are added when the linker decides to include that
file (which could itself be in a library) in the link. Dependent libraries
behave as if they were appended to the command line after all other options. As
a consequence the set of dependent libraries are searched last to resolve
symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
strings in a .deplibs section by; first, handling the string as if it was
specified on the command line; second, by looking for the string in each of the
library search paths in turn; third, by looking for a lib<string>.a or
lib<string>.so (depending on the current mode of the linker) in each of the
library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
dependent libraries.
Rationale for the above points:
1. Adding the dependent libraries last makes the process simple to understand
from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
will affect all of the dependent libraries. There is a potential problem of
surprise for developers, who might not realize that these options would apply
to these "invisible" input files; however, despite the potential for surprise,
this is easy for developers to reason about and gives developers the control
that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
find input files. The different search methods are tried by the linker in most
obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
is not necessary: if finer control is required developers can fall back to using
the command line directly.
RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.
Differential Revision: https://reviews.llvm.org/D60274
llvm-svn: 360984
r360876 didn't fix 2 call sites in clang.
Expected<ArrayRef<uint8_t>> may be better but use Expected<StringRef> for now.
Follow-up of D61781.
llvm-svn: 360892
It broke the Clang build, see llvm-commits thread.
> Expected<ArrayRef<uint8_t>> may be better but use Expected<StringRef> for now.
>
> Follow-up of D61781.
llvm-svn: 360878
In the r360676 "Apply clang format. NFC" I applied clang-format
for whole ELFDumper.cpp. It caused a little discussion,
one of the points mentioned was that previously nicely lined up
tables are not so nice now.
This patch reverts them.
llvm-svn: 360860
Patch adds support for dumping of file headers with llvm-readobj. XCOFF
object files are added to test dumping a well formed file, and dumping
both negative timestamps and negative symbol counts, both of which are
allowed in the XCOFF definition.
Differential Revision: https://reviews.llvm.org/D60878
llvm-svn: 359878
Summary:
It currently receives an output parameter and returns
std::error_code. Expected<StringRef> fits for this purpose perfectly.
Differential Revision: https://reviews.llvm.org/D61421
llvm-svn: 359774
We use both -long-option and --long-option in tests. Switch to --long-option for consistency.
In the "llvm-readelf" mode, -long-option is discouraged as it conflicts with grouped short options and it is not accepted by GNU readelf.
While updating the tests, change llvm-readobj -s to llvm-readobj -S to reduce confusion ("s" is --section-headers in llvm-readobj but --symbols in llvm-readelf).
llvm-svn: 359649
For well-known type IDs, include the name of the type.
To not duplicate the ID->name map, make llvm-readobj call this new
function as well. It has slightly different output, so this also
requires updating a few tests.
Differential Revision: https://reviews.llvm.org/D61086
llvm-svn: 359153
This is a resubmission of a previous patch that caused test failures,
with the fixes for the relevant tests included.
Fixes bug 40630: https://bugs.llvm.org/show_bug.cgi?id=40630
This patch changes the error message when the section specified by
--string-dump cannot be found by including the name of the section in
the error message and changing the prefix text to not imply that the
file itself was invalid. As part of this change some uses of
std::error_code have been replaced with the llvm Error class to better
encapsulate the error info (rather than passing File strings around),
and the WithColor class replaces string literal error prefixes.
llvm-svn: 358395
The size field of a location can be different for each entry, so it is useful to have this displayed in the output of llvm-readobj -stackmap. Below is an example of how the output would look:
Record ID: 2882400000, instruction offset: 16
3 locations:
#1: Constant 1, size: 8
#2: Constant 2, size: 8
#3: Constant 3, size: 8
0 live-outs: [ ]
Patch By: jacob.hughes@kcl.ac.uk (with heavy modification by me)
Differential Revision: https://reviews.llvm.org/D59169
llvm-svn: 358324
Summary:
This ensures that object files will continue to validate as
WebAssembly modules in the presence of bulk memory operations. Engines
that don't support bulk memory operations will not recognize the
DataCount section and will report validation errors, but that's ok
because object files aren't supposed to be run directly anyway.
Reviewers: aheejin, dschuff, sbc100
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60623
llvm-svn: 358315
The new value is taken from <mach/machine.h> in the MacOSX10.14 SDK from
Xcode 10.1. Update llvm-objdump and llvm-readobj accordingly.
Differential Revision: https://reviews.llvm.org/D58636
llvm-svn: 357945
Fixes bug 40630: https://bugs.llvm.org/show_bug.cgi?id=40630
This patch changes the error message when the section specified by
--string-dump cannot be found by including the name of the section in
the error message and changing the prefix text to not imply that the
file itself was invalid. As part of this change some uses of
std::error_code have been replaced with the llvm Error class to better
encapsulate the error info (rather than passing File strings around),
and the WithColor class replaces string literal error prefixes.
Differential Revision: https://reviews.llvm.org/D59946
llvm-svn: 357772
Summary: Currently, `llvm-readobj` do not support GNU style dumper for symbol versioning sections. In this patch, I would like to implement dumper for `.gnu.version` section
Reviewers: jhenderson, rupprecht, grimar
Reviewed By: jhenderson, rupprecht
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59877
llvm-svn: 357578
Summary: Support reading notes that don't have a standard note name.
Reviewers: MaskRay
Reviewed By: MaskRay
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59969
llvm-svn: 357271
The majority of the printRelocation and printDynamicRelocation functions
were identical. This patch factors this all out into a new function.
There are a couple of minor differences to do with printing of symbols
without names, but I think these are harmless, and in some cases a small
improvement.
Reviewed by: grimar, rupprecht, Higuoxing
Differential Revision: https://reviews.llvm.org/D59823
llvm-svn: 357246
Summary: When implementing `GNU style` dumper for `.gnu.version` section, we should find symbol version name by `vs_index`.
Reviewers: jhenderson, rupprecht
Reviewed By: rupprecht
Subscribers: arphaman, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59545
llvm-svn: 357164
Summary:
Currently, llvm-readobj can dump symbol version sections only in LLVM style. In this patch, I would like to separate these dumpers into GNU style and
LLVM style for future implementation.
Reviewers: grimar, jhenderson, mattd, rupprecht
Reviewed By: jhenderson, rupprecht
Subscribers: ormris, dyung, RKSimon, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59186
llvm-svn: 356881
Summary:
Currently, llvm-readobj can dump symbol version sections only in LLVM style. In this patch, I would like to separate these dumpers into GNU style and
LLVM style for future implementation.
Reviewers: grimar, jhenderson, mattd, rupprecht
Reviewed By: rupprecht
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59186
llvm-svn: 356764
Summary:
This commit introduces a new AMDGPUPALMetadata class that:
* is inside the AMDGPU target;
* keeps an in-memory representation of PAL metadata;
* provides a method to read the frontend-supplied metadata from LLVM IR;
* provides methods for the asm printer to set metadata items;
* provides methods to write the metadata as a binary blob to put in a
.note record or as an asm directive;
* provides a method to read the metadata as a binary blob from a .note
record.
Because llvm-readobj cannot call directly into a target, I had to remove
llvm-readobj's ability to dump PAL metadata, pending a resolution to
https://reviews.llvm.org/D52821
Differential Revision: https://reviews.llvm.org/D57027
Change-Id: I756dc830894fcb6850324cdcfa87c0120eb2cf64
llvm-svn: 356582
Summary:
MsgPackDocument is the lighter-weight replacement for MsgPackTypes. This
commit switches AMDGPU HSA metadata processing to use MsgPackDocument
instead of MsgPackTypes.
Differential Revision: https://reviews.llvm.org/D57024
Change-Id: I0751668013abe8c87db01db1170831a76079b3a6
llvm-svn: 356081
Specifically, compute and Print Type and Section columns.
This is a re-commit of rL354833, after fixing the Asan problem found a a buildbot.
Differential Revision: https://reviews.llvm.org/D59060
llvm-svn: 355742
George Rimar