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
This adds support for the arm64_32 watchOS ABI to LLVM's low level tools,
teaching them about the specific MachO choices and constants needed to
disassemble things.
llvm-svn: 360663
This fixes the https://bugs.llvm.org/show_bug.cgi?id=41355.
Previously with -r we printed relocation section name instead of the target section name.
It was like this: "RELOCATION RECORDS FOR [.rel.text]"
Now it is: "RELOCATION RECORDS FOR [.text]"
Also when relocation target section has more than one relocation section,
we did not combine the output. Now we do.
Differential revision: https://reviews.llvm.org/D61312
llvm-svn: 360143
This improves readability and the behavior is consistent with GNU objdump.
The new test test/tools/llvm-objdump/X86/disassemble-section-name.s
checks we print newlines before and after "Disassembly of section ...:"
Differential Revision: https://reviews.llvm.org/D61127
llvm-svn: 359668
-t is --symbols in llvm-readobj but --section-details (unimplemented) in readelf.
The confusing option should not be used since we aim for improving
compatibility.
Keep just one llvm-readobj -t use case in test/tools/llvm-readobj/symbols.test
llvm-svn: 359661
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
This relands rL358418. It missed one test that should also use -macho
Note, all the other -private-header -exports-trie tests are used
together with -macho.
llvm-svn: 358472
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
This updates the StackMap parser in the llvm-readobj tool to parse version 3 StackMaps, which were bumped in https://reviews.llvm.org/D32629.
Version 3 StackMaps differ in that they have a uint16 sized "location size" field which was added to the Location block in a StackMap record. The record has additional padding for alignment. This was a backwards incompatible change resulting in a StackMap version bump.
Patch By: jacob.hughes@kcl.ac.uk (with a rewrite of tests by me)
Differential Revision: https://reviews.llvm.org/D59020
llvm-svn: 358325
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
Currently, YAML has the following syntax for describing the symbols:
Symbols:
Local:
LocalSymbol1:
...
LocalSymbol2:
...
...
Global:
GlobalSymbol1:
...
Weak:
...
GNUUnique:
I.e. symbols are grouped by their bindings. That is not very convenient,
because:
It does not allow to set a custom binding, what can be useful for producing
broken/special outputs for test cases. Adding a new binding would require to
change a syntax (what we observed when added GNUUnique recently).
It does not allow to change the order of the symbols in .symtab/.dynsym,
i.e. currently all Local symbols are placed first, then Global, Weak and GNUUnique
are following, but we are not able to change the order.
It is not consistent. Binding is just one of the properties of the symbol,
we do not group them by other properties.
It makes the code more complex that it can be. This patch shows it can be simplified
with the change performed.
The patch changes the syntax to just:
Symbols:
Symbol1:
...
Symbol2:
...
...
With that, we are able to work with the binding field just like with any other symbol property.
Differential revision: https://reviews.llvm.org/D60122
llvm-svn: 357595
Summary:
getRelocatedValue may compute incorrect value for SHT_RELA-typed relocation entries.
// DWARFDataExtractor.cpp
uint64_t DWARFDataExtractor::getRelocatedValue(uint32_t Size, uint32_t *Off,
...
// This formula is correct for REL, but may be incorrect for RELA if the value
// stored in the location (getUnsigned(Off, Size)) is not zero.
return getUnsigned(Off, Size) + Rel->Value;
In this patch, we
* refactor these visit* functions to include a new parameter `uint64_t A`.
Since these visit* functions are no longer used as visitors, rename them to resolve*.
+ REL: A is used as the addend. A is the value stored in the location where the
relocation applies: getUnsigned(Off, Size)
+ RELA: The addend encoded in RelocationRef is used, e.g. getELFAddend(R)
* and add another set of supports* functions to check if a given relocation type is handled.
DWARFObjInMemory uses them to fail early.
Reviewers: echristo, dblaikie
Reviewed By: echristo
Subscribers: mgorny, aprantl, aheejin, fedor.sergeev, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57939
llvm-svn: 356729
Currently, this fails with many tools, e.g.
$ clang -fembed-bitcode-marker -c -o test.o test.c
$ nm test.o
nm: test.o The file was not recognized as a valid object file
-fembed-bitcode-marker creates a LLVM,bitcode section consisting of a single
byte. When reading the object file, IRObjectFile::findBitcodeInObject succeeds,
causing SymbolicFile::createSymbolicFile to try to read the "bitcode" rather
than using the outer Mach-O data - when then fails.
Fix this by making findBitcodeInObject return an error if the section size <= 1.
Patched by: Nicholas Allegra
Differential Revision: https://reviews.llvm.org/D44373
llvm-svn: 356718
Prior to this change, the "Symbol" field of a relocation would always be
assumed to be a symbol name, and if no such symbol existed, the
relocation would reference index 0. This confused me when I tried to use
a literal symbol index in the field: since "0x1" was not a known symbol
name, the symbol index was set as 0. This change falls back to treating
unknown symbol names as integers, and emits an error if the name is not
found and the string is not an integer.
Note that the Symbol field is optional, so if a relocation doesn't
reference a symbol, it shouldn't be specified. The new error required a
number of test updates.
Reviewed by: grimar, ruiu
Differential Revision: https://reviews.llvm.org/D58510
llvm-svn: 355938
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
Summary:
This patch will obtain the section name for symbols that refer to a section. Prior to this patch the Name field for STT_SECTIONs was blank, now it is populated.
Before:
```
Symbol table '.symtab' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 SECTION LOCAL DEFAULT 1
2: 0000000000000000 0 SECTION LOCAL DEFAULT 3
3: 0000000000000000 0 SECTION LOCAL DEFAULT 4
4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _GLOBAL_OFFSET_TABLE_
5: 0000000000000000 0 TLS GLOBAL DEFAULT UND sym
```
With this patch:
```
Symbol table '.symtab' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 SECTION LOCAL DEFAULT 1 .text
2: 0000000000000000 0 SECTION LOCAL DEFAULT 3 .data
3: 0000000000000000 0 SECTION LOCAL DEFAULT 4 .bss
4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _GLOBAL_OFFSET_TABLE_
5: 0000000000000000 0 TLS GLOBAL DEFAULT UND sym
```
This fixes PR40788
Reviewers: jhenderson, rupprecht, espindola
Reviewed By: rupprecht
Subscribers: emaste, javed.absar, arichardson, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58796
llvm-svn: 355207
Summary:
Changes from using a total ordering of known sections to using a
dependency graph approach. This allows our tools to accept and process
binaries that are compliant with the spec and tool conventions that
would have been previously rejected. It also means our own tools can
do less work to enforce an artificially imposed ordering. Using a
general mechanism means fewer special cases and exceptions in the
ordering logic.
Reviewers: aheejin, dschuff
Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58312
llvm-svn: 354426
See https://github.com/WebAssembly/tool-conventions/pull/95.
This is less typing and IMHO more readable, and it also fits with
our naming around the binary format which tends to use the short name.
e.g.
include/llvm/BinaryFormat/Wasm.h
tools/llvm-objdump/WasmDump.cpp
etc..
Differential Revision: https://reviews.llvm.org/D57611
llvm-svn: 353062
Summary:
The previous implementation reported `.comment` sections as '?'
GNU uses 'n' which means "The symbol is a debugging symbol." `.note` sections are represented as 'n' too.
The test related to this change was updated to CHECK-NEXT to ensure
order and that we did not miss any symbols in the dump.
Reviewers: jhenderson
Reviewed By: jhenderson
Subscribers: rupprecht, llvm-commits
Differential Revision: https://reviews.llvm.org/D57544
llvm-svn: 352891
Summary:
Previously, llvm-nm would report symbols for .debug and .note sections as: '?' with an empty section name:
```
00000000 ?
00000000 ?
...
```
With this patch the output more closely resembles GNU nm:
```
00000000 N .debug_abbrev
00000000 n .note.GNU-stack
...
```
This patch calls `getSectionName` for sections that belong to symbols of type `ELF::STT_SECTION`, which returns the name of the section from the section string table.
Reviewers: Bigcheese, davide, jhenderson
Reviewed By: davide, jhenderson
Subscribers: rupprecht, jhenderson, llvm-commits
Differential Revision: https://reviews.llvm.org/D57105
llvm-svn: 352785
I faced with the fact that obj2yaml does not dump the sh_entsize field.
A problem arose when I tried to dump ELF versioning sections.
This is close to what D50235 did, but D50235 did the change for yaml2obj, and now
I had to do the same for obj2yaml.
Differential revision: https://reviews.llvm.org/D57229
llvm-svn: 352373
When --section-headers is used, GNU objdump prints both LMA and VMA for sections.
llvm-objdump does not do that what makes it's output be slightly inconsistent.
Patch teaches llvm-objdump to print LMA/VMA for ELF file formats.
The behavior for other formats remains unchanged.
Differential revision: https://reviews.llvm.org/D57146
llvm-svn: 352366
Summary:
guessLibraryShortName() separates a full Mach-O dylib install name path
into a short name and a dyld image suffix. The short name is the name
of the dylib without its path or extension. The dyld image suffix is a
string used by dyld to load variants of dylibs if available at runtime;
for example, "when binding this process, load 'debug' variants of all
required dylibs." dyld knows exactly what the image suffix is, but
by convention diagnostic tools such as llvm-nm attempt to guess suffix
names by looking at the install name path.
These dyld image suffixes are separated from the short name by a '_'
character. Because the '_' character is commonly used to separate words
in filenames guessLibraryShortName() cannot reliably separate a dylib's
short name from an arbitrary image suffix; imagine if both the short
name and the suffix contains an '_' character! To better deal with this
ambiguity, guessLibraryShortName() will recognize only "_debug" and
"_profile" as valid Suffix values. Calling code needs to be tolerant of
guessLibraryShortName() guessing incorrectly.
The previous implementation of guessLibraryShortName() did not allow
'_' characters to appear in short names. When present, the short name
would be truncated, e.g., "libcompiler_rt" => "libcompiler". This
change allows "libcompiler_rt" and "libcompiler_rt_debug" to both be
recognized as "libcompiler_rt".
rdar://47412244
Reviewers: kledzik, lhames, pete
Reviewed By: pete
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D56978
llvm-svn: 352104
There can be multiple local symbols with the same name (for e.g.
comdat sections), and thus the symbol name itself isn't enough
to disambiguate symbols.
Differential Revision: https://reviews.llvm.org/D56140
llvm-svn: 350288
Summary:
Import libraries as created by llvm-dlltool always use the same archive
member name for every object file (namely, the DLL library name). Ensure
that long names are not repeatedly stored in the string table.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D55860
llvm-svn: 349637
Summary:
This patch checks if the section order is correct when reading a wasm
object file in `WasmObjectFile` and converting YAML to wasm object in
yaml2wasm. (It is not possible to check when reading YAML because it is
handled exclusively by the YAML reader.)
This checks the ordering of all known sections (core sections + known
custom sections). This also adds section ID DataCount section that will
be scheduled to be added in near future.
Reviewers: sbc100
Subscribers: dschuff, mgorny, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D54924
llvm-svn: 349221
Update tests using llvm-objdump since check strings don't
match anymore due to the extra `O` in place. This is a
followup for rL346610.
llvm-svn: 346611
Summary:
This updates generated binaries and corresponding test cases up to date
after applying FixFunctionBitcasts pass.
Reviewers: sbc100
Subscribers: dschuff, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D54070
llvm-svn: 346286
* Support writing the DARWIN64 symbol table format.
* In darwin archives, emit a symbol table whenever requested, even
when there are no members, as the apple linker will abort if given
an archive without a symbol table.
Added tests for same, and also simplified and moved the GNU 64-bit
symbol table test into archive-symtab.test.
llvm-svn: 344183
Summary:
The POSIX spec says:
```
If the −t option is used with the −v option, the standard output format shall be:
"%s %u/%u %u %s %d %d:%d %d %s\n", <member mode>, <user ID>,
<group ID>, <number of bytes in member>,
<abbreviated month>, <day-of-month>, <hour>,
<minute>, <year>, <file>
where:
...
<abbreviated month>
Equivalent to the format of the %b conversion specification format in date.
<day-of-month>
Equivalent to the format of the %e conversion specification format in date.
<hour> Equivalent to the format of the %H conversion specification format in date.
<minute> Equivalent to the format of the %M conversion specification format in date.
<year> Equivalent to the format of the %Y conversion specification format in date.
```
This actually used to be the format printed by llvm-ar. It was apparently accidentally changed (see r207385 followed by comments in r207387). This makes it conform to GNU ar for easier replacement.
Reviewers: MaskRay
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D52940
llvm-svn: 343901
This matches the output of binutils' nm and ensures that any scripts
or tools that use nm and expect empty output in case there no symbols
don't break.
Differential Revision: https://reviews.llvm.org/D52943
llvm-svn: 343887
This change ensures that the (membername,timestamp) tuple uniquely
identifies an entry in an archive for format=darwin, in deterministic
mode (which is the default).
That, then, enables lldb and dsymutil to locate the appropriate object
within the archive.
Differential Revision: https://reviews.llvm.org/D47659
llvm-svn: 343805
Summary:
GNU nm (and other nm implementations, such as "go tool nm") prints an explicit "no symbols" message when an object file has no symbols. Currently llvm-nm just doesn't print anything. Adding an explicit "no symbols" message will allow llvm-nm to be used in place of nm: some scripts and build processes use `nm <file> | grep "no symbols"` as a test to see if a file has no symbols. It will also be more familiar to anyone used to nm.
That said, the format implemented here is slightly different, in that it doesn't print the tool name in the message (which IMHO is not useful to include).
Demo:
```
$ for nm in nm bin/llvm-nm ; do echo "nm implementation: $nm"; $nm /tmp/foo{1,2}.o; echo; done
nm implementation: nm
/tmp/foo1.o:
nm: /tmp/foo1.o: no symbols
/tmp/foo2.o:
0000000000000000 T foo2
nm implementation: bin/llvm-nm
/tmp/foo1.o:
no symbols
/tmp/foo2.o:
0000000000000000 T foo2
```
Reviewers: MaskRay
Reviewed By: MaskRay
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D52810
llvm-svn: 343742
George Rimar