D64136 and D65584, while fixing STB_WEAK issues and improving our
compatibility with ld.bfd, can cause another STB_WEAK problem related to
LTO:
If %tundef.o has an undefined reference on f,
and %tweakundef.o has a weak undefined reference on f,
%tdef.o has a definition of f
```
ld.lld %tundef.o %tweakundef.o --start-lib %tdef.o --end-lib
```
1) `%tundef.o` doesn't set the `referenced` bit.
2) `%weakundef.o` changes the binding from STB_GLOBAL to STB_WEAK
3) `%tdef.o` is not fetched because the binding is weak.
Step (1) is incorrect. This patch sets the `referenced` bit of Undefined
created by bitcode files.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D66992
llvm-svn: 370437
lld currently selects the relocation model automatically depending on
the link flags specified, but in some cases it'd be useful to allow
explicitly overriding the relocation model using a flag.
llvm-svn: 366644
This matches the wasm lld and GNU ld behavior.
The ELF linker has special handling for bitcode archives but if that
doesn't kick in we probably want to error out rather than silently
ignore the library.
Differential Revision: https://reviews.llvm.org/D63781
llvm-svn: 364998
Add Triple::riscv64 and Triple::riscv32 to getBitcodeMachineKind for get right
e_machine during LTO.
Reviewed By: ruiu, MaskRay
Differential Revision: https://reviews.llvm.org/D52165
llvm-svn: 364996
r360841 introduced CommonSymbol class. An unintended behavioral change
introduced by that change was that common symbols are not internalized
by LTO under some condition. This patch fixes that issue.
The issue occurred under the following condition:
1. There exists a common symbol
2. At least one DSO is given to lld or -pie is used
If the above conditions are met, Symbol::includeInDynsym() returned a
wrong value for a common symbol.
Fixes https://bugs.llvm.org/show_bug.cgi?id=41978
Differential Revision: https://reviews.llvm.org/D63752
llvm-svn: 364273
Use -fsave-optimization-record=<format> to specify a different format
than the default, which is YAML.
For now, only YAML is supported.
llvm-svn: 363573
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
Module IDs can appear in diagnostic messages.
This patch adds some auxiliary symbols to improve their readability.
Differential Revision: https://reviews.llvm.org/D61857
llvm-svn: 360858
Summary:
The gold plugin behavior (creating empty index files for lazy bitcode
files) was added in D46034, but it missed the case when there is no
non-lazy bitcode files, e.g.
ld.lld -shared crti.o crtbeginS.o --start-lib bitcode.o --end-lib ...
crti.o crtbeginS.o are not bitcode, but our distributed build system
wants bitcode.o.thinlto.bc to confirm all expected outputs are created
based on all of the modules provided to the linker.
Differential Revision: https://reviews.llvm.org/D61420
llvm-svn: 359788
Also change some options that have different semantics (cause confusion) in llvm-readelf mode:
-s => -S
-t => --symbols
-sd => --section-data
llvm-svn: 359651
D58391 changed the LTO pipelines to add the tailcall elimination pass.
This caused three LLD tests to fail.
Differential Revision: https://reviews.llvm.org/D59604
llvm-svn: 356593
We allow an archive file without symbol table as a linker input as a
workaround for a very common error in LTO build. But that logic worked
even for an archive file containing non-bitcode files, which is not
expected. This patch limits that workaround to one that contains only
bitcode files.
Differential Revision: https://reviews.llvm.org/D59373
llvm-svn: 356186
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss)
New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss)
The placement of | indicates page alignment caused by PT_GNU_RELRO. The
new layout has simpler rules and saves space for many cases.
Old size: roundup(.data) + roundup(.data.rel.ro)
New size: roundup(.data.rel.ro + .bss.rel.ro) + .data
Other advantages:
* At runtime the 3 memory mappings decrease to 2.
* start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This
simplifies binary manipulation tools.
GNU strip before 2.31 discards PT_GNU_RELRO if its
address is not equal to the start of its associated PT_LOAD.
This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f
But with this change, we will be compatible with GNU strip before 2.31
* Before, .got.plt (non-relro by default) was placed before .got (relro
by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_
(start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END)
(https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we
can improve on this regard if we'd like to.
Reviewers: ruiu, espindola, pcc
Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert
Differential Revision: https://reviews.llvm.org/D56828
llvm-svn: 356117
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.
This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`
will only emit the remarks coming from the pass `inline`.
This adds:
* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin
Differential Revision: https://reviews.llvm.org/D59268
Original llvm-svn: 355964
llvm-svn: 355984
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.
This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`
will only emit the remarks coming from the pass `inline`.
This adds:
* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin
Differential Revision: https://reviews.llvm.org/D59268
llvm-svn: 355964
This unit test fails if 'zed' appears in your build path, as lld is
echoing out the path of the source file. Change the unit test to
explicitly only match everything after the 'Symbols [' line of the
output, to make sure that this test doesn't inadvertently fail due to
the build path.
llvm-svn: 355748
If the permission does not permit writing and the standard input is a
terminal, rm gives an annoying prompt. chmod u+w to make the output
directory easier to delete.
llvm-svn: 355382
Summary:
The gold linker allowed you to output the ELF files after LTO was run. It did
it by using the 'obj-path' option. This replicates that behavior.
Reviewers: espindola, ruiu, MaskRay, pcc
Reviewed By: MaskRay, pcc
Subscribers: grimar, emaste, inglorion, arichardson, steven_wu, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D56046
llvm-svn: 354917
llvm-readobj currently has a bug (see PR40097) where it prints '@' at
the end of unversioned dynamic symbols. This bug will be fixed in a
separate later commit, but these tests need fixing first.
Reviewed by: ruiu, Higuoxing
Differential Revision: https://reviews.llvm.org/D56388
llvm-svn: 350614
`--plugin-opt=emit-llvm` is an option for LTO. It makes the linker to
combine all bitcode files and write the result to an output file without
doing codegen. Gold LTO plugin has this option.
This option is being used for some post-link code analysis tools that
have to see a whole program but don't need to see them in the native
machine code.
Differential Revision: https://reviews.llvm.org/D55717
llvm-svn: 349198
Summary: llvm-readobj/readelf accepts both -s and -S as aliases for --sections. However with GNU readelf only -S means --section, and -s means --symbols. I would like to make llvm-readelf more compatible.
Reviewers: MaskRay, espindola
Reviewed By: MaskRay
Subscribers: emaste, arichardson, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D54118
llvm-svn: 346164
Summary:
It is difficult to touch a file with a relative mtime across different OSes as POSIX touch -d is rigid. While we may construct relative timestamps with `date`, POSIX date is inadequate to do so as various OSes' date do not agree on a common format (OpenBSD uses `date -r seconds`, FreeBSD uses `date -v-2M` while GNU accepts `-d '-2 min'`)
Just use python os.utime()
Original description:
The case may randomly fail if we test it with command "
while llvm-lit tools/lld/test/ELF/lto/cache.ll; do true; done". It is because the llvmcache-foo file is younger than llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6. But due to timestamp precision reason their timestamp is the same. Given the same timestamp, the file prune policy is to remove bigger size file first, so mostly foo file is removed for its bigger size. And the files size is under threshold after deleting foo file. That's what test case expect.
However sometimes, the precision is enough to measure that timestamp of llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6 are smaller than foo, so llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6 are deleted first. Since the files size is still above the file size threshold after deleting the 2 files, the foo file is also deleted. And then the test case fails, because it expect only one file should be deleted instead of 3.
The fix is to change the timestamp of llvmcache-foo file to meet the thinLTO prune policy.
The same fix is applied to llvm code at https://reviews.llvm.org/D52452.
Patch by Luo Yuanke.
Reviewers: ruiu, craig.topper, smaslov, Jianping, espindola, LuoYuanke, tejohnson
Reviewed By: tejohnson
Subscribers: sbc100, krytarowski, aheejin, llvm-commits, dexonsmith, steven_wu, arichardson, inglorion, emaste, bjope, rupprecht
Differential Revision: https://reviews.llvm.org/D54039
llvm-svn: 346006
Summary:
The case may randomly fail if we test it with command "
while llvm-lit tools/lld/test/ELF/lto/cache.ll; do true; done". It is because the llvmcache-foo file is younger than llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6. But due to timestamp precision reason their timestamp is the same. Given the same timestamp, the file prune policy is to remove bigger size file first, so mostly foo file is removed for its bigger size. And the files size is under threshold after deleting foo file. That's what test case expect.
However sometimes, the precision is enough to measure that timestamp of llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6 are smaller than foo, so llvmcache-349F039B8EB076D412007D82778442BED3148C4E and llvmcache-A8107945C65C2B2BBEE8E61AA604C311D60D58D6 are deleted first. Since the files size is still above the file size threshold after deleting the 2 files, the foo file is also deleted. And then the test case fails, because it expect only one file should be deleted instead of 3.
The fix is to change the timestamp of llvmcache-foo file to meet the thinLTO prune policy.
The same fix is applied to llvm code at https://reviews.llvm.org/D52452.
Patch by Luo Yuanke.
Reviewers: ruiu, craig.topper, smaslov, Jianping, espindola, LuoYuanke
Subscribers: rupprecht, bjope, emaste, inglorion, arichardson, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D53123
llvm-svn: 345977
All the PassBuilder::parse interfaces now return descriptive StringError
instead of a plain bool. It allows to make -passes/aa-pipeline parsing
errors context-specific and thus less confusing.
TODO: ideally we should also make suggestions for misspelled pass names,
but that requires some extensions to PassBuilder.
Reviewed By: philip.pfaffe, chandlerc
Differential Revision: https://reviews.llvm.org/D53246
llvm-svn: 344685
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
We have an issue with -wrap that the option doesn't work well when
renamed symbols get PLT entries. I'll explain what is the issue and
how this patch solves it.
For one -wrap option, we have three symbols: foo, wrap_foo and real_foo.
Currently, we use memcpy to overwrite wrapped symbols so that they get
the same contents. This works in most cases but doesn't when the relocation
processor sets some flags in the symbol. memcpy'ed symbols are just
aliases, so they always have to have the same contents, but the
relocation processor breaks that assumption.
r336609 is an attempt to fix the issue by memcpy'ing again after
processing relocations, so that symbols that are out of sync get the
same contents again. That works in most cases as well, but it breaks
ASan build in a mysterious way.
We could probably fix the issue by choosing symbol attributes that need
to be copied after they are updated. But it feels too complicated to me.
So, in this patch, I fixed it once and for all. With this patch, we no
longer memcpy symbols. All references to renamed symbols point to new
symbols after wrapSymbols() is done.
Differential Revision: https://reviews.llvm.org/D50569
llvm-svn: 340387
Summary:
Before this change, pruning order was based on size. This changes it
to be based on time of last use instead, preferring to keep recently
used files and prune older ones.
Reviewers: pcc, rnk, espindola
Reviewed By: rnk
Subscribers: emaste, arichardson, hiraditya, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51062
llvm-svn: 340374
Summary:
For -thinlto-object-suffix-replace=old\;new, in
tools/gold/gold-plugin.cpp, the thinlto object filename is Path minus
optional old suffix.
static std::string getThinLTOObjectFileName(StringRef Path, StringRef OldSuffix,
StringRef NewSuffix) {
if (OldSuffix.empty() && NewSuffix.empty())
return Path;
StringRef NewPath = Path;
NewPath.consume_back(OldSuffix);
std::string NewNewPath = NewPath;
NewNewPath += NewSuffix;
return NewNewPath;
}
Currently lld will error that the path does not end with old suffix.
This patch makes lld accept such paths but only add new suffix if Path
ends with old suffix. This fixes a link error where bitcode members in
an archive are regular LTO objects without old suffix.
Acording to tejohnson, this will "enable supporting mix and match of
minimized ThinLTO bitcode files with normal ThinLTO bitcode files in a
single link (where we want to apply the suffix replacement to the
minimized files, and just ignore it for the normal ThinLTO files)."
Reviewers: ruiu, pcc, tejohnson, espindola
Reviewed By: tejohnson
Subscribers: emaste, inglorion, arichardson, eraman, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51055
llvm-svn: 340364
Adding all libcall symbols to the link can have undesired consequences.
For example, the libgcc implementation of __sync_val_compare_and_swap_8
on 32-bit ARM pulls in an .init_array entry that aborts the program if
the Linux kernel does not support 64-bit atomics, which would prevent
the program from running even if it does not use 64-bit atomics.
This change makes it so that we only add libcall symbols to the
link before LTO if we have to, i.e. if the symbol's definition is in
bitcode. Any other required libcall symbols will be added to the link
after LTO when we add the LTO object file to the link.
Differential Revision: https://reviews.llvm.org/D50475
llvm-svn: 339301
Summary:
The issue with the python path is that the path to python on Windows can contain spaces. To make the tests always work, the path to python needs to be surrounded by quotes.
This is a companion change to: https://reviews.llvm.org/D50206
Reviewers: asmith, zturner, espindola
Subscribers: emaste, sbc100, arichardson, aheejin, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D50282
llvm-svn: 339075
Summary:
Optimization remark format is slightly changed by LLVM patch D49412.
One test is fixed with expected messages changed.
Frankly speaking I have not tested this change yet. I will test when manage to setup the project.
Reviewers: xbolva00, espindola
Reviewed By: xbolva00
Subscribers: emaste, arichardson, steven_wu, dexonsmith
Differential Revision: https://reviews.llvm.org/D50242
llvm-svn: 338970
Amy Huang