LLD previously used to handle dynamic lists and version scripts in the
exact same way, even though they have very different semantics for
shared libraries and subtly different semantics for executables. r315114
untangled their semantics for executables (building on previous work to
correct their semantics for shared libraries). With that change, dynamic
lists won't set the default version to VER_NDX_LOCAL, and so resetting
the version to VER_NDX_GLOBAL in scanShlibUndefined is unnecessary.
This was causing an issue because version scripts containing `local: *`
work by setting the default version to VER_NDX_LOCAL, but scanShlibUndefined
would override this default, and therefore symbols which should have
been local would end up in the dynamic symbol table, which differs from
both bfd and gold's behavior. gold silently keeps the symbol hidden in
such a scenario, whereas bfd issues an error. I prefer bfd's behavior
and plan to implement that in LLD in a follow-up (and the test case
added here will be updated accordingly).
Differential Revision: https://reviews.llvm.org/D41639
llvm-svn: 321982
We normally avoid "switch (Config->EKind)", but in this case I think
it is worth it.
It is only executed when there is an error and it allows detemplating
a lot of code.
llvm-svn: 321404
Specifically, libwidevinecdm.so in Chrome has such bad symbol.
It seems the BFD linker handles them as local symbols, so instead
of inserting them to the symbol table, we should skip them too.
Differential Revision: https://reviews.llvm.org/D41257
llvm-svn: 320770
By using an index instead of a pointer for verdef we can put the index
next to the alignment field. This uses the otherwise wasted area and
reduces the shared symbol size.
By itself the performance change of this is in the noise, but I have a
followup patch to remove another 8 bytes that improves performance
when combined with this.
llvm-svn: 320449
This includes a fix to mark copy reloc aliases as used.
Original message:
[ELF] Do not keep symbols if they referenced only from discarded sections.
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
llvm-svn: 319215
Currently we mark every shared symbol as STB_WEAK.
That is a hack to make it easy to decide when a .so is needed or not
because of a reference to a given symbol.
That hack leaks when we create copy relocations as shown by the update
to relocation-copy-alias.s.
This patch stores the original binding when we first read a shared
symbol. We still have to update the binding to weak if we see a weak
undef, but I find the logic easier to read where it is now.
llvm-svn: 319127
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
Differential Revision: https://reviews.llvm.org/D38790
llvm-svn: 319008
The Traced flag is unnecessary because we only need to set the index
to -1 to mark a symbol for tracing.
Differential Revision: https://reviews.llvm.org/D39672
llvm-svn: 317450
Now that DefinedRegular is the only remaining derived class of
Defined, we can merge the two classes.
Differential Revision: https://reviews.llvm.org/D39667
llvm-svn: 317448
Common symbols are now represented with a DefinedRegular that points
to a BssSection, even during symbol resolution.
Differential Revision: https://reviews.llvm.org/D39666
llvm-svn: 317447
r317396 changed the way how we handle the -defsym option. The option is
now handled using the infrastructure for the linker script.
We used to handle both -defsym and -wrap using the same set of functions
in the symbol table. Now, we don't need to do that.
This patch rewrites the functions so that they become more straightforward.
The new functions directly handle -wrap rather than abstract it.
llvm-svn: 317426
Now that we have only SymbolBody as the symbol class. So, "SymbolBody"
is a bit strange name now. This is a mechanical change generated by
perl -i -pe s/SymbolBody/Symbol/g $(git grep -l SymbolBody lld/ELF lld/COFF)
nd clang-format-diff.
Differential Revision: https://reviews.llvm.org/D39459
llvm-svn: 317370
This is PR34826.
Currently LLD is unable to report line number when reporting
duplicate declaration of some variable.
That happens because for extracting line information we always use
.debug_line section content which describes mapping from machine
instructions to source file locations, what does not help for
variables as does not describe them.
In this patch I am taking the approproate information about
variables locations from the .debug_info section.
Differential revision: https://reviews.llvm.org/D38721
llvm-svn: 317080
SymbolBody and Symbol were separated classes due to a historical reason.
Symbol used to be a pointer to a SymbolBody, and the relationship
between Symbol and SymbolBody was n:1.
r2681780 changed that. Since that patch, SymbolBody and Symbol are
allocated next to each other to improve memory locality, and they have
1:1 relationship now. So, the separation of Symbol and SymbolBody no
longer makes sense.
This patch merges them into one class. In order to avoid updating too
many places, I chose SymbolBody as a unified name. I'll rename it Symbol
in a follow-up patch.
Differential Revision: https://reviews.llvm.org/D39406
llvm-svn: 317006
DSO is short for dynamic shared object, so the function name was a
little confusing because it sounded like it didn't work when we were
a creating statically-linked executable or something.
What we mean by "DSO" here is the current output file that we are
creating. Thus the new name. Alternatively, we could call it the current
ELF module, but "module" is a overloaded word, so I avoided that.
llvm-svn: 316809
Summary:
The COFF linker and the ELF linker have long had similar but separate
Error.h and Error.cpp files to implement error handling. This change
introduces new error handling code in Common/ErrorHandler.h, changes the
COFF and ELF linkers to use it, and removes the old, separate
implementations.
Reviewers: ruiu
Reviewed By: ruiu
Subscribers: smeenai, jyknight, emaste, sdardis, nemanjai, nhaehnle, mgorny, javed.absar, kbarton, fedor.sergeev, llvm-commits
Differential Revision: https://reviews.llvm.org/D39259
llvm-svn: 316624
I hadn't synced past the change that changed the default hash style
to --hash-style=both, so my test had the symbols in the wrong order.
llvm-svn: 315119
Dynamic lists in an executable are additive, not restrictive, so we
must continue to export preempted symbols even with a dynamic list.
This fixes sanitizer interception of libc symbols (and should also fix
symbol preemption by users of sanitizers).
Differential Revision: https://reviews.llvm.org/D38647
llvm-svn: 315114
Before this patch we would copy foo into real_foo and wrap_foo into
foo. The net result is that __wrap_foo shows up twice in the symbol
table.
With this patch we:
* save a copy of __real_foo before copying foo.
* drop one of the __wrap_foo from the symbol table.
* if __real_foo was not undefined, add a *new* symbol with that content to
the symbol table.
The net result is that
Anything using foo now uses __wrap_foo
Anything using __real_foo now uses foo.
Anything using __wrap_foo still does.
And the symbol table has foo, __wrap_foo and __real_foo (if defined).
Which I think is the desired behavior.
llvm-svn: 315097
SymbolTable::insert() is a hot path function. When linking a clang debug
build, the function is called 3.7 million times. The total amount of "Name"
string contents is 300 MiB. That means this `Name.find("@@")` scans almost
300 MiB of data. That's far from negligible.
StringRef::find(StringRef) uses a sophisticated algorithm, but the
function is slow for a short needle. This patch replaces it with
StringRef::find(char).
This patch alone speeds up a clang debug build link time by 0.5 seconds
from 8.2s to 7.7s. That's 6% speed up. It seems too good for this tiny
change, but looks like it's real.
llvm-svn: 314192
In order to keep track of symbol renaming, we used to have
Config->SymbolRenaming, and whether a symbol is in the map or not
affects its symbol attribute (i.e. "LinkeRedefined" bit).
This patch adds "CanInline" bit to Symbol to aggreagate symbol
information in one place and removed the member from Config since
no one except SymbolTable now uses the table.
llvm-svn: 314088
This patch removes lot of static Instances arrays from different input file
classes and introduces global arrays for access instead. Similar to arrays we
have for InputSections/OutputSectionCommands.
It allows to iterate over input files in a non-templated code.
Differential revision: https://reviews.llvm.org/D35987
llvm-svn: 313619
This allows combining --dynamic-list and version scripts too. The
version script controls which symbols are visible, and
--dynamic-list controls which of those are preemptible.
Unlike previous versions, undefined symbols are still considered
preemptible, which was the issue breaking the cfi tests.
This fixes pr34053.
llvm-svn: 312806
If --dynamic-list is given, only those symbols are preemptible.
This allows combining --dynamic-list and version scripts too. The
version script controls which symbols are visible, and --dynamic-list
controls which of those are preemptible.
This fixes pr34053.
llvm-svn: 312757
Patch by Rafael Espíndola.
This is PR34053.
The implementation is a bit of a hack, given the precise location where
IsPreemtible is set, it cannot be used from
SymbolTable::handleAnonymousVersion.
I could add another method to SymbolTable if you think that would be
better.
Differential Revision: https://reviews.llvm.org/D36499
llvm-svn: 311468
With this Symbol has the same size as before, but DefinedRegular goes
from 72 to 64 bytes.
I also find this a bit easier to read. There are fewer places
initializing File for example.
This has a small but measurable speed improvement on all tests (1%
max).
llvm-svn: 310142
In addition this includes a change to prefer symbols with a default
version @@ over unversioned symbols.
Original commit message:
[ELF] - Handle symbols with default version early.
This fixes last testcase provided in PR28414.
In short issue is next: when we had X@@Version symbol in object A,
we did not resolve it to X early. Then when in another object B
we had reference to undefined X, symbol X from archive was fetched.
Since both archive and object A contains another symbol Z, duplicate
symbol definition was triggered as a result.
Correct behavior is to use X@@Version from object A instead and do not fetch
any symbols from archive.
Differential revision: https://reviews.llvm.org/D35059
llvm-svn: 308492
This fixes PR33712.
Imagine following script and code:
VER1 { global: foo; local: *; };
VER2 { global: foo; };
.global bar
bar:
.symver bar, foo@VER1
.global zed
zed:
.symver zed, foo@@VER2
We add foo@@VER2 as foo to symbol table, because have to resolve references to
foo for default symbols.
Later we are trying to assign symbol versions from script. For that we are searching for 'foo'
again. Here it is placed under VER1 and VER2 at the same time, we find it twice and trying to
set version again both times, hence LLD shows a warning.
Though sample code is correct: we have 2 different versions of foo.
Patch gives a symbol version extracted from name a priority over version set by script.
Differential revision: https://reviews.llvm.org/D35207
llvm-svn: 307792
When version script was used, binding opf undefined weak symbols sometimes
was calculated as STB_LOCAL, making them non-preemtible what
broke correct relocations handling logic for them.
Fixes PR33738.
Differential revision: https://reviews.llvm.org/D35263
llvm-svn: 307767
This fixes last testcase provided in PR28414.
In short issue is next: when we had X@@Version symbol in object A,
we did not resolve it to X early. Then when in another object B
we had reference to undefined X, symbol X from archive was fetched.
Since both archive and object A contains another symbol Z, duplicate
symbol definition was triggered as a result.
Correct behavior is to use X@@Version from object A instead and do not fetch
any symbols from archive.
Differential revision: https://reviews.llvm.org/D35059
llvm-svn: 307364
This is PR28414.
Previously LLD was unable to link following:
(failed with undefined symbol bar)
Version script:
SOME_VERSION { global: *; };
.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
jmp bar
Manual has next description:
.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename.
The difference is name2@@nodename will also be used to resolve references to name2 by the linker
https://sourceware.org/binutils/docs/as/Symver.html
Patch implements that. If we have name@@ver symbol and name is undefined, name@@ver is used to resolve references to name.
If name is defined then multiple definition error is emited, that is consistent with what bfd do.
Differential revision: https://reviews.llvm.org/D33680
llvm-svn: 307077
This is PR28414.
Previously LLD was unable to link following:
(failed with undefined symbol bar)
```
Version script:
SOME_VERSION { global: *; };
.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
jmp bar
```
Manual has next description:
//
.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename.
**The difference is name2@@nodename will also be used to resolve references to name2 by the linker**
https://sourceware.org/binutils/docs/as/Symver.html
//
Patch implements that. If we have name@@ver symbol and name is undefined,
name@@ver is used to resolve references to name.
Differential revision: https://reviews.llvm.org/D33680
llvm-svn: 306813
We could have add this function either Symbol or SymbolBody. I added it
to Symbol at first. But I noticed that if I've added it to SymbolBody,
we could've removed SymbolBody::setName(). So I'll do that in this patch.
llvm-svn: 306590
Previously, when symbol A is renamed B, both A and B end up having
the same name. This is because name is a symbol's attribute, and
we memcpy symbols for symbol renaming.
This pathc saves the original symbol name and restore it after memcpy
to keep the original name.
This patch shouldn't change program's meaning, but names in symbol
tables make more sense than before.
llvm-svn: 306036
The --exclude-libs option is not a popular option, but at least some
programs in Android depend on it, so it's worth to support it.
Differential Revision: https://reviews.llvm.org/D34422
llvm-svn: 305920
procedural optimizations to prevent dropping symbols and allow the linker
to process re-directs.
PR33145: --wrap doesn't work with lto.
Differential Revision: https://reviews.llvm.org/D33621
llvm-svn: 304719
Shoaib Meenai