Summary:
This patch adds a new flag, --warn-ifunc-textrel, to work around a glibc bug. When a code with ifunc symbols is used to produce an object file with text relocations, lld always succeeds. However, if that object file is linked using an old version of glibc, the resultant binary just crashes with segmentation fault when it is run (The bug is going to be corrected as of glibc 2.19).
Since there is no way to tell beforehand what library the object file will be linked against in the future, there does not seem to be a fool-proof way for lld to give an error only in cases where the binary will crash. So, with this change (dated 2018-09-25), lld starts to give a warning, contingent on a new command line flag that does not have a gnu counter part. The default value for --warn-ifunc-textrel is false, so lld behaviour will not change unless the user explicitly asks lld to give a warning. Users that link with a glibc library with version 2.19 or newer, or does not use ifunc symbols, or does not generate object files with text relocations do not need to take any action. Other users may consider to start passing warn-ifunc-textrel to lld to get early warnings.
Reviewers: ruiu, espindola
Reviewed By: ruiu
Subscribers: grimar, MaskRay, markj, emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D52430
llvm-svn: 343628
-z interpose sets the DF_1_INTERPOSE flag, marking the object as an
interposer.
Via FreeBSD PR 230604, linking Valgrind with lld failed.
Differential Revision: https://reviews.llvm.org/D52094
llvm-svn: 342239
--push-state implemented in this patch saves the states of --as-needed,
--whole-archive and --static. It saves less number of flags than GNU linkers.
Since even GNU linkers save different flags, no one seems to care about the
details. In this patch, I tried to save the minimal number of flags to not
complicate the implementation and the siutation.
I'm not personally happy about adding the --{push,pop}-state flags though.
That options seem too hacky to me. However, gcc started using the options
since GCC 8 when GNU ld is available at the build time. Therefore, lld
is no longer a drop-in replacmenet for GNU linker for that machine
without supporting the flags.
Fixes https://bugs.llvm.org/show_bug.cgi?id=34567
Differential Revision: https://reviews.llvm.org/D47542
llvm-svn: 333646
Also remove the space between --lto-O and value, as the option with a
space is not accepted at present.
Leave --opt-remarks-filename as it does not currently accept the = form.
llvm.org/pr36563
llvm-svn: 326536
The argument is section=address, not just address.
(For compatibility with GNU linkers we need to, but do not yet, accept
--section-start=section=address.)
llvm-svn: 326463
We intend to maintain compatibility with GNU ld, and in the GNU world
long options are conventionally specified as --long-option=value. For
whatever reason GNU ld.bfd accepts both --long-option value and
--long-option=value, but documents the former. Follow suit.
Some lld long options do not accept the = form; this is probably a bug
to be fixed (along with a man page update).
Reported by Ingo Schwarze, for --entry.
llvm-svn: 326459
Initial ld.lld.1 man page commit in r324512 crossed paths with r324502
which added --build-id=fast, allowing --build-id to be documented as a
synonym for --build-id=fast. Catch up with that change in the man page.
Differential Revision: https://reviews.llvm.org/D43039
llvm-svn: 324528
One of the FreeBSD requirements for enabling lld as the system linker is
that it has a man page. Other FreeBSD developers and I created one using
lld's --help output as a starting point. This is an expanded and
improved version of that.
This man page would benefit from additional content, but it provides
basic user-facing coverage of lld's options and serves as a good
starting point.
Differential Revision: https://reviews.llvm.org/D42963
llvm-svn: 324512
This linker backend is still a work in progress but is
enough to link simple programs including linking against
library archives.
Differential Revision: https://reviews.llvm.org/D34851
llvm-svn: 318539
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
New lld's files are spread under lib subdirectory, and it isn't easy
to find which files are actually maintained. This patch moves maintained
files to Common subdirectory.
Differential Revision: https://reviews.llvm.org/D37645
llvm-svn: 314719
The /appcontainer flag was added in r299728, and the lib.exe dependency
for creating import libraries was removed in r275242. Update the docs
accordingly.
The PDB support also needs updating, but I'll leave that for someone
who's more familiar with the current status (probably rnk).
llvm-svn: 307998
Looks like it is not allowed to have an .rst file in this directory
that does not belong to a document tree. I don't know why. This patch
adds a file back to fix a bot.
llvm-svn: 296087
This patch implements a new design for the symbol table that stores
SymbolBodies within a memory region of the Symbol object. Symbols are mutated
by constructing SymbolBodies in place over existing SymbolBodies, rather
than by mutating pointers. As mentioned in the initial proposal [1], this
memory layout helps reduce the cache miss rate by improving memory locality.
Performance numbers:
old(s) new(s)
Without debug info:
chrome 7.178 6.432 (-11.5%)
LLVMgold.so 0.505 0.502 (-0.5%)
clang 0.954 0.827 (-15.4%)
llvm-as 0.052 0.045 (-15.5%)
With debug info:
scylla 5.695 5.613 (-1.5%)
clang 14.396 14.143 (-1.8%)
Performance counter results show that the fewer required indirections is
indeed the cause of the improved performance. For example, when linking
chrome, stalled cycles decreases from 14,556,444,002 to 12,959,238,310, and
instructions per cycle increases from 0.78 to 0.83. We are also executing
many fewer instructions (15,516,401,933 down to 15,002,434,310), probably
because we spend less time allocating SymbolBodies.
The new mechanism by which symbols are added to the symbol table is by calling
add* functions on the SymbolTable.
In this patch, I handle local symbols by storing them inside "unparented"
SymbolBodies. This is suboptimal, but if we do want to try to avoid allocating
these SymbolBodies, we can probably do that separately.
I also removed a few members from the SymbolBody class that were only being
used to pass information from the input file to the symbol table.
This patch implements the new design for the ELF linker only. I intend to
prepare a similar patch for the COFF linker.
[1] http://lists.llvm.org/pipermail/llvm-dev/2016-April/098832.html
Differential Revision: http://reviews.llvm.org/D19752
llvm-svn: 268178
The Native file format was designed to be the fastest on-memory or
on-disk file format for object files. The problem is that no one
is working on that. No LLVM tools can produce object files in
the Native, thus the feature of supporting the format is useless
in the linker.
This patch removes the Native file support. We can add it back
if we really want it in future.
llvm-svn: 234641
Before this patch there was a cyclic dependency between lldCore and
lldReaderWriter. Only lldConfig could be built as a shared library.
* Moved Reader and Writer base classes into lldCore.
* The following shared libraries can now be built:
lldCore
lldYAML
lldNative
lldPasses
lldReaderWriter
Differential Revision: http://reviews.llvm.org/D7105
From: Greg Fitzgerald <garious@gmail.com>
llvm-svn: 226732
The code is able to statically link the simplest case of:
int main() { return 0; }
* Only works with ARM code - no Thumb code, no interwork (-marm -mno-thumb-interwork)
* musl libc built with no interwork and no Thumb code
Differential Revision: http://reviews.llvm.org/D6716
From: Denis Protivensky <dprotivensky@accesssoftek.com>
llvm-svn: 226643
The original commit had an issue with Mac OS dylib files. It didn't
handle fat binary dylib files correctly. This patch includes a fix.
A test for that case has already been committed in r225764.
llvm-svn: 226123
r225764 broke a basic functionality on Mac OS. This change reverts
r225764, r225766, r225767, r225769, r225814, r225816, r225829, and r225832.
llvm-svn: 225859
This patch adds the initial ELF/AArch64 support to lld. Only a basic "Hello
World" app has been successfully tested for both dynamic and static compiling.
Differential Revision: http://reviews.llvm.org/D4778
Patch by Daniel Stewart <stewartd@codeaurora.org>!
llvm-svn: 215544
``html_favicon`` seem to conflict with [what it in the sphinx
docs](http://sphinx-doc.org/config.html#confval-html_favicon).
So I've copied the comments from there to conf.py and changed its
value appropriately to remove the missing favicon.ico warning.
llvm-svn: 214971
Previously section groups are doubly linked to their children.
That is, an atom representing a group has group-child references
to its group contents, and content atoms also have group-parent
references to the group atom. That relationship was invariant;
if X has a group-child edge to Y, Y must have a group-parent
edge to X.
However we were not using group-parent references at all. The
resolver only needs group-child edges.
This patch simplifies the section group by removing the unused
reverse edge. No functionality change intended.
Differential Revision: http://reviews.llvm.org/D3945
llvm-svn: 210066
Also change some local variable names: "ti" -> "context" and
"_targetInfo" -> "_context".
Differential Revision: http://llvm-reviews.chandlerc.com/D1301
llvm-svn: 187823
The major changes are:
1) LinkerOptions has been merged into TargetInfo
2) LinkerInvocation has been merged into Driver
3) Drivers no longer convert arguments into an intermediate (core) argument
list, but instead create a TargetInfo object and call setter methods on
it. This is only how in-process linking would work. That is, you can
programmatically set up a TargetInfo object which controls the linking.
4) Lots of tweaks to test suite to work with driver changes
5) Add the DarwinDriver
6) I heavily doxygen commented TargetInfo.h
Things to do after this patch is committed:
a) Consider renaming TargetInfo, given its new roll.
b) Consider pulling the list of input files out of TargetInfo. This will
enable in-process clients to create one TargetInfo the re-use it with
different input file lists.
c) Work out a way for Drivers to format the warnings and error done in
core linking.
llvm-svn: 178776
now Reader and Writer subclasses for each file format. Each Reader and
Writer subclass defines an "options" class which controls how that Reader
or Writer operates.
llvm-svn: 157774
class. Change Resolver to no longer use Platform. Core linking
now issues errors directly. We need to factor that out later.
Rework how Darwin executable writer finds "main" atom. It now
adds to core linking an Atom which has a Reference to "main".
llvm-svn: 155060
Ed Maste