Separate output sections for selected text section prefixes to enable TLB optimizations and for readablilty.
Differential Revision: https://reviews.llvm.org/D45841
llvm-svn: 331823
Our promise is that as long as there's no fatal error (i.e. broken
file is given to the linker), our main function returns to the caller.
So we can't use exit() in the regular code path.
Differential Revision: https://reviews.llvm.org/D46442
llvm-svn: 331690
Android AOSP has started specifying -m aarch64_elf64_le_vec as supported
by gold and BFD. This is a simple change to add the emulation so that LLD
doesn't immediately error when used as a linker in an AOSP build.
Differential Revision: https://reviews.llvm.org/D46429
llvm-svn: 331521
Now that getSectionPiece is fast (uses a hash) it is probably OK to
split merge sections early.
The reason I want to do this is to split eh_frame sections in the same
place.
This does mean that we have to decompress early. Given that the only
compressed sections are debug info, I don't think we are missing much.
It is a small improvement: 0.5% on the geometric mean.
llvm-svn: 331058
The fix is to copy Used when replacing the symbol.
Original message:
Do not keep shared symbols created from garbage-collected eliminated DSOs.
If all references to a DSO happen to be weak, and if the DSO is
specified with --as-needed, the DSO is not added to DT_NEEDED.
If that happens, we also need to eliminate shared symbols created
from the DSO. Otherwise, they become dangling references that point
to non-exsitent DSO.
Fixes https://bugs.llvm.org/show_bug.cgi?id=36991
Differential Revision: https://reviews.llvm.org/D45536
llvm-svn: 330788
This is causing large numbers of Chromium test executables to crash on
shutdown. The relevant symbol seems to be __cxa_finalize, which gets
removed from the dynamic symbol table for some of the support libraries.
llvm-svn: 330164
If all references to a DSO happen to be weak, and if the DSO is
specified with --as-needed, the DSO is not added to DT_NEEDED.
If that happens, we also need to eliminate shared symbols created
from the DSO. Otherwise, they become dangling references that point
to non-exsitent DSO.
Fixes https://bugs.llvm.org/show_bug.cgi?id=36991
Differential Revision: https://reviews.llvm.org/D45536
llvm-svn: 329960
I'm proposing a new command line flag, --warn-backrefs in this patch.
The flag and the feature proposed below don't exist in GNU linkers
nor the current lld.
--warn-backrefs is an option to detect reverse or cyclic dependencies
between static archives, and it can be used to keep your program
compatible with GNU linkers after you switch to lld. I'll explain the
feature and why you may find it useful below.
lld's symbol resolution semantics is more relaxed than traditional
Unix linkers. Therefore,
ld.lld foo.a bar.o
succeeds even if bar.o contains an undefined symbol that have to be
resolved by some object file in foo.a. Traditional Unix linkers
don't allow this kind of backward reference, as they visit each
file only once from left to right in the command line while
resolving all undefined symbol at the moment of visiting.
In the above case, since there's no undefined symbol when a linker
visits foo.a, no files are pulled out from foo.a, and because the
linker forgets about foo.a after visiting, it can't resolve
undefined symbols that could have been resolved otherwise.
That lld accepts more relaxed form means (besides it makes more
sense) that you can accidentally write a command line or a build
file that works only with lld, even if you have a plan to
distribute it to wider users who may be using GNU linkers. With
--check-library-dependency, you can detect a library order that
doesn't work with other Unix linkers.
The option is also useful to detect cyclic dependencies between
static archives. Again, lld accepts
ld.lld foo.a bar.a
even if foo.a and bar.a depend on each other. With --warn-backrefs
it is handled as an error.
Here is how the option works. We assign a group ID to each file. A
file with a smaller group ID can pull out object files from an
archive file with an equal or greater group ID. Otherwise, it is a
reverse dependency and an error.
A file outside --{start,end}-group gets a fresh ID when
instantiated. All files within the same --{start,end}-group get the
same group ID. E.g.
ld.lld A B --start-group C D --end-group E
A and B form group 0, C, D and their member object files form group
1, and E forms group 2. I think that you can see how this group
assignment rule simulates the traditional linker's semantics.
Differential Revision: https://reviews.llvm.org/D45195
llvm-svn: 329636
I tried a few different designs to find a way to implement it without
too much hassle and settled down with this. Unlike before, object files
given as arguments for --just-symbols are handled as object files, with
an exception that their section tables are handled as if they were all
null.
Differential Revision: https://reviews.llvm.org/D42025
llvm-svn: 328852
This is an option to print out a table of symbols and filenames.
The output format of this option is the same as GNU, so that it can be
processed by the same scripts as before after migrating from GNU to lld.
This option is mildly useful; we can live without it. But it is pretty
convenient sometimes, and it can be implemented in 50 lines of code, so
I think lld should support this option.
Differential Revision: https://reviews.llvm.org/D44336
llvm-svn: 327565
This implements INSERT AFTER in a following way:
During reading scripts it collects all insert statements.
After we done and read all files it inserts statements into script commands list.
With that:
* Rest of code does know nothing about INSERT.
* Approach is straightforward and have no visible limitations.
* It is also easy to support INSERT BEFORE (was seen in clang code once).
* Should work for PR35877 and similar cases.
Cons:
* It assumes we have "main" scripts that describes sections.
Differential revision: https://reviews.llvm.org/D43468
llvm-svn: 327003
GNU linkers by convention supports both `--foo bar` and `--foo=bar` styles
for all long options that take arguments.
Differential Revision: https://reviews.llvm.org/D43972
llvm-svn: 326506
This should resolve the issue that lld build fails in some hosts
that uses case-insensitive file system.
Differential Revision: https://reviews.llvm.org/D43788
llvm-svn: 326339
It should be possible to resolve undefined symbols in dynamic libraries
using symbols defined in a linker script.
Differential Revision: https://reviews.llvm.org/D43011
llvm-svn: 326176
This patch provides migitation for CVE-2017-5715, Spectre variant two,
which affects the P5600 and P6600. It implements the LLD part of
-z hazardplt. Like the Clang part of this patch, I have opted for that
specific option name in case alternative migitation methods are required
in the future.
The mitigation strategy suggested by MIPS for these processors is to use
hazard barrier instructions. 'jalr.hb' and 'jr.hb' are hazard
barrier variants of the 'jalr' and 'jr' instructions respectively.
These instructions impede the execution of instruction stream until
architecturally defined hazards (changes to the instruction stream,
privileged registers which may affect execution) are cleared. These
instructions in MIPS' designs are not speculated past.
These instructions are defined by the MIPS32R2 ISA, so this mitigation
method is not compatible with processors which implement an earlier
revision of the MIPS ISA.
For LLD, this changes PLT stubs to use 'jalr.hb' and 'jr.hb'.
Reviewers: atanasyan, ruiu
Differential Revision: https://reviews.llvm.org/D43488
llvm-svn: 325647
Previously wasm used a separate header to declare markLive
and ELF used to declare ICF. This change makes each backend
consistently declare these in their own headers.
Differential Revision: https://reviews.llvm.org/D43529
llvm-svn: 325631
We are running lld tests with "--full-shutdown" option because we don't
want to call _exit() in lld if it is running tests. Regular shutdown
is needed for leak sanitizer.
This patch changes the way how we tell lld that it is running tests.
Now "--full-shutdown" is removed, and LLD_IN_TEST environment variable
is used instead.
This patch enables full shutdown on all ports, e.g. ELF, COFF and wasm.
Previously, we enabled it only for ELF.
Differential Revision: https://reviews.llvm.org/D43410
llvm-svn: 325413
There seems to be no reason to collect this list of symbols.
Also fix a bug where --exclude-libs would apply to all symbols that
appear in an archive's symbol table, even if the relevant archive
member was not added to the link.
Differential Revision: https://reviews.llvm.org/D43369
llvm-svn: 325380
Summary:
This follows up on r321889 where writing of Elf_Rel addends was partially
moved to RelocationBaseSection. This patch ensures that the addends are
always written to the output section when a input section uses RELA but the
output is REL.
Differential Revision: https://reviews.llvm.org/D42843
llvm-svn: 325328
When we are emitting a relocatable output, we should keep the original
symbol name including "@" part. Previously, we drop that part unconditionally
which resulted in dropping versions from symbols.
Differential Revision: https://reviews.llvm.org/D43307
llvm-svn: 325204
This patch addresses a minor compatibility issue with GNU linkers.
Previously, --export-dynamic-symbol is completely ignored if you
pass --export-dynamic together.
Differential Revision: https://reviews.llvm.org/D43266
llvm-svn: 325152
There are a number of different situations when symbols are requested
to be ordered in the --symbol-ordering-file that cannot be ordered for
some reason. To assist with identifying these symbols, and either
tidying up the order file, or the inputs, a number of warnings have
been added. As some users may find these warnings unhelpful, due to how
they use the symbol ordering file, a switch has also been added to
disable these warnings.
The cases where we now warn are:
* Entries in the order file that don't correspond to any symbol in the input
* Undefined symbols
* Absolute symbols
* Symbols imported from shared objects
* Symbols that are discarded, due to e.g. --gc-sections or /DISCARD/ linker script sections
* Multiple of the same entry in the order file
Reviewed by: rafael, ruiu
Differential Revision: https://reviews.llvm.org/D42475
llvm-svn: 325125
This is for compatiblity with GNU gold. GNU gold tries to resolve
symbols specified by --export-dynamic-symbol. So, if a symbol specified
by --export-dynamic-symbol is in an archive file, lld's result is
currently different from gold's.
Interestingly, that behavior is different for --dynamic-list.
I added a new test to ensure that.
Differential Revision: https://reviews.llvm.org/D43103
llvm-svn: 324752
When you omit an argument, most options fall back to their defaults.
For example, --color-diagnostics is a synonym for --color-diagnostics=auto.
We don't have a way to specify the default choice for --build-id, so we
can't describe --build-id (without an argument) in that way.
This patch adds "fast" for the default build-id choice.
Differential Revision: https://reviews.llvm.org/D43032
llvm-svn: 324502
Previously we ignored -plugin-opt=mcpu=<xxx>
and the only way to set CPU string was to pass
-mllvm -mcpu=<xxx>
Though clang may pass it with use of plugin options:
-plugin-opt=mcpu=x86-64
Since we are trying to be compatible in command line
with gold plugin, seems we should support it too.
Differential revision: https://reviews.llvm.org/D42956
llvm-svn: 324459
Sriraman Tallam