Previously, in r320472, I moved the calculation of section offsets and sizes
for compressed debug sections into maybeCompress, which happens before
assignAddresses, so that the compression had the required information. However,
I failed to take account of relocations that patch such sections. This had two
effects:
1. A race condition existed when a debug section referred to a different debug
section (see PR35788).
2. References to symbols in non-debug sections would be patched incorrectly.
This is because the addresses of such symbols are not calculated until after
assignAddresses (this was a partial regression caused by r320472, but they
could still have been broken before, in the event that a custom layout was used
in a linker script).
assignAddresses does not need to know about the output section size of
non-allocatable sections, because they do not affect the value of Dot. This
means that there is no longer a reason not to support custom layout of
compressed debug sections, as far as I'm aware. These two points allow for
delaying when maybeCompress can be called, removing the need for the loop I
previously added to calculate the section size, and therefore the race
condition. Furthermore, by delaying, we fix the issues of relocations getting
incorrect symbol values, because they have now all been finalized.
llvm-svn: 321986
Moving the SHF_LINK_ORDER processing out of OutputSection::finalize()
means that we no longer need to copy all InputSections as we now only need
the first one.
Differential Revision: https://reviews.llvm.org/D40966
llvm-svn: 320478
By moving this step before thunk creation and other processing that depends
on the size of sections, we permit removal of duplicates in the .ARM.exidx
section.
Differential Revision: https://reviews.llvm.org/D40964
llvm-svn: 320477
The size of an OutputSection is calculated early, to aid handling of compressed
debug sections. However, subsequent to this point, unused synthetic sections are
removed. In the event that an OutputSection, from which such an InputSection is
removed, is still required (e.g. because it has a symbol assignment), and no longer
has any InputSections, dot assignments, or BYTE()-family directives, the size
member is never updated when processing the commands. If the removed InputSection
had a non-zero size (such as a .got.plt section), the section ends up with the
wrong size in the output.
The fix is to reset the OutputSection size prior to processing the linker script
commands relating to that OutputSection. This ensures that the size is correct even
in the above situation.
Additionally, to reduce the risk of developers misusing OutputSection Size and
InputSection OutSecOff, they are set to simply the number of InputSections in an
OutputSection, and the corresponding index respectively. We cannot completely
stop using them, due to SHF_LINK_ORDER sections requiring them.
Compressed debug sections also require the full size. This is now calculated in
maybeCompress for these kinds of sections.
Reviewers: ruiu, rafael
Differential Revision: https://reviews.llvm.org/D38361
llvm-svn: 320472
When an output section has no byte commands and has no input sections then it
would be ideal if the type of the section is SHT_NOBITS so that the file can
take up less space. This change sets the default type of of output sections to
SHT_NOBITS instead of SHT_PROGBITS to allow this. This required some minor test
changes (which double as tests for this new behavior) but extend-pt-load.s had
be changed in a non-trivial way. Since it seems to me that the point of the
test is to point out the consequences of how flags are assigned to output
sections that don't have input sections I changed the test to work and still
show how the memsize of the executable segment was changed.
Differential Revision: https://reviews.llvm.org/D41082
llvm-svn: 320437
An output section can include elements from two input sections with
different sh_entsize. When that happens the output section itself
should not have a sh_entsize.
llvm-svn: 318311
That class is used only by LinkerScript.cpp, so we should move it to
that file. Also, it no longer has to be a "factory" class. It can just
be a non-member function.
llvm-svn: 317427
Stop using SectionKey for creating output sections.
Initially SectionKey was designed because we merged section with
use of Flags and Alignment fields. Currently LLD merges them by name only,
except the case when -relocatable output is produced. In that case
we still merge sections only with the same flags and alignment.
There is probably no issue at all to stop using Flags and Alignment for -r and
just disable the merging in that case.
After doing that change we can get rid of using SectionKey. That is not only
simplifies the code, but also gives some perfomance boost.
I tried to link chrome and mozilla, results are next:
* chrome link time goes from 1,666750355s to 1,551585364s, that is about 7%.
* mozilla time changes from 3,210261947 to 3,153782940, or about 2%.
Differential revision: https://reviews.llvm.org/D39594
llvm-svn: 317406
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
It does not seem that createSections() is a good place for
applying sorting. Patch changes code to do that inside
sortSections(), which looks more appropriate place.
Differential revision: https://reviews.llvm.org/D39371
llvm-svn: 316893
This moves reporting of garbage collected sections right after
we do GC. That simplifies things.
Differential revision: https://reviews.llvm.org/D39058
llvm-svn: 316759
Summary:
This will allow using the functionality from other linkers. It is also
a prerequisite for sharing the error logging code.
Reviewers: ruiu
Reviewed By: ruiu
Subscribers: emaste, mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D38822
llvm-svn: 315725
"Commands" was ambiguous because in the linker script, everything is
a command. We used to handle only SECTIONS commands, and at the time,
it might make sense to call them the commands, but it is no longer
the case. We handle not only SECTIONS but also MEMORY, PHDRS, VERSION,
etc., and they are all commands.
llvm-svn: 315409
Previously, when we added an input section to an output section, we
called `OutputSectionFactory::addInputSec`. This isn't a good design
because, a factory class is intended to create a new object and
return it, but in this use case, it will never create a new object.
This patch fixes the design flaw.
llvm-svn: 315138
Factory::addInputSec added an output section to Script->Opt.Commands,
but that is too subtle. This patch makes it explicit so that it is easy
to see when a new element is added to Script->Opt.Commands.
llvm-svn: 315129
addSection function was hard to read because it behaves differently
depending on its arguments but what exactly it does is not clear.
Now it should be better. Still, it is not clear (not what but) why
it does what it does, but I'll take a look at it later.
llvm-svn: 315124
This is PR34506.
Imagine we have 2 sections the same name but different COMDAT groups:
.section .foo,"axG",@progbits,bar,comdat
.section .foo,"axG",@progbits,zed,comdat
When linking relocatable we do not merge SHT_GROUP sections. But still would merge
both input sections .foo into single output section .foo.
As a result we will have 2 different SHT_GROUPs containing the same section, what
is wrong.
Patch fixes the issue, preventing merging SHF_GROUP sections with any others.
Differential revision: https://reviews.llvm.org/D37574
llvm-svn: 313621
Patch removes one of OutputSectionFactory::addInputSec methods.
That allows to simplify reporting of discarded sections and
should help to D37561.
Differential revision: https://reviews.llvm.org/D37735
llvm-svn: 313361
This is PR33889,
Patch adds support of combination of linkerscript and
-symbol-ordering-file option.
If no sorting commands are present in script inside section declaration
and no --sort-section option specified, code uses sorting from ordering
file if any exist.
Differential revision: https://reviews.llvm.org/D35843
llvm-svn: 310045
This is a bit of a hack, but it is *so* convenient.
Now that we create synthetic linker scripts when none is provided, we
always have to handle paired OutputSection and OutputsectionCommand and
keep a mapping from one to the other.
This patch simplifies things by merging them and creating what used to
be OutputSectionCommands really early.
llvm-svn: 309311
SHF_GROUP bit doesn't make sense in executables or DSOs, so linkers are
expected to remove that bit from section flags. We did that when we create
output sections.
This patch is to do that earlier than before. Now the flag is dropped when
we instantiate input section objects.
This change improves ICF. Previously, two sections that differ only in
SHF_GROUP flag were not merged, because when the control reached ICF,
the flag was still there. Now the flag is dropped before reaching to ICF,
so the difference is ignored naturally.
This issue was found by pcc.
Differential Revision: https://reviews.llvm.org/D34074
llvm-svn: 305134
Previously we would merge relocation sections by name.
That did not work in some cases, like testcase shows.
Patch implements logic to merge relocation sections if their target
sections were merged into the same output section.
Differential revision: https://reviews.llvm.org/D33824
llvm-svn: 304886
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.
Differential Revision: https://reviews.llvm.org/D33843
llvm-svn: 304864
Previously LLD would fail for case when there are multiple comdats and -r.
That happened because it merged all ".group" (SHT_GROUP) sections into single
output, producing broken result. Such sections may have similar name, alignment and flags
and other properties. We need to produce separate output section for each such input one.
Differential revision: https://reviews.llvm.org/D33643
llvm-svn: 304769
This change alters the sorting for OutputSections with the SHF_LINK_ORDER
flag in OutputSection::finalize() to use the InputSectionDescription
representation and not the OutputSection::Sections representation.
Differential revision: https://reviews.llvm.org/D33772
llvm-svn: 304700
Rafael Espindola