gold linker manual describes them as:
-z text Do not permit relocations in read-only segments
-z notext Permit relocations in read-only segments (default)
In LLD default is to not permit them. Patch implements -z notext.
Differential revision: https://reviews.llvm.org/D30530
llvm-svn: 297366
.eh_frame_hdr is a header constructed for .eh_frame sections.
We do not proccess .eh_frame when doing relocatable output,
so should not try to create .eh_frame_hdr too.
Previous behavior without this patch is segfault.
Fixes PR32118.
Differential revision: https://reviews.llvm.org/D30566
llvm-svn: 297365
Previously, if you have foo=bar in a definition file, this assertion
could fire because when symbols are read from file they could be mangled.
It seems that due to historical reasons underscore mangling scheme is
really ad-hoc, and I cannot find a clean way to handle this. I had
to just de-mangle symbols to search again.
llvm-svn: 297357
With this we have a single section hierarchy. It is a bit less code,
but the main advantage will be in a future patch being able to handle
foo = symbol_in_obj;
in a linker script. Currently that fails since we try to find the
output section of symbol_in_obj. With this we should be able to just
return an InputSection from the expression.
llvm-svn: 297313
This change moves the calls to finalizeContent() for each synthetic section
before createThunks(). This will allow us to assign addresses prior to
calling createThunks(). As addition of thunks may add to the static
symbol table and may affect the size of the mips got section we introduce a
couple of additional member functions to update these values.
Differential revision: https://reviews.llvm.org/D29983
llvm-svn: 297277
Some archive files created during chromium build contains both BC
and native files. If that's the case, we want to pass the archive
file to link.exe. Otherwise, the MSVC linker would complain that
there's an unresolved symbol in a given set of files.
I cannot explain why link.exe doesn't complain about the presence
of bitcode files in this case, but it seems link.exe doesn't touch BC.
llvm-svn: 297229
If /msvclto is specified, we compile bitcode files and pass it to the
MSVC linker, stripping all bitcode files. We haven't stripped archive
files, because I was thinking that the MSVC linker wouldn't touch files
in archive files. When we pass an object file to link.exe, all symbols
have been resolved already, so link.exe shoulnd't need any of the files
in archives.
It turns out that even though link.exe doesn't need to do that, it
seems to try to read each file in all archives. And if there's a non-
COFF file in an archive, it exists with an error message. So we need
to remove archives from the command line too.
llvm-svn: 297191
This change fixes a bug in which the Mips LA25 Thunks are always assigned
to the same Output section as the caller and not the callee as expected.
Differential Revision: https://reviews.llvm.org/D30637
llvm-svn: 297135
This puts us at parity with bfd, which could already gc this case.
I noticed the sections not being gced when linking a modified freebsd
kernel. A section that was not gced and not mentioned in the linker
script would end up breaking the expected layout. Since fixing the gc
is relatively simple and an improvement, that seems better than trying
to hack the orphan placement code.
There are 173 input section in the entire link whose names are valid C
identifiers, so this is probably not too performance critical.
llvm-svn: 297049
In compare with D30458, this makes Bss/BssRelRo to be pure
synthetic sections.
That removes CopyRelSection class completely, making
Bss/BssRelRo to be just regular synthetics.
SharedSymbols involved in creating copy relocations are
converted to DefinedRegular, what also simplifies things.
Differential revision: https://reviews.llvm.org/D30541
llvm-svn: 297008
Prior to MSVC 2015 we had to manually include this header any
time we were going to include <thread> or <future> due to a
bug in MSVC's STL implementation. This has been fixed in MSVC
for some time now, and we require VS 2015 minimum, so we can
remove this across all subprojects.
llvm-svn: 296906
After several smaller patches to get most of the core improvements
finished up, this patch is a straight move and header fixup of
the source.
Differential Revision: https://reviews.llvm.org/D30266
llvm-svn: 296810
We were not gcing any section whose name was a C identifier. Both gold
and bfd only keep those if they are used.
To avoid having to create the __start/__stop symbols early or doing
string lookups in resolvedReloc, this patch just looks for undefined
symbols __start/__stop to decide if a section is needed or not.
llvm-svn: 296723
This patch adds an option named --thinlto-cache-dir, which specifies the
path to a directory in which to cache native object files for ThinLTO
incremental builds.
Differential Revision: https://reviews.llvm.org/D30509
llvm-svn: 296702
That class had three member functions, and all of them are just reader
methods that did not depend on class members, so they can be just non-
member functions.
Probably we should reorganize the functions themselves because their
return types doesn't make much sense to me, but for now I just moved
these functions out of the class.
llvm-svn: 296700
Looks like .gdb.index and its support classes do things that they don't
have to or shouldn't do do. This patch addresses one of these issues.
GdbHashTab class is a hash table class. Just like other in-memory hash
tables, that incrementally updates its internal data and resizes buckets
as new elements are added so that key lookup is always fast.
But that is completely not necessary.
Unlike debuggers, we only produce hash tables for .gdb.index and
never read them. So incrementally updating a hash table in memory is
just a waste of resource and complicates the code. What we should
do is to accumulate symbols and then create the final hash table
at once.
llvm-svn: 296678
In many places we reset Size to 0 before calling assignOffsets()
manually. Sometimes we don't do that.
It looks we can just always do that inside.
Previous code had:
template <class ELFT> void OutputSection::assignOffsets() {
uint64_t Off = Size;
And tests feels fine with Off = 0.
I think Off = Size make no sence.
Differential revision: https://reviews.llvm.org/D30463
llvm-svn: 296609
This implementation is probably slightly inefficient than before,
but that should be negligible because this is not a performance-
critical pass.
llvm-svn: 296570
Previously, LLD merged all read-only sections. So the following
program prints out "true" if -icf=all is specified.
static const int foo = 1;
static const int bar = 1;
int main() { printf("%s\n", &foo == &bar ? "true" : "false"); }
This is somewhat counter-intuitive, and it actually caused nasty issues.
One example is https://bugs.chromium.org/p/chromium/issues/detail?id=682773#c24.
This patch changes the way how it works. Now ICF merges only functions
(i.e. executable sections).
Differential Revision: https://reviews.llvm.org/D30365
llvm-svn: 296534
I do not fully understand why we had these values in the tests, but
the new value matches what ld.bfd and ld.gold set, so I guess that
was just a mistake.
Differential Revision: https://reviews.llvm.org/D30441
llvm-svn: 296505
This reverts commit r296378.
I am pretty sure this is incorrect. In particular, for just
.cfi_startproc
nop
.cfi_endproc
We now add an extra 4 zeros that neither bfd nor gold add.
llvm-svn: 296503
There are many special cases and a layer of abstraction or two in the
way, but the VA calculation in the typical case is actually very simple
and probably makes perfect sense even to somebody new to linkers.
Also, this line brings together many components and is a good place to
start understanding the linker (or improve one's existing
understanding).
llvm-svn: 296451
Naively it seemed at first like getVA had the responsibility of adding
the addend, and getSymVA had the responsibility of getting the symbol
VA.
So it was not obvious to me at first why getVA passes Addend to
getSymVA. In fact, it passes it as a mutable reference.
It turns out that it only matters for SHF_MERGE sections, and in
particular only for STT_SECTION symbols that are used as a hack for
reducing the number of local symbols (e.g. to avoid a local symbol for
each string in the string table).
llvm-svn: 296448
In other places in LLD, we use write32<E> instead of Elf_Word.
This patch uses the same technique in the hash table classes.
The hash table classes needs improving as they have almost no
comments. We at least need to describe the hash table structure
and why we have to support two different on-disk hash tables
for the same purpose. I'll do that later.
llvm-svn: 296439
Previously, these two functions put their symbols in different queues.
Now that the queues have been merged. So there's no point to keep two
separate functions.
llvm-svn: 296435
That function doesn't use any member of SymbolTableSection, so I
couldn't see a reason to make it a member of that class. The function
takes a SymbolBody, so it is more natural to make it a member of
SymbolBody.
llvm-svn: 296433
Previously, there were three conditions: .symtab, .dynsym or we are
producing a relocatable output. Turned out that the third condition is
the same as the first one. This patch removes that third condition and
simplify code.
llvm-svn: 296431
We really need to find a way to get this info from a single point of
truth in the LLVM backend, but it seems that the EM_* constants are
buried deep inside the constructors of the MCAsmBackend's.
For now, just fill in entries as we run into cases. AFAIK these mappings
are largely immutable, so we get a 75% discount on the technical debt
(code is duplicated, but little chance of divergence).
llvm-svn: 296429
The previous code was a bit hard to understand because it unnecessarily
distinguished local and non-local symbols. It had NumLocals member
variable, but that variable didn't have a number of local symbols but
had some value that I cannot describe easily.
This patch rewrites SynbolTableSection::finalizeContents and
SymbolTableSection::writeTo to make it easy to understand. NumLocals
member variable has been removed, and writeGlobalSymbols and
writeLocalSymbols have been merged into one function.
There's still a piece of code that I think unnecessary. I'm not removing
that code in this patch, but will do in a follow-up patch.
llvm-svn: 296423
Before the endianness was specified on each call to read
or write of the StreamReader / StreamWriter, but in practice
it's extremely rare for streams to have data encoded in
multiple different endiannesses, so we should optimize for the
99% use case.
This makes the code cleaner and more general, but otherwise
has NFC.
llvm-svn: 296415
This part of code is hard to understand because NumLocals does not
actually mean the number of local symbols but something else (!).
We need to rewrite. But before that we need to clean it up.
llvm-svn: 296400
This was reverted because it was breaking some builds, and
because of incorrect error code usage. Since the CL was
large and contained many different things, I'm resubmitting
it in pieces.
This portion is NFC, and consists of:
1) Renaming classes to follow a consistent naming convention.
2) Fixing the const-ness of the interface methods.
3) Adding detailed doxygen comments.
4) Fixing a few instances of passing `const BinaryStream& X`. These
are now passed as `BinaryStreamRef X`.
llvm-svn: 296394
Patch by Mark Kettenis.
Currenlty ld.lld does not add a terminator (a CIE with its length field
set to zero) to the .eh_frame sections it generates. While the relevant
standards (the AMD64 SysV ABI and the Linux LSB) are not explicit about
this, such a terminator is expected by some unwinder implementations and
seems to be always emitted by ld.bfd. In addition to that, the Linux LSB
https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html#EHFRAME
explicitly says that
The .eh_frame section shall contain 1 or more Call Frame Information
(CFI) records.
Currently, if the .eh_frame sections of the input files only contain
terminators, ld.lld emits a zero=sized .eh_frame section
which clearly doesn't meet that requirement.
The diff makes sure a terminator gets added to each .eh_frame section
and adjusts all the relevant tests to account for that. An additional
test isn't needed as these adjustments mean that the existence of the
terminator is tested for by several tests already.
Differential Revision: https://reviews.llvm.org/D30335
llvm-svn: 296378
The list of all input sections was defined in SymbolTable class for a
historical reason. The list itself is not a template. However, because
SymbolTable class is a template, we needed to pass around ELFT to access
the list. This patch moves the list out of the class so that it doesn't
need ELFT.
llvm-svn: 296309
r296215, "[PDB] General improvements to Stream library."
r296217, "Disable BinaryStreamTest.StreamReaderObject temporarily."
r296220, "Re-enable BinaryStreamTest.StreamReaderObject."
r296244, "[PDB] Disable some tests that are breaking bots."
r296249, "Add static_cast to silence -Wc++11-narrowing."
std::errc::no_buffer_space should be used for OS-oriented errors for socket transmission.
(Seek discussions around llvm/xray.)
I could substitute s/no_buffer_space/others/g, but I revert whole them ATM.
Could we define and use LLVM errors there?
llvm-svn: 296258
This adds various new functionality and cleanup surrounding the
use of the Stream library. Major changes include:
* Renaming of all classes for more consistency / meaningfulness
* Addition of some new methods for reading multiple values at once.
* Full suite of unit tests for reader / writer functionality.
* Full set of doxygen comments for all classes.
* Streams now store their own endianness.
* Fixed some bugs in a few of the classes that were discovered
by the unit tests.
llvm-svn: 296215
This is part of a larger effort to get the Stream code moved
up to Support. I don't want to do it in one large patch, in
part because the changes are so big that it will treat everything
as file deletions and add, losing history in the process.
Aside from that though, it's just a good idea in general to
make small changes.
So this change only changes the names of the Stream related
source files, and applies necessary source fix ups.
llvm-svn: 296211
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
__ehdr_start should be pointing to ELF file headers, not program
headers.
This is a reland of D30319.
Differential Revision: https://reviews.llvm.org/D30323
llvm-svn: 296085
Summary: Creates bitcode files suitable for use with ThinLTO, then checks that the linker can build an executable from them.
Reviewers: ruiu, pcc
Reviewed By: pcc
Subscribers: mehdi_amini, Prazek, llvm-commits
Differential Revision: https://reviews.llvm.org/D30277
llvm-svn: 296042
With this we complete the transition out of special output sections,
and with the previous patches it should be possible to merge
OutputSectionBase and OuputSection.
llvm-svn: 296023
With the current design an InputSection is basically anything that
goes directly in a OutputSection. That includes plain input section
but also synthetic sections, so this should probably not be a
template.
llvm-svn: 295993
For functions the linker uses a related hack: creating a plt in the
main executable that preempts the function.
Like bfd and gold, we don't disable it with nocopyreloc.
llvm-svn: 295976
We have InputSection, MergeInputSection and EhInputSection, so
isa<MergeInputSection> is equivalent to !isa<InputSection> && !isa<
EhInputSection>.
llvm-svn: 295937
George Rimar