Previously the alignment of the .bss section was not
properly set because of a bug in AtomizeDefinedSymbolsInSection.
We set the alignment of the section at the end of the function,
but we use an eraly return for the .bss section, so the code had
been skipped.
llvm-svn: 212571
This converts the very complicated mach-o arm
relocations into the simple Reference Kinds in lld.
The next patch will use the internal Reference kinds
to fix up arm/thumb code.
llvm-svn: 212306
Unfortunately, the creation of (the default) output file, a.out races with all
the other tests in this directory. When the wrong one is read by macho-dump,
the test fails.
llvm-svn: 212269
When trying to map atom types to sections, we were iterating through an array
until we hit a sentinel value. There's no need for such dances when range-based
for loops are available.
llvm-svn: 212035
This isn't really the right place to put them in final object files (that would
be __TEXT,__unwind_info), but the format is different between relocatable and
final objects, which means we really need a pass to handle the translation.
For now, re-emitting in __LD,__compact_unwind is harmless (dyld ignores it and
moves straight on to inspecting __TEXT,__eh_frame), and sidesteps an assertion
failure when processing files containing compact-unwind info.
llvm-svn: 212032
Segments must occupy a multiple of the page size in memory (4096 currently). We
check for this when emitting files, but the placement algorithm broke down for
the second non-__TEXT segment encountered: the offset wasn't aligned up to 4096
before starting its layout.
llvm-svn: 212031
Because of how we were calculating fileOffset and fileSize for segments, most
ended up at a single offset in a finalised MachO file. This meant the data
often didn't even get written in the final object, let alone where it would be
useful.
llvm-svn: 212030
This is first step in reworking how mach-o relocations are processed.
The existing KindHandler is going to become a delgate/helper object for
processing architecture specific references. The KindHandler knows how
to convert mach-o relocations into References and back, as well, as fixing
up the content the relocation is on.
One of the messy things about mach-o relocations is that they sometime
come in pairs, but the pairs still convert to one lld::Reference. So, the
conversion has to detect pairs (arch specific) and change the stride.
llvm-svn: 211921
The previous function returned true for "s < s", which could completely mess up
the sorting of symbols within a section.
Unfortunately, I don't think there's a robust way to write a test for this.
Anything I come up with will be making assumptions about the particular
implementation of std::sort.
llvm-svn: 211704
When looking through sections with zero-terminated string-literals (__cstring
or __ustring) we were constantly rechecking the first few bytes of the string
for '\0' rather than advancing along. This obviously failed unless all strings
within the section had the same length as that first one.
llvm-svn: 211682
We were trying to examine the first symbol in a section that we wanted to
atomize by symbols, even when there wasn't one. Instead, we should make the
initial anonymous symbol cover the entire section in that situation.
llvm-svn: 211681
dynamic symbol table populating and DT_NEEDED tag creation.
The `isDynSymEntryRequired` function returns true if the specified shared
library atom requires a dynamic symbol table entry. The `isNeededTagRequired`
function returns true if we need to create DT_NEEDED tag for the shared
library defined specified shared atom.
By default the both functions return true. So there is no functional changes
for all targets except MIPS. Probably we need to spread the same modifications
on other ELF targets but I want to implement and fully tested complete set of
changes for MIPS target first.
For MIPS we create a dynamic symbol table entry for a shared library atom iif
this atom is referenced by a regular defined atom. For example, if library L1
defines symbol T1, library L2 defines symbol T2 and uses symbol T1
and executable file E1 uses symbol T2 but does not use symbol T1 we create
an entry in the E1 dynamic symbol table for symbol T2 and do not create
an entry for T1.
The patch creates DT_NEEDED tags for shared libraries contain shared library
atoms which a) referenced by regular defined atoms; b) have corresponding
copy dynamic relocations (R_MIPS_COPY).
Now the patch does not take in account --as-needed / --no-as-needed command
line options. So it is too restrictive and create DT_NEEDED tags for really
needed shared libraries only. I plan to fix that by subsequent patches.
llvm-svn: 211674
COFF supports a feature similar to ELF's section groups. This
patch implements it.
In ELF, section groups are identified by their names, and they are
treated somewhat differently from regular symbols. In COFF, the
feature is realized in a more straightforward way. A section can
have an annotation saying "if Nth section is linked, link this
section too."
I added a new reference type, kindAssociate. If a target atom is
coalesced away, the referring atom is removed by Resolver, so that
they are treated as a group.
Differential Revision: http://reviews.llvm.org/D4028
llvm-svn: 211106
This code was never being used and any use of it would look fairly strange.
For example, it would try to map a NativeReaderError::file_malformed to
std::errc::invalid_argument.
llvm-svn: 210913
The previous commit uncovered a bug in the mach-o writer whereby two __text
sections were created. But the test case did not catch that. So I updated
the test case to run the linker a second time, reading the output of the
first pass.
llvm-svn: 210624
isCoalescedAway(x) is faster than replacement(x) != x as the former
does not follow the replacement atom chain. Also it's easier to use.
llvm-svn: 210242
COFF supports a feature similar to ELF's section groups. This
patch implements it.
In ELF, section groups are identified by their names, and they are
treated somewhat differently from regular symbols. In COFF, the
feature is realized in a more straightforward way. A section can
have an annotation saying "if Nth section is linked, link this
section too."
Implementing such feature is easy. We can add a reference from a
target atom to an original atom, so that if the target is linked,
the original atom is also linked. If not linked, both will be
dead-stripped. So they are treated as a group.
I added a new reference type, kindAssociate. It does nothing except
preventing referenced atoms from being dead-stripped.
No change to the Resolver is needed.
Reviewers: Bigcheese, shankarke, atanasyan
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D3946
llvm-svn: 210240
This provides support for the autoconfing & make build style.
The format, style and implementation follows that used within the llvm and clang projects.
TODO: implement out-of-source documentation builds.
llvm-svn: 210177
Previously FileArchive ctor comment said that only its subclasses
can be instantiated, but the ctor is actually public and is
instantiated by ArchiveReader.
Remove the wrong comment and reorder the member functions so that
public members appear before private ones.
llvm-svn: 210175
In sections that are broken into atoms at symbols, if the first symbol in the
section is not at the start of the section, then make an anonymous atom for
the section content that is before the first symbol.
llvm-svn: 210142
Previously each section kind had its own code to loop over the section and
parse it into atoms. This refactoring has two tables. The first maps sections
to ContentType. The second maps ContentType to information on how to find
the atom boundaries.
A few bugs in test cases were discovered as part of the refactoring.
No change in functionality intended.
llvm-svn: 210138
FileToMutable is what this class does, but this class (or, to be precise,
an instance of this class) is a wrapper of the other SimpleFile. It's odd
that the class was named like a function.
llvm-svn: 210089
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
Layout-before edges are no longer used for layout, but they are
still there for dead-stripping. If we would just remove them
from code, LLD would wrongly remove live atoms that were
referenced by layout-befores.
This patch fixes the issue. Before dead-stripping, it scans all
atoms to construct a reverse map for layout-after edges. Dead-
stripping pass uses the map to traverse the graph.
Differential Revision: http://reviews.llvm.org/D3986
llvm-svn: 210057
Reference::target() never returns a nullptr, so NULL check
is not needed and is more harmful than doing nothing.
No functionality change.
llvm-svn: 210008
Arrange .ctors/.dtors sections in the following order:
.ctors from crtbegin.o or crtbegin?.o
.ctors from regular object files
.ctors.* (sorted) from regular object files
.ctors from crtend.o or crtend?.o
This order is specific for MIPS traget. For example, on X86
the .ctors.* sections are merged into the .init_array section.
llvm-svn: 209987
The main problem is in the predicate passed to the `std::stable_sort()`.
This predicate always returns false if **both** section's names do not
start with `.init_array` or `.fini_array` prefixes. In short, it does not
define a strict weak orderng. Suppose we have the following sections:
.A .init_array.1 .init_array.2
The predicate states that:
not .init_array.1 < .A
not .A < .init_array.2
but .init_array.1 < .init_array.2 !!!
The second problem is that `.init_array` section without number should
go last in the list. Not it has the lowest priority '0' and goes first.
The patch fixes both of the problems.
llvm-svn: 209875
This is a short-term fix to allow lld Readers to return error messages
with dynamic content.
The long term fix will be to enhance ErrorOr<> to work with errors other
than error_code. Or to change the interface to Readers to pass down a
diagnostics object through which all error messages are written.
llvm-svn: 209681
/alternatename is a command line option to define a weak alias. You
can use it as /alternatename:foo=bar to define "foo" as a weak alias
for "bar".
Because it's a command line option, the weak alias mapping is in the
LinkingContext object, and not in a object file being read.
Previously, we looked up the mapping each time we read a new symbol
from a file, to check if there is a weak alias defined for the symbol.
That's not wrong, but had made function signature's a bit complicated --
we had to pass the mapping object to many functions. Now their
parameter lists are much cleaner.
This also has another (unrealized) benefit. parseFile() now read a
file and then add alias symbols to the file. In the first pass a
LinkingContext object is not used at all. That should make it easy
to read files from archive files speculatively, as the first pass
is free from side effect.
llvm-svn: 209486
Alias symbols are SimpleDefinedAtoms and are platform neutral. They
don't have to belong ELF. This patch is to make it available to all
platforms. No functionality change intended.
Differential Revision: http://reviews.llvm.org/D3862
llvm-svn: 209475
addResolvableSymbols() queues input files, and readAllSymbols() reads
from them. In practice it's currently safe because they are called from
a single thread. But it's not guaranteed.
Also, acquiring the same mutex is needed not to see inconsistent memory
contents that is allowed in the C++ memory model.
llvm-svn: 209254
ExportedSymbolRenameFile is not always used. In most cases we don't
need to read given files at all. So lazy load would help. This doesn't
change the meaining of the program.
llvm-svn: 208818
In r205566, I made a change to Resolver so that Resolver revisit
only archive files in --start-group and --end-group pair. That's
not correct, as it also has to revisit DSO files.
This patch is to fix the issue.
Added a test to demonstrate the fix. I confirmed that it succeeded
before r205566, failed after r205566, and is ok with this patch.
Differential Revision: http://reviews.llvm.org/D3734
llvm-svn: 208797
As written in the comment in this patch, symbol names specified with
/export option is resolved in a special way; for /export:foo, linker
finds a foo@<number> symbol if such symbols exists.
On Windows, a function in stdcall calling convention is mangled with
a leading underscore and following "@" and numbers. This name
mangling is kind of automatic, so you can sometimes omit _ and @number
when specifying a symbol. /export option is that case.
Previously, if a file in an archive file foo.lib provides a symbol
_fn@8, and /export:fn is specified, LLD failed to resolve the symbol.
It only tried to find _fn, and failed to find _fn@8. With this patch,
_fn@8 will be searched on the second iteration.
Differential Revision: http://reviews.llvm.org/D3736
llvm-svn: 208754
Make it possible to add observers to an Input Graph, so that files
returned from an Input Graph can be examined before they are
passed to Resolver.
To implement some PE/COFF features we need to know all the symbols
that *can* be solved, including ones in archive files that are not
yet to be read.
Currently, Resolver only maintains a set of symbols that are
already read. It has no knowledge on symbols in skipped files in
an archive file.
There are many ways to implement that. I chose to apply the
observer pattern here because it seems most non-intrusive. We don't
want to mess up Resolver with architecture specific features.
Even in PE/COFF, the feature that needs this mechanism is minor.
So I chose not to modify Resolver, but add a hook to Input Graph.
Differential Revision: http://reviews.llvm.org/D3735
llvm-svn: 208753
If one or more dynamic relocation might modify a read-only section,
dynamic table should contain DT_TEXTREL tag.
The patch introduces new `RelocationTable::canModifyReadonlySection()`
method. This method checks through the relocations to see if any modifies
a read-only section. The DynamicTable class calls this method and emits
the DT_TEXTREL tag if necessary.
The patch reviewed by Rui Ueyama and Shankar Easwaran.
llvm-svn: 208670
We did not actively try to resolve dllexported symbols specified
by /export or by a module definition file. So if exported symbols
would be resolved for other reasons, like other symbols refer to
them, that was fine, but if (unreferenced) exported symbols were
in an archive file, and no one refers to that file in the archive,
they remained unresolved.
That would obviously cause the issue that dllexported symbols are
not in a resultant DLL.
In this patch, we create an undefined symbol for each dllexported
symbol, to let the core linker to resolve it.
llvm-svn: 208452
Previously the handling of exported symbol was wrong if it's
specified in a module definition file in the form of
<externalname>=<internalname>. Export the correct symbol.
llvm-svn: 208446
Previously only GNU driver calls InputGraph::normalize, but its
functionality is not and should not be limited to GNU ld. Other
driver should be able to use it.
Currently only linker scripts use the feature, so this change
won't change the existing behavior.
llvm-svn: 208266
Previously only the toplevel elements were expanded by expandElements().
Now we recursively call getReplacements() to expand input elements even
if they are in, say, in a group.
llvm-svn: 208144
Nick Kledzik