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
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
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
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
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
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
isAlias always returns false and no one is using it. It was
originally added Atom to query if an atom is an alias for another
atom, assuming that alias atoms are different from normal atoms.
We now support atom aliasing, but the way that's implemented is
in a different way than what isAlias assumed. An alias atom is
just a regular defined atom with no content, and it has a layout-
before edge to alias-to atom so that they are layed out at the
same location in the result. So this is dead code, and it doesn't
make much sense to keep it.
llvm-svn: 207884
Export definitions in a module definition file is as follows:
exportedname[=internalname] [@ordinal [NONAME]] [PRIVATE] [DATA]
Previously we did not support =internalname, so users couldn't export
symbols from a DLL with a different name.
llvm-svn: 207827
In general the linker scripts's GROUP command works like a pair
of command line options --start-group/--end-group. But there is
a difference in the files look up algorithm.
The --start-group/--end-group commands use a trivial approach:
a) If the path has '-l' prefix, add 'lib' prefix and '.a'/'.so'
suffix and search the path through library search directories.
b) Otherwise, use the path 'as-is'.
The GROUP command implements more compicated approach:
a) If the path has '-l' prefix, add 'lib' prefix and '.a'/'.so'
suffix and search the path through library search directories.
b) If the path does not have '-l' prefix, and sysroot is configured,
and the path starts with the / character, and the script being
processed is located inside the sysroot, search the path under
the sysroot. Otherwise, try to open the path in the current
directory. If it is not found, search through library search
directories.
https://www.sourceware.org/binutils/docs-2.24/ld/File-Commands.html
The patch reviewed by Shankar Easwaran, Rui Ueyama.
llvm-svn: 207769
Rafael Espindola