In COFF, an undefined symbol can have up to one alternative name. If a symbol
is resolved by its regular name, then it's linked normally. If a symbol is not
found in any input files, all references to the regular name are resolved using
the alternative name. If the alternative name is not found, it's a link error.
This mechanism is called "weak externals".
To support this mechanism, I added a new member function fallback() to undefined
atom. If an undefined atom has the second name, fallback() returns a new undefined
atom that should be used instead of the original one to resolve undefines. If it
does not have the second name, the function returns nullptr.
Differential Revision: http://llvm-reviews.chandlerc.com/D1550
llvm-svn: 190625
We need to order atoms that exist in the same chain. This is to make sure that
the command line order is preserved when we emit the atoms to the output file.
Credits: BigCheese for finding the bug.
Adds a test which otherwise would fail.
llvm-svn: 190608
Mangling scheme varies on platform, and prepending an underscore is valid only
on 32-bit x86. Added a method to mangle name to PECOFFLinkingContext and use
it to avoid hard coding mangled names.
llvm-svn: 190585
Process::GetEnv() uses GetEnvironmentVariableW, which is a Windows API
to get an environment variable and is preferable over getenv().
llvm-svn: 190431
attribute in LinkerInput to isWholeArchive and use that for deciding
whether library archives should be expanded. Implement the -all_load
option of the Darwin linker using this flag and drop the support for it
in GNU mode.
llvm-svn: 190275
It looks like there is a possibility of seeing RO/RW note sections
and we would need to create an appropriate RO/RW segment associated
with them.
Adds a test too.
llvm-svn: 189907
The compiler is allowed to add a linker option starting with -?<name> to
.drectve section. If the linker can interpret -<name>, it's processed as if
there's no question mark there. If not, such option is silently ignored.
This is a COFF's feature to allow the compiler to emit new linker options
while keeping compatibility with older linkers.
llvm-svn: 189897
Before this patch, name of driver implementation is not consistent with its
option table file. Specifically, LDOptions has a different prefix than
GnuLdDriver.
This patch renames option files, so that the option files have the same prefix
as the corresponding driver files.
Differential Revision: http://llvm-reviews.chandlerc.com/D1591
llvm-svn: 189895
This changes the interface of createLinkerInput to use ErrorOr, so that
errors from the linker can be captured.
Also adds a convenience function for error strings to be returned from
file nodes.
llvm-svn: 189871
Rui Ueyama