This adds LinkerScript support by creating a type Script which is of type
FileNode in the InputGraph. Once the LinkerScript Parser converts the
LinkerScript into a sequence of command, the commands are handled by the
equivalent LinkerScript node for the current Flavor/Target. For ELF, a
ELFGNULdScript gets created which converts the commands to ELF nodes and ELF
control nodes(ELFGroup for handling Group nodes).
Since the Inputfile type has to be determined in the Driver, the Driver needs
to determine the complete path of the file that needs to be processed by the
Linker. Due to this, few tests have been removed since the Driver uses paths
that doesnot exist.
llvm-svn: 195583
Hidden nodes could be a result of expansion, where a flavor might decide to keep
the node that we want to expand but discard it from being processed by the
resolver.
Verifies with unittests.
llvm-svn: 195516
Flavors may like to expand InputGraph nodes, when a filenode after parsing
results in more elements. One such example is while parsing GNU linker scripts.
The linker scripts after parsing would result in a lot of filenodes and probably
controlnodes too.
Adds unittests to verify functionality.
llvm-svn: 195515
This adds functionality to limit shared library undefined atoms to be added
only once by the Resolver.
Dynamic libraries may be processed more than once if they exist within a
Group.
Also adds a test to verify the change.
llvm-svn: 195307
It's allowed to specify library files *before* object files in the command
line. Object files seems to be processed first, and then their undefined
symbols are resolved from the libraries. This patch implements the compatible
behavior.
llvm-svn: 195295
NativeReferenceIvarsV1 cannot handle more than 65535 relocation targets
because its field to point to the target table is of type uint16_t. Because
of that limitation, the LLD couldn't link a file containing more than 65535
relocations. 65535 is not a big number - the LLD couldn't even link itself
with V1.
This patch solves the issue by adding NativeReferenceIvarsV2 support. The
new structure has more bits for the target table, so it can handle a large
number of relocatinos.
V2 structure is larger than V1. In order to prevent file bloating, V2 format
is used only when the resulting file cannot be represented in V1 format. The
writer and the reader support both V1 and V2 formats.
Differential Revision: http://llvm-reviews.chandlerc.com/D2217
llvm-svn: 195270
The fallback atom was used only when it's searching for a symbol in a library;
if an undefined symbol was not found in a library, the LLD looked for its
fallback symbol in the library.
Although it worked in most cases, because symbols with fallbacks usually occur
only in OLDNAMES.LIB (a standard library), that behavior was incompatible with
link.exe. This patch fixes the issue so that the semantics is the same as
MSVC's link.exe
The new (and correct, I believe) behavior is this:
- If there's no definition for an undefined atom, replace the undefined atom
with its fallback and then proceed (e.g. look in the next file or stop
linking as usual.)
Weak External symbols are underspecified in the Microsoft PE/COFF spec. However,
as long as I observed the behavior of link.exe, this seems to be what we want
for compatibility.
Differential Revision: http://llvm-reviews.chandlerc.com/D2162
llvm-svn: 195269
The maximum number of references the file with NativeReferenceIvarsV1 can
contain is 65534. If a file larger than that is converted to Native format,
the conversion will fail without any error message. This caused a subtle bug
that the LLD would produce a broken executable only when input files contain
too many references.
This issue exists since the RoundTripNativeTest is introduced in r193585. Since
then, it seems that nobody have linked any program having more than 65534
relocations with the LLD. Otherwise we would have found it earlier.
llvm-svn: 194987
This patch does not change the meaning of the program, but if something's wrong
in the linker or the compiler and the control reaches to the gap of imported
function table, it will stop immediately because of the presence of INT3. If
NOP, it'd fall through to the next call instruction, which is usually a
completely foreign function call.
llvm-svn: 194860
We can add multiple undefined atoms having the same name to the symbol table.
If such atoms are added, the symbol table compares their canBeNull attributes,
and select one having a stronger constraint. If their canBeNulls are the same,
the choice is arbitrary. Currently it choose the existing one.
This patch changes the preference, so that the symbol table choose the new one
if the new atom has a greater canBeNull or a fallback atom. This shouldn't
change the behavior except the case described below.
A new undefined atom may have a new fallback atom attribute. By choosing the new
atom, we can update the fallback atom during Core Linking. PE/COFF actually need
that. For example, _lseek is an alias for __lseek on Windows. One of an object
file in OLDNAMES.LIB has an undefined atom for _lseek with the fallback to
__lseek. When the linker tries to resolve _read, it supposed to read the file
from OLDNAMES.LIB and use the new fallback from the file. Currently LLD cannot
handle such case because duplicate undefined atoms with the same attributes are
ignored.
Differential Revision: http://llvm-reviews.chandlerc.com/D2161
llvm-svn: 194777
YAML files tend to be very large compared to binary formats because of ASCII
format inefficiency. And the YAML reader consumes an excessively large amount
of memory when parsing a large file. It's very slow too.
For example, I observed that 6MB executable became 120MB YAML file, and the
YAML reader consumed more than 1.5GB memory to load it. The YAML reader even
caused OOM error on 32 bit, causing the entire process to fail.
This patch sets the limit on the YAML file size the linker will try to load in
the RoundTripYAML test as a safeguard.
llvm-svn: 194666
The result of sizeof(SymbolTable<ELFT>::SymbolEntry) in DynamicSymbolTable
<ELFT>::write() was different from the same expression in RelocationTable
<ELFT>::write(), although the same template parameters were passed. They were
40 and 32, respectively. As a result, the same vector was treated as a
vector of 40 byte values in some places and a vector of 32 values in other
places. That caused an weird issue, resulting in collapse of the rela.dyn
section.
I suspect that this is a padding size calculation bug in MSVC 2012, but I
may be wrong. Reordering the fields to eliminate padding seems to fix the
issue.
llvm-svn: 194349
This patch adds support for converting normalized mach-o to and from binary
mach-o. It also changes WriterMachO (which previously directly wrote a
mach-o binary given a set of Atoms) to instead do it in two steps. The first
step uses normalizedFromAtoms() to convert Atoms to normalized mach-o, and the
second step uses writeBinary() which to generate the mach-o binary file.
llvm-svn: 194167
These fields are for /align option. Section alignment can be set per-section
basis with /section option too. In order to avoid name conflicts, rename the
existing identifiers to become more specific. No functionality change.
llvm-svn: 194160
/section command line option is to set/reset attributes of the Characteristics
field in the section header. You can set non-default values with this option.
You can make .data section executable with this, for example.
This patch implements the parser of the command line option. The code to use
the parsed values will be committed in a separate patch.
llvm-svn: 194133
I'm not sure if it is really an alias for /nodefaultlib, but I can say that
they are at least similar. Making it an alias would be better than ignoring it.
llvm-svn: 194131
/defaultlib options can be specified implicitly via the .drectve section, and
it's pretty common that multiple object files add the same library, such as
user32.lib, to the input. We shouldn't add the same library multiple times.
llvm-svn: 194129
We wrapped the linker internal file with a virtual archive file, so that the
linker internal file was linked only when it's actually used. This was to avoid
__ImageBase being included to the resulting executable. __ImageBase used to
occupy four bytes when emitted to executable.
And then it turned out that the implementation of __ImageBase was wrong -- it
shouldn't have been a regular atom but an absolute atom. Absolute atoms point
to some memory location, but they don't occupy disk space themselves. So it
wouldn't increase executable size (except the symbol table.) That means that
it's OK to link the linker internal file unconditionally.
So this patch does that, removing the wrapper archive file. Doing this
simplifies the code.
llvm-svn: 194127
msvcrt.lib contains "/disallowlib" command line option in its .drectve section.
I couldn't spot any documentation for the option. Ignore it for now so that we
can link the library without error.
llvm-svn: 194114
This patch should fix the test when it runs on Windows, by allowing drive
letter separator (colon) in the path. Now all LLD ELF tests passed on MSVC
2012 32-bit. Hooray!
llvm-svn: 193978
n_desc field in MachO string table was not initialized. On Unix,
test/darwin/hello-world.objtxt did not fail because I think an nlist object
is always allocated to a fresh heap initialized with zeros. On Windows,
uninitialized fields are filled with 0xCC when compiled with /GZ. Because
of that the test was failing on Windows.
llvm-svn: 193909
On Windows, neither "(" nor ")" are shell special characters, so -\( is passed
as-is to LLD. Because of that this test was failing on Windows.
llvm-svn: 193905
This patch adds "-target x86_64" to the command line. Without this option,
a 32 bit object file would be created on 32 bit machine, resulting in test
failure.
llvm-svn: 193904
Bugs that would be caught by this assertion would also be caught by
RoundTripYAMLPass test. We've enabled the pass for PECOFF, so we can remove
this.
llvm-svn: 193886
The data directory in the PE/COFF header consisted of list of data directory
atoms. This patch changes it -- now there's only one data directory entry that
contains former data directories. That's easier to handle in the writer as well
as to write to/read from YAML/Native files. The main purpose of this refactoring
is to enable RoundTrip tests for PE/COFF.
There's no functionality change.
llvm-svn: 193854
This reverts commit r193479.
The atoms are already added to the file, so re-adding them caused the YAML
writer to write the same atoms twice. That made the YAML reader to fail with
"duplicate atom name" error.
This is not the only error we've got for RoundTripYAMLPass for PECOFF, so we
cannot enable the test yet. More fixes will come.
Differential Revision: http://llvm-reviews.chandlerc.com/D2069
llvm-svn: 193762
Enable this for the following flavors
a) core
b) gnu
c) darwin
Its disabled for the flavor PECOFF. Convenient markers are added with FIXME
comments in the Driver that would be removed and code removed from each flavor.
llvm-svn: 193585
__ImageBase is an absolute symbol whose address is the same as the image base
address. What we did before this patch was to create __ImageBase symbol as a
symbol whose *contents* (not location) is the image base address, which is
clearly wrong.
llvm-svn: 193565
intended for debugging and diagnostic output), just inspect the spelling
to check for specific prefixes in drectve section flags.
In addition to being significantly cheaper and not relying on
a debugging interface, this also avoids creating a temporary string and
binding it to StringRef variable. We then went on to access it after the
memory had been deallocated.
This bug too was caught by ASan. I love ASan so much. =]
llvm-svn: 193487
More important than any performance concerns, the code was dropping the
temporary string on the floor after assigning it to a StringRef, and
then used the StringRef later. Caught by running the LLD tests under
ASan.
llvm-svn: 193486
Shankar Easwaran