This is a direct port of the new PE/COFF linker to ELF.
It can take a single object file and generate a valid executable that executes at the first byte in the text section.
llvm-svn: 242088
This is an initial patch for a section-based COFF linker.
The patch has 2300 lines of code including comments and blank lines.
Before diving into details, you want to start from reading README
because it should give you an overview of the design.
All important things are written in the README file, so I write
summary here.
- The linker is already able to self-link on Windows.
- It's significantly faster than the existing implementation.
The existing one takes 5 seconds to link LLD on my machine,
while the new one only takes 1.2 seconds, even though the new
one is not multi-threaded yet. (And a proof-of-concept multi-
threaded version was able to link it in 0.5 seconds.)
- It uses much less memory (250MB vs. 2GB virtual memory space
to self-host).
- IMHO the new code is much simpler and easier to read than
the existing PE/COFF port.
http://reviews.llvm.org/D10036
llvm-svn: 238458
This doesn't compile with MSVC 2013:
include\lld/ReaderWriter/PECOFFLinkingContext.h(356) : error C2797:
'lld::PECOFFLinkingContext::_imageVersion': list initialization
inside member initializer list or non-static data member initializer
is not implemented
include\lld/ReaderWriter/PECOFFLinkingContext.h(357) : error C2797:
'lld::PECOFFLinkingContext::_imageVersion': list initialization
inside member initializer list or non-static data member initializer
is not implemented
llvm-svn: 234676
This patch defines implicit conversion between integers and PowerOf2
instances, so uses of the classes is now implicit and look like
regular integers. Now we are ready to remove the scaffolding.
llvm-svn: 233245
The new constructor's type is the same, but this one takes not a log2
value but an alignment value itself, so the meaning is totally differnet.
llvm-svn: 233244
This patch is to make instantiation and conversion to an integer explicit,
so that we can mechanically replace all occurrences of the class with
integer in the next step.
Now get() returns an alignment value rather than its log2 value.
llvm-svn: 233242
This commit implements the behaviour of the SECTIONS linker script directive,
used to not only define a custom mapping between input and output sections, but
also order input sections in the output file. To do this, we modify
DefaultLayout with hooks at important places that allow us to re-order input
sections according to a custom order. We also add a hook in SegmentChunk to
allow us to calculate linker script expressions while assigning virtual
addresses to the input sections that live in a segment.
Not all SECTIONS constructs are currently supported, but only the ones that do
not use special sort orders. It adds two LIT test as practical examples of
which sections directives are currently supported.
In terms of high-level changes, it creates a new class "script::Sema" that owns
all linker script ASTs and the logic for linker script semantics as well.
ELFLinkingContext owns a single copy of Sema, which will be used throughout
the object file writing process (to layout sections as proposed by the linker
script).
Other high-level change is that the writer no longer uses a "const" copy of
the linking context. This happens because linker script expressions must be
calculated *while* calculating final virtual addresses, which is a very late
step in object file writing. While calculating these expressions, we need to
update the linker script symbol table (inside the semantics object), and, thus,
we are "modifying our context" as we prepare to write the file.
http://reviews.llvm.org/D8157
llvm-svn: 232402
The expression evaluation is needed when interpreting linker scripts, in order
to calculate the value for new symbols or to determine a new position to load
sections in memory. This commit extends Expression nodes from the linker script
AST with evaluation functions, and also contains a unit test.
http://reviews.llvm.org/D8156
llvm-svn: 231707
Previously we have a string -> string map to keep the weak alias
symbol mapping. Naturally we can't define more than one weak alias
with that data structure.
This patch is to allow multiple aliases for the same symbol by
changing the map type to string -> set of string map.
llvm-svn: 230702
The round-trip passes were introduced in r193300. The intention of
the change was to make sure that LLD is capable of reading end
writing such file formats.
But that turned out to be yet another over-designed stuff that had
been slowing down everyday development.
The passes ran after the core linker and before the writer. If you
had an additional piece of information that needs to be passed from
front-end to the writer, you had to invent a way to save the data to
YAML/Native. These passes forced us to do that even if that data
was not needed to be represented neither in an object file nor in
an executable/DSO. It doesn't make sense. We don't need these passes.
http://reviews.llvm.org/D7480
llvm-svn: 230069
Only search library directories explicitly specified
on the command line. Library directories specified in linker
scripts (including linker scripts specified on the command
line) are ignored.
llvm-svn: 228375
INPUT directive is a variant of GROUP in the sense that that specifies
a list of input files. The only difference is whether the entire file
list is wrapped with a --start-group/--end-group or not.
http://reviews.llvm.org/D7390
llvm-svn: 228060
This is needed, among others by the FreeBSD kernel linker script.
Patch by Davide Italiano!
Reviewers: ruiu, rafaelauler
Differential Revision: http://reviews.llvm.org/D7220
llvm-svn: 227694
* Removed cyclic dependency between lldPECOFF and lldDriver
* Added missing dependencies in unit tests
Differential Revision: http://reviews.llvm.org/D7185
llvm-svn: 227134
InputElement was named that because it's an element of an InputGraph.
It's losing the origin because the InputGraph is now being removed.
InputElement's subclass is FileNode, that naming inconsistency needed
to be fixed.
llvm-svn: 226147
These changes depended on r225674 and had been rolled back in r225859.
Because r225674 has been re-submitted, it's safe to re-submit them.
llvm-svn: 226132
The original commit had an issue with Mac OS dylib files. It didn't
handle fat binary dylib files correctly. This patch includes a fix.
A test for that case has already been committed in r225764.
llvm-svn: 226123
r225764 broke a basic functionality on Mac OS. This change reverts
r225764, r225766, r225767, r225769, r225814, r225816, r225829, and r225832.
llvm-svn: 225859
getNextFile used to have a complex logic to determine which file
should be processed by the Resolver on next iteration.
Now, it is just a sequential accessor to the internal array and
provides no sensible feature.
This patch also removes InputGraph::getGroupSize and InputGraph::
skipGroup to simplify the code.
llvm-svn: 225832
PECOFF was the only user of the API, and the reason why we created
the API is because, although the driver creates a list of input files,
it has no knowledge on what files are being created. It was because
everything was hidden behind the InputGraph abstraction.
Now the driver knows what that's doing. We no longer need this
indirection to get the file list being processed.
llvm-svn: 225767
Rui Ueyama