Commit Graph

50 Commits

Author SHA1 Message Date
Simon Atanasyan 09dae7c3e7 [ELF][MIPS] Handle R_MIPS_HI16/LO16 relocations against _gp_disp symbol
The `_gp_disp` is a magic symbol designates offset between start of
function and gp pointer into GOT. Only `R_MIPS_HI16` and `R_MIPS_LO16`
relocations are permitted with `_gp_disp`. The patch adds the `_gp_disp`
as an ignored symbol and adjusts symbol value before call the `relocateOne`
for `R_MIPS_HI16/LO16` relocations.

Differential Revision: http://reviews.llvm.org/D15480

llvm-svn: 255768
2015-12-16 14:45:09 +00:00
Igor Kudrin 15cd9ffd1e [ELF2] Add GOT section for MIPS target.
This patch implements R_MIPS_GOT16 relocation for global symbols in order to
generate some entries in GOT. Only reserved and global entries are supported
for now. For the detailed description about GOT in MIPS, see "Global Offset
Table" in Chapter 5 in the followin document:
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf

In addition, the platform specific symbol "_gp" is added, see "Global Data
Symbols" in Chapter 6 in the aforementioned document.

Differential revision: http://reviews.llvm.org/D14211

llvm-svn: 252275
2015-11-06 07:43:03 +00:00
Rui Ueyama c4aaed9255 ELF2: Implement --gc-sections.
Section garbage collection is a feature to remove unused sections
from outputs. Unused sections are sections that cannot be reachable
from known GC-root symbols or sections. Naturally the feature is
implemented as a mark-sweep garbage collector.

In this patch, I added Live bit to InputSectionBase. If and only
if Live bit is on, the section will be written to the output.
Starting from GC-root symbols or sections, a new function, markLive(),
visits all reachable sections and sets their Live bits. Writer then
ignores sections whose Live bit is off, so that such sections are
excluded from the output.

This change has small negative impact on performance if you use
the feature because making sections means more work. The time to
link Clang changes from 0.356s to 0.386s, or +8%.

It reduces Clang size from 57,764,984 bytes to 55,296,600 bytes.
That is 4.3% reduction.

http://reviews.llvm.org/D13950

llvm-svn: 251043
2015-10-22 18:49:53 +00:00
Rui Ueyama c7cc6ecf08 ELF2: Use ELFT to template OutputSections.
This patch is to use ELFT instead of Is64Bits to template OutputSection
and its subclasses. This increases code size slightly because it creates
two identical functions for some classes, but that's only 20 KB out of
33 MB, so it's negligible.

This is as per discussion with Rafael. He's not fan of the idea but OK
with this. We'll revisit later to this topic.

llvm-svn: 250466
2015-10-15 22:27:29 +00:00
Rui Ueyama d9189ceb23 ELF2: Implement __start_SECNAME and __stop_SECNAME.
If a section name is valid as a C identifier (which is rare because of
the leading '.'), linkers are expected to define __start_<secname> and
__stop_<secname> symbols. They are at beginning and end of the section,
respectively. This is not requested by the ELF standard, but GNU ld and
gold provide this feature.

llvm-svn: 250432
2015-10-15 17:11:03 +00:00
Rafael Espindola ae81a7bf49 Use OutputSectionBase in a few cases where we don't need a OutputSection.
NFC. This is just preparation for adding a new OutputSection dedicated to
SHF_MERGE input sections.

llvm-svn: 250419
2015-10-15 15:29:53 +00:00
Rui Ueyama 93bfee5f70 ELF2: Avoid using "finalize" as a function name.
"finalize" does not give a hint about what that function is actually
going to do. This patch make it more specific by renaming scanShlibUndefined.
Also add a comment that we basically ignore undefined symbols in DSOs except
this function.

llvm-svn: 250191
2015-10-13 18:10:33 +00:00
Rui Ueyama f8432d97f3 ELF2: Fix BSD's __progname symbol issue.
BSD's DSO files have undefined symbol "__progname" which is defined
in crt1.o. On that system, both user programs and system shared
libraries depend on each other.

In general, we need to put symbols defined by user programs which are
referenced by shared libraries to user program's .dynsym.

http://reviews.llvm.org/D13637

llvm-svn: 250176
2015-10-13 16:34:14 +00:00
George Rimar 53b581c522 Removed undefined and unused member. NFC.
llvm-svn: 250163
2015-10-13 15:16:01 +00:00
Rui Ueyama 3d45179d56 ELF2: Split SymbolTable::addFile(). NFC.
llvm-svn: 250073
2015-10-12 18:03:21 +00:00
Rafael Espindola b9ca7bb6ab Delete getFirstELF.
llvm-svn: 250030
2015-10-12 11:52:31 +00:00
Rafael Espindola af70764aa1 Simplify the InputFile type hierarchy.
Now that the SymbolTable is templated, we don't need the ELFData class or
multiple inheritance.

llvm-svn: 250005
2015-10-12 01:55:32 +00:00
Rui Ueyama ff77768569 ELF2: Move Target and entry initialization from SymbolTable to Driver.
SymbolTable was not a right place for initialization. We had to do that
because Driver didn't know what type of ELF objects are being handled.
We taught Driver that, so we can now move this code to Driver.

llvm-svn: 249904
2015-10-09 21:12:40 +00:00
Rui Ueyama 3ce825ed26 ELF2: Make SymbolTable a template class.
SymbolTable was not a template class. Instead we had switch-case-based
type dispatch to call desired functions. We had to do that because
SymbolTable was created before we know what ELF type objects had been
passed.

Every time I tried to add a new function to the symbol table, I had to
define a dispatcher which consist of a single switch statement.

It also brought an restriction what the driver can do. For example,
we cannot add undefined symbols before any files are added to the symbol
table. That's because no symbols can be added until the symbol table
knows the ELF type, but when it knows about that, it's too late.

In this patch, the driver makes a decision on what ELF type objects
are being handled. Then the driver creates a SymbolTable object for
an appropriate ELF type.

http://reviews.llvm.org/D13544

llvm-svn: 249902
2015-10-09 21:07:25 +00:00
Rafael Espindola 444576d4c4 Add support for comdats.
The implementation is a direct translation to c++ of the rules in the ELF spec.

llvm-svn: 249881
2015-10-09 19:25:07 +00:00
Igor Kudrin 65bddeaacf [ELF2] Check for TLS mismatch in symbol resolution.
The linker should generate an error if a TLS symbol is resolved
for a non-TLS reference and vice versa.

The patch addresses PR24244 (https://llvm.org/bugs/show_bug.cgi?id=24244)

Differential Revision: http://reviews.llvm.org/D13550

llvm-svn: 249817
2015-10-09 09:58:39 +00:00
Rui Ueyama e66e001c90 ELF2: Use the same name as COFF.
llvm-svn: 249635
2015-10-07 23:20:23 +00:00
Rui Ueyama e1f91529c8 ELF2: Rename dupError() -> reportConflict().
llvm-svn: 249622
2015-10-07 21:37:24 +00:00
Denis Protivensky 22220d5d5f [ELF2] Add --undefined option
Add symbol specified with -u as undefined which may cause additional
object files from archives to be linked into the resulting binary.

Differential Revision: http://reviews.llvm.org/D13345

llvm-svn: 249295
2015-10-05 09:43:57 +00:00
Rafael Espindola 5d41326751 Still define __init_array_(start|end) if there is no .init_array.
This matches the behavior of other linkers and seems necessary to link
in some older systems.

llvm-svn: 249077
2015-10-01 21:22:26 +00:00
Rafael Espindola 6a3b5ded8a Don't include shared libraries multiple times.
llvm-svn: 249061
2015-10-01 19:52:48 +00:00
Rafael Espindola 0e604f913a Add support for creating the symbols __init_array_start and __init_array_end.
llvm-svn: 248604
2015-09-25 18:56:53 +00:00
Rafael Espindola 5a5fdf7f73 Fix typo.
Thanks to Sean Silva for noticing.

llvm-svn: 248488
2015-09-24 12:58:44 +00:00
Rafael Espindola 1a49e58181 Print more information about duplicated symbols.
llvm-svn: 248380
2015-09-23 14:10:24 +00:00
Rafael Espindola 01205f79a4 Start adding target abstractions.
This is just enough to get PLT working on 32 bit x86.

The idea behind using a virtual interface is that it should be easy to
convert any of the functions to template parameters if any turns out to be
performance critical.

llvm-svn: 248308
2015-09-22 18:19:46 +00:00
Rafael Espindola 40102eb27f Use a MapVector to output symbols in a deterministic order.
We used to sort the symbols at the very end, but we need to know the order
earlier so that we can create reference to them in the dynamic relocations.

Thanks to Igor Kudrin for pointing out the problem.

llvm-svn: 247911
2015-09-17 18:26:25 +00:00
Rafael Espindola 67a5da60ed Add support of Elf_Rel dynamic relocations.
llvm-svn: 247888
2015-09-17 14:02:10 +00:00
Rafael Espindola 4340aad144 Start adding support for creating shared libraries.
They are not fully functional yet, but this implements enough support for lld
itself to read them.

With that, delete the .so binary we were using for tests and start eating our
own dog food.

llvm-svn: 247487
2015-09-11 22:42:45 +00:00
Michael J. Spencer ac5f048e09 [lld][elf2] Address review comments.
llvm-svn: 247096
2015-09-08 22:51:46 +00:00
Michael J. Spencer 546c64c733 [lld][elf2] Fix hard coded entry address.
llvm-svn: 247089
2015-09-08 22:34:57 +00:00
Rafael Espindola 740fafe54d Start creating the .dynamic section.
For now it is always empty.

llvm-svn: 247056
2015-09-08 19:43:27 +00:00
Rafael Espindola 4f624b9581 Simplify reporting of undefined symbols.
llvm-svn: 247016
2015-09-08 14:32:29 +00:00
Michael J. Spencer 1b348a68e5 [elf2] Add basic archive file support.
llvm-svn: 246886
2015-09-04 22:28:10 +00:00
Rafael Espindola 824d1a975f Add a template helper to avoid multiple switches over the ELF kind. NFC.
llvm-svn: 246823
2015-09-04 00:09:43 +00:00
Rafael Espindola f98d6d84cd Start adding support for shared libraries.
This just adds the types and enough support to detect incompatibilities among
shared libraries and object files.

llvm-svn: 246797
2015-09-03 20:03:54 +00:00
Rafael Espindola 8aeb13fec1 Add a helper function for getting the first object file.
Also preparation for shared objects. It will become the first ELF file.

llvm-svn: 246796
2015-09-03 19:13:13 +00:00
Rafael Espindola 222edc66d6 Make ObjectFiles private. NFC.
Just preparation for adding support for shared libraries.

llvm-svn: 246793
2015-09-03 18:56:20 +00:00
Rafael Espindola ee1364f7f6 Don't leave unused strings in the string table.
llvm-svn: 246593
2015-09-01 21:47:21 +00:00
Rafael Espindola 5b3942f54a Don't include hidden or internal symbols in the symbol table.
llvm-svn: 246583
2015-09-01 20:36:51 +00:00
Rafael Espindola f7d45f0869 Delete SyntheticUndefined.
Now that resolved is templated anyway, we can use the regular Undefined.

llvm-svn: 246407
2015-08-31 01:46:20 +00:00
Rafael Espindola daa92a6193 Keep the largest common symbol.
This requires templating some functions over ELFT, but that opens other cleanup
opportunities for future patches.

llvm-svn: 246405
2015-08-31 01:16:19 +00:00
Rafael Espindola 4c3aa0f228 Delete unused forward declarations.
llvm-svn: 245055
2015-08-14 14:51:11 +00:00
Rafael Espindola beee25e484 Make these headers as being c++.
llvm-svn: 245050
2015-08-14 14:12:54 +00:00
Rafael Espindola 62b81b875a Start populating the symbol table.
With this patch only the name is set. I will set the other fields shortly.

For now the table doesn't include local symbols. This is equivalent to using
--discard-all with gnu ld. This is OK for now since the symbols are not
needed for execution and for testing symbol resolution we only need the
global symbols.

llvm-svn: 245044
2015-08-14 13:07:05 +00:00
Rafael Espindola 2ffdd4d0e5 The SymbolTable doesn't need to be a template.
It was already using just code that is common to all object files.

llvm-svn: 243985
2015-08-04 14:29:01 +00:00
Rafael Espindola b89951457d Remove SymbolTable::getChunks.
When we were using a std::sort over all the chunks we needed to put them in a
single storage.

Now that we just iterate over them and use a map to find the output section,
we can avoid allocating the temporary storage.

llvm-svn: 243980
2015-08-04 13:39:30 +00:00
Rui Ueyama b4731a5847 ELF2: Use DenseMap instead of std::map for a symbol table.
We use DenseMap for COFF too.

llvm-svn: 243534
2015-07-29 16:30:40 +00:00
Michael J. Spencer 84487f1174 [ELF2] Add a new ELF linker based on the new PE/COFF linker.
Differential Revision: http://reviews.llvm.org/D11188

llvm-svn: 243161
2015-07-24 21:03:07 +00:00
Michael J. Spencer bae540e945 Revert ELF port. Posting to mailing list.
llvm-svn: 242118
2015-07-14 04:49:48 +00:00
Michael J. Spencer 8a4145411f Initial ELF port.
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
2015-07-13 23:48:06 +00:00