Commit Graph

512 Commits

Author SHA1 Message Date
James Henderson d621037788 [ELF] Rework debug line parsing to use llvm::Error and callbacks (LLD-side)
Reviewed by: ruiu, grimar, espindola

Differential Revision: https://reviews.llvm.org/D44562

Summary:
r331971 changes the debug line parser interface to report LLVM errors in an
interface that different executables can use, rather than always being printed
directly as warnings to stderr. This change allows LLD to make use of the new
interface and call its own warning methods to report problems.

llvm-svn: 331972
2018-05-10 10:52:21 +00:00
Rumeet Dhindsa d366e36bbf Added support for ThinLTO plugin options : thinlto-index-only and thinlto-prefix-replace
Differential Revision: https://reviews.llvm.org/D46034

llvm-svn: 331405
2018-05-02 21:40:07 +00:00
Rui Ueyama 50bf643cfb Do not set RequiresNullTerminator. NFC.
When reading object files, we don't need '\0' at end of each file.

llvm-svn: 331045
2018-04-27 15:32:04 +00:00
Rui Ueyama 1d92aa7380 Add --warn-backrefs to maintain compatibility with other linkers
I'm proposing a new command line flag, --warn-backrefs in this patch.
The flag and the feature proposed below don't exist in GNU linkers
nor the current lld.

--warn-backrefs is an option to detect reverse or cyclic dependencies
between static archives, and it can be used to keep your program
compatible with GNU linkers after you switch to lld. I'll explain the
feature and why you may find it useful below.

lld's symbol resolution semantics is more relaxed than traditional
Unix linkers. Therefore,

  ld.lld foo.a bar.o

succeeds even if bar.o contains an undefined symbol that have to be
resolved by some object file in foo.a. Traditional Unix linkers
don't allow this kind of backward reference, as they visit each
file only once from left to right in the command line while
resolving all undefined symbol at the moment of visiting.

In the above case, since there's no undefined symbol when a linker
visits foo.a, no files are pulled out from foo.a, and because the
linker forgets about foo.a after visiting, it can't resolve
undefined symbols that could have been resolved otherwise.

That lld accepts more relaxed form means (besides it makes more
sense) that you can accidentally write a command line or a build
file that works only with lld, even if you have a plan to
distribute it to wider users who may be using GNU linkers.  With
--check-library-dependency, you can detect a library order that
doesn't work with other Unix linkers.

The option is also useful to detect cyclic dependencies between
static archives. Again, lld accepts

  ld.lld foo.a bar.a

even if foo.a and bar.a depend on each other. With --warn-backrefs
it is handled as an error.

Here is how the option works. We assign a group ID to each file. A
file with a smaller group ID can pull out object files from an
archive file with an equal or greater group ID. Otherwise, it is a
reverse dependency and an error.

A file outside --{start,end}-group gets a fresh ID when
instantiated. All files within the same --{start,end}-group get the
same group ID. E.g.

  ld.lld A B --start-group C D --end-group E

A and B form group 0, C, D and their member object files form group
1, and E forms group 2. I think that you can see how this group
assignment rule simulates the traditional linker's semantics.

Differential Revision: https://reviews.llvm.org/D45195

llvm-svn: 329636
2018-04-09 23:05:48 +00:00
Rafael Espindola b4d3dfefb7 Avoid some temporary allocations.
Some system libraries have a lot of versioned symbols. When linking
scylla this brings the number of malloc calls from 49154 to 37944.

llvm-svn: 329453
2018-04-06 20:53:06 +00:00
Rui Ueyama 24a47201fd Merge LazyArchive::fetch() and ArchiveFile::getMember(). NFC.
They are to pull out an object file for a symbol, but for a historical
reason the code is written in two separate functions. This patch
merges them.

llvm-svn: 329039
2018-04-03 02:06:57 +00:00
Rui Ueyama 5a67a6ec4a Re-implement --just-symbols as a regular object file.
I tried a few different designs to find a way to implement it without
too much hassle and settled down with this. Unlike before, object files
given as arguments for --just-symbols are handled as object files, with
an exception that their section tables are handled as if they were all
null.

Differential Revision: https://reviews.llvm.org/D42025

llvm-svn: 328852
2018-03-30 01:15:36 +00:00
Rui Ueyama efe9af9f07 Rename NonLocal -> Global.
NonLocal is technically more accurate, but we already use the term
"Global" to specify the non-local part of the symbol table, and
Local <-> Global is easier to digest.

llvm-svn: 328740
2018-03-28 22:55:40 +00:00
Rafael Espindola c8f774b393 Strip @VER suffices from the LTO output.
This fixes pr36623.

The problem is that we have to parse versions out of names before LTO
so that LTO can use that information.

When we get the LTO produced .o files, we replace the previous symbols
with the LTO produced ones, but they still have @ in their names.

We could just trim the name directly, but calling parseSymbolVersion
to do it is simpler.

llvm-svn: 328738
2018-03-28 22:45:39 +00:00
Rafael Espindola 35aad41c1b Force SHF_MERGE optimizations with -r.
Some tools (dwarfdump for example) get confused by the current -O0 -r
output since it has multiple copies of .debug_str.

We cannot just merge sections with the same name as they can have
different sh_entsize.

We could have duplicated logic for merging sections based on name and
sh_entsize, but it seems better to just use the existing logic by
enabling optimizations.

llvm-svn: 328640
2018-03-27 17:09:23 +00:00
Rui Ueyama bc0d3b4e0f Remove extraneous local variable. NFC.
llvm-svn: 328605
2018-03-27 02:53:08 +00:00
Rui Ueyama b3e2f74517 Update comments.
llvm-svn: 328604
2018-03-27 02:52:58 +00:00
Rui Ueyama b391288af7 Refactor SharedFile::parseRest. NFC.
SharedFile::parseRest function grew organically and got a bit hard to
understand. This patch refactor it. This patch also adds comments.

Differential Revision: https://reviews.llvm.org/D44860

llvm-svn: 328579
2018-03-26 19:57:38 +00:00
Rui Ueyama d37c33aff2 Do not add a dummy entry to SharedFile::Verdefs. NFC.
Previously, we used 0 as an alias for VER_NDX_GLOBAL and had a dummy
entry in SharedFile::Verdefs so that the access to the array is within
its boundary. But that's not straightforwad. We can just stop doing both.

llvm-svn: 328401
2018-03-24 00:25:24 +00:00
Rui Ueyama bd63adcb26 Remove "FIXME" from a comment.
A bug in BFD linker is not our FIXME item.

llvm-svn: 328381
2018-03-23 22:48:17 +00:00
Rafael Espindola 85e77b26be Fix the MSVC build.
llvm-svn: 328285
2018-03-23 00:42:47 +00:00
Rafael Espindola 3c3ebcc5f4 Fix PR36793.
With this patch lld will iterate over compile units to find the line
tables instead of assuming there is only one at offset 0.

llvm-svn: 328284
2018-03-23 00:35:27 +00:00
Rafael Espindola c08e5afb7c Replace a std::pair with a struct.
This is more readable and should reduce the noise in a followup patch.

llvm-svn: 328164
2018-03-21 22:32:17 +00:00
Rui Ueyama 8e53917a26 Add a comment about ELF spec and the symbol table's sh_info.
llvm-svn: 327645
2018-03-15 17:10:50 +00:00
George Rimar 59ebd4adf0 [ELF] - Formatted comment, fixed mistype. NFC.
llvm-svn: 327280
2018-03-12 15:18:35 +00:00
George Rimar 1136ec64e8 [ELF] - Fix crash relative to SHF_LINK_ORDER sections.
Our code assumes all input sections in an output SHF_LINK_ORDER
section has SHF_LINK_ORDER flag. We do not check that and that can cause a crash.

That happens because we call 
std::stable_sort(Sections.begin(), Sections.end(), compareByFilePosition);, 
where compareByFilePosition predicate does not expect to see
null when calls getLinkOrderDep. 

The same might happen when sections refer to non-regular sections. 
Test cases demonstrate the issues, patch fixes them.

Differential revision: https://reviews.llvm.org/D44193

llvm-svn: 327006
2018-03-08 15:06:58 +00:00
Rui Ueyama e66d7a798f Return early. NFC.
We don't need to handle an object file having more than one symbol table,
so as soon as we find the first one, we can process it and then return
from the function.

llvm-svn: 326977
2018-03-08 01:22:30 +00:00
Rui Ueyama c13d858b6d Simplify LazyobjFile and readElfSymbols.
addElfSymbols and readJustSymbolsFile still has duplicate code, but
I didn't come up with a good idea to eliminate them. Since this patch
is an improvement, I'm sending this for review.

Differential Revision: https://reviews.llvm.org/D44187

llvm-svn: 326972
2018-03-08 01:05:58 +00:00
James Henderson cb4c19f315 [ELF] Prevent crash when reporting errors if debug line cannot be parsed
LLD uses the debug info and debug line sections to determine the location of
e.g. references to undefined symbols, when producing error messages. In the
event that debug info was present, but debug line parsing failed for some
reason, then a nullptr would end up being dereferenced by the location-lookup
code.

Differential Revision: https://reviews.llvm.org/D44205

Reviewers: grimar
llvm-svn: 326899
2018-03-07 15:22:58 +00:00
Rui Ueyama 09fcd4c34c Implement --just-symbols.
Differential Revision: https://reviews.llvm.org/D39348

llvm-svn: 326835
2018-03-06 21:25:37 +00:00
Rafael Espindola 3f4c673d38 Put undefined symbols from shared libraries in the symbol table.
With the recent fixes these symbols have more in common than not with
regular undefined symbols.

llvm-svn: 326242
2018-02-27 20:31:22 +00:00
Igor Kudrin 3345c9ac18 [ELF] Create and export symbols provided by a linker script if they referenced by DSOs.
It should be possible to resolve undefined symbols in dynamic libraries
using symbols defined in a linker script.

Differential Revision: https://reviews.llvm.org/D43011

llvm-svn: 326176
2018-02-27 07:18:07 +00:00
Peter Collingbourne 09e04af42f ELF: Stop collecting a list of symbols in ArchiveFile.
There seems to be no reason to collect this list of symbols.

Also fix a bug where --exclude-libs would apply to all symbols that
appear in an archive's symbol table, even if the relevant archive
member was not added to the link.

Differential Revision: https://reviews.llvm.org/D43369

llvm-svn: 325380
2018-02-16 20:23:54 +00:00
Simon Atanasyan 85815a3149 [ELF][MIPS] Ignore incorrect version definition index for _gp_disp symbol
MIPS BFD linker puts _gp_disp symbol into DSO files and assigns zero
version definition index to it. This value means 'unversioned local
symbol' while _gp_disp is a section global symbol. We have to handle
this bug in the LLD because BFD linker is used for building MIPS
toolchain libraries.

Differential revision: https://reviews.llvm.org/D42486

llvm-svn: 324467
2018-02-07 10:02:49 +00:00
George Rimar f9dc10cd89 [ELF] - Report valid binary filename when reporting error.
We did not report valid filename for duplicate symbol error when
symbol came from binary input file.
Patch fixes it.

Differential revision: https://reviews.llvm.org/D42635

llvm-svn: 324217
2018-02-05 09:47:24 +00:00
Rui Ueyama f46d3d1be9 Strip .note.gnu.build-id sections if --build-id is given.
Differential Revision: https://reviews.llvm.org/D42823

llvm-svn: 324146
2018-02-02 21:56:24 +00:00
Paul Robinson bf750c80e9 [DWARFv5] Re-enable dumping a line table with no CU.
r323476 added support for DW_FORM_line_strp, and incorrectly made that
depend on having a DWARFUnit available.  We shouldn't be tracking
.debug_line_str in DWARFUnit after all.  After this patch, I can do an
NFC follow up and undo a bunch of the "plumbing" part of r323476.

Differential Revision: https://reviews.llvm.org/D42609

llvm-svn: 323691
2018-01-29 20:57:43 +00:00
Rafael Espindola 9a84f6b954 Detemplate reportDuplicate.
We normally avoid "switch (Config->EKind)", but in this case I think
it is worth it.

It is only executed when there is an error and it allows detemplating
a lot of code.

llvm-svn: 321404
2017-12-23 17:21:39 +00:00
Rafael Espindola ce3b52c186 Pass an InputFile to the InputSection constructor.
This simplifies toRegularSection and reduces the noise in a followup
patch.

llvm-svn: 321240
2017-12-21 02:11:51 +00:00
Rafael Espindola 604032729c Convert a few more InputFiles to references.
We use null files in sections to represent linker created sections,
so ObjFile<ELFT> is never null.

llvm-svn: 321238
2017-12-21 02:03:39 +00:00
Rafael Espindola 920d7d80e2 clang-format. NFC.
llvm-svn: 321216
2017-12-20 19:59:47 +00:00
Rafael Espindola 8cd6674f5b Use a reference in addLazyArchive. NFC.
llvm-svn: 321194
2017-12-20 17:48:28 +00:00
Rafael Espindola a32ddc4639 Use a reference for the shared symbol file.
Every shared symbol has a file, so we can use a reference.

llvm-svn: 321187
2017-12-20 16:28:19 +00:00
Rafael Espindola 7b5cc6c5dc Use a reference for a value that is never null. NFC.
llvm-svn: 321186
2017-12-20 16:19:48 +00:00
Rafael Espindola f1687125ba Use a reference for a value that is never null. NFC.
llvm-svn: 321185
2017-12-20 16:16:40 +00:00
Rafael Espindola 75ebe9a3bf Handle a VersymIndex of 0 as an error.
I noticed that the continue this patch deletes was not tested. Trying
to add a test I realized that we never put a VER_NDX_LOCAL symbol in
the dynamic symbol table. There doesn't seem to be any reason for a
linker to use VER_NDX_LOCAL for a defined shared symbol.

llvm-svn: 320817
2017-12-15 14:52:40 +00:00
Rui Ueyama 29ceba7961 Fix error messages.
llvm-svn: 320772
2017-12-15 00:07:15 +00:00
Rui Ueyama fbe68a3584 Use warn() instead of error() to report a bad symbol in a DSO.
Specifically, libwidevinecdm.so in Chrome has such bad symbol.
It seems the BFD linker handles them as local symbols, so instead
of inserting them to the symbol table, we should skip them too.

Differential Revision: https://reviews.llvm.org/D41257

llvm-svn: 320770
2017-12-15 00:01:33 +00:00
Rui Ueyama d44a81c3a8 Inline a small function.
Differential Revision: https://reviews.llvm.org/D41204

llvm-svn: 320652
2017-12-13 22:53:59 +00:00
Rafael Espindola cee2933408 Remove unnecessary use of Repl.
This runs before ICF, so Sec->Repl == Sec.

llvm-svn: 320543
2017-12-13 02:09:14 +00:00
Rafael Espindola 8f619ab826 Compact symbols from 96 to 88 bytes.
By using an index instead of a pointer for verdef we can put the index
next to the alignment field. This uses the otherwise wasted area and
reduces the shared symbol size.

By itself the performance change of this is in the noise, but I have a
followup patch to remove another 8 bytes that improves performance
when combined with this.

llvm-svn: 320449
2017-12-12 01:45:49 +00:00
Rui Ueyama c0081639cc Remove checkToString functions and use toString instead.
Differential Revision: https://reviews.llvm.org/D40928

llvm-svn: 320005
2017-12-07 03:24:57 +00:00
Rui Ueyama bdc5150984 Always evaluate the second argument for CHECK() lazily.
This patch is to rename check CHECK and make it a C macro, so that
we can evaluate the second argument lazily.

Differential Revision: https://reviews.llvm.org/D40915

llvm-svn: 319974
2017-12-06 22:08:17 +00:00
Rafael Espindola b6e2ca4597 Convert a check to checkLazy.
This brings memory allocations when linking clang from 270.96MB to
267.80MB.

llvm-svn: 319932
2017-12-06 19:17:20 +00:00
Rafael Espindola aca3df5479 Convert a few uses of check to checkLazy.
Linking clang goes from 292.68MB to 281.80MB allocated.

llvm-svn: 319927
2017-12-06 19:08:10 +00:00