MIPS N64 ABI introduces .MIPS.options section which specifies miscellaneous
options to be applied to an object/shared/executable file. LLVM as well as
modern versions of GNU tools read and write the only type of the options -
ODK_REGINFO. It is exact copy of .reginfo section used by O32 ABI.
llvm-svn: 268485
Both bfd and gold have this. It allows disabling build-id when it is the
default with by adding -Wl,--build-id=none no the clang command line.
llvm-svn: 268435
Introduce a special symbol type to indicate that we have not yet seen a type
for the symbol, so we should not report TLS mismatches for that symbol.
Differential Revision: http://reviews.llvm.org/D19836
llvm-svn: 268411
We want --reproduce to
* not rewrite scripts and thin archives
* work with absolute paths
Given that, it pretty much has to create a full directory tree. On windows that
is problematic because of the very short maximum path limit. On most cases
users can still work around it with "--repro c:\r", but that is annoying and
not viable for automated testing.
We then need to produce some form of archive with the files. The first option
that comes to mind is .a files since we already have code for writing them.
There are a few problems with them
The format has a dedicated string table, so we cannot start writing it until
all members are known.
Regular implementations don't support creating directories. We could make
llvm-ar support that, but that is probably not a good idea.
The next natural option would be tar. The problem is that to support long path
names (which is how this started) it needs a "pax extended header" making this
an annoying format to write.
The next option I looked at seems a natural fit: cpio files.
They are available on pretty much every unix, support directories and long path
names and are really easy to write. The only slightly annoying part is a
terminator, but at least gnu cpio only prints a warning if it is missing, which
is handy for crashes. This patch still makes an effort to always create it.
llvm-svn: 268404
Weak undefined symbols resolve to the image base. This is a little strange,
but it allows us to link function calls to such symbols. Normally such a
call will be guarded with a comparison, which will load a zero from the GOT.
There's one example of such a function call in crti.o in Linux's CRT.
As part of this change, I also needed to make the synthetic start and end
symbols image base relative in the case where their sections were empty,
so that PC-relative references to those symbols would continue to work.
Differential Revision: http://reviews.llvm.org/D19844
llvm-svn: 268350
This change simplifies the BuildId classes by removing a few member
functions and variables from them. It should also make it easy to
parallelize hash computation in future because now each BuildId object
see all inputs rather than one at a time.
llvm-svn: 268333
This patch increases the size of Undefined by the size of a pointer,
but it wouldn't actually increase the size of memory that LLD uses
because we are not allocating the exact size but the size of the
largest SymbolBody.
llvm-svn: 268310
With this it is possible to use chroot/fakechroot to have a completely
reproducible link even when thin archives or linker scripts have
absolute paths.
llvm-svn: 268231
Patch implements one of suggestions from Rafael Ávila de Espíndola,
to fix segfault after section that contains personality being
garbage collected.
Suggestion was just to keep alive all non executable sections
referenced by .eh_frame.
This fixes PR27529.
Differential revision: http://reviews.llvm.org/D19656
llvm-svn: 268228
This patch implements a new design for the symbol table that stores
SymbolBodies within a memory region of the Symbol object. Symbols are mutated
by constructing SymbolBodies in place over existing SymbolBodies, rather
than by mutating pointers. As mentioned in the initial proposal [1], this
memory layout helps reduce the cache miss rate by improving memory locality.
Performance numbers:
old(s) new(s)
Without debug info:
chrome 7.178 6.432 (-11.5%)
LLVMgold.so 0.505 0.502 (-0.5%)
clang 0.954 0.827 (-15.4%)
llvm-as 0.052 0.045 (-15.5%)
With debug info:
scylla 5.695 5.613 (-1.5%)
clang 14.396 14.143 (-1.8%)
Performance counter results show that the fewer required indirections is
indeed the cause of the improved performance. For example, when linking
chrome, stalled cycles decreases from 14,556,444,002 to 12,959,238,310, and
instructions per cycle increases from 0.78 to 0.83. We are also executing
many fewer instructions (15,516,401,933 down to 15,002,434,310), probably
because we spend less time allocating SymbolBodies.
The new mechanism by which symbols are added to the symbol table is by calling
add* functions on the SymbolTable.
In this patch, I handle local symbols by storing them inside "unparented"
SymbolBodies. This is suboptimal, but if we do want to try to avoid allocating
these SymbolBodies, we can probably do that separately.
I also removed a few members from the SymbolBody class that were only being
used to pass information from the input file to the symbol table.
This patch implements the new design for the ELF linker only. I intend to
prepare a similar patch for the COFF linker.
[1] http://lists.llvm.org/pipermail/llvm-dev/2016-April/098832.html
Differential Revision: http://reviews.llvm.org/D19752
llvm-svn: 268178
The aim of this patch is to make it easy to re-run the command without
updating paths in the command line. Here is a use case.
Assume that Alice is having an issue with lld and is reporting the issue
to developer Bob. Alice's current directly is /home/alice/work and her
command line is "ld.lld -o foo foo.o ../bar.o". She adds "--reproduce repro"
to the command line and re-run. Then the following text will be produced as
response.txt (notice that the paths are rewritten so that they are
relative to /home/alice/work/repro.)
-o home/alice/work/foo home/alice/work/foo.o home/alice/bar.o
The command also produces the following files by copying inputs.
/home/alice/repro/home/alice/work/foo.o
/home/alice/repro/home/alice/bar.o
Alice zips the directory and send it to Bob. Bob get an archive from Alice
and extract it to his home directory as /home/bob/repro. Now his directory
have the following files.
/home/bob/repro/response.txt
/home/bob/repro/home/alice/work/foo.o
/home/bob/repro/home/alice/bar.o
Bob then re-run the command with these files by the following commands.
cd /home/bob/repro
ld.lld @response.txt
This command will run the linker with the same command line options and
the same input files as Alice's, so it is very likely that Bob will see
the same issue as Alice saw.
Differential Revision: http://reviews.llvm.org/D19737
llvm-svn: 268169
These would just crash at runtime.
If we ever decide to support rw text segments this should make it easier
to implement as there is now a single point where we notice the problem.
I have tested this with a freebsd buildworld. It found a non pic
assembly file being linked into a .so,. With that fixed, buildworld
finished.
llvm-svn: 268149
This patch redefines the default optimization level as 1 and adds
new level 0. In the command line, it is -O0. The flag disables
costly but optional features so that the linker produces semantically
correct but larger output quickly. Currently it only disables
section merging.
This flag is not intended to be used for final production linking.
It is intended to be used in compile-link-test cycle.
Time to link clang with debug info is about 2x faster with the flag.
Head:
13.24 seconds
Output size: 1227189664 bytes
With this patch:
7.41 seconds
Output size: 2490281784 bytes
Differential Revision: http://reviews.llvm.org/D19705
llvm-svn: 268056
Using multiple context used to be a really big memory saving because we
could free memory from each file while the linker proceeded with the
symbol resolution. We are getting lazier about reading data from the
bitcode, so I was curious if this was still a good tradeoff.
One thing that is a bit annoying is that we still have to copy the
symbol names. The problem is that the names are stored in the Module and
get freed when we move the module bits during linking.
Long term I think the solution is to add a symbol table to the bitcode.
That way IRObject file will not need to use a Module or a Context and we
can drop it while still keeping a StringRef to the names.
This patch is still be an interesting medium term improvement.
When linking llvm-as without debug info this patch is a small speedup:
master: 29.861877513 seconds
patch: 29.814533787 seconds
With debug info the numbers are
master: 34.765181469 seconds
patch: 34.563351584 seconds
The peak memory usage when linking llvm-as with debug info was
master: 599.10MB
patch: 600.13MB
llvm-svn: 267921
Relocations against sections with no SHF_ALLOC bit are R_ABS relocations.
Currently we are creating Relocations vector for them, but that is wasteful.
This patch is to skip vector construction and to directly apply relocations
in place.
This patch seems to be pretty effective for large executables with debug info.
r266158 (Rafael's patch to change the way how we apply relocations) caused a
temporary performance degradation for such executables, but this patch makes
it even faster than before.
Time to link clang with debug info (output size is 1070 MB):
before r266158: 15.312 seconds (0%)
r266158: 17.301 seconds (+13.0%)
Head: 16.484 seconds (+7.7%)
w/patch: 13.166 seconds (-14.0%)
Differential Revision: http://reviews.llvm.org/D19645
llvm-svn: 267917
There seems to be no reason to keep st_size of undefined symbols.
This patch removes the member for it. This patch will change outputs
in cases that undefined symbols are copied to output, but I think
this is unimportant.
Differential Revision: http://reviews.llvm.org/D19574
llvm-svn: 267826
It is now used only for relocations that only set the low bits inside a
page. Everything else is handled by getRelExpr.
I will send a another review renaming and better documenting
isRelRelative.
llvm-svn: 267705
The semantics of the -u flag are to load the lazy symbol named by the flag. We
were previously relying on this behavior falling out of symbol resolution
against a synthetic undefined symbol, but that didn't quite give us the
correct behavior, so we needed a flag to mark symbols created with -u so
we could treat them specially in the writer. However, it's simpler and less
error prone to implement the required behavior directly and remove the flag.
This fixes an issue where symbols loaded with -u would receive hidden
visibility even when the definition in an object file had wider visibility.
Differential Revision: http://reviews.llvm.org/D19560
llvm-svn: 267639
When --reproduce <path> is given, then we need to concatenate input
file paths to the given path to save input files to the directory.
Previously, path concatenation didn't handle Windows drive letters
so it could generate invalid paths such as "C:\D:\foo". It also didn't
handle ".." path components, so it could produce some bad paths
such as "foo/../../etc/passwd".
In this patch, Windows drive letters and ".." are removed before
concatenating paths.
Differential Revision: http://reviews.llvm.org/D19551
llvm-svn: 267600
We were only doing it for .so and --export-dynamic, but those are not
the only ways a symbol ends up in the dynamic symbol table.
Problem diagnostic and earlier patch version by Peter Collingbourne.
llvm-svn: 267568
This remove a fixme, cleans up the weak undef interaction with archives and
lets us keep weak undefs still weak if they resolve to shared.
llvm-svn: 267555
--reproduce dumps the object files in a directory chosen
(preserving the file system layout) and the linker invocation
so that people can create an archive and upload for debugging.
Differential Revision: http://reviews.llvm.org/D19494
llvm-svn: 267497
MIPS is the only target requires GOT header. We already have MIPS
specific code in the `GotSection` class, so move MIPS GOT header
generation there and delete redundant stuff like `GotHeaderEntriesNum`
field and `writeGotHeader` method.
Differential Revision: http://reviews.llvm.org/D19465
llvm-svn: 267460
Fixes check-llvm when bootstrapping.
Also remove mostly dead and most likely incorrect logic regarding preemption
of weak undefined symbols.
llvm-svn: 267314
Previously, we have re-implemented utility functions such as `expect`
or `next` in LinkerScript.cpp. This patch reuses the existing
implementation that is in ScriptParser.cpp.
llvm-svn: 267255
ScriptParserBase class is a container of collection of various methods
to parse linker script-ish text. It had a virtual method `run` to run
the parser. But we don't have to enforce its descendents to implement
that. It's up to them.
This patch removes pure virtual function `run`.
llvm-svn: 267246
The fix is to handle local symbols referring to SHF_MERGE sections.
Original message:
GC entries of SHF_MERGE sections.
It is a fairly direct extension of the gc algorithm. For merge sections
instead of remembering just a live bit, we remember which offsets
were used.
This reduces the .rodata sections in chromium from 9648861 to 9477472
bytes.
llvm-svn: 267233
This patch is to remove -lto-no-discard-value-names flag and
instead to use -save-temps as we discussed in the post-commit
review thread for r267020.
Differential Revision: http://reviews.llvm.org/D19437
llvm-svn: 267230
This patch only implements support for version scripts of the form:
{ [ global: symbol1; symbol2; [...]; symbolN; ] local: *; };
No wildcards are supported, other than for the local entry. Symbol versioning
is also not supported.
It works by introducing a new Symbol flag which tracks whether a symbol
appears in the global section of a version script.
This patch also simplifies the logic in SymbolBody::isPreemptible(), and
teaches it to handle the case where symbols with default visibility in DSOs
do not appear in the dynamic symbol table because of a version script.
Fixes PR27482.
Differential Revision: http://reviews.llvm.org/D19430
llvm-svn: 267208
These are properties of a symbol name, rather than a particular instance
of a symbol in an object file. We can simplify the code by collecting these
properties in Symbol.
The MustBeInDynSym flag has been renamed ExportDynamic, as its semantics
have been changed to be the same as those of --dynamic-list and
--export-dynamic-symbol, which do not cause hidden symbols to be exported.
Differential Revision: http://reviews.llvm.org/D19400
llvm-svn: 267183
It is a fairly direct extension of the gc algorithm. For merge sections
instead of remembering just a live bit, we remember which offsets were
used.
This reduces the .rodata sections in chromium from 9648861 to 9477472
bytes.
llvm-svn: 267164
It turns out that this will read data from the section to properly
handle Elf_Rel implicit addends.
Sorry for the noise.
Original messages:
Try to fix Windows lld build.
Move getRelocTarget to ObjectFile.
It doesn't use anything from the InputSection.
llvm-svn: 267163
llvm\tools\lld\ELF\MarkLive.cpp(49): error C2872: 'ObjectFile': ambiguous symbol
llvm\tools\lld\elf\InputFiles.h(100): note: could be 'lld:🧝:ObjectFile'
llvm\include\llvm/Object/IRObjectFile.h(26): note: or 'llvm::object::ObjectFile'
llvm\tools\lld\ELF\MarkLive.cpp(133): note: see reference to function template instantiation
'void forEachSuccessor<ELFT>(lld:🧝:InputSection<ELFT> *,
std::function<void (lld:🧝:InputSectionBase<ELFT> *)>)'
being compiled with
[ ELFT=llvm::object::ELF32LE ]
llvm\tools\lld\ELF\MarkLive.cpp(136): note: see reference to function template instantiation
'void lld:🧝:markLive<llvm::object::ELF32LE>(lld:🧝:SymbolTable<llvm::object::ELF32LE> *)
being compiled
llvm-svn: 267161
I will eventually make `evaluate` function a usual parse function
rather than a function that works on a separate token list.
This is the first step toward that.
llvm-svn: 267083
You can instruct the linker to not discard sections even if they
are unused and --gc-sections option is given. The linker script
command for doing that is KEEP. The syntax is KEEP(foo) where foo
is a section name. KEEP commands are written in SECTIONS command,
so you can specify the order of sections *and* which sections
will be kept.
Each sub-command in SECTIONS command are translated into SectionRule
object. Previously, each SectionRule has `Keep` bit. However,
if you think about it, this hid information in too deep in elements
of a list. Semantically, KEEP commands aren't really related to
SECTIONS subcommands. We can keep the section list for KEEP in a
separate list. This patch does that.
llvm-svn: 267065
Since there is a copy in every translation unit that uses them, they can
be omitted from the symbol table if the address is not significant.
This still doesn't catch as many cases as the gold plugin. The
difference is that we check canBeOmittedFromSymbolTable in each file and
use lazy loading which limits what it can do. Gold checks it in the merged file.
I think the correct way of getting the same results as gold is just to
cache in the IR the result of canBeOmittedFromSymbolTable.
llvm-svn: 267063
I noticed that I was looking for the definition of SymPair when hacking
the Writer, only to find that it is just a pair of DefinedRegular symbols.
I don't think it provides more values than the cost of using brainpower
to memorize the type. I didn't roll back r266317, which introduced SymPair,
because the patch removes code repetitions. I ported that change to new
code.
llvm-svn: 267047
GNU ld and gold only support the discard-all and discard-locals with two dashes.
Retain the compatibility with the one dash spelling, but also accept the two
dashed form.
llvm-svn: 267032
`--add-needed` and `--no-add-needed` have been deprecated due to the similarity
of their spelling to `--as-needed` and `--no-as-needed`. They have been renamed
to `--copy-dt-needed-entries` and `--no-copy-dt-needed-entries`.
llvm-svn: 267031
Rafael reported on the mailing list that this reduces peak memory
usage while linking llvm-as by 15%. It makes sense to make it
the default, and introduce an inverse knob -lto-no-discard-value-names
for those who want to restore the old behavior.
llvm-svn: 267020
SectionOrder vector was a part of LinkerScript class.
It can be removed because Commands vector contains the
same information and SectiorOrder is just a subset.
Differential revision: http://reviews.llvm.org/D19171
llvm-svn: 266974
These relocations are calculated as S + A - DTPREL or S + A - TPREL,
where DTPREL = TlsVA - 0x8000, TPREL = TlsVA - 0x7000. So the result
is relative to the TLS output section and is not an absolut value
The fix allows to escape creation of unnecessary dynamic relocations
in case of DSO linking.
llvm-svn: 266923
MIPS ABI turns using of GOT and dynamic relocations inside out. While
regular ABI uses dynamic relocations to fill up GOT entries MIPS ABI
requires dynamic linker to fills up GOT entries using specially sorted
dynamic symbol table. This affects even dynamic relocations against
symbols which do not require GOT entries creation explicitly, i.e. do
not have any GOT-relocations. So if a preemptible symbol has a dynamic
relocation we anyway have to create a GOT entry for it.
If a non-preemptible symbol has a dynamic relocation against it, dynamic
linker takes it st_value, adds offset and writes down result of the
dynamic relocation. In case of preemptible symbol dynamic linker
performs symbol resolution, writes the symbol value to the GOT entry and
reads the GOT entry when it needs to perform a dynamic relocation.
Differential Revision: http://reviews.llvm.org/D18948
llvm-svn: 266921
With the llvm change in r266919 this is the matching needed change to the lld code
now that libObject’s getName() for symbols now returning Expected<...> .
llvm-svn: 266920
Previously the function reads an operator and the rest of
the expressions. This patch makes it to actually parse an expression
which starts with a primary pexression followed by other expressions
concatenated with operators.
llvm-svn: 266912
Originally, linker scripts were basically an alternative way to specify
options to the command line options. But as we add more features to hanlde
symbols and sections, many member functions needed to be templated.
Now most the members are templated. It is probably time to template the
entire class.
Previously, LinkerScript is an executor of the linker script as well as
a storage of linker script configurations. This is not suitable to template
the class because when we are reading linker script files, we don't know
the ELF type yet, so we can't instantiate ELF-templated classes.
In this patch, I defined a new class, ScriptConfiguration, to store
linker script configurations. ScriptParser writes parse results to it,
and LinkerScript uses them.
Differential Revision: http://reviews.llvm.org/D19302
llvm-svn: 266908
It is now redundant. Writer.cpp can reason that 2 dynamic relocations
are needed: one to find the final got entry address and one to fill the
got entry.
llvm-svn: 266876
This reverts commit r266618. It breaks basically everything.
I think VS2013 doesn't interpret this code in the same way.
The size field (at least) is left uninitialized, causing all sorts of havok
(e.g. creating a 34GB file for a trivial hello world program).
The offending compiler reports itself as follows:
c:\release-vs2013>cl /?
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.40629 for x64
Copyright (C) Microsoft Corporation. All rights reserved.
llvm-svn: 266857
This patch is based heavily on George Rimor's patch
http://reviews.llvm.org/D19221.
In the linker script, you can write expressions to compute addresses.
Currently we only support "+" operator. This adds a few more operators.
Since this patch adds * and /, we need to handle operator precedences
properly. I implemented that using the operator-precedence grammar.
Differential Revision: http://reviews.llvm.org/D19237
llvm-svn: 266798
This requires adding a few more expression types, but is already a small
simplification. Having Writer.cpp know the exact expression will also
allow further simplifications.
llvm-svn: 266604
* Do script driven layout only if SECTIONS section exist.
Initial commit message:
[ELF] - Implemented basic location counter support.
This patch implements location counter support.
It also separates assign addresses for sections to assignAddressesScript() if it scipt exists.
Main testcase is test/ELF/linkerscript-locationcounter.s, It contains some work with location counter. It is basic now.
Implemented location counter assignment and '+' operations.
Patch by myself with LOTS of comments and design suggestions from Rui Ueyama.
Differential revision: http://reviews.llvm.org/D18499
llvm-svn: 266526
Parallelism level can be chosen using the new --lto-jobs=K option
where K is the number of threads used for CodeGen. It currently
defaults to 1.
llvm-svn: 266484
This patch implements location counter support.
It also separates assign addresses for sections to assignAddressesScript() if it scipt exists.
Main testcase is test/ELF/linkerscript-locationcounter.s, It contains some work with location counter. It is basic now.
Implemented location counter assignment and '+' operations.
Patch by myself with LOTS of comments and design suggestions from Rui Ueyama.
Differential revision: http://reviews.llvm.org/D18499
llvm-svn: 266457
The _gp_disp symbol designates offset between start of function and 'gp'
pointer into GOT. The following code is a typical MIPS function preamble
used to setup $gp register:
lui $gp, %hi(_gp_disp)
addi $gp, $gp, %lo(_gp_disp)
To calculate R_MIPS_HI16 / R_MIPS_LO16 relocations results we use
the following formulas:
%hi(_gp - P + A)
%lo(_gp - P + A + 4),
where _gp is a value of _gp symbol, A is addend, and P current address.
The R_MIPS_LO16 relocation references _gp_disp symbol is always the second
instruction. That is why we need four byte adjustments. The patch assigns
R_PC type for R_MIPS_LO16 relocation and adjusts its addend by 4. That fix
R_MIPS_LO16 calculation.
For details see p. 4-19 at ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
Differential Revision: http://reviews.llvm.org/D19115
llvm-svn: 266368
We never need to iterate over the K,V pairs, so we can avoid copying the
key as MapVector does.
This is a small speedup on most benchmarks.
llvm-svn: 266364
The DenseMap doesn't store hash results. This means that when it is
resized it has to recompute them.
This patch is a small hack that wraps the StringRef in a struct that
remembers the hash value. That way we can be sure it is only hashed
once.
llvm-svn: 266357
That was removed in r266304, but leads to warnings by Clang.
Thanks to Rafael Espíndola for pointing on that.
Though I think change was legal from point of C++.
llvm-svn: 266306
They are unnecessary, as the dynamic loader can apply the original relocations
directly. This was also resulting in the creation of copy relocations in PIEs.
Differential Revision: http://reviews.llvm.org/D19089
llvm-svn: 266273
This patch implements the --dynamic-list option, which adds a list of
global symbol that either should not be bounded by default definition
when creating shared libraries, or add in dynamic symbol table in the
case of creating executables.
The patch modifies the ScriptParserBase class to use a list of Token
instead of StringRef, which contains information if the token is a
quoted or unquoted strings. It is used to use a faster search for
exact match symbol name.
The input file follow a similar format of linker script with some
simplifications (it does not have scope or node names). It leads
to a simplified parser define in DynamicList.{cpp,h}.
Different from ld/gold neither glob pattern nor mangled names
(extern 'C++') are currently supported.
llvm-svn: 266227
Previously each archive file was reported no matter were it's member used or not,
like:
lib/libLLVMSupport.a
Now lld prints line for each used internal file, like:
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/StringSaver.cpp.o)
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/Host.cpp.o)
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/ConvertUTF.c.o)
That should be consistent with what gold do.
This fixes PR27243.
Differential revision: http://reviews.llvm.org/D19011
llvm-svn: 266220
This simplifies the code by allowing us to remove the visibility argument
to functions that create synthetic symbols.
The only functional change is that the visibility of the MIPS "_gp" symbol
is now hidden. Because this symbol is defined in every executable or DSO, it
would be difficult to observe a visibility change here.
Differential Revision: http://reviews.llvm.org/D19033
llvm-svn: 266208
We need to ensure that the address of an undefined weak symbol evaluates to
zero. We were getting this right for non-PIC executables (where the symbol
can be evaluated directly) and for DSOs (where we emit a symbolic relocation
for these symbols, as they are preemptible). But we weren't getting it right
for PIEs. Probably the simplest way to ensure that these symbols evaluate
to zero is by not creating a relocation in .got for them.
Differential Revision: http://reviews.llvm.org/D19044
llvm-svn: 266161
With this patch we use the first scan over the relocations to remember
the information we found about them: will them be relaxed, will a plt be
used, etc.
With that the actual relocation application becomes much simpler. That
is particularly true for the interfaces in Target.h.
This unfortunately means that we now do two passes over relocations for
non SHF_ALLOC sections. I think this can be solved by factoring out the
code that scans a single relocation. It can then be used both as a scan
that record info and for a dedicated direct relocation of non SHF_ALLOC
sections.
I also think it is possible to reduce the number of enum values by
representing a target with just an OutputSection and an offset (which
can be from the start or end).
This should unblock adding features like relocation optimizations.
llvm-svn: 266158
The _gp* family of symbols is defined as an offset in .got, and it is
not at all clear what should happen when .got is not defined.
This will allow some simplifications on how these symbols are handled.
llvm-svn: 266063
It is possible to have FDEs with duplicate PCs if ICF was able to merge
functions with FDEs, or if the input files for some reason contained duplicate
FDEs. We previously weren't handling this correctly when producing the
contents of the .eh_frame_hdr section; we were dropping entries and leaving
null entries at the end of the section, which confused consumers of unwind
data, such as the backtrace() function.
Fix the bug by setting the FDE count to the number of FDEs actually emitted
into .eh_frame_hdr, rather than the number of FDEs in .eh_frame.
Differential Revision: http://reviews.llvm.org/D18911
llvm-svn: 265957
It is possible that the same symbol referenced by two kinds of
relocations at the same time. The first type requires say GOT entry
creation, the second type requires dynamic copy relocation. For MIPS
targets they might be R_MIPS_GOT16 and R_MIPS_HI16 relocations. For X86
target they might be R_386_GOT32 and R_386_32 respectively.
Now LLD never creates GOT entry for a symbol if this symbol already has
related copy relocation. This patch solves this problem.
Differential Revision: http://reviews.llvm.org/D18862
llvm-svn: 265910
Previously, Lazy symbols were created for undefined symbols even though
such symbols cannot be resolved by loading object files. This patch
fixes that bug.
llvm-svn: 265847
Now MustBeInDynSym is only true if the symbol really must be in the
dynamic symbol table.
IsUsedInRegularObj is only true if the symbol is used in a .o or -u. Not
a .so or a .bc.
A benefit is that this is now done almost entirilly during symbol
resolution. The only exception is copy relocations because of aliases.
This includes a small fix in that protected symbols in .so don't force
executable symbols to be exported.
This also opens the way for implementing internalize for -shared.
llvm-svn: 265826
The spec says:
If a symbol definition with STV_PROTECTED visibility from a shared
object is taken as resolving a reference from an executable or another
shared object, the SHN_UNDEF symbol table entry created has STV_DEFAULT
visibility.
llvm-svn: 265792
This patch fixes dynamic relocation creation from GOT access in dynamic
objects on aarch64. Current code creates a plt relative one
(R_AARCH64_JUMP_SLOT) instead of a got relative (R_AARCH64_GLOB_DAT).
It leads the programs fails with:
$ cat t.cc
std::string test = "hello...\n";
int main ()
{
printf ("%s\n", test.c_str());
return 0;
}
$ clang++ t.cc -fpic -o t
$ ./t
hello...
Segmentation fault (core dumped)
Due the fact it will try to access the plt instead of the got for
__cxa_atexit registration for the std::string destruction. It will
lead in a bogus function address in atexit.
llvm-svn: 265784
Previously, we supported only one hash function, FNV-1, so
BuildIdSection directly handled hash computation. In this patch,
I made BuildIdSection an abstract class and defined two subclasses,
BuildIdFnv1 and BuildIdMd5.
llvm-svn: 265737
start-lib and end-lib are options to link object files in the same
semantics as archive files. If an object is in start-lib and end-lib,
the object is linked only when the file is needed to resolve
undefined symbols. That means, if an object is in start-lib and end-lib,
it behaves as if it were in an archive file.
In this patch, I introduced a new notion, LazyObjectFile. That is
analogous to Archive file type, but that works for a single object
file instead of for an archive file.
http://reviews.llvm.org/D18814
llvm-svn: 265710
This requires knowing input section offsets in output sections before
scanRelocs. This is generally a good thing and should allow further
simplifications in the creation of dynamic relocations.
llvm-svn: 265673
Stack is not executable by default in LLD-built executables unless
you pass -z execstack option. So --warn-execstack option does not make
sense to us.
llvm-svn: 265619
Simon Atanasyan