-warn-common
Warn when a common symbol is combined with another common symbol
or with a symbol definition. Unix linkers allow this somewhat
sloppy practice, but linkers on some other operating systems do
not. This option allows you to find potential problems from
combining global symbols.
Differential revision: http://reviews.llvm.org/D17998
llvm-svn: 263413
At least Linux has the kernel configuration to include the first page
of the executable into core files. We want build ID section to be
included in core files to identify them.
Here is the link to the description about the kernel configuration.
097f70b3c4/fs/Kconfig.binfmt (L46)
llvm-svn: 263351
which was reverted because included
unrelative changes by mistake.
Original commit message:
[ELF] - Change all messages to lowercase to be consistent.
That is directly opposite to http://reviews.llvm.org/D18045,
which was reverted.
This patch changes all messages to start from lowercase letter if
they were not before.
That is done to be consistent with clang.
Differential revision: http://reviews.llvm.org/D18085
llvm-svn: 263337
This patch implements --build-id. After the linker creates an output file
in the memory buffer, it computes the FNV1 hash of the resulting file
and set the hash to the .note section as a build-id.
GNU ld and gold have the same feature, but their default choice of the
hash function is different. Their default is SHA1.
We made a deliberate choice to not use a secure hash function for the
sake of performance. Computing a secure hash is slow -- for example,
MD5 throughput is usually 400 MB/s or so. SHA1 is slower than that.
As a result, if you pass --build-id to gold, then the linker becomes about
10% slower than that without the option. We observed a similar degradation
in an experimental implementation of build-id for LLD. On the other hand,
we observed only 1-2% performance degradation with the FNV hash.
Since build-id is not for digital certificate or anything, we think that
a very small probability of collision is acceptable.
We considered using other signals such as using input file timestamps as
inputs to a secure hash function. But such signals would have an issue
with build reproducibility (if you build a binary from the same source
tree using the same toolchain, the build id should become the same.)
GNU linkers accepts --build-id=<style> option where style is one of
"MD5", "SHA1", or an arbitrary hex string. That option is out of scope
of this patch.
http://reviews.llvm.org/D18091
llvm-svn: 263292
That is directly opposite to http://reviews.llvm.org/D18045,
which was reverted.
This patch changes all messages to start from lowercase letter if
they were not before.
That is done to be consistent with clang.
Differential revision: http://reviews.llvm.org/D18085
llvm-svn: 263252
It was discussed to make all messages be
lowercase to be consistent with clang.
(also reverts the r263128 which fixed
build bot fail after r263125)
Original commit message:
[ELF] - Consistent spelling for error/warning messages
Previously error and warnings were not consistent in lld.
Some of them started from lowercase letter, others from
uppercase. Also there was one or two which had a dot at the end.
This patch changes all messages to start from uppercase letter if
they were not before.
Differential revision: http://reviews.llvm.org/D18045
llvm-svn: 263240
This is reduced from an issue found in practice.
The original version of D18012 needed another patch to handle this, but
it now works since we are using a more correct GV->hasAppendingLinkage()
check that Rafael suggested.
This is what remains of that other patch.
llvm-svn: 263181
Summary:
More generally, appending linkage is a special case that we don't want
to create a SymbolBody for.
Reviewers: rafael, ruiu
Subscribers: Bigcheese, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D18012
llvm-svn: 263179
R_X86_64_DTPOFF64 was not handled properly.
Next sample app was impossible to link before this patch:
~/pg/release/bin/clang -target x86_64-pc-linux testthread.cpp -c -g
~/pg/d+a/bin/ld.lld testthread.o
"Unknown TLS optimization" (value was 17)
__thread int x = 0;
void _start() {
}
It works fine now.
Differential revision: http://reviews.llvm.org/D18039
llvm-svn: 263150
(http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/8662).
Test fails on linux only.
Original commit message:
[ELF] - Consistent spelling for error/warning messages
Previously error and warnings were not consistent in lld.
Some of them started from lowercase letter, others from
uppercase. Also there was one or two which had a dot at the end.
This patch changes all messages to start from uppercase letter if
they were not before.
Differential revision: http://reviews.llvm.org/D18045
llvm-svn: 263128
Previously error and warnings were not consistent in lld.
Some of them started from lowercase letter, others from
uppercase. Also there was one or two which had a dot at the end.
This patch changes all messages to start from uppercase letter if
they were not before.
Differential revision: http://reviews.llvm.org/D18045
llvm-svn: 263125
Summary:
They are needed for inline asm during LTO.
In particular we hit the report_fatal_error on
llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp:138
LLVM ERROR: Inline asm not supported by this streamer because we don't have an asm parser for this target
Reviewers: ruiu, rafael
Subscribers: Bigcheese, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D18027
llvm-svn: 263094
Summary:
This implements another part of -save-temps.
After this, the only remaining part is dumping the optimized bitcode. But
currently LLD's LTO doesn't have a non-intrusive place to put this.
Eventually we probably will and it will make sense to add it then.
Reviewers: ruiu, rafael
Subscribers: joker.eph, Bigcheese, llvm-commits
Differential Revision: http://reviews.llvm.org/D18009
llvm-svn: 263070
Summary:
This is useful for debugging issues with LTO.
The option follows the analogous option in ld64 and the gold plugin (per
Rafael's suggestion).
For starters, this only dumps the combined bitcode file.
In a future patch I will add dumping for the .o file.
The naming of the output follows ld64's convention which is slightly more
consistent IMO (consistent `.lto.<extension>` for all the files).
Reviewers: rafael, ruiu
Subscribers: joker.eph, Bigcheese, llvm-commits
Differential Revision: http://reviews.llvm.org/D18006
llvm-svn: 263055
Summary:
At the very least we hit
Assertion failed: (((Flags & RF_HaveUnmaterializedMetadata) || Node->isResolved()) && "Unexpected unresolved node"), function MapMetadataImpl, file /Users/Sean/pg/llvm/lib/Transforms/Utils/ValueMapper.cpp, line 375.
on the included test case.
We currently do things like parse the module twice to keep the
implementation minimal. I think it makes sense to add start with eager
loading for similar reasons.
Reviewers: rafael
Subscribers: ruiu, Bigcheese, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D17982
llvm-svn: 263045
Each object file compiled in split stack mode will have an empty
section with a special name: .note.GNU-split-stack
We don't support this in linker now, so patch just adds an error out for that.
Differential revision: http://reviews.llvm.org/D17918
llvm-svn: 263039
Summary:
Is there any other code needed for correctly handling appending linkage?
Do we need to do something more with @llvm.global_ctors in
SymbolTable.cpp:addBitcodeFile; otherwise the combined bitcode module
won't have all the global ctors.
Reviewers: rafael
Subscribers: Bigcheese, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D17975
llvm-svn: 262992
Summary:
This causes the issue in PR26872 to go away now that we aren't creating
symbols for the string literals, but that may just be concealing a
deeper problem, so best to keep that PR open.
Reviewers: rafael
Subscribers: Bigcheese, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D17971
llvm-svn: 262968
It was a badly specified hack for when a tls relocation should be
propagated to the dynamic relocation table.
This replaces it with a not as bad hack of saying that a local dynamic
tls relocation is never preempted.
I will try to remove even that second hack in the next patch.
llvm-svn: 262955
It was causing errors like
/lib/libc.so.6 is incompatible with elf_x86_64
when linking on Fedora.
Every system has different default paths. It seems better to just trust
the driver to pass the correct -L options.
This reverts commit 262910.
llvm-svn: 262941
This has a few advantages:
* If lld selected a non bitcode symbol, be the bitcode GV is not merged
* lib/Linker is not redoing symbol resolution.
llvm-svn: 262773
When generating relocatable output SHT_NOBITS sections
were still occupy the file space.
Differential revision: http://reviews.llvm.org/D17857
llvm-svn: 262650
The hack of using a plt address as the address of an undefined function
only works in executables. Don't try it with shared libraries.
llvm-svn: 262642
There was a known limitation for -r option:
relocations against local symbols were not supported.
For example rel[a].eh_frame sections contained relocations against sections
and that was not supported for -r before. Patch fixes that.
Differential review: http://reviews.llvm.org/D17813
llvm-svn: 262590
The patch fixes two related problems:
- If CIE augmentation string has 'L' token the CIE contains a byte
defines LSDA encoding. We should skip this byte in `getFdeEncoding`
routine. Before this fix we do not skip it and if the next token
is 'R' treat this byte as FDE encoding.
- FDE encoding format has separate flags e.g. DW_EH_PE_pcrel for
definition of relative pointers. We should add .eh_frame address to
the PC value iif the DW_EH_PE_pcrel is specified.
http://www.airs.com/blog/archives/460
There is one more not fixed problem in this code. If PC value is encoded
using signed relative format e.g. DW_EH_PE_sdata4 | DW_EH_PE_pcrel we
should sign extend result of read32 to perform calculation correctly.
I am going to fix that in a separate patch.
Differential Revision: http://reviews.llvm.org/D17733
llvm-svn: 262461
__start_/__end_ <section-name> symbols and other specials like:
preinit_array_start/end
init_array_start/end
fini_array_start/end
should not be created by linker when creating relocatable files.
Differential revision: http://reviews.llvm.org/D17774
llvm-svn: 262366
BSD linker scripts contain special cases to add NOP
padding to code sections. Syntax is next:
.init:
{
KEEP (*(.init))
} =0x90909090
(0x90 is NOP)
This patch implements that functionality.
llvm-svn: 262020
https://docs.oracle.com/cd/E53394_01/html/E54766/u-etext-3c.html
It is said that:
_etext - The address of _etext is the first
location after the last read-only loadable segment.
_edata - The address of _edata is the first
location after the last read-write loadable segment.
_end - If the address of _edata is greater than the address
of _etext, the address of _end is same as the address of _edata.
In real life _end and _edata has different values for that case.
Both gold/bfd set _edata to the end of the last non SHT_NOBITS section.
This patch do the same for consistency.
It should fix the https://llvm.org/bugs/show_bug.cgi?id=26729.
Differential revision: http://reviews.llvm.org/D17601
llvm-svn: 262019
For shared libraries we allow any weak undefined symbol to eventually be
resolved, even if we never see a definition in another .so. This matches
the behavior when handling other undefined symbols in a shared library.
For executables, we require seeing a definition in a .so or resolve it
to zero. This is also similar to how non weak symbols are handled.
llvm-svn: 262017
R_MIPS_GOT16 relocation against local symbol requires index of a local
GOT entry which contains page address corresponds to sum of the symbol
address and addend. The addend in that case is calculated using addends
from the R_MIPS_GOT16 and paired R_MIPS_LO16 relocations.
Differential Revision: http://reviews.llvm.org/D17610
llvm-svn: 261930
This patch implements the same algorithm as LLD/COFF's ICF. I'm
not going to repeat the same description about how it works, so you
want to read the comment in ICF.cpp in this patch if you want to know
the details. This algorithm should be more powerful than the ICF
algorithm implemented in GNU gold. It can even merge mutually-recursive
functions (which is harder than one might think).
ICF is a fairly effective size optimization. Here are some examples.
LLD: 37.14 MB -> 35.80 MB (-3.6%)
Clang: 59.41 MB -> 57.80 MB (-2.7%)
The lacking feature is "safe" version of ICF. This merges all
identical sections. That is not compatible with a C/C++ language
requirement that two distinct functions must have distinct addresses.
But as long as your program do not rely on the pointer equality
(which is in many cases true), your program should work with the
feature. LLD works fine for example.
GNU gold implements so-called "safe ICF" that identifies functions
that are safe to merge by heuristics -- for example, gold thinks
that constructors are safe to merge because there is no way to
take an address of a constructor in C++. We have a different idea
which David Majnemer suggested that we add NOPs at beginning of
merged functions so that two or more pointers can have distinct
values. We can do whichever we want, but this patch does not
include neither.
http://reviews.llvm.org/D17529
llvm-svn: 261912
-r, -relocatable - Generate relocatable output
Currently does not have support for files containing
relocation sections with entries that refer to local
symbols (like rel[a].eh_frame which refer to sections
and not to symbols)
Differential revision: http://reviews.llvm.org/D14382
llvm-svn: 261838
This commit does two related thing. At first, it enumerates supported
absolute MIPS relocations in the `MipsTargetInfo<ELFT>::isRelRelative`
method. In that case the code is shorter and the case switch does not
tend to grow. At second, it prevents R_MIPS_COPY and PLT creation for
relative relocations. For almost all relative MIPS relocations like
R_MIPS_PC19_S2, R_MIPS_PCHI16 etc it does not have a sence. The only
exception is R_MIPS_PC32. GNU linker creates a copy relocation or PLT
entry for it. But I could not find any real test case uses R_MIPS_PC32
with DSO defined symbol as a target. So for now I prefer to skip this
case to simplify the LLD code.
llvm-svn: 261822
There is nothing aarch64 specific in here. If a symbol can be preempted,
we need to copy the full relocation to the dynamic linker.
If a symbol cannot be preempted, we can make the dynamic linker life
easier and produce a relative relocation.
This is directly equivalent to R_X86_64_64 to R_x86_64_RELATIVE
conversion.
llvm-svn: 261678
The .tbss section is in the middle of a PT_LOAD. Whatever treatment we
give to its address we must also give to the offset.
We were ignoring it for address computations, but not for offset.
Fixes pr26712.
llvm-svn: 261667
This patch moves BitcodeFile instantiation into createObjectFile.
Previously, we handle bitcode files outside that function and did
not handle for --whole-archive.
http://reviews.llvm.org/D17527
llvm-svn: 261663
This patch fixes the R_AARCH64_ABS64 relocation when used in shared mode,
where it requires a dynamic R_AARCH64_RELATIVE relocation. To correct set
the addend on the dynamic relocation (since it will be used by the dynamic
linker), a new TargetInfo specific hook was created (getDynRelativeAddend)
to get the correct addend based on relocation type.
The patch fixes the issues when creating shared library code against
{init,fini}_array, where it issues R_AARCH64_ABS64 relocation against
local symbols.
llvm-svn: 261651
When link-time garbage collection is in use (-gc-sections), it is
often useful to mark sections that should not be eliminated.
This is accomplished by surrounding an input section's wildcard
entry with KEEP(). Patch implements that command.
Differential revision: http://reviews.llvm.org/D17242
llvm-svn: 261616
A weak undefined should not fetch archive members, so we have to keep
the Lazy symbol.
That means the lazy symbol has to encode information about the original
weak undef.
Fixes pr25762.
llvm-svn: 261591
This reduces the .rodata of scyladb from 4501932 to 4334639 bytes (1.038
times smaller).
I don't think it is critical to support tail merging, just exact
duplicates, but given the code organization it was actually a bit easier
to support both.
llvm-svn: 261327
Each rule in SECTIONS commands is something like ".foo *(.baz.*)",
which instructs the linker to collect all sections whose name matches
".baz.*" from all files and put them into .foo section.
Previously, we didn't recognize the wildcard character. This patch
adds that feature.
Performance impact is a bit concerning because a linker script can
contain hundreds of SECTIONS rules, and doing pattern matching against
each rule would be too expensive. We could merge all patterns into
single DFA so that it takes O(n) to the input size. However, it is
probably too much at this moment -- we don't know whether the
performance of pattern matching matters or not. So I chose to
implement the simplest algorithm in this patch. I hope this simple
pattern matcher is sufficient.
llvm-svn: 260745
This patch adds some TLS relocations and relaxations for AArch64.
Some Global-Dynamic relocation are handled by optimizing them to
Local-Exec (Initial-Exec is not yet supported). They are:
- R_AARCH64_TLSDESC_ADR_PAGE21
- R_AARCH64_TLSDESC_LD64_LO12_NC
- R_AARCH64_TLSDESC_ADD_LO12_NC
- R_AARCH64_TLSDESC_CALL
Also some Init-Exec is optimized to Local-Exec if possible. They are:
- R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21
- R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC
Finally some Local-Exec relocation are handled in relocateOne:
- R_AARCH64_TLSLE_ADD_TPREL_HI12
- R_AARCH64_TLSLE_ADD_TPREL_LO12_NC
This work is mainly for compiler bootstrap, where static binaries is
showing good progress (although shared object still lacking support
from both TLS aarch64 backend and some other issues).
llvm-svn: 260677
Previously, if both A and B are ".ctors", both compCtors(A, B) and
compCtors(B, A) are true, which is a violation of the strict weak
ordering because such function is not antisymmetric.
llvm-svn: 260633
They don't count for the memory or file size, so this is mostly just a
simplification.
The only noticeable difference should be fewer empty program headers.
llvm-svn: 260465
Global constructors and destructors are guaranteed to be called
in the order as they appear in a translation unit. So we don't want
to mess up the order if they have the same priority.
llvm-svn: 260463
The patch adds lazy relocation support for MIPS and R_MIPS_26 relocation
handing.
R_MIPS_26 relocation might require PLT entry creation. In that case it
is fully supported by the patch. But if the relocation target is a local
symbol we need to use a different expression to calculate the relocation
result. This case is not implemented yet because there is no method to
get know the kind of relocation target in the `relocateOne` routine.
Differential Revision: http://reviews.llvm.org/D16982
llvm-svn: 260424
This is the function equivalent of a copy relocation.
Since functions are expected to change sizes, we cannot use copy
relocations. In situations where one would be needed, what is done
instead is:
* Create a plt entry
* Output an undefined symbol whose addr is the plt entry.
The dynamic linker makes sure any shared library uses the plt entry as
the function address.
llvm-svn: 260224
I removed "CIE/FIE size is too large" error because that was not
checking for correct error conditions. [UINT_MAX - 4, UINT_MAX) is
a correct range as a size of a CIE/FDE record. It's just that the
size cannot be larger than the section size.
llvm-svn: 259951
Summary:
LLVM3.3 (and earlier) would fail to include a relocation section in
the group that the section it was relocating is in. Object files
affected by this issue have been encountered in the wild when using LLD.
This would result in a siutation like:
Section {
Index: 5
Name: .text._Z3fooIiEvv (6)
Type: SHT_PROGBITS (0x1)
Flags [ (0x206)
SHF_ALLOC (0x2)
SHF_EXECINSTR (0x4)
SHF_GROUP (0x200)
]
Address: 0x0
Offset: 0x48
Size: 5
Link: 0
Info: 0
AddressAlignment: 1
EntrySize: 0
}
Section {
Index: 6
Name: .rela.text._Z3fooIiEvv (1)
Type: SHT_RELA (0x4)
Flags [ (0x0)
]
Address: 0x0
Offset: 0x3F0
Size: 24
Link: 8
Info: 5
AddressAlignment: 8
EntrySize: 24
}
In LLD, during symbol resolution, we discard the section containing the
weak symbol, but this amounts to replacing it with
InputSection<ELFT>::Discarded.
When we later saw the corresponding relocation section, we would then
end up pusing onto InputSection<ELFT>::Discarded.RelocSections, which is
bogus.
Reviewers: ruiu, rafael
Subscribers: llvm-commits, Bigcheese
Differential Revision: http://reviews.llvm.org/D16898
llvm-svn: 259831
If relocation against symbol requires GOT entry creation and this symbol
is defined in DSO, the GOT entry should be created in the 'global' part
of the GOT even if we link executable file. Also we do not need to create
a dynamic symbol table entry for global symbol corresponding to the
local GOT entry.
llvm-svn: 259778
On some Windows environment, this test did not fail, because opening NUL
with FileOutputBuffer didn't fail. Thanks to George Rimar for reporting.
llvm-svn: 259669
It can fail to open an output file for various reasons, including
lack of permission, too long filename, or the output file is not
a mmap'able file.
llvm-svn: 259596
Previously, we used both single quotes and double quotes, and
some single-quoted tokens are concatenated with next tokens because
there were no spaces between them. That may be a cause of test flakiness
on Windows, which is reported as https://llvm.org/bugs/show_bug.cgi?id=26388.
The new test commands are more straightforward than before.
llvm-svn: 259559
This patch adds "Error" field to LinkerScript class. That field
is false by default, and set to true if there is a syntax error
in an input file. The linker script parser is a recursive-descedent
parser. Each function returns if Error is true -- so that
eventually the whole parser returns to a caller.
http://reviews.llvm.org/D16667
llvm-svn: 259557
-Bsymbolic-functions:
When creating a shared library, bind references to global
function symbols to the definition within the shared library, if any.
This patch also fixed behavior of already existent -Bsymbolic:
previously PLT entries were created even if -Bsymbolic was specified.
Differential revision: http://reviews.llvm.org/D16411
llvm-svn: 259481
Some dynamic table tags like RELSZ and PLTRELSZ depens on result of
finalizing corresponding relocation sections. Therefore we have to
finalize .dynamic section at the end.
Differential Revision: http://reviews.llvm.org/D16799
llvm-svn: 259478
If object files are drawn from archive files, the error message should
be something like "conflict symbols in foo.a(bar.o) and baz.o" instead
of "conflict symbols in bar.o and baz.o". This patch implements that.
llvm-svn: 259475
This avoids the need to have reserve and addString in sync.
We avoid hashing the global symbols again. This means that we don't
merge a global symbol that has the same name as some other string, but
that doesn't seem very common. The string table size is the same in
clang an scylladb with or without hashing global symbols again.
llvm-svn: 259136
Main executable did not export symbols that exist both in the main executable and in DSOs before this patch.
Symbols from object files that override symbols in DSO should be added to .dynsym table.
Differential revision: http://reviews.llvm.org/D16405
llvm-svn: 258672
There was an off by one error because the StringRef.substr functions
second argument is a length, not the end index.
Also updated a few ELF files which failed when run on Jenkins with paths
including the @ character. This is often used in Jenkins for shared
workspace plugin.
Reviewed by Rui Ueyama
llvm-svn: 258583
Some MIPS relocation (for now R_MIPS_GOT16) requires creation of GOT
entries for symbol not included in the dynamic symbol table. They are
local symbols and non-local symbols with 'local' visibility. Local GOT
entries occupy continuous block between GOT header and regular GOT
entries.
The patch adds initial support for handling local GOT entries. The main
problem is allocating local GOT entries for local symbols. Such entries
should be initialized by high 16-bit of the symbol value. In ideal world
there should be no duplicated entries with the same values. But at the
moment of the `Writer::scanRelocs` call we do not know a value of the
symbol. In this patch we create new local GOT entry for each relocation
against local symbol, though we can exhaust GOT quickly. That needs to
be optimized later. When we calculate relocation we know a final symbol
value and request local GOT entry index. To do that we maintain map
between addresses and local GOT entry indexes. If we start to calculate
relocations in parallel we will have to serialize access to this map.
Differential Revision: http://reviews.llvm.org/D16324
llvm-svn: 258388
Added check for terminator CIE/FDE which has zero data size.
void EHOutputSection<ELFT>::addSectionAux(
...
// If CIE/FDE data length is zero then Length is 4, this
// shall be considered a terminator and processing shall end.
if (Length == 4)
break;
...
After this "Bug 25923 - lld/ELF2 linked application crashes if exceptions were used." is fixed for me. Self link of clang also works.
Initial commit message:
[ELF] - implemented --eh-frame-hdr command line option.
--eh-frame-hdr
Request creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME" segment header.
Both gold and the GNU linker support an option --eh-frame-hdr which tell them to construct a header for all the .eh_frame sections. This header is placed in a section named .eh_frame_hdr and also in a PT_GNU_EH_FRAME segment. At runtime the unwinder can find all the PT_GNU_EH_FRAME segments by calling dl_iterate_phdr.
This section contains a lookup table for quick binary search of FDEs.
Detailed info can be found here:
http://www.airs.com/blog/archives/462
Differential revision: http://reviews.llvm.org/D15712
llvm-svn: 257889
MIPS ABI has relocations like R_MIPS_JALR which is just a hint for
linker to make some code optimization. Such relocations should not be
handled as a regular ones and lead to say dynamic relocation creation.
The patch introduces new virtual `Target::isHintReloc` method, overrides
it in the `MipsTargetInfo` class and calls it in the `Writer<ELFT>::scanRelocs`
method.
Differential Revision: http://reviews.llvm.org/D16193
llvm-svn: 257798
George Rimar