Previously the next sample script would generate 2 entries in
Config->SymbolVersions with the same version name.
VERSION {
global: c;
};
That happened because parseVersionSymbols() was called twice.
At first for "global:" and since there is no local tag, it was called again.
Patch fixes the issue, testcase was updated to demonstrate.
Differential revision: http://reviews.llvm.org/D21640
llvm-svn: 273663
Patch implements support of zlib style compressed sections.
SHF_COMPRESSED flag is used to recognize that decompression is required.
After that decompression is performed and flag is removed from output.
Differential revision: http://reviews.llvm.org/D20272
llvm-svn: 273661
The patch adds one more partition to the MIPS GOT. This time it is for
TLS related GOT entries. Such entries are located after 'local' and 'global'
ones. We cannot get a final offset for these entries at the time of
creation because we do not know size of 'local' and 'global' partitions.
So we have to adjust the offset later using `getMipsTlsOffset()` method.
All MIPS TLS relocations which need GOT entries operates MIPS style GOT
offset - 'offset from the GOT's beginning' - MipsGPOffset constant. That
is why I add new types of relocation expressions.
One more difference from othe ABIs is that the MIPS ABI does not support
any TLS relocation relaxations. I decided to make a separate function
`handleMipsTlsRelocation` and put MIPS TLS relocation handling code
there. It is similar to `handleTlsRelocation` routine and duplicates its
code. But it allows to make the code cleaner and prevent pollution of
the `handleTlsRelocation` by MIPS 'if' statements.
Differential Revision: http://reviews.llvm.org/D21606
llvm-svn: 273569
Patch by Shridhar Joshi.
This option provides names of all the link time modules which define and
reference symbols requested by user. This helps to speed up application
development by detecting references causing undefined symbols.
It also helps in detecting symbols being resolved to wrong (unintended)
definitions in case of applications containing multiple definitions for
same symbols with different types, bindings.
Implements PR28226.
llvm-svn: 273536
Peter Smith found while trying to support thunk creation for ARM that
LLD sometimes creates broken thunks for MIPS. The cause of the bug is
that we assign file offsets to input sections too early. We need to
create all sections and then assign section offsets because appending
thunks changes file offsets for all following sections.
This patch separates the pass to assign file offsets from thunk
creation pass. This effectively reverts r265673.
Differential Revision: http://reviews.llvm.org/D21598
llvm-svn: 273532
This fixes PR28218. Thanks to Rafael for spotting a failure in
the SHARED_LIBS build!
Differential Revision: http://reviews.llvm.org/D21577
llvm-svn: 273451
Patch implements hierarchies for version scripts.
This allows to handle script files with dependencies, like next one has:
LIBSAMPLE_1.0{
global:
a;
};
LIBSAMPLE_2.0
{
global:
b;
}LIBSAMPLE_1.0;
Differential revision: http://reviews.llvm.org/D21556
llvm-svn: 273423
For next version script:
VER1{
global:
a;
};
VER2{
global:
a;
};
gold would produce warning like:
"warning: using 'VER1' as version for 'a' which is also named in version 'VER2' in script."
Documentation also says we do not want this duplications (https://people.freebsd.org/~deischen/symver/library_versioning.txt):
"Note that you do not want to duplicate symbols in the map file. The .symver directives are all that is required to add compatibility
symbols into old versions."
This patch restricts such mixing and makes lld to produce error in this case.
Differential revision: http://reviews.llvm.org/D21555
llvm-svn: 273396
This patch is to rewrite the function with a table-lookup-ish approach
so that it can read as a series of "convert this pattern to this" pattern.
llvm-svn: 273238
With fix:
-soname flag was not set in testcase. Hash calculated for base def was different on local
and bot machines because filename fos used for calculating.
Initial commit message:
Patch implements basic support of versioned symbols.
There is no wildcards patterns matching except local: *;
There is no support for hierarchies.
There is no support for symbols overrides (@ vs @@ not handled).
This patch allows programs that using simple scripts to link and run.
Differential revision: http://reviews.llvm.org/D21018
llvm-svn: 273152
Patch implements basic support of versioned symbols.
There is no wildcards patterns matching except local: *;
There is no support for hierarchies.
There is no support for symbols overrides (@ vs @@ not handled).
This patch allows programs that using simple scripts to link and run.
Differential revision: http://reviews.llvm.org/D21018
llvm-svn: 273143
There are two motivations for this patch. The first one is a preparation
for support MIPS TLS relocations. It might sound like a joke but for GOT
entries related to TLS relocations MIPS ABI uses almost regular approach
with creation of dynamic relocations for each GOT enty etc. But we need
to separate these 'regular' TLS related entries from MIPS specific local
and global parts of GOT. ABI declare simple solution - all TLS related
entries allocated at the end of GOT after local/global parts. The second
motivation it to support GOT relocations for non-preemptible symbols
with addends. If we have more than one GOT relocations against symbol S
with different addends we need to create GOT entries for each unique
Symbol/Addend pairs.
So we store all MIPS GOT entries in separate containers. For non-preemptible
symbols we have to maintain two data structures. The first one is MipsLocal
vector. Each entry corresponds to the GOT entry from the 'local' part
of the GOT contains the symbol's address plus addend. The second one
is MipsLocalMap. It is a map from Symbol/Addend pair to the GOT index.
Differential Revision: http://reviews.llvm.org/D21297
llvm-svn: 273127
Doing that in an anonymous version is a bit silly, but this opens the
way for supporting it in general.
Since we don't support actual versions, for now we just disable the
version script if we detect that it is missing a local.
llvm-svn: 273000
Patch updates the version script parser to parse versioned files.
In a simple way, just adding them to VersionScriptGlobals list.
Differential revision: http://reviews.llvm.org/D21439
llvm-svn: 272934
Add support for the R_ARM_THM relocations used in the objects present
in arm-linux-gnueabihf-gcc. These are:
R_ARM_THM_CALL
R_ARM_THM_JUMP11
R_ARM_THM_JUMP19
R_ARM_THM_JUMP24
R_ARM_THM_MOVT_ABS
R_ARM_THM_MOVW_ABS_NC
Interworking between ARM and Thumb is partially supported with BLX.
The R_ARM_CALL relocation for ARM instructions and R_ARM_THM_CALL
relocation for Thumb instructions will write out a BL or BLX depending
on the state of the Target.
Assumptions:
- Availability of BLX and extended range of Thumb 4-byte Branch
instructions.
- In relocateOne if (Val & 0x1) == 1 target is Thumb, 0 is ARM.
This will hold for objects that comply with the ABI for the
ARM architecture.
This is sufficient for hello world to work with a recent
arm-linux-gnueabihf distribution.
Limitations:
No interworking for R_ARM_JUMP24, R_ARM_THM_JUMP24, R_ARM_THM_JUMP19
and the deprecated R_ARM_PLT32 and R_ARM_PC24 instructions as these
cannot be written out as a BLX and need a state change thunk.
No range extension thunks. The R_ARM_JUMP24 and R_ARM_THM_CALL have a
range of 16Mb
llvm-svn: 272881
This should never happen with correct programs, but it is trivial
write a testcase where lld would crash or report duplicated
symbols. We now behave like when an archive is used and include the
file only once.
llvm-svn: 272724
Previously message told us that relocations could
not be used when making shared object. That was
correct because message could appear (and it is expected)
when we linked executable.
Message should have being changed to something
that says we can't use a subset of relocations against shared
symbols.
Patch fixes the text.
llvm-svn: 272478
Initially we wanted to check that these two relocations are not present when linking DSO because of
possible overflow in runtime. Patch moves them to writable segment in testcases to allow
proper error check to trigger.
Otherwise error message about using dynamic relocations against text segment was shown.
Differential revision: http://reviews.llvm.org/D21184
llvm-svn: 272379
It was reported in PR28020, that lld does not link code which
gold do. But in fact that is expected behavior as we do not
support DT_TEXTREL.
This patch changes error message as it can report about relocations against
text segments exclusively, other dynamic relocations errors can
be handled separately.
Differential revision: http://reviews.llvm.org/D21133
llvm-svn: 272377
We can now use this to decide whether to emit a verneed during the final
pass over the symbols. We were previously wrongly creating a verneed entry
in the case where all references to a DSO's symbols were weak.
In a future change we may also want to use the used bit to control whether
shared symbols are preemptible and appear in the dynsym. This seems a little
tricky to do at the moment because isNeeded() is templated.
The only other functional change here is that we emit a DT_NEEDED for DSOs
whose symbols are all preempted by objects that appear later in the link. But
that doesn't seem too important to me.
Differential Revision: http://reviews.llvm.org/D21171
llvm-svn: 272282
If the symbol is local we don't need to create a R_X86_64_DTPOFF64, we
can just write the correct value in the got.
Should fix pr28018.
llvm-svn: 272205
Previously this test performed check of binary data. Since
llvm-readobj currently able to dump all 3 types of version relative
sections, that can be used to make this test more transparent.
Patch do that.
Differential revision: http://reviews.llvm.org/D21024
llvm-svn: 272120
Add support for an ARM Target and the initial set of relocations
and PLT entries that are necessary for an ARM only hello world to
link. This has been tested against an ARM only sysroot from the
4.2.0 CodeSourcery Lite release.
Tests have been added to test/ELF for the support that has been
implemented.
Main limitations:
- No Thumb support
- Relocations incomplete
- No C++ exceptions support
- No TLS support
- No range extension or interworking veneer (thunk) support
- No Build Attribute support
- No Big-endian support
The deprecated relocations R_ARM_PLT32 and R_ARM_PC24 have been
implemented as these are used by the 4.2.0 CodeSourcery Lite release.
llvm-svn: 271993
This is mostly extracted from http://reviews.llvm.org/D18960.
The general idea for tlsdesc is that the two GD got entries are used
for a function pointer and its argument. The dynamic linker sets
both. In the non-dlopen case the dynamic linker sets the function to
the identity and the argument to the offset in the tls block.
All that the static linker has to do in the non-dlopen case is
relocate the code to point to the got entries and create a dynamic
relocation.
The dlopen case is more complicated, but can be implemented in another patch.
llvm-svn: 271569
Patch implements next relaxation from latest ABI:
"Convert memory operand of test and binop into immediate operand, where binop is one of adc, add, and, cmp, or,
sbb, sub, xor instructions, when position-independent code is disabled."
It is described in System V Application Binary Interface AMD64 Architecture Processor
Supplement Draft Version 0.99.8 (https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-r249.pdf,
B.2 "B.2 Optimize GOTPCRELX Relocations").
Differential revision: http://reviews.llvm.org/D20793
llvm-svn: 271405
When we undefine, we also preserve type of symbol so that we get
it right in the combined LTO object.
Differential Revision: http://reviews.llvm.org/D20851
llvm-svn: 271403
In case of MIPS, GP-relative relocations always resolve to a definition
in a regular input file, ignoring the one-definition rule. Such
relocations are used to setup GP relative offsets in a function's
prologue. So we, for example, should not attempt to create a dynamic
relocation even if the target symbol is preemptible.
Fixes bug 27880.
Differential Revision: http://reviews.llvm.org/D20664
llvm-svn: 271100
MIPS .reginfo and .MIPS.options sections are consumed by the linker, and
the linker produces a single output section. But it is possible that
input files contain section symbol points to the corresponding input
section. In case of generation a relocatable output we need to write
such symbols to the output file.
Fixes bug 27878.
Differential Revision: http://reviews.llvm.org/D20688
llvm-svn: 270910
D15779 introduced basic approach to support new relaxations.
This patch implements relaxations for jmp and call instructions,
described in System V Application Binary Interface AMD64 Architecture Processor
Supplement Draft Version 0.99.8 (https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-r249.pdf,
B.2 "B.2 Optimize GOTPCRELX Relocations")
Differential revision: http://reviews.llvm.org/D20622
llvm-svn: 270721
Add another possible error that may be reported for the same case. The
original reproduction case that prompted r270706 produced the error
"corrupted CIE" instead of "corrupted or unsupported CIE information".
The specific error depends on arbitrary data later in the file so
check that neither is emitted in case the input is ever changed.
Document the process used to create the input .o and rename the test
file to .s, as requested by Rafael.
llvm-svn: 270709
"A zero length string indicates that no augmentation data is present."
The FreeBSD/mips toolchain (GCC 4.2.1) generates .debug_frame sections
containing CIE records that have an empty augmentation string.
Differential Revision: http://reviews.llvm.org/D19928
llvm-svn: 270706
System V Application Binary Interface AMD64 Architecture Processor Supplement Draft Version 0.99.8
(https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-r249.pdf, B.2 "B.2 Optimize GOTPCRELX Relocations")
introduces possible relaxations for R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX.
That patch implements the next relaxation:
mov foo@GOTPCREL(%rip), %reg => lea foo(%rip), %reg
and also opens door for implementing all other ones.
Implementation was suggested by Rafael Ávila de Espíndola with few additions and testcases by myself.
Differential revision: http://reviews.llvm.org/D15779
llvm-svn: 270705
Previously, we created a .bss section when needed. We had a function
ensureBss() for that purpose. Turned out that was error-prone
because it was easy to forget to call that function before accessing
the .bss section.
This patch always make the BSS section. The section is added to the
output when it's not empty.
llvm-svn: 270527
Copy relocations are relocations to copy data from DSOs to
executable's .bss segment at runtime. It doesn't make sense to
create such relocations for zero-sized symbols.
GNU linkers don't agree with each other. ld rejects such
relocation/symbol pair. gold don't reject that but do not create
copy relocations as well. I took the former approach because
I don't think the latter is what user wants.
llvm-svn: 270525
Previously, EhFrameHdr section computed addresses to which FDEs are
applied to. This is not an ideal design because EhFrameHdr does not
know much about FDEs unless EhFrame passes the information to EhFrameHdr.
It is what we did.
This patch simplifies the code by making EhFrame to compute the
values and pass the cooked information to EhFrameHdr. EhFrameHdr no
longer have to know about the details of FDEs such as FDE encodings.
llvm-svn: 270393
This patch refactors EHOutputSection using SectionPiece struct.
EHRegion class was removed since we can now directly use SectionPiece.
An incomplete support of large CIE/FDE record (> 2^32 bytes) was removed
because it silently created broken executable. There are several places
in the existing code that "size" field is always 4 bytes and at offset 4
in the record, which is not true for 64-bit size records. We will have to
support that in future, but it is better to error out instead of creating
malformed eh_frame sections.
llvm-svn: 270382
the linker script. The cycle in the ELF/LinkerScript.cpp:assignAddresses()
routine will be used to go through all the sections and set all the
addresses correctly.
Add new test to check this case.
llvm-svn: 270090
Lazy binding is quite important for use case like a shared build of
llvm. Also, if someone wants to disable it, it is better done in the
compiler (disable plt generation).
The only reason to keep it is to make it easier to add a new
architecture. But it doesn't really help much as it is possible to start
with non lazy relocation and plt code but still let the generic part
create a dedicated .got.plt and .rela.plt.
llvm-svn: 269982
If you specify the option in the form of --build-id=0x<hexstring>,
that hexstring is set as a build ID. We observed that the feature
is actually in use in some builds, so we want this feature.
llvm-svn: 269495
The Elf_Rela has an explicit addend. It doesn't need the addend to be
written to the section being relocated.
Since relative relocations are very common in the output, this is a
noticeable speedup. The results I got were
chromium
master 4.778149487
patch 4.761120792 0.996436131802
chromium fast
master 1.896253636
patch 1.840990582 0.970856718241
the gold plugin
master 0.399337811
patch 0.392279276 0.982324401032
clang
master 0.666873675
patch 0.665895708 0.998533504865
llvm-as
master 0.037101095
patch 0.037123149 1.00059442989
the gold plugin fsds
master 0.422473396
patch 0.414192879 0.980399909016
clang fsds
master 0.747302008
patch 0.744843964 0.996710775599
llvm-as fsds
master 0.033146245
patch 0.033064531 0.997534743377
scylla
master 4.08857525
patch 4.082245184 0.998451767275
llvm-svn: 269417
Just do not allow to link shared library if there are
undefined symbols.
This fixes PR27447
Differential revision: http://reviews.llvm.org/D20169
llvm-svn: 269183
This is the option which sorts relocs to optimize dynamic linker performance.
-z combelocs is the default in gold, also it ignores -z nocombreloc,
this patch do the same.
Patch sorts relocations by symbols only and do not create any
DT_REL[A]COUNT entries. That is different with what gold/bfd do.
More information about option is here:
http://www.airs.com/blog/archives/186http://people.redhat.com/jakub/prelink.pdf, p.2
Differential revision: http://reviews.llvm.org/D19528
llvm-svn: 269066
MIPS N64 ABI packs multiple relocations into the single relocation
record. In general, all up to three relocations can have arbitrary types.
In fact, Clang and GCC uses only a few combinations. For now, we support
two of them. That is allow to pass at least all LLVM test suite cases.
<any relocation> / R_MIPS_SUB / R_MIPS_HI16 | R_MIPS_LO16
<any relocation> / R_MIPS_64 / R_MIPS_NONE
The first relocation is a 'real' relocation which is calculated using
the corresponding symbol's value. The second and the third relocations
used to modify result of the first one: extend it to 64-bit, extract
high or low part etc. For details, see part 2.9 'Relocation' at
https://dmz-portal.mips.com/mw/images/8/82/007-4658-001.pdf
llvm-svn: 268876
We were creating the copy relocations just fine, but then thinking that
the .bss position could be preempted and creating a dynamic relocation
to it, which would crash at runtime since that memory is read only.
llvm-svn: 268668
This allows the combined LTO object to provide a definition with the same
name as a symbol that was internalized without causing a duplicate symbol
error. This normally happens during parallel codegen which externalizes
originally-internal symbols, for example.
In order to make this work, I needed to relax the undefined symbol error to
only report an error for symbols that are used in regular objects.
Differential Revision: http://reviews.llvm.org/D19954
llvm-svn: 268649
We were previously using an output offset of -1 for both GC'd and tail
merged pieces. We need to distinguish these two cases in order to filter
GC'd symbols from the symbol table -- we were previously asserting when we
asked for the VA of a symbol pointing into a dead piece, which would end
up asking the tail merging string table for an offset even though we hadn't
initialized it properly.
This patch fixes the bug by using an offset of -1 to exclusively mean GC'd
pieces, using 0 for tail merges, and distinguishing the tail merge case from
an offset of 0 by asking the output section whether it is tail merge.
Differential Revision: http://reviews.llvm.org/D19953
llvm-svn: 268604
It is insanely hard to write a test that works both on Windows and Unix.
I tried to workaround it with cpio's minor options, but the behaviors of
the options were myterious. It just doesn't worth to spend time on it.
And probably minor options could break buildbots that doesn't have the
GNU version of cpio command.
In this patch, I simply added a separate test file that runs only on
Windows.
llvm-svn: 268596
MIPS N64 ABI packs multiple relocations into the single relocation
record. Particularly it requires to represent dynamic relative
relocation as a combination of R_MIPS_REL32 and R_MIPS_64 relocations.
llvm-svn: 268565
We were already checking for non relative relocations.
If we ever decide to add support for rw text segments this means we will
have a single spot to add the flag.
llvm-svn: 268558
Currently we don't check when creating relative relocations if the
section is read only or not. I am about to fix that, so first update the
patches that depend on the current behavior.
llvm-svn: 268542
These relocations introduced by MIPS N64 ABI. R_MIPS_GOT_DISP references
GOT entry with full symbol's address, R_MIPS_GOT_PAGE creates GOT entry
with address of memory page which includes symbol's address,
R_MIPS_GOT_OFST used together with R_MIPS_GOT_PAGE. This relocation
calculates offset from beginning of memory page to the symbol address.
llvm-svn: 268525
As requested by Rafael Espindola in his post-commit comments on r268036. This
makes the previous behaviour the default while still allowing verification of
IAS.
llvm-svn: 268496
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
The test is now unexpectedly passing on
llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast which is treated as an error.
For now, disable Windows testing of the feature.
Rafael is working on generating an archive, which will hopefully allow
us to turn this test back on.
Unfortunately, we don't have a way to temporarily XFAIL this test just
on llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast.
llvm-svn: 268351
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
`REQUIRES: shell` is not appropriate because that would mean that there
are no windows bots testing this, and that is precisely where it needs
the most testing.
Rafael or Rui are working on generating an archive directly, which
should avoid this issue.
We can try to move the bot to a shorter build directory path.
llvm-svn: 268345
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
We currently don't do a good job of diagnosing inputs that would require
dynamic relocations to be applied to read only segments.
I am about to improve lld in that area, but unfortunately we developed
tests that depend on the current behavior.
To make clear what is actually changing, this first patch just updates
tests to not depend on the current behavior. In most cases this just
means using a rw section instead of a ro one, but that unfortunately
changes many addresses.
llvm-svn: 268145
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
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
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
Previously, the test didn't work on Windows because it tried to
concatenate two (possibly) absolute paths. If two paths are absolute
paths that have drive letters, then the result would become something
like C:\foo\D:\bar. That's not a valid path. I changed the test to
use relative paths.
llvm-svn: 267588
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
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
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
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
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
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
The gold plugin logic for common symbols is a little bit convoluted
as the plugin API has not an explicit way to update the alignment.
In gold, then, we need to keep the bitcode symbol @a around because
that's the only way to get the alignment right in the final object.
In lld, this is not true. We already have all the informations we
need about common symbols (size/alignment) so we don't have to
keep the existing symbol and pass it to the mover.
llvm-svn: 267007
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
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
Manifest file is a separate or embedded XML file having metadata
of an executable. As it is XML, it can contain various types of
information. Probably the most popular one is to request escalated
priviledges.
Usually the linker creates an XML file and embed that file into
an executable. However, there's a way to supply an XML file from
command line. /manifestniput is it.
Apparently it is over-designed here, but if you supply two or more
manifest files, then the linker needs to merge the files into a
single XML file. A good news is that we don't need to do that ourselves.
MT.exe command can do that, so we call the command from the linker
in this patch.
llvm-svn: 266704
* 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
At the moment almost every lit.site.cfg.in contains two lines comment:
## Autogenerated by LLVM/Clang configuration.
# Do not edit!
The patch adds variable LIT_SITE_CFG_IN_HEADER, that is replaced from
configure_lit_site_cfg with the note and some useful information.
llvm-svn: 266521
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
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
Similar to r265462, TLS related relocations aren't marked as relative,
meaning that we end up generating R_AARCH64_RELATIVE relocations for
them. This change adds TLS relocations that I've seen on my system. With
this patch applied CloudABI's unit testing binary now passes on aarch64.
Approved by: ruiu
Differential Revision: http://reviews.llvm.org/D18816
llvm-svn: 265575
We have to differentiate undefined symbols from bitcode and undefined
symbols from other sources.
Undefined symbols from bitcode should not inhibit the symbol being
internalized. Undefined symbols from other sources should.
llvm-svn: 265536
When error, this adds the text line of script to the output
and a marks exact incorrect token under it:
line 1: <error text here>
UNKNOWN_TAG {
^
Differential revision: http://reviews.llvm.org/D18699
llvm-svn: 265523
While trying to get PIE work on CloudABI for x86-64, I noticed that even
though GNU ld would generate functional binaries, LLD would not. It
turns out that we generate relocations for referencing TLS objects
inside of the text segment, which shouldn't happen.
This change extends the isRelRelative() function to list some additional
relocation types that should be treated as relative. This makes my C
library unit testing binary work on x86-64.
Approved by: ruiu
Differential Revision: http://reviews.llvm.org/D18688
Fixes bug: https://llvm.org/bugs/show_bug.cgi?id=27174
llvm-svn: 265462
Where Clang's AArch64 backend seems to differ from the X86 backend is
that it tends to use the GOT more aggressively.
After getting CloudABI PIEs working on x86-64, I noticed that accessing
global variables would still crash on aarch64. Tracing it down, it turns
out that the GOT was filled with entries assuming the base address was
zero.
It turns out that we skip generating relocations for GOT entries in case
the relocation pointing towards the GOT is relative. Whether the thing
pointing to the GOT is absolute or relative shouldn't make any
difference; the GOT entry itself should contain the absolute address,
thus needs a relocation regardless.
Approved by: rafael
Differential Revision: http://reviews.llvm.org/D18739
llvm-svn: 265453
Make sure to copy the MustBeInDynSym field when replacing shared symbols with
bitcode symbols, and when replacing bitcode symbols with regular symbols
in addCombinedLtoObject. Fixes interposition of DSO symbols with bitcode
symbols in the main executable.
Differential Revision: http://reviews.llvm.org/D18780
llvm-svn: 265371
For each copy relocation that we create, look through the DSO's symbol table
for aliases and create a dynamic symbol for each one. This causes the copy
relocation to correctly interpose any aliases.
Copy relocations are relatively uncommon (on my machine, 56% of binaries in
/usr/bin have no copy relocations probably due to being PIEs, 97% of them
have <10, and the binary with the largest number of them has 97) so it's
probably fine to do this in a relatively inefficient way.
Differential Revision: http://reviews.llvm.org/D18731
llvm-svn: 265354
This test didn't actually test the functionality. The new test
verifies that "-verify" is passed if and only if -disable-verify
is not given.
llvm-svn: 265316
The only way to get an object file with symbols marked by the STO_MIPS_PIC
flag is to link PIC and non-PIC object files and generate a relocatable
output using '-r' command line option. Now LLD is able to generate a relocatable
output but does not mark PIC symbols by the STO_MIPS_PIC flag. So I have
to use binary input mips-sto-pic.o generated by GNU BFD linker.
llvm-svn: 265310
Our symbol representation was redundant, and some times would get out of
sync. It had an Elf_Sym, but some fields were copied to SymbolBody.
Different parts of the code were checking the bits in SymbolBody and
others were checking Elf_Sym.
There are two general approaches to fix this:
* Copy the required information and don't store and Elf_Sym.
* Don't copy the information and always use the Elf_Smy.
The second way sounds tempting, but has a big problem: we would have to
template SymbolBody. I started doing it, but it requires templeting
*everything* and creates a bit chicken and egg problem at the driver
where we have to find ELFT before we can create an ArchiveFile for
example.
As much as possible I compared the test differences with what gold and
bfd produce to make sure they are still valid. In most cases we are just
adding hidden visibility to a local symbol, which is harmless.
In most tests this is a small speedup. The only slowdown was scylla
(1.006X). The largest speedup was clang with no --build-id, -O3 or
--gc-sections (i.e.: focus on the relocations): 1.019X.
llvm-svn: 265293
So, there are some cases when the IR Linker produces a broken
module (which doesn't pass the verifier) and we end up asserting
inside the verifier. I think it's always a bug producing a module
which does not pass the verifier but there are some cases in which
people can live with the broken module (e.g. if only DebugInfo
metadata are broken). The gold plugin has something similar.
This commit is motivated by a situation I found in the
wild. It seems that somebody else discovered it independently
and reported in PR24923.
llvm-svn: 265258
We already got this right, but it never hurts adding another
test, in case we'll change the handling in the future, to ensure
we don't break it.
llvm-svn: 265256
Currently we create a file called .lto.bc. In UNIX,
ls(1) by default doesn't show up files starting with
a dot, as they're (only by convention) hidden.
This makes the output of -save-temps a little bit
hard to find. Use "a.out.lto.bc" instead if the
output file is not specified.
While here, change an existing -save-temps test to
exercise this more interesting behaviour.
llvm-svn: 265254
If a symbol is defined in an archive, when we replace its body
the isUsedInRegularObj wasn't set correctly. Internalize makes
its decision based on that bit so we ended up internalizing
symbols that we shouldn't (because they're referenced).
This should fix. Thanks to Peter and Rafael for discussion
and help diagnosing the issue!
Found during LTO of unittests.
llvm-svn: 265208
This fixes bootstrap of llvm-tblgen (with LTO) and PR27150.
Slightly longer explanation follows.
Emission of .init_array instead of .ctors is supported only on a
subset of the Target LLVM supports. Codegen needs to be conservative
and always emit .ctors unless instructed otherwise (based on target).
If the dynamic linker sees .init_array it completely ignores
what's inside .ctors and therefore some constructors are not called
(and this causes llvm-tblgen to crash on startup).
Teach LLD/LTO about the Codegen options so we end up always emitting
.init_array and avoid this issue.
In future, we might end up supporting mix of .ctors and .init_array
in different input files if this shows up as a real-world use case.
The way gold handles this case is mapping .ctors from input into
.init_array in output. There's also another caveat because
as far as I understand .ctors run in reverse order so when we do
the copy/mapping we need to reverse copy in the output if there's
more than one ctor. That's why I'd rather avoid this complicate logic
unless there's a real need.
An analogous reasoning holds for .dtors/.fini_array.
llvm-svn: 265085
George Rimar