Summary:
Before:
```
wasm-ld: error: Relocations not in offset order
```
After
```
wasm-ld: error: While processing `libjulia.so`: Relocations not in offset order
```
At least this way you get to find out which input file is malformed.
Reviewers: sbc100
Differential Revision: https://reviews.llvm.org/D63694
llvm-svn: 364368
Summary:
The list of relocations with addend in lld was missing `R_WASM_MEMORY_ADDR_REL_SLEB`,
causing `wasm-ld` to generate corrupted output. This fixes that problem and while
we're at it pulls the list of such relocations into the Wasm.h header, to avoid
duplicating it in multiple places.
Reviewers: sbc100
Differential Revision: https://reviews.llvm.org/D63696
llvm-svn: 364367
This is fairly common with wasm since GNU ar (most likely the system ar)
doesn't support the wasm object format so user who don't override AR
will end up with archives without an index. We don't want to silently
ignore this issue.
In the future we could choose to instead behave like the ELF backend and
read the symbols from each object file in the archive if they are all of
the same type. However, error'ing out seem like a conservative approach
for now.
Fixes: PR42376
Differential Revision: https://reviews.llvm.org/D63739
llvm-svn: 364338
(In effect, reverting "[ELF] Error on relocations to STT_SECTION symbols if the sections were discarded".)
It caused debug info problems in LibreOffice [1] and Chromium/V8 [2].
Reverting until those can be fixed.
It also reverts r362497 "STT_SECTION symbol should be defined" on .eh_frame, .debug*, .zdebug* and .gcc_except_table"
which was landed as a follow-up to the above.
> With -r or --emit-relocs, we warn `STT_SECTION symbol should be defined`
> on relocations to discarded section symbol. This was added as an error
> in rLLD319404, but was not so effective before D61583 (it turned the
> error to a warning).
>
> Relocations from .eh_frame .debug* .zdebug* .gcc_except_table to
> discarded .text are very common and somewhat expected. Don't warn/error
> on them. As a reference, ld.bfd has a similar logic in
> _bfd_elf_default_action_discarded() to allow these cases.
>
> Delete invalid-undef-section-symbol.test because what it intended to
> check is now covered by the updated comdat-discarded-reloc.s
>
> Delete relocatable-eh-frame.s because we allow relocations from
> .eh_frame as a special case now.
And finally it reverts r362218 "[ELF] Replace a dead test in getSymVA() with assert()"
as that also depended on the main change reverted here.
> Symbols relative to discarded comdat sections are Undefined instead of
> Defined now (after D59649 and D61583). The `== &InputSection::Discarded`
> test becomes dead. I cannot find a test related to this behavior.
[1] http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190603/659848.html
[2] https://bugs.chromium.org/p/chromium/issues/detail?id=978067
llvm-svn: 364321
lld/coff already deduplicated undefined symbols on a TU level: It would
group all references to a symbol from a single TU. This makes it so that
references from all TUs to a single symbol are grouped together.
Since lld/coff almost did what I thought it did already, the patch is
much smaller than the elf version. The only not local change is that
getSymbolLocations() now returns a vector<string> instead of a string,
so that the undefined symbol reporting code can know how many references
to a symbol exist in a given TU.
Fixes PR42260 for lld/coff.
Differential Revision: https://reviews.llvm.org/D63646
llvm-svn: 364285
r360841 introduced CommonSymbol class. An unintended behavioral change
introduced by that change was that common symbols are not internalized
by LTO under some condition. This patch fixes that issue.
The issue occurred under the following condition:
1. There exists a common symbol
2. At least one DSO is given to lld or -pie is used
If the above conditions are met, Symbol::includeInDynsym() returned a
wrong value for a common symbol.
Fixes https://bugs.llvm.org/show_bug.cgi?id=41978
Differential Revision: https://reviews.llvm.org/D63752
llvm-svn: 364273
Similar to R_AARCH64_ABS32, R_PPC64_ADDR32 can represent either a signed
value or unsigned value, thus we should use `[-2**(n-1), 2**n)` instead of
`[-2**(n-1), 2**(n-1))` to check overflows.
The issue manifests as a bogus linker error when linking the powerpc64le Linux kernel.
The new behavior is compatible with ld.bfd's complain_overflow_bitfield.
The upper bound of the error message is not correct. Fix it as well.
The changes to R_PPC_ADDR16, R_PPC64_ADDR16, R_X86_64_8 and R_X86_64_16 are similar.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63690
llvm-svn: 364164
Summary:
Our rule to create R_*_RELATIVE for absolute relocation types were
loose. D63121 made it stricter but it failed to create R_*_RELATIVE for
R_ARM_TARGET1 and R_PPC64_TOC. rLLD363236 worked around that by
reinstating the original behavior for ARM and PPC64.
This patch is an attempt to simplify the logic.
Note, in ld.bfd, R_ARM_TARGET2 --target2=abs also creates
R_ARM_RELATIVE. This seems a very uncommon scenario (moreover,
--target2=got-rel is the default), so I do not implement any logic
related to it.
Also, delete R_AARCH64_ABS32 from AArch64::getDynRel. We don't have
working ILP32 support yet. Allowing it would create an incorrect
R_AARCH64_RELATIVE.
For MIPS, the (if SymbolRel, then RelativeRel) code is to keep its
behavior unchanged.
Note, in ppc64-abs64-dyn.s, R_PPC64_TOC gets an incorrect addend because
computeAddend() doesn't compute the correct address. We seem to have the
wrong behavior for a long time. The important thing seems that a dynamic
relocation R_PPC64_TOC should not be created as the dynamic loader will
error R_PPC64_TOC is not supported.
Reviewers: atanasyan, grimar, peter.smith, ruiu, sfertile, espindola
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63383
llvm-svn: 363928
ARM and RISC-V do not support TLS relaxations. However, for General
Dynamic and Local Dynamic models, if we are producing an executable and
the symbol is non-preemptable, we know it must be defined and the
R_ARM_TLS_DTPMOD32/R_RISCV_TLS_DTPMOD{32,64} dynamic relocation can be
omitted because it is always 1. This may be necessary for static linking
as DTPMOD may not be expected at load time.
Merge handleARMTlsRelocation() into handleTlsRelocation(). This requires
more logic to R_TLSGD_PC and R_TLSLD_PC. Because we use SymbolicRel to
resolve the relocation at link time, R_ARM_TLS_DTPMOD32 can be deleted
from relocateOne(). It cannot be used as a static relocation type.
As a bonus, the additional logic in R_TLSGD_PC code can be shared by the
TLS support for RISC-V (D63220).
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63333
llvm-svn: 363927
Some versions of the Visual C++ 2015 runtime have line tables with the
subsection kind of 0x800000F2. In cvinfo.h, 0x80000000 is documented to
be DEBUG_S_IGNORE. This appears to implement the intended behavior.
llvm-svn: 363724
Use -fsave-optimization-record=<format> to specify a different format
than the default, which is YAML.
For now, only YAML is supported.
llvm-svn: 363573
This matches how it is done for .xdata and .pdata already.
On i386, the symbol name in the section name suffix does not contain
the extra underscore prefix.
This is one part of a fix for PR42217.
Differential Revision: https://reviews.llvm.org/D63350
llvm-svn: 363456
In processRelocAux(), our handling of 1) link-time constant and 2) weak
undef is the same, so put them together to simplify the logic.
This moves the weak undef code around. The result is that: in a writable
section (or -z notext), we will no longer emit dynamic relocations for
weak undefined symbols.
The new behavior seems to match GNU linkers, and improves consistency
with the case of a readonly section.
The condition `!Config->Shared` was there probably because it is common
for a -shared link not to specify full dependencies. Keep it now but we
may revisit the decision in the future.
gABI says:
> The behavior of weak symbols in areas not specified by this document is
> implementation defined. Weak symbols are intended primarily for use in
> system software. Applications using weak symbols are unreliable since
> changes in the runtime environment might cause the execution to fail.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63003
llvm-svn: 363399
This patch adds new command line option `--undefined-glob` to lld.
That option is a variant of `--undefined` but accepts wildcard
patterns so that all symbols that match with a given pattern are
handled as if they were given by `-u`.
`-u foo` is to force resolve symbol foo if foo is not a defined symbol
and there's a static archive that contains a definition of symbol foo.
Now, you can specify a wildcard pattern as an argument for `--undefined-glob`.
So, if you want to include all JNI symbols (which start with "Java_"), you
can do that by passing `--undefined-glob "Java_*"` to the linker, for example.
In this patch, I use the same glob pattern matcher as the version script
processor is using, so it does not only support `*` but also `?` and `[...]`.
Differential Revision: https://reviews.llvm.org/D63244
llvm-svn: 363396
If .sdata is absent, linker synthesized __global_pointer$ gets a section index of SHN_ABS.
(ld.bfd has a similar issue: binutils PR24678)
Scrt1.o may use `lla gp, __global_pointer$` to reference the symbol PC
relatively. In -pie/-shared mode, lld complains if a PC relative
relocation references an absolute symbol (SHN_ABS) but ld.bfd doesn't:
ld.lld: error: relocation R_RISCV_PCREL_HI20 cannot refer to lute symbol: __global_pointer$
Let the reference of __global_pointer$ to force creation of .sdata to
fix the problem. This is similar to _GLOBAL_OFFSET_TABLE_, which forces
creation of .got or .got.plt .
Also, change the visibility from STV_HIDDEN to STV_DEFAULT and don't
define the symbol for -shared. This matches ld.bfd, though I don't
understand why it uses STV_DEFAULT.
Reviewed By: ruiu, jrtc27
Differential Revision: https://reviews.llvm.org/D63132
llvm-svn: 363351
PDBs may not necessarily contain an IPI stream. Handle this case
gracefully.
The test case was verified to work with MS link.exe.
Patch by Vladimir Panteleev, with a small simplification
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D63178
llvm-svn: 363213
An unrecognized signature (magic) at the beginning of a debug section
should not be a fatal error; it only means that the debug information
is in a format that is not supported by LLD. This can be due to it
being in CodeView versions 3 or earlier. These can occur in old import
libraries from legacy SDKs.
The test case was verified to work with MS link.exe.
Patch by Vladimir Panteleev!
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D63177
llvm-svn: 363212
r363016 let lld-link and llvm-lib share the /machine: parsing code.
This lets llvm-cvtres share it as well.
Making llvm-cvtres depend on llvm-lib seemed a bit strange (it doesn't
need llvm-lib's dependencies on BinaryFormat and BitReader) and I
couldn't find a good place to put this code. Since it's just a few
lines, put it in lib/Object for now.
Differential Revision: https://reviews.llvm.org/D63120
llvm-svn: 363144
R_RISCV_{ADD,SET,SUB}* are used for local label computation.
Add a new RelExpr member R_RISCV_ADD to represent them.
R_RISCV_ADD is treated as a link-time constant because otherwise
R_RISCV_{ADD,SET,SUB}* are not allowed in -pie/-shared mode.
In glibc Scrt1.o, .rela.eh_frame contains such relocations.
Because .eh_frame is not writable, we get this error:
ld.lld: error: can't create dynamic relocation R_RISCV_ADD32 against symbol: .L0 in readonly segment; recompil object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output
>>> defined in ..../riscv64-linux-gnu/lib/Scrt1.o
With D63076 and this patch, I can run -pie/-shared programs linked against glibc.
Note llvm-mc cannot currently produce R_RISCV_SET* so they are not tested.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63183
llvm-svn: 363128
Summary:
clang (as of 2019-06-12) / gcc (as of 8.2.1) PPC64 may emit a .rela.toc
which references an embedded switch table in a discarded .rodata/.text
section. The .toc and the .rela.toc are incorrectly not placed in the
comdat.
Technically a relocation from outside the group is not allowed by the ELF spec:
> A symbol table entry with STB_LOCAL binding that is defined relative
> to one of a group's sections, and that is contained in a symbol table
> section that is not part of the group, must be discarded if the group
> members are discarded. References to this symbol table entry from
> outside the group are not allowed.
Don't report errors to work around the bug.
This should fix the ppc64le-lld-multistage-test bot while linking llvm-tblgen:
ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
>>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o
>>> referenced by CodeGenRegisters.cpp
>>> utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o:(.toc+0x0)
Some other PPC specific sections may have similar problems. We can blacklist more
section names when problems occur.
// A simple program that reproduces the bug.
// Note .rela.toc (outside the group) references a section symbol (STB_LOCAL) in a group.
void puts(const char *);
struct A {
void foo(int a) {
switch (a) {
case 0: puts("0"); break;
case 1: puts("1"); puts("1"); break;
case 2: puts("2"); break;
case 3: puts("3"); puts("4"); break;
case 4: puts("4"); break;
case 5: puts("5"); puts("5"); break;
case 6: puts("6"); break;
}
}
int a;
};
void foo(A x) { x.foo(x.a); }
Reviewers: ruiu, sfertile, espindola
Reviewed By: ruiu
Subscribers: emaste, nemanjai, arichardson, kbarton, jsji, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63182
llvm-svn: 363126
This reverts commit r363060 and restores r362867.
r362867 is innocent. The ppc64le-lld-multistage-test bot failure was due to a clang/gcc .toc bug:
ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
>>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o
>>> referenced by CodeGenRegisters.cpp
>>> utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o:(.toc+0x0)
It will be worked around by D63182.
llvm-svn: 363124
Summary: Deduplicate S_CONSTANTS when linking, if they have the same value.
Reviewers: rnk
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63151
llvm-svn: 363089
Users are exepcted to pass all .res files to the linker, which then
merges all the resource in all .res files into a tree structure and then
converts the final tree structure to a .obj file with .rsrc$01 and
.rsrc$02 sections and then links that.
If the user instead passes several .obj files containing such resources,
the correct thing to do would be to have custom code to merge the trees
in the resource sections instead of doing normal section merging -- but
link.exe rejects if multiple resource obj files are passed in with
LNK4078, so let lld-link do that too instead of silently writing broken
.rsrc sections in that case.
The only real way to run into this is if users manually convert .res
files to .obj files by running cvtres and then handing the resulting
.obj files to lld-link instead, which in practice likely never happens.
(lld-link is slightly stricter than link.exe now: If link.exe is passed
one .obj file created by cvtres, and a .res file, for some reason it
just emits a warning instead of an error and outputs strange looking
data. lld-link now errors out on mixed input like this.)
One way users could accidentally run into this is the following
scenario: If a .res file is passed to lib.exe, then lib.exe calls
cvtres.exe on the .res file before putting it in the output .lib.
(llvm-lib currently doesn't do this.)
link.exe's /wholearchive seems to only add obj files referenced from the
static library index, but lld-link current really adds all files in the
archive. So if lld-link /wholearchive is used with .lib files produced
by lib.exe and .res files were among the files handed to lib.exe, we
previously silently produced invalid output, but now we error out.
link.exe's /wholearchive semantics on the other hand mean that it
wouldn't load the resource object files from the .lib file at all.
Since this scenario is probably still an unlikely corner case,
the difference in behavior here seems fine -- and lld-link might have to
change to use link.exe's /wholearchive semantics in the future anyways.
Vaguely related to PR42180.
Differential Revision: https://reviews.llvm.org/D63109
llvm-svn: 363078
So that R_RISCV_PCREL_LO12_[IS] are considered as link-time constants in
-pie mode, otherwise there are bogus errors:
ld.lld: error: can't create dynamic relocation R_RISCV_PCREL_LO12_I against symbol: .L0 in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63123
llvm-svn: 363064
The current rule is loose: `!Sym.IsPreemptible || Expr == R_GOT`.
When the symbol is non-preemptable, this allows absolute relocation
types with smaller numbers of bits, e.g. R_X86_64_{8,16,32}. They are
disallowed by ld.bfd and gold, e.g.
ld.bfd: a.o: relocation R_X86_64_8 against `.text' can not be used when making a shared object; recompile with -fPIC
This patch:
a) Add TargetInfo::SymbolicRel to represent relocation types that resolve to a
symbol value (e.g. R_AARCH_ABS64, R_386_32, R_X86_64_64).
As a side benefit, we currently (ab)use GotRel (R_*_GLOB_DAT) to resolve
GOT slots that are link-time constants. Since we now use Target->SymbolRel
to do the job, we can remove R_*_GLOB_DAT from relocateOne() for all targets.
R_*_GLOB_DAT cannot be used as static relocation types.
b) Change the condition to `!Sym.IsPreemptible && Type != Target->SymbolicRel || Expr == R_GOT`.
Some tests are caught by the improved error checking (ld.bfd/gold also
issue errors on them). Many misuse .long where .quad should be used
instead.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63121
llvm-svn: 363059
For lld, pass in Config->Timestamp (which is set based on lld's
/timestamp: and /Brepro flags). Since the writeWindowsResourceCOFF()
data is only used in-memory by LLD and the obj's timestamp isn't used
for anything in the output, this doesn't change behavior.
For llvm-cvtres, add an optional /timestamp: parameter, and use the
current behavior of calling time() if the parameter is not passed in.
This doesn't really change observable behavior (unless someone passes
/timestamp: to llvm-cvtres, which wasn't possible before), but it
removes the last unqualified call to time() from llvm/lib, which seems
like a good thing.
Differential Revision: https://reviews.llvm.org/D63116
llvm-svn: 363050
Otherwise the getPartition() accessor may return an OOB pointer. Found
using _GLIBCXX_DEBUG.
The error is benign (we never dereference the pointer for the end marker)
so this wasn't caught by e.g. the sanitizer bots.
llvm-svn: 363026
And share some code with lld-link.
While here, also add a FIXME about PR42180 and merge r360150 to llvm-lib.
Differential Revision: https://reviews.llvm.org/D63021
llvm-svn: 363016
The previous name "%lib" doesn't trigger any actual replacement. It
creates the file "./tools/lld/test/ELF/%lib.o" in the test directory.
llvm-svn: 362988
Patch by Erik McClure with a modification to rebase to HEAD.
When calling `COFF::link()` with `CanExitEarly` set to `false`, the
function needs to clean up several global variable caches to ensure that
the next invocation of the function starts from a clean slate. The
`MergeChunk::Instances` cache is missing from this cleanup code, and as
a result will create nondeterministic memory access errors and sometimes
infinite loops due to invalid memory being referenced on the next call
to `COFF::link()`.
This fix simply clears `MergeChunk::Instances` before exiting the function.
An additional review of the COFF library was made to try and find any
other missing global caches, but I was unable to find any other than
`MergeChunk`. Someone more familiar with the global variables might want
to do their own check.
This fix was made to support inNative
<https://github.com/innative-sdk/innative>'s `.wast` script compiler,
which must build multiple incremental builds. It relies on statically
linking LLD because the entire compiler must be a single statically
embeddable library, thus preventing it from being able to call LLD as a
new process.
Differential Revision: https://reviews.llvm.org/D63042
llvm-svn: 362930
Fix buildbot failure on native AArch64 buildbot that does not have X86
backend compiled in.
Differential Revision: https://reviews.llvm.org/D63071
llvm-svn: 362926
This is implemented by the lld-link option -include:, just like
--require-defined. Contrary to --require-defined, the -u/--undefined
option allows the symbol to remain undefined in the end.
This should fix PR42121.
Differential Revision: https://reviews.llvm.org/D62876
llvm-svn: 362882
This works like /include, but is not fatal if the requested symbol
wasn't found. This allows implementing the GNU ld option -u.
Differential Revision: https://reviews.llvm.org/D62976
llvm-svn: 362881
I've change the variable names used in PPC64.cpp from "Instr" to "Insn"
because "Insn" is a more common abbreviation for "instruction".
While changing PPC64.cpp relocateOne(), make R_PPC64_ADDR16_LO{_DS}
slightly more efficient by saving a read and a write for the TocOptimize
case.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63043
llvm-svn: 362867
Summary:
When handling exports from the command line or from .def files, the
linker does a "fuzzy" string lookup to allow finding mangled symbols.
However, when the symbol is re-exported under a new name, the linker has
to transfer the decorations from the exported symbol over to the new
name. This is implemented by taking the mangled symbol that was found in
the object and replacing the original symbol name with the export name.
Before this patch, LLD implemented the fuzzy search by adding an
undefined symbol with the unmangled name, and then during symbol
resolution, checking if similar mangled symbols had been added after the
last round of symbol resolution. If so, LLD makes the original symbol a
weak alias of the mangled symbol. Later, to get the original symbol
name, LLD would look through the weak alias and forward it on to the
import library writer, which copies the symbol decorations. This
approach doesn't work when bar is itself a weak alias, as is the case in
asan. It's especially bad when the aliasee of bar contains the string
"bar", consider "bar_default". In this case, we would end up exporting
the symbol "foo_default" when we should've exported just "foo".
To fix this, don't look through weak aliases to find the mangled name.
Save the mangled name earlier during fuzzy symbol lookup.
Fixes PR42074
Reviewers: mstorsjo, ruiu
Subscribers: thakis, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62984
llvm-svn: 362849
We create several types of synthetic sections for loadable partitions, including:
- The dynamic symbol table. This allows code outside of the loadable partitions
to find entry points with dlsym.
- Creating a dynamic symbol table also requires the creation of several other
synthetic sections for the partition, such as the dynamic table and hash table
sections.
- The partition's ELF header is represented as a synthetic section in the
combined output file, and will be used by llvm-objcopy to extract partitions.
Differential Revision: https://reviews.llvm.org/D62350
llvm-svn: 362819
Branch Target Identification (BTI) and Pointer Authentication (PAC) are
architecture features introduced in v8.5a and 8.3a respectively. The new
instructions have been added in the hint space so that binaries take
advantage of support where it exists yet still run on older hardware. The
impact of each feature is:
BTI: For executable pages that have been guarded, all indirect branches
must have a destination that is a BTI instruction of the appropriate type.
For the static linker, this means that PLT entries must have a "BTI c" as
the first instruction in the sequence. BTI is an all or nothing
property for a link unit, any indirect branch not landing on a valid
destination will cause a Branch Target Exception.
PAC: The dynamic loader encodes with PACIA the address of the destination
that the PLT entry will load from the .plt.got, placing the result in a
subset of the top-bits that are not valid virtual addresses. The PLT entry
may authenticate these top-bits using the AUTIA instruction before
branching to the destination. Use of PAC in PLT sequences is a contract
between the dynamic loader and the static linker, it is independent of
whether the relocatable objects use PAC.
BTI and PAC are independent features that can be combined. So we can have
several combinations of PLT:
- Standard with no BTI or PAC
- BTI PLT with "BTI c" as first instruction.
- PAC PLT with "AUTIA1716" before the indirect branch to X17.
- BTIPAC PLT with "BTI c" as first instruction and "AUTIA1716" before the
first indirect branch to X17.
The use of BTI and PAC in relocatable object files are encoded by feature
bits in the .note.gnu.property section in a similar way to Intel CET. There
is one AArch64 specific program property GNU_PROPERTY_AARCH64_FEATURE_1_AND
and two target feature bits defined:
- GNU_PROPERTY_AARCH64_FEATURE_1_BTI
-- All executable sections are compatible with BTI.
- GNU_PROPERTY_AARCH64_FEATURE_1_PAC
-- All executable sections have return address signing enabled.
Due to the properties of FEATURE_1_AND the static linker can tell when all
input relocatable objects have the BTI and PAC feature bits set. The static
linker uses this to enable the appropriate PLT sequence.
Neither -> standard PLT
GNU_PROPERTY_AARCH64_FEATURE_1_BTI -> BTI PLT
GNU_PROPERTY_AARCH64_FEATURE_1_PAC -> PAC PLT
Both properties -> BTIPAC PLT
In addition to the .note.gnu.properties there are two new command line
options:
--force-bti : Act as if all relocatable inputs had
GNU_PROPERTY_AARCH64_FEATURE_1_BTI and warn for every relocatable object
that does not.
--pac-plt : Act as if all relocatable inputs had
GNU_PROPERTY_AARCH64_FEATURE_1_PAC. As PAC is a contract between the loader
and static linker no warning is given if it is not present in an input.
Two processor specific dynamic tags are used to communicate that a non
standard PLT sequence is being used.
DTI_AARCH64_BTI_PLT and DTI_AARCH64_BTI_PAC.
Differential Revision: https://reviews.llvm.org/D62609
llvm-svn: 362793
It was added by D46654 but is actually never used.
R_PPC64_CALL_PLT (was: R_PPC_CALL_PLT) is a static link-time constant.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62994
llvm-svn: 362788
When a function is excluded via comdat we shouldn't add it to the
final list of init functions.
Differential Revision: https://reviews.llvm.org/D62983
llvm-svn: 362769
Many -static/-no-pie/-shared/-pie applications linked against glibc or musl
should work with this patch. This also helps FreeBSD PowerPC64 to migrate
their lib32 (PR40888).
* Fix default image base and max page size.
* Support new-style Secure PLT (see below). Old-style BSS PLT is not
implemented, so it is not suitable for FreeBSD rtld now because it doesn't
support Secure PLT yet.
* Support more initial relocation types:
R_PPC_ADDR32, R_PPC_REL16*, R_PPC_LOCAL24PC, R_PPC_PLTREL24, and R_PPC_GOT16.
The addend of R_PPC_PLTREL24 is special: it decides the call stub PLT type
but it should be ignored for the computation of target symbol VA.
* Support GNU ifunc
* Support .glink used for lazy PLT resolution in glibc
* Add a new thunk type: PPC32PltCallStub that is similar to PPC64PltCallStub.
It is used by R_PPC_REL24 and R_PPC_PLTREL24.
A PLT stub used in -fPIE/-fPIC usually loads an address relative to
.got2+0x8000 (-fpie/-fpic code uses _GLOBAL_OFFSET_TABLE_ relative
addresses).
Two .got2 sections in two object files have different addresses, thus a PLT stub
can't be shared by two object files. To handle this incompatibility,
change the parameters of Thunk::isCompatibleWith to
`const InputSection &, const Relocation &`.
PowerPC psABI specified an old-style .plt (BSS PLT) that is both
writable and executable. Linkers don't make separate RW- and RWE segments,
which causes all initially writable memory (think .data) executable.
This is a big security concern so a new PLT scheme (secure PLT) was developed to
address the security issue.
TLS will be implemented in D62940.
glibc older than ~2012 requires .rela.dyn to include .rela.plt, it can
not handle the DT_RELA+DT_RELASZ == DT_JMPREL case correctly. A hack
(not included in this patch) in LinkerScript.cpp addOrphanSections() to
work around the issue:
if (Config->EMachine == EM_PPC) {
// Older glibc assumes .rela.dyn includes .rela.plt
Add(In.RelaDyn);
if (In.RelaPlt->isLive() && !In.RelaPlt->Parent)
In.RelaDyn->getParent()->addSection(In.RelaPlt);
}
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62464
llvm-svn: 362721
We were not previously testing the comdat exclusion in bitcode objects
because we were linking two copies of the .bc file and the
`linkonce_odr` linkage type was removing the duplicate `_start` at
the LTO stage.
Now we link an bitcode and non-bitcode version both of which contains a
copy of _start. We link them in both orders, which means this test will
fail if comdat exclusion is not working correctly in bitcode parsing.
Differential Revision: https://reviews.llvm.org/D62923
llvm-svn: 362650
With r362638, llc doesn't support -relocation-model=pic with non-Emscripten
triples. Update these tests in lld which use -relocation-model=pic to also
use Emscripten triples.
llvm-svn: 362645
Any symbols defined in the LTO object are by definition the ones we
want in the final output so we skip the comdat group checking in those
cases.
This change makes the ELF code more explicit about this and means
that wasm and ELF do this in the same way.
Differential Revision: https://reviews.llvm.org/D62884
llvm-svn: 362625
Although many relocatable objects will have a single
GNU_PROPERTY_X86_FEATURE_1_AND in the .note.gnu.property section it is
permissible to have more than one, and there are tests in ld.bfd that use
it. The behavior that ld.bfd follows is to set the feature bit for a
relocatable object if any of the GNU_PROPERTY_X86_FEATURE_1_AND
have the feature bit set.
Differential Revision: https://reviews.llvm.org/D62862
llvm-svn: 362591
The age field is only there to say how many times an OBJ or a PDB was incrementally linked. It shouldn't be used to validate the link between the OBJ and the PDB.
Differential Revision: https://reviews.llvm.org/D62837
llvm-svn: 362572
Summary:
Make `wasm-ld --verbose` show data section start virtual address and name
as well, instead of just showing the size. This makes it much easier to
track which global variable is in which address when used in conjunction
with `--no-merge-data-sections`.
Patch by Guanzhong Chen
Reviewers: tlively, aheejin, sbc100, ruiu
Reviewed By: sbc100, ruiu
Subscribers: ruiu, dschuff, jgravelle-google, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62834
llvm-svn: 362548
Summary:
With -r or --emit-relocs, we warn `STT_SECTION symbol should be defined`
on relocations to discarded section symbol. This was added as an error
in rLLD319404, but was not so effective before D61583 (it turned the
error to a warning).
Relocations from .eh_frame .debug* .zdebug* .gcc_except_table to
discarded .text are very common and somewhat expected. Don't warn/error
on them. As a reference, ld.bfd has a similar logic in
_bfd_elf_default_action_discarded() to allow these cases.
Delete invalid-undef-section-symbol.test because what it intended to
check is now covered by the updated comdat-discarded-reloc.s
Delete relocatable-eh-frame.s because we allow relocations from
.eh_frame as a special case now.
Reviewers: grimar, phosek, ruiu, espindola
Reviewed By: ruiu
Subscribers: emaste, arichardson, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62840
llvm-svn: 362497
We currently (ab)use the Live bit on output sections to track whether
the section has ever had an input section added to it, and then later
use it during orphan placement. This will conflict with one of my upcoming
partition-related changes that will assign all output sections to a partition
(thus marking them as live) so that they can be added to the correct segment
by the code that creates program headers.
Instead of using the Live bit for this purpose, create a new flag and
start using it to track the property explicitly.
Differential Revision: https://reviews.llvm.org/D62348
llvm-svn: 362444
Summary:
- Fixes inline call frame line table display in windbg.
- Improve llvm-pdbutil to dump extra file ids.
- Warn on unknown subsections so we don't have this kind of bug in the
future.
Reviewers: inglorion, akhuang, aganea
Subscribers: eraman, zturner, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62701
llvm-svn: 362429
We need to have all input files ready before doing debuginfo type merging.
This patch is moving the late PDB type server discovery much earlier in the process, when the explicit inputs (OBJs, LIBs) are loaded.
The short term goal is to parallelize type merging.
Differential Revision: https://reviews.llvm.org/D60095
llvm-svn: 362393
The following abstract relocation types (RelExpr) are PPC64 ELFv2 ABI specific,
not used by PPC32. So rename them to prevent confusion when the PPC32 port is improved.
* R_PPC_CALL R_PPC_CALL_PLT:
R_PPC_CALL_PLT represents R_PPC64_REL14 and R_PPC64_REL24.
If the function is not preemptable, R_PPC_CALL_PLT can be optimized to R_PPC_CALL:
the formula adjusts the symbol VA from the global entry point to the local entry point.
* R_PPC_TOC: represents R_PPC64_TOC. We don't have a test. Add one to ppc64-relocs.s
Rename it to R_PPC64_TOCBASE because `@tocbase` is the assembly form.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62800
llvm-svn: 362359
In ELF v2 ABI, R_PPC64_GOT_DTPREL16* are not relaxed.
This family of relocation types are used for variables outside of 2GiB
of the TLS block. 2 instructions cannot materialize a DTPREL offset that
is not 32-bit.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62737
llvm-svn: 362357
Fixes the remaining issue of PR41673 after D61186: with `/DISCARD/ { ... } :NONE`,
we may create an output section named `/DISCARD/`.
Note, if an input section is named `/DISCARD/`, ld.bfd discards it but
lld keeps it. It is probably not worth copying this behavior as it is unrealistic.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62768
llvm-svn: 362356
(1) {gcc,clang} -fuse-ld=bfd -pie -fPIE -nostdlib a.c => .interp created
(2) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c => .interp not created
(3) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c a.so => .interp created
The inconsistency of (2) is due to the condition `!Config->SharedFiles.empty()`.
To make lld behave more like ld.bfd, we could change the condition to:
Config->HasDynSymTab && !Config->DynamicLinker.empty() && Script->needsInterpSection();
However, that would bring another inconsistency as can be observed with:
(4) {gcc,clang} -fuse-ld=bfd -no-pie -nostdlib a.c => .interp not created
So instead, use `!Config->DynamicLinker.empty() && Script->needsInterpSection()`,
which is both simple and consistent in these cases.
The inconsistency of (4) likely originated from ld.bfd and gold's choice to have a default --dynamic-linker.
Their condition to create .interp is ANDed with (not -shared).
Since lld doesn't have a default --dynamic-linker,
compiler drivers (gcc/clang) don't pass --dynamic-linker for -shared,
and direct ld users are not supposed to specify --dynamic-linker for -shared,
we do not need the condition !Config->Shared.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62765
llvm-svn: 362355
Delete aarch64-got.s because it is covered by aarch64-tls-iele.s
Merge got-aarch64.s into aarch64-fpic-got.s by adding disassembly to the latter
Create aarch64-gnu-ifunc-nonpreemptable to unify aarch64-gnu-ifunc3.s (position-dependent executable) and aarch64-gnu-ifunc-address-pie.s (PIE)
Rename aarch64-got-reloc.s to aarch64-got-weak-undef.s
Add --no-show-raw-insn to llvm-objdump -d RUN lines
Add -pie test to arch64-tls-iele.s
Delete aarch64-tls-pie.s: it is covered by arch64-tls-iele.s and aarch64-tls-le.s
Rename aarch64-copy2.s to aarch64-nopic-plt.s: "copy2" gives false impression that the test is related to copy relocation
llvm-svn: 362294
GotEntrySize and GotPltEntrySize were added in D22288. Later, with
the introduction of wordsize() (then Config->Wordsize), they become
redundant, because there is no target that sets GotEntrySize or
GotPltEntrySize to a number different from Config->Wordsize.
Reviewed By: grimar, ruiu
Differential Revision: https://reviews.llvm.org/D62727
llvm-svn: 362220
Symbols relative to discarded comdat sections are Undefined instead of
Defined now (after D59649 and D61583). The `== &InputSection::Discarded`
test becomes dead. I cannot find a test related to this behavior.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62725
llvm-svn: 362218
The test (the only test that checks getLinkerScriptLocation()) deleted
by r358652 can be restored by replacing R_X86_64_PLT32 with
R_X86_64_PC32, and changing -pie to -shared (preemptable). Then, the
symbol will not be a link-time constant and a -fPIC error will be
issued.
llvm-svn: 362207
Summary:
Add the names of the input files responsible for each error to the
messages.
Reviewers: sbc100, azakai
Subscribers: dschuff, jgravelle-google, aheejin, sunfish, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62704
llvm-svn: 362162
Summary:
This updates all places in documentation that refer to "Mac OS X", "OS X", etc.
to instead use the modern name "macOS" when no specific version number is
mentioned.
If a specific version is mentioned, this attempts to use the OS name at the time
of that version:
* Mac OS X for 10.0 - 10.7
* OS X for 10.8 - 10.11
* macOS for 10.12 - present
Reviewers: JDevlieghere
Subscribers: mgorny, christof, arphaman, cfe-commits, lldb-commits, libcxx-commits, llvm-commits
Tags: #clang, #lldb, #libc, #llvm
Differential Revision: https://reviews.llvm.org/D62654
llvm-svn: 362113
This is a leftover from r325379.
The intention of this test was to check in a non-pic link, R_X86_64_PC32
to a STT_FUNC created a PLT. However, after the llvm-mc change in
r325569, this code path is no longer exercised. Use the r325379 trick to
keep testing R_X86_64_PC32.
llvm-svn: 362095
For the Local Dynamic case of TLSDESC, _TLS_MODULE_BASE_ is defined as a
special TLS symbol that makes:
1) Without relaxation: it produces a dynamic TLSDESC relocation that
computes 0. Adding @dtpoff to access a TLS symbol.
2) With LD->LE relaxation: _TLS_MODULE_BASE_@tpoff = 0 (lowest address in
the TLS block). Adding @tpoff to access a TLS symbol.
For 1), this saves dynamic relocations and GOT slots as otherwise
(General Dynamic) we would create an R_X86_64_TLSDESC and reserve two
GOT slots for each symbol.
Add ElfSym::TlsModuleBase and change the signature of getTlsTpOffset()
to special case _TLS_MODULE_BASE_.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62577
llvm-svn: 362078
This data structure is only needed temporarily while symbols are being
created.
This is a followup on rL361678.
Differential Revision: https://reviews.llvm.org/D62548
llvm-svn: 361977
There's no guarantee that the other partition will be loaded, so it
can't be reused.
Differential Revision: https://reviews.llvm.org/D62365
llvm-svn: 361926
This change causes us to read partition specifications from partition
specification sections and split output sections into partitions according
to their reachability from partition entry points.
This is only the first step towards a full implementation of partitions. Later
changes will add additional synthetic sections to each partition so that
they can be loaded independently.
Differential Revision: https://reviews.llvm.org/D60353
llvm-svn: 361925
This handles two initial relocation types R_X86_64_GOTPC32_TLSDESC and
R_X86_64_TLSDESC_CALL, as well as the GD->LE and GD->IE relaxations.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62513
llvm-svn: 361911
We need to have all input files ready before doing debuginfo type merging.
This patch is moving the late PDB type server discovery much earlier in the process, when the explicit inputs (OBJs, LIBs) are loaded.
The short term goal is to parallelize type merging.
Differential Revision: https://reviews.llvm.org/D60095
llvm-svn: 361842
This is implemented by creating Undefined (instead of Defined) for such
local STT_SECTION symbols. It allows us to catch errors when there are
relocations to such discarded sections (e.g. in PR41693, ld.bfd and gold
error but we don't). Updated comdat-discarded-error.s checks we emit
friendly error message.
For relocatable-eh-frame.s, ld.lld -r a.o a.o will now error
"STT_SECTION symbol should be defined" because the section .eh_frame
refers to is now an Undefined instead of a Defined.
So I have to change `error()` to `warn()` to retain the output.
rLLD361144 inadvertently enabled the error for --gdb-index
(in LLDDwarfObj<ELFT>::findAux()).
Relocations from .debug_info (not in comdat) to .text.* (in comdat) for
DW_AT_low_pc are common. If an .text.* was discarded, rLLD361144 would error,
which was unexpected. (Note, if we don't error as this patch does,
InputSection::relocateNonAlloc() will resolve such relocations).
llvm-svn: 361830
This is implemented by creating Undefined (instead of Defined) for such
local STT_SECTION symbols. It allows us to catch errors when there are
relocations to such discarded sections (e.g. in PR41693, ld.bfd and gold
error but we don't). Updated comdat-discarded-error.s checks we emit
friendly error message.
For relocatable-eh-frame.s, ld.lld -r a.o a.o will now error
"STT_SECTION symbol should be defined" because the section .eh_frame
refers to is now an Undefined instead of a Defined.
So I have to change `error()` to `warn()` to retain the output.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D61583
llvm-svn: 361792
This patch simplifies ELFFile instance initialization by merging
two similar functions into a single function and call it from the
ctor.
llvm-svn: 361789
When function signatures don't match and the undefined function is not
called directly (i.e. only has its address taken) we don't issue a
warning or create a runtime thunk for the undefined function.
Instead in this case we simply use the defined version of the function.
This is possible since checking signatures of dynamic calls happens
at runtime so any invalid usage will still result in a runtime error.
This is needed to allow C++ programs to link without generating
warnings. Its not uncommon in C++ for vtables to be populated by
function address whee the signature of the function is not known in the
compilation unit. In this case clang declares the method as void(void)
and relies on the vtable caller casting the data back to the correct
signature.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=40412
Differential Revision: https://reviews.llvm.org/D62153
llvm-svn: 361678
Shaves another pointer off of SectionChunk, reducing the size from 96 to
88 bytes, down from 144 before I started working on this. Combined with
D62356, this reduced peak memory usage when linking chrome_child.dll
from 713MB to 675MB, or 5%.
Create NonSectionChunk to provide virtual dispatch to the rest of the
chunk types.
Reviewers: ruiu, aganea
Differential Revision: https://reviews.llvm.org/D62362
llvm-svn: 361667
Shaves another 8 bytes off of SectionChunk, the most commonly allocated
type in LLD.
These indices are only valid after we've assigned chunks to output
sections and removed empty sections, so do that in a new pass.
Reviewers: ruiu, aganea
Differential Revision: https://reviews.llvm.org/D62356
llvm-svn: 361657
This can be useful for post-link tools and for testing. Sometimes
it can be useful to produces a regular executable but with relocations
preserved.
Differential Revision: https://reviews.llvm.org/D62378
llvm-svn: 361635
Patch by Stefan Schmidt.
This adds the /filealign parameter to lld, which allows to specify the
section alignment in the output file (as it does on Microsoft's
link.exe).
This is required to be able to load dynamically linked libraries on the
original Xbox, where the debugger monitor expects the section alignment
in the file to be the same as in memory.
llvm-svn: 361634
GNU readelf tool prints slightly different dynamic table "header" and
surrounds dynamic tag names by brackets. This patch implements the same
formatting for GNU-style output of the `llvm-readobj`.
LLVM
```
DynamicSection [ (13 entries)
Tag Type Name/Value
0x00000006 SYMTAB 0x168
...
]
```
GNU
```
Dynamic section at offset 0x1d0 contains 13 entries:
Tag Type Name/Value
0x00000006 (SYMTAB) 0x168
...
```
Differential Revision: https://reviews.llvm.org/D62256
llvm-svn: 361633
This only needs to be done for MergeChunks, so just do that in a
separate pass in the Writer.
This is one small step towards eliminating the vtable in Chunk.
llvm-svn: 361573
The KeepUnique bit is used during ICF, which only operates on
SectionChunks, so only SectionChunks need it. This frees up a byte in
Chunk, which I plan to use in a follow-up change.
llvm-svn: 361549
OptTable treats arguments starting with / that aren't a known option
as filenames. This means lld-link's and clang-cl's typo correction for
unknown flags didn't do spell checking for misspelled options that start
with /.
I first tried changing OptTable, but that got pretty messy, see PR41787
comments 2 and 3.
Instead, let lld-link's and clang's (including clang-cl's) "file not
found" diagnostic check if a non-existent file looks like it could be a
mis-spelled option, and if so add a "did you mean" suggestion to the
"file not found" diagnostic.
While here, make formatting of a few diagnostics a bit more
self-consistent.
Fixes PR41787.
Differential Revision: https://reviews.llvm.org/D62276
llvm-svn: 361518
My recent commits separated symbol resolution from the symbol table,
so the functions to resolve symbols are now in a somewhat wrong file.
This patch moves it to Symbols.cpp.
The functions are now member functions of the symbol.
This is code move change. I modified function names so that they are
appropriate as member functions, though. No functionality change
intended.
Differential Revision: https://reviews.llvm.org/D62290
llvm-svn: 361474
--{start,end}-lib give files grouped by the options the archive file
semantics. That is, each object file between them acts as if it were
in an archive file whose sole member is the file.
Therefore, files between --{start,end}-lib are linked to the final
output only if they are needed to resolve some undefined symbols.
Previously, the feature was implemented this way:
1. We read a symbol table and insert defined symbols to the symbol
table as lazy symbols.
2. If an undefind symbol is resolved to a lazy symbol, that lazy
symbol instantiate ObjFile class for that symbol, which re-insert
all defined symbols to the symbol table.
So, if an ObjFile is instantiated, defined symbols are inserted to the
symbol table twice. Since inserting long symbol names is not cheap,
there's a room to optimize here.
This patch optimzies it. Now, LazyObjFile remembers symbol handles and
passed them over to a new ObjFile instance, so that the ObjFile
doesn't insert the same strings.
Here is a quick benchmark to link clang. "Original" is the original
lld with unmodified command line options. For "Case 1" and "Case 2", I
extracted all files from archive files and replace .a's in a command
line with .o's wrapped with --{start,end}-lib. I used the original lld
for Case 1" and use this patch for Case 2.
Original: 5.892
Case 1: 6.001 (+1.8%)
Case 2: 5.701 (-3.2%)
So, interestingly, --{start,end}-lib are now faster than the regular
linking scheme with archive files. That's perhaps not too surprising,
though, because for regular archive files, we look up the symbol table
with the same string twice.
Differential Revision: https://reviews.llvm.org/D62188
llvm-svn: 361473
This is a minor improvement inspired by https://bugs.llvm.org/show_bug.cgi?id=38303.
A person reported that he observed message complaining about unsupported R_ARM_V4BX:
error: can't create dynamic relocation R_ARM_V4BX against local symbol in readonly segment; recompile object files with -fPIC
But with -z notext he only saw a relocation number, what is not convenient:
error: ../../gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.o:(.text+0x4F0): unrecognized reloc 40
Also, in the error messages we use relocation but not reloc.
With this patch we start to print one of the following messages:
error: file.o: unrecognized relocation Unknown(999)
error: file.o: unrecognized relocation R_X_KNOWN_BY_LLVM_BUT_UNSUPPORTED_BY_LLD_NAME
There is no way to write a test for that I believe.
Differential revision: https://reviews.llvm.org/D62237
llvm-svn: 361472
Summary:
Before we can assign entries in the function of global index space
we need to know the total number of function and global imports
respectively.
To avoid programmer error this change seals that imports section before
assigned function and global index space. Any attempt to add an import
after the section is sealed will assert.
The lack this such as check caused https://reviews.llvm.org/D61876
to be reverted. I'm also trying to craft a test case the this
failure.
Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62240
llvm-svn: 361470
Also renames it LinkerDriver::compileBitcodeFiles.
The function doesn't logically belong to SymbolTable. We added this
function to the symbol table because symbol table used to be a
container of input files. This is no longer the case.
Differential Revision: https://reviews.llvm.org/D62291
llvm-svn: 361469
The previous patch lost the call to PowerOf2Ceil, which causes LLD to
crash when handling common symbols with a non-power-of-2 size. I tweaked
the existing common.test to make the bsspad16 common symbol be 15 bytes
to add coverage for this case.
llvm-svn: 361426
Symbol's NameSize is computed lazily. Currently, when we replace a symbol,
a cached length value can be discarded. This patch propagates that value.
Differential Revision: https://reviews.llvm.org/D62234
llvm-svn: 361364
Rather than report "undefined symbol: ", give more informative message
about the object file that defines the discarded section.
In particular, PR41133, if the section is a discarded COMDAT, print the
section group signature and the object file with the prevailing
definition. This is useful to track down some ODR issues.
We need to
* add `uint32_t DiscardedSecIdx` to Undefined for this feature.
* make ComdatGroups public and change its type to DenseMap<CachedHashStringRef, const InputFile *>
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D59649
llvm-svn: 361359
This reverts commit 7804dbddcc.
This change broke a bunch of tests of the WebAssembly waterfall.
Will hopefully reland with increased test coverage.
llvm-svn: 361273
--reproduce is a convenient option for debugging. If you invoke lld
with `--reproduce=repro.tar`, it creates `repro.tar` with all input
files and the command line options given to the linker, so that it is
very easy to run lld with the exact same inputs.
ELF and Windows lld have this option.
This patch add that option to lld/wasm.
Differential Revision: https://reviews.llvm.org/D62170
llvm-svn: 361244
Major refactor to better match the structure of the ELF linker.
- Split out relocation processing into scanRelocations
- Split out synthetic sections into their own classes.
Differential Revision: https://reviews.llvm.org/D61811
llvm-svn: 361233
For memory5.test, ld.bfd appears to ignore `. += 0x2000;`, so the test was testing
a wrong behavior. After deleting the code added in rLLD336335, we match ld.bfd and thus fix PR41357.
PR37836 (memory4.test) seems to have been fixed by another change.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62177
llvm-svn: 361228
For a reference to a local symbol, ld.bfd and gold error if the symbol
is defined in a discarded section but accept it if the symbol is
undefined. This inconsistent behavior seems unnecessary for us (it
probably makes sense for them as they differentiate local/global
symbols, the error would mean more code).
Catch such errors. Symbol index 0 may be used by marker relocations,
e.g. R_*_NONE R_ARM_V4BX. Don't error on them.
The difference from D61563 (which caused msan failure) is we don't call
Sym.computeBinding() on local symbols - VersionId is uninitialized.
llvm-svn: 361213
Summary:
Valid section or chunk alignments are powers of 2 in the range [1,
8192]. These can be stored more canonically in log2 form to free up some
bits in Chunk. Combined with D61696, SectionChunk gets 8 bytes smaller.
Reviewers: ruiu, aganea
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61698
llvm-svn: 361206
This patch is a fix for https://bugs.llvm.org/show_bug.cgi?id=41804.
We try to solve the precedence of user-specified symbol ordering file and C3 ordering provided as call graph. It deals with two case:
(1) When both --symbol-ordering-file=<file> and --call-graph-order-file=<file> are present, whichever flag comes later will take precedence.
(2) When only --symbol-ordering-file=<file> is present, it takes precedence over implicit call graph (CGProfile) generated by CGProfilePass enabled in new pass manager.
llvm-svn: 361190
We currently sort dynamic relocations by (!is_relative,symbol_index).
Add r_offset as the third key. This makes `readelf -r` debugging easier
(relocations to the same symbol are ordered by r_offset).
Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.
The difference from the reverted D61477 is that we keep !is_relative as
the first key. In local dynamic TLS model, DTPMOD (e.g.
R_ARM_TLS_DTPMOD32 R_X86_64_DTPMOD and R_PPC{,64}_DTPMOD) may use 0 as
the symbol index.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D62141
llvm-svn: 361164
This reverts commit r361144. It causes a use-of-uninitialized-value in
maybeReportUndefined at llvm/tools/lld/ELF/Relocations.cpp:682, as
detected by MemorySanitizer when local-undefined-symbol.s test is run.
llvm-svn: 361162
This reverts commit r361125. This linker change breaks shared libraries
in some subtle way on x86_64. (Specifically, gold segfaults when
loading the LLVMgold.so plugin linked with lldb with this patch.)
llvm-svn: 361150
For R_TLS:
1) Delete Sym.isTls() . The assembler ensures the symbol is STT_TLS.
If not (the input is broken), we would crash (dereferencing null Out::TlsPhdr).
2) Change Sym.isUndefWeak() to Sym.isUndefined(), otherwise with --noinhibit-exec
we would still evaluate the symbol and crash.
3) Return A if the symbol is undefined. This is PR40570.
The case is probably unrealistic but returning A matches R_ABS and the
behavior of several dynamic loaders.
R_NEG_TLS is obsoleted Sun TLS we don't fully support, but
R_RELAX_TLS_GD_TO_LE_NEG is still used by GD->LE relaxation (subl $var@tpoff,%eax).
They should add the addend. Unfortunately I can't test it as compilers don't seem to generate non-zero implicit addends.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62098
llvm-svn: 361146
For a reference to a local symbol, ld.bfd and gold error if the symbol
is defined in a discarded section but accept it if the symbol is
undefined. This inconsistent behavior seems unnecessary for us (it
probably makes sense for them as they differentiate local/global
symbols, the error would mean more code).
Weaken the condition to getSymbol(Config->IsMips64EL) == 0 to catch such
errors. The symbol index can be 0 (e.g. R_*_NONE R_ARM_V4BX) and we shouldn't error on them.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D61563
llvm-svn: 361144
Fixes PR41692.
We currently sort dynamic relocations by (!is_relative,symbol_index).
Change it to (symbol_index,r_offset). We still place relative
relocations first because R_*_RELATIVE are the only dynamic relocations
with 0 symbol index (except on MIPS, which doesn't use DT_REL[A]COUNT
anyway).
This makes `readelf -r` debugging easier (relocations to the same symbol
are ordered by r_offset).
Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D61477
llvm-svn: 361125
This is a mechanical rewrite of replaceSymbol(A, B) to A->replace(B).
I also added a comment to Symbol::replace().
Technically this change is not necessary, but this change makes code a
bit more concise.
Differential Revision: https://reviews.llvm.org/D62117
llvm-svn: 361123
Otherwise, we may set IsPreemptible (e.g. --dynamic-list) then clear it
(in replaceCommonSymbols()).
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62107
llvm-svn: 361122
This reverts D53906.
D53906 increased p_align of PT_TLS on ARM/AArch64 to 32/64 to make the
static TLS layout compatible with Android Bionic's ELF TLS. However,
this may cause glibc ARM/AArch64 programs to crash (see PR41527).
The faulty PT_TLS in the executable satisfies p_vaddr%p_align != 0. The
remainder is normally 0 but may be non-zero with the hack in place. The
problem is that we increase PT_TLS's p_align after OutputSections'
addresses are fixed (assignAddress()). It is possible that
p_vaddr%old_p_align = 0 while p_vaddr%new_p_align != 0.
For a thread local variable defined in the executable, lld computed TLS
offset (local exec) is different from glibc computed TLS offset from
another module (initial exec/generic dynamic). Note: PR41527 said the
bug affects initial exec but actually generic dynamic is affected as
well.
(glibc is correct in that it compute offsets that satisfy
`offset%p_align == p_vaddr%p_align`, which is a basic ELF requirement.
This hack appears to work on FreeBSD rtld, musl<=1.1.22, and Bionic, but
that is just because they (and lld) incorrectly compute offsets that
satisfy `offset%p_align = 0` instead.)
Android developers are fine to revert this patch, carry this patch in
their tree before figuring out a long-term solution (e.g. a dummy .tdata
with sh_addralign=64 sh_size={0,1} in crtbegin*.o files. The overhead is
now insignificant after D62059).
Reviewed By: rprichard, srhines
Differential Revision: https://reviews.llvm.org/D62055
llvm-svn: 361090
After D62059, we don't align p_memsz of PT_TLS to p_align. The
getRelocTargetVA formula should align it instead.
It becomes clear that R_NEG_TLS and R_TLS are opposite from each other.
In i386-tls-le-align.s, I put ret after call ___tls_get_addr@plt as
otherwise ld.bfd would reject the relaxation:
TLS transition from R_386_TLS_GD to R_386_TLS_LE_32 against `a' at 0x3 in section `.text' failed
llvm-svn: 361088
As Ryan Prichard pointed out, after D62059, the TP offset is incorrect.
Add x86-64-tls-le-align.s to check this. Better formulae for both
variants should take p_vaddr%p_align into account (offset%p_align =
p_vaddr%p_align is a basic ELF requirement), but I can't find a way to
test the behavior.
llvm-svn: 361084
On Elf*_Rel targets, for a relocation to a section symbol, an R_ABS is
added which will be used by relocateOne() to compute the implicit
addend.
Addends of R_*_NONE should be ignored, so don't emit an R_ABS.
This fixes crashes on X86 and ARM because their relocateOne() do not
handle R_*_NONE.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D62052
llvm-svn: 361036
The code was added in r252352, probably to address some layout issues.
Actually PT_TLS's p_memsz doesn't need to be aligned on either variant.
ld.bfd doesn't do that.
In case of larger alignment (e.g. 64 for Android Bionic on AArch64, see
D62055), this may make the overhead smaller.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62059
llvm-svn: 361029
Libtool concludes that the linker doesn't support shared libraries,
unless this flag is listed in the output of --help.
Differential Revision: https://reviews.llvm.org/D62053
llvm-svn: 361017
When integrating PDB output in mingw targeting build systems, it
might be a lot of extra work to specify unique file names for
the pdb output. Therefore allow omitting the actual file name
and let it implicitly be the same name as the linker output, with
a pdb extension.
As the current form of the pdb option takes a separate parameter value,
e.g. "-pdb out.pdb", it is impractical to leave out the parameter value.
Therefore, introduce a second syntax for the option, with an equals
sign, like -pdb=out.pdb, where the value easily can be omitted.
The form -pdb= for requesting pdb files with an implicit name should
work fine, even though it looks a bit unconventional in that form.
Differential Revision: https://reviews.llvm.org/D62004
llvm-svn: 361014
Change R_{386,AARCH64}_NONE yaml2obj tests/icf10.test to use assembly
Add relocation-none-{arm,x86_64}.s.
Check the referenced section survives under --gc-sections.
Check -r copies R_X86_64_NONE R_AARCH64_NONE. (Elf*_Rel arches currently have a bug)
Delete the dtrace tests as they are covered by the R_X86_64_NONE test.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62051
llvm-svn: 361013
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.
Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.
The design goals were to provide:
- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
environments (MSVC in particular).
Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.
In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:
1. There are no competing defined symbols in a given set of libraries, or
if they exist, the program owner doesn't care which is linked to their
program.
2. There may be circular dependencies between libraries.
The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:
.section ".deplibs","MS",@llvm_dependent_libraries,1
.asciz "foo"
For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.
LLD processes the dependent library specifiers in the following way:
1. Dependent libraries which are found from the specifiers in .deplibs sections
of relocatable object files are added when the linker decides to include that
file (which could itself be in a library) in the link. Dependent libraries
behave as if they were appended to the command line after all other options. As
a consequence the set of dependent libraries are searched last to resolve
symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
strings in a .deplibs section by; first, handling the string as if it was
specified on the command line; second, by looking for the string in each of the
library search paths in turn; third, by looking for a lib<string>.a or
lib<string>.so (depending on the current mode of the linker) in each of the
library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
dependent libraries.
Rationale for the above points:
1. Adding the dependent libraries last makes the process simple to understand
from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
will affect all of the dependent libraries. There is a potential problem of
surprise for developers, who might not realize that these options would apply
to these "invisible" input files; however, despite the potential for surprise,
this is easy for developers to reason about and gives developers the control
that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
find input files. The different search methods are tried by the linker in most
obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
is not necessary: if finer control is required developers can fall back to using
the command line directly.
RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.
Differential Revision: https://reviews.llvm.org/D60274
llvm-svn: 360984
This is the last patch of the series of patches to make it possible to
resolve symbols without asking SymbolTable to do so.
The main point of this patch is the introduction of
`elf::resolveSymbol(Symbol *Old, Symbol *New)`. That function resolves
or merges given symbols by examining symbol types and call
replaceSymbol (which memcpy's New to Old) if necessary.
With the new function, we have now separated symbol resolution from
symbol lookup. If you already have a Symbol pointer, you can directly
resolve the symbol without asking SymbolTable to do that.
Now that the nice abstraction become available, I can start working on
performance improvement of the linker. As a starter, I'm thinking of
making --{start,end}-lib faster.
--{start,end}-lib is currently unnecessarily slow because it looks up
the symbol table twice for each symbol.
- The first hash table lookup/insertion occurs when we instantiate a
LazyObject file to insert LazyObject symbols.
- The second hash table lookup/insertion occurs when we create an
ObjFile from LazyObject file. That overwrites LazyObject symbols
with Defined symbols.
I think it is not too hard to see how we can now eliminate the second
hash table lookup. We can keep LazyObject symbols in Step 1, and then
call elf::resolveSymbol() to do Step 2.
Differential Revision: https://reviews.llvm.org/D61898
llvm-svn: 360975
The change broke some scenarios where debug information is still
needed, although MarkLive cannot see it, including the
Chromium/Android build. Reverting to unbreak that build.
llvm-svn: 360955
Previously these sections were being generated during their
constructors. This moves the work to finalizeContent, and also does
the same for the relocation sections because their contents depends
on the final layout too.
This change is part of a larger refactor to how we deal with synthetic
sections: https://reviews.llvm.org/D61811
Differential Revision: https://reviews.llvm.org/D61971
llvm-svn: 360941
Module IDs can appear in diagnostic messages.
This patch adds some auxiliary symbols to improve their readability.
Differential Revision: https://reviews.llvm.org/D61857
llvm-svn: 360858
Previously, we handled common symbols as a kind of Defined symbol,
but what we were doing for common symbols is pretty different from
regular defined symbols.
Common symbol and defined symbol are probably as different as shared
symbol and defined symbols are different.
This patch introduces CommonSymbol to represent common symbols.
After symbols are resolved, they are converted to Defined symbols
residing in a .bss section.
Differential Revision: https://reviews.llvm.org/D61895
llvm-svn: 360841
SymbolTable's add-family functions have lots of parameters because
when they have to create a new symbol, they forward given arguments
to Symbol's constructors. Therefore, the functions take at least as
many arguments as their corresponding constructors.
This patch simplifies the add-family functions. Now, the functions
take a symbol instead of arguments to construct a symbol. If there's
no existing symbol, a given symbol is memcpy'ed to the symbol table.
Otherwise, the functions attempt to merge the existing and a given
new symbol.
I also eliminated `CanOmitFromDynSym` parameter, so that the functions
take really one argument.
Symbol classes are trivially constructible, so looks like constructing
them to pass to add-family functions is as cheap as passing a lot of
arguments to the functions. A quick benchmark showed that this patch
seems performance-neutral.
This is a preparation for
http://lists.llvm.org/pipermail/llvm-dev/2019-April/131902.html
Differential Revision: https://reviews.llvm.org/D61855
llvm-svn: 360838
Keno Fischer