MVP object files may import at most one table, and if they do, it must
be assigned table number zero in the output, as the references to that
table are not relocatable. Ensure that this is the case, even if some
inputs define other tables.
Differential Revision: https://reviews.llvm.org/D96001
This reverts commit ac2be2b6a3.
This causes a whole much of emscripten tests to fail due to newly
undefined symbols appearing. Will investigate and look into re-landing
later.
This fixes two somewhat related issues. Firstly we were never
generating imports for weak functions (even with the `import-functions`
policy for undefined symbols). Adding a direct call to foo in the
`weak-undefined-pic.s` exposed a crash in the linker which this
change fixes.
Secondly we were failing to call `handleWeakUndefines` for the `-pie`
case which is PIC but doesn't set the undefined symbol policy to
`import-functions`. With this change `-pie` binaries will by default
call `handleWeakUndefines` which generates the undefined stub handlers
for any weakly undefined symbols.
Fixes: https://github.com/emscripten-core/emscripten/issues/13337
Differential Revision: https://reviews.llvm.org/D95914
With dynamic linking we have the current limitation that there can be
only a single active data segment (since we use __memory_base as the
load address and we can't do arithmetic in constant expresions).
This change delays the merging of active segments until a little later
in the linking process which means that the grouping of data by section,
and the magic __start/__end symbols work as expected under dynamic
linking.
Differential Revision: https://reviews.llvm.org/D96453
When parsing an object file, LLD interleaves undefined symbol resolution (which
may recursively fetch other lazy objects) with defined symbol resolution.
This may lead to surprising results, e.g. if an object file defines currently
undefined symbols and references another lazy symbol, we may interleave defined
symbols with the lazy fetch, potentially leading to the defined symbols
resolving to different files.
As an example, if both `a.a(a.o)` and `a.a(b.o)` define `foo` (not in COMDAT
group, or in different COMDAT groups) and `__profd_foo` (in COMDAT group
`__profd_foo`). LLD may resolve `foo` to `a.a(a.o)` and `__profd_foo` to
`b.a(b.o)`, i.e. different files.
```
parse ArchiveFile a.a
entry fetches a.a(a.o)
parse ObjectFile a.o
define entry
define foo
reference b
b fetches a.a(b.o)
parse ObjectFile b.o
define prevailing __profd_foo
define (ignored) non-prevailing __profd_foo
```
Assuming a set of interconnected symbols are defined all or none in several lazy
objects. Arguably making them resolve to the same file is preferable than making
them resolve to different files (some are lazy objects).
The main argument favoring the new behavior is the stability. The relative order
between a defined symbol and an undefined symbol does not change the symbol
resolution behavior. Only the relative order between two undefined symbols can
affect fetching behaviors.
---
The real world case is reduced from a Fuchsia PGO usage: `a.a(a.o)` has a
constructor within COMDAT group C5 while `a.a(b.o)` has a constructor within
COMDAT group C2. Because they use different group signatures, they are not
de-duplicated. It is not entirely whether Clang behavior is entirely conforming.
LLD selects the PGO counter section (`__profd_*`) from `a.a(b.o)` and the
constructor section from `a.a(a.o)`. The `__profd_*` is a SHF_LINK_ORDER section
linking to its own non-prevailing constructor section, so LLD errors
`sh_link points to discarded section`. This patch fixes the error.
Differential Revision: https://reviews.llvm.org/D95985
Multi-configuration generators (such as Visual Studio and Xcode) allow the specification of a build flavor at build time instead of config time, so the lit configuration files need to support that - and they do for the most part. There are several places that had one of two issues (or both!):
1) Paths had %(build_mode)s set up, but then not configured, resulting in values that would not work correctly e.g. D:/llvm-build/%(build_mode)s/bin/dsymutil.exe
2) Paths did not have %(build_mode)s set up, but instead contained $(Configuration) (which is the value for Visual Studio at configuration time, for Xcode they would have had the equivalent) e.g. "D:/llvm-build/$(Configuration)/lib".
This seems to indicate that we still have a lot of fragility in the configurations, but also that a number of these paths are never used (at least on Windows) since the errors appear to have been there a while.
This patch fixes the configurations and it has been tested with Ninja and Visual Studio to generate the correct paths. We should consider removing some of these settings altogether.
Reviewed By: JDevlieghere, mehdi_amini
Differential Revision: https://reviews.llvm.org/D96427
The code previously assumed that `getChunk` would return a non-null pointer for
every symbol, but in fact it only returns non-null pointers for DefinedFunction
and DefinedData symbols. This patch fixes the segfault by checking whether
`getChunk` returns a null for each symbol and skipping the mapping output for
any symbols for which it does.
Differential Revision: https://reviews.llvm.org/D88369
This moves the error checking until after all optional
symbols (including the section start/end symbols) have
been created.
Differential Revision: https://reviews.llvm.org/D96318
Since we emit diagnostics for undefineds in Writer::scanRelocations()
and symbols referenced by -u flags aren't referenced by any relocations,
this needs some manual code (similar to the entry point).
Differential Revision: https://reviews.llvm.org/D94371
`extern const bfd_target aarch64_elf64_le_vec;` is a variable in BFD.
It was somehow misused as an emulation by Android.
```
% aarch64-linux-gnu-ld -m aarch64_elf64_le_vec a.o
aarch64-linux-gnu-ld: unrecognised emulation mode: aarch64_elf64_le_vec
Supported emulations: aarch64linux aarch64elf aarch64elf32 aarch64elf32b aarch64elfb armelf armelfb aarch64linuxb aarch64linux32 aarch64linux32b armelfb_linux_eabi armelf_linux_eabi
```
Acked by Stephen Hines, who removed the flag from Android a while back.
Rewritting the path of the sample profile file in response.txt to be relative to the repro tar.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D96193
This is an initial base commit for ARM64 target arch support. I don't represent that it complete or bug-free, but wish to put it out for review now that some basic things like branch target & load/store address relocs are working.
I can add more tests to this base commit, or add them in follow-up commits.
It is not entirely clear whether I use the "ARM64" (Apple) or "AArch64" (non-Apple) naming convention. Guidance is appreciated.
Differential Revision: https://reviews.llvm.org/D88629
The LSDA pointers are encoded as offsets from the image base,
and arranged in one big contiguous array. Each second-level page records
the offset within that LSDA array which corresponds to the LSDA for its
first CU entry.
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D95810
Note that there is a triple indirection involved with
personalities and compact unwind:
1. Two bits of each CU encoding are used as an offset into the
personality array.
2. Each entry of the personality array is an offset from the image base.
The resulting address (after adding the image base) should point within the
GOT.
3. The corresponding GOT entry contains the actual pointer to the
personality function.
To further complicate things, when the personality function is in the
object file (as opposed to a dylib), its references in
`__compact_unwind` may refer to it via a section + offset relocation
instead of a symbol relocation. Since our GOT implementation can only
create entries for symbols, we have to create a synthetic symbol at the
given section offset.
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D95809
GNU as does not sort local symbols. This has several advantages:
* The .symtab order is roughly the symbol occurrence order.
* The closest preceding STT_SECTION symbol is the definition of a local symbol.
* The closest preceding STT_FILE symbol is the defining file of a local symbol, if there are multiple default-version .file directives. (Not implemented in MC.)
A SHF_LINK_ORDER .gcc_except_table is similar to a .gcc_except_table in
a section group. The associated text section is responsible for retaining it.
LLD still does not support GC of non-group non-SHF_LINK_ORDER .gcc_except_table -
but that is not necessary because we can teach the compiler to set SHF_LINK_ORDER.
The Mach kernel & codesign on arm64 macOS has strict requirements for alignment and sequence of segments and sections. Dyld probably is just as picky, though kernel & codesign reject malformed Mach-O files before dyld ever has a chance.
I developed this diff by incrementally changing alignments & sequences to match the output of ld64. I stopped when my hello-world test program started working: `codesign --verify` succeded, and `execve(2)` didn't immediately fail with `errno == EBADMACHO` = `"Malformed Mach-O file"`.
Differential Revision: https://reviews.llvm.org/D94935
The current diagnostic has confused users. The new wording is adapted from one suggested by Ian Lance Taylor.
Differential Revision: https://reviews.llvm.org/D95917
binutils 2.36 introduced the new section flag SHF_GNU_RETAIN (for ELFOSABI_GNU &
ELFOSABI_FREEBSD) to mark a sections as a GC root. Several LLVM side toolchain
folks (including me) were involved in the design process of SHF_GNU_RETAIN and
were happy with this proposal.
Currently GNU ld only respects SHF_GNU_RETAIN semantics for ELFOSABI_GNU &
ELFOSABI_FREEBSD object files
(https://sourceware.org/bugzilla/show_bug.cgi?id=27282). GNU ld sets EI_OSABI
to ELFOSABI_GNU for relocatable output
(https://sourceware.org/bugzilla/show_bug.cgi?id=27091). In practice the single
value EI_OSABI is neither a good indicator for object file compatibility, nor a
useful mechanism marking used ELF extensions.
For input, we respect SHF_GNU_RETAIN semantics even for ELFOSABI_NONE object
files. This is compatible with how LLD and GNU ld handle (mildly useful) STT_GNU_IFUNC
/ (emitted by GCC, considered misfeature by some folks) STB_GNU_UNIQUE input.
(As of LLVM 12.0.0, the integrated assembler does not set ELFOSABI_GNU for
STT_GNU_IFUNC/STB_GNU_UNIQUE).
Arguably STT_GNU_IFUNC/STB_GNU_UNIQUE probably need indicators in object files
but SHF_GNU_RETAIN is more likely accepted by more OSABI platforms.
For output, we take a step further than GNU ld: we don't promote ELFOSABI_NONE
to ELFOSABI_GNU for all output.
Differential Revision: https://reviews.llvm.org/D95749
In GCC emitted .debug_info sections, R_386_GOTOFF may be used to
relocate DW_AT_GNU_call_site_value values
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98946).
R_386_GOTOFF (`S + A - GOT`) is one of the `isStaticLinkTimeConstant` relocation
type which is not PC-relative, so it can be used from non-SHF_ALLOC sections. We
current allow new relocation types as needs come. The diagnostic has caught some
bugs in the past.
Differential Revision: https://reviews.llvm.org/D95994
This extends {D92539} to work even when we are loading archive
members via `-force_load`. I uncovered this issue while trying to
force-load archives containing bitcode -- we were segfaulting.
In addition to fixing the `-force_load` case, this diff also addresses
the behavior of `-ObjC` when LTO bitcode is involved -- we need to
force-load those archive members if they contain ObjC categories.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D95265
This makes our error messages more informative. But the bigger motivation is for
LTO symbol resolution, which will be in an upcoming diff. The changes in this
one are largely mechanical.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D94316
On z/OS, other error messages are not matched correctly in lit tests.
```
EDC5121I Invalid argument.
EDC5111I Permission denied.
```
This patch adds a lit substitution to fix it.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D95808
Add per-reloc-type attribute bits and migrate code from per-target file into target independent code, driven by reloc attributes.
Many cleanups
Differential Revision: https://reviews.llvm.org/D95121
The option catches incompatibility between `R_*_IRELATIVE` and DT_TEXTREL/DF_TEXTREL
before glibc 2.29. Newer glibc versions are more common nowadays and I don't
think this option has ever been used. Diagnosing this problem is also
straightforward by reading the stack trace.
On z/OS, the following error message is not matched correctly in lit tests.
```
EDC5129I No such file or directory.
```
This patch uses a lit config substitution to check for platform specific error messages.
Reviewed By: muiez, jhenderson
Differential Revision: https://reviews.llvm.org/D95246
Identify dynamically exported symbols (--export-dynamic[-symbol=],
--dynamic-list=, or definitions needed to preempt shared objects) and
prevent their LTO visibility from being upgraded.
This helps avoid use of whole program devirtualization when there may
be overrides in dynamic libraries.
Differential Revision: https://reviews.llvm.org/D91583
A default version (@@) is only available for defined symbols.
Currently we use "@@" for undefined symbols too.
This patch fixes the issue and improves our test case.
Differential revision: https://reviews.llvm.org/D95219
Whilst migrating/retiring some downstream testing, I came across a test
for weak undef IE and LD TLS references, but was unable to find any
equivalent in LLD's upstream testing. There does seem to be some slight
subtle differences that could be worth testing compared to LE TLS
references, in particular that IE can be relaxed to LE in this case,
hence this change.
Differential Revision: https://reviews.llvm.org/D95124
Reviewed by: grimar, MaskRay
Just getting rid of some logspew as I test LLD under existing build
systems.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D95213
If foo is referenced in any object file, bitcode file or shared object,
`__wrap_foo` should be retained as the redirection target of sym
(f96ff3c0f8).
If the object file defining foo has foo references, we cannot easily distinguish
the case from cases where foo is not referenced (we haven't scanned
relocations). Retain `__wrap_foo` because we choose to wrap sym references
regardless of whether sym is defined to keep non-LTO/LTO/relocatable links' behaviors similar
https://sourceware.org/bugzilla/show_bug.cgi?id=26358 .
If foo is defined in a shared object, `__wrap_foo` can still be omitted
(`wrap-dynamic-undef.s`).
Reviewed By: andrewng
Differential Revision: https://reviews.llvm.org/D95152
Fixes PR48523. When the linker errors with "output file too large",
one question that comes to mind is how the section sizes differ from
what they were previously. Unfortunately, this information is lost
when the linker exits without writing the output file. This change
makes it so that the error message includes the sizes of the largest
sections.
Reviewed By: MaskRay, grimar, jhenderson
Differential Revision: https://reviews.llvm.org/D94560
This makes the following improvements.
For `SHT_GNU_versym`:
* yaml2obj: set `sh_link` to index of `.dynsym` section automatically.
For `SHT_GNU_verdef`:
* yaml2obj: set `sh_link` to index of `.dynstr` section automatically.
* yaml2obj: set `sh_info` field automatically.
* obj2yaml: don't dump the `Info` field when its value matches the number of version definitions.
For `SHT_GNU_verneed`:
* yaml2obj: set `sh_link` to index of `.dynstr` section automatically.
* yaml2obj: set `sh_info` field automatically.
* obj2yaml: don't dump the `Info` field when its value matches the number of version dependencies.
Also, simplifies few test cases.
Differential revision: https://reviews.llvm.org/D94956
The relocation offsets were incorrect. I fixed them with llvm-readobj
-codeview -codeview-subsection-bytes, which has a helpful printout of
the relocations that apply to a given symbol record with their offsets.
With this, I was able to update the relocation offsets in the yaml to
fix the line table and the S_DEFRANGE_REGISTER records.
There is still some remaining inconsistency in yaml2obj and obj2yaml
when round tripping MSVC objects, but that isn't a blocker for relanding
D94267.
Run the ObjCARCContractPass during LTO. The legacy LTO backend (under
LTO/ThinLTOCodeGenerator.cpp) already does this; this diff just adds that
behavior to the new LTO backend. Without that pass, the objc.clang.arc.use
intrinsic will get passed to the instruction selector, which doesn't know how to
handle it.
In order to test both the new and old pass managers, I've also added support for
the `--[no-]lto-legacy-pass-manager` flags.
P.S. Not sure if the ordering of the pass within the pipeline matters...
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D94547
Andy Wingo