Similar to D66992.
In GNU ld, a -u specified symbol is a STB_DEFAULT undefined.
It cannot be changed to STB_WEAK by a later STB_WEAK undefined in a regular object file.
The behavior is consistent with our model because -u means "we need to fetch a lazy definition".
It should not be altered just because there is also a STB_WEAK undefined.
Note, our -u semantics are still different from GNU ld (https://github.com/ClangBuiltLinux/linux/issues/515):
we don't force the specified symbol to appear in .symtab This is a deliberate decision.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D88945
Add Thread Local Storage support for the 34 bit relocation R_PPC64_GOT_TLSGD_PCREL34 used in General Dynamic.
The compiler will produce code that looks like:
```
pla r3, x@got@tlsgd@pcrel R_PPC64_GOT_TLSGD_PCREL34
bl __tls_get_addr@notoc(x@tlsgd) R_PPC64_TLSGD
R_PPC64_REL24_NOTOC
```
LLD should be able to correctly compute the relocation for R_PPC64_GOT_TLSGD_PCREL34 as well as do the following two relaxations where possible:
General Dynamic to Local Exec:
```
paddi r3, r13, x@tprel
nop
```
and General Dynamic to Initial Exec:
```
pld r3, x@got@tprel@pcrel
add r3, r3, r13
```
Note:
This patch adds support for the PC Relative (no TOC) version of General Dynamic on top of the existing support for the TOC version of General Dynamic.
The ABI does not provide any way to tell by looking only at the relocation `R_PPC64_TLSGD` when it is being used in a TOC instruction sequence or and when it is being used in a no TOC sequence. The TOC sequence should always be 4 byte aligned. This patch adds one to the offset of the relocation when it is being used in a no TOC sequence. In this way LLD can tell by looking at the alignment of the offset of `R_PPC64_TLSGD` whether or not it is being used as part of a TOC or no TOC sequence.
Reviewed By: NeHuang, sfertile, MaskRay
Differential Revision: https://reviews.llvm.org/D87318
Add Thread Local Storage support for the 34 bit relocation R_PPC64_GOT_TLSGD_PCREL34 used in General Dynamic.
The compiler will produce code that looks like:
```
pla r3, x@got@tlsgd@pcrel R_PPC64_GOT_TLSGD_PCREL34
bl __tls_get_addr@notoc(x@tlsgd) R_PPC64_TLSGD
R_PPC64_REL24_NOTOC
```
LLD should be able to correctly compute the relocation for R_PPC64_GOT_TLSGD_PCREL34 as well as do the following two relaxations where possible:
General Dynamic to Local Exec:
```
paddi r3, r13, x@tprel
nop
```
and General Dynamic to Initial Exec:
```
pld r3, x@got@tprel@pcrel
add r3, r3, r13
```
Note:
This patch adds support for the PC Relative (no TOC) version of General Dynamic on top of the existing support for the TOC version of General Dynamic.
The ABI does not provide any way to tell by looking only at the relocation `R_PPC64_TLSGD` when it is being used in a TOC instruction sequence or and when it is being used in a no TOC sequence. The TOC sequence should always be 4 byte aligned. This patch adds one to the offset of the relocation when it is being used in a no TOC sequence. In this way LLD can tell by looking at the alignment of the offset of `R_PPC64_TLSGD` whether or not it is being used as part of a TOC or no TOC sequence.
Reviewed By: NeHuang, sfertile, MaskRay
Differential Revision: https://reviews.llvm.org/D87318
When adding an archive member with a problem, e.g. a new bitcode with an
old archiver, containing an unsupported attribute, or an ELF file with a
malformed symbol table, the archiver would throw away the error and
simply add the member to the archive without any symbol entries. This
meant that the resultant archive could be silently unusable when not
using --whole-archive, and result in unexpected undefined symbols.
This change fixes this issue by addressing two FIXMEs and only throwing
away not-an-object errors. However, this meant that some LLD tests which
didn't need symbol tables and were using invalid members deliberately to
test the linker's malformed input handling no longer worked, so this
patch also stops the archiver from looking for symbols in an object if
it doesn't require a symbol table, and updates the tests accordingly.
Differential Revision: https://reviews.llvm.org/D88288
Reviewed by: grimar, rupprecht, MaskRay
The routing rules are:
sym -> __wrap_sym
__real_sym -> sym
__wrap_sym and sym are routing targets, so they need to be exposed to the symbol
table. __real_sym is not and can be eliminated if not used by regular object.
The R2 save stub will now support offsets up to 64 bits.
There are three cases that will be used.
1) The offset fits in 26 bits.
```
b <26 bit offset>
```
2) The offset does not fit in 26 bits but fits in 34 bits.
```
paddi r12, 0, <34 bit offset>, 1
mtctr r12
bctr
```
3) The offset does not fit in 34 bits. Since this is an R2 save stub we can use
the TOC in R2. We are not loading the offset but the actual address we want to
branch to.
```
addis r12, r2, <address in TOC lo>
ld r12 <address in TOC hi>(r12)
mtctr r12
bctr
```
In case 1) the stub is only 8 bytes while in cases 2) and 3) the stub will be
20 bytes.
Reviewed By: MaskRay, sfertile, NeHuang
Differential Revision: https://reviews.llvm.org/D87916
".text.split." holds symbols which are split out from functions in
other input sections. For example, with -fsplit-machine-functions,
placing the cold parts in .text.split instead of .text.unlikely mitigates
against poor profile inaccuracy. Techniques such as hugepage remapping can
make conservative decisions at the section granularity.
Differential Revision: https://reviews.llvm.org/D87840
This patch expands two LTO test cases to check other aspects.
1) weak.ll has been expanded to show that it doesn't matter whether the
first appearance of a weak symbol appears in a bitcode file or native
object - that one is picked.
2) reproduce-lto.ll has been expanded to show that the bitcode files are
stored in the reproduce package and that intermediate files (such as
the LTO-compiled object) are not.
Differential Revision: https://reviews.llvm.org/D88094
Reviewed by: grimar, MaskRay
Update the thunk range error report for PPC64PCRelLongBranchThunk and add a range
error test case for PPC64R12SetupStub.
Differential Revision: https://reviews.llvm.org/D87381
Add Thread Local Storage Initial Exec support to LLD.
This patch adds the computation for the relocations as well as the relaxation from Initial Exec to Local Exec.
Initial Exec:
```
pld r9, x@got@tprel@pcrel
add r9, r9, x@tls@pcrel
```
or
```
pld r9, x@got@tprel@pcrel
lbzx r10, r9, x@tls@pcrel
```
Note that @tls@pcrel is actually encoded as R_PPC64_TLS with a one byte displacement.
For the above examples relaxing Intitial Exec to Local Exec:
```
paddi r9, r9, x@tprel
nop
```
or
```
paddi r9, r13, x@tprel
lbz r10, 0(r9)
```
Reviewed By: nemanjai, MaskRay, #powerpc
Differential Revision: https://reviews.llvm.org/D86893
Large files are cumbersome on some filesystems and can more easily trigger ENOSPC.
Some tests use two text sections with output section addresses to test branch ranges.
Use two text segments to prevent LLD from filling the gap and unnecessarily increasing the output size.
With this change, there is no test/ELF temporary file larger than 100MiB.
Reviewed By: psmith
Differential Revision: https://reviews.llvm.org/D88037
A repeated typo in lld/test/ELF/map-file.s prevented a number of checks from being executed.
CHECk-NEXT -> CHECK-NEXT
^ ^
After correcting the typo, a small adjustment was needed to match the size of the synthetic .comment section (which always contains "LLD 1.0" in the test environment).
Differential revision: https://reviews.llvm.org/D88023
The additional testing is testing we previously had in a downstream test
suite.
Reviewed by: grimar, MaskRay
Differential Revision: https://reviews.llvm.org/D87824
Add Thread Local Storage Local Exec support to LLD. This is to support PC Relative addressing of Local Exec.
The patch teaches LLD to handle:
```
paddi r9, r13, x1@tprel
```
The relocation is:
```
R_PPC_TPREL34
```
Reviewed By: NeHuang, MaskRay
Differential Revision: https://reviews.llvm.org/D86608
Prefer `errorOrWarn` to `fatal` for recoverable errors and graceful degradation
when --noinhibit-exec is specified.
Mention the destination symbol, otherwise the diagnostic is not really actionable.
Two errors are not tested but the patch does not intend to add the coverage.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D87486
Currently we treat SHT_RISCV_ATTRIBUTES like a normal section and
concatenate all such input sections, yielding invalid output unless only
a single attributes section is present in the input. Instead, pick the
first as with SHT_ARM_ATTRIBUTES. We do not currently need to condition
our behaviour on the contents, unlike Arm. In future, we should both do
stricter validation of the input and merge all sections together to
ensure we have, for example, the full arch string requirement, but this
rudimentary implementation is good enough for most common cases.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D86309
Following 97febb1, fix the out-of-memory error associated with buffering the output
in-memory by writing to an allocated file with the minimum offset and running it
on ppc system-linux only.
Peer reviewed by: nemanjai
Following 0becc27ebf, `ppc64-pcrel-long-branch-error.s` fails in some
environments with out-of-memory errors associated with buffering the
output in-memory. Since the alternative of writing to an allocated file
is also known to cause problems, we will disable the test
unconditionally (pending a mechanism to disable the test selectively).
In this patch, a pc-rel based long branch thunk is added for the local
call protocol that caller and callee does not use TOC.
Reviewed By: sfertile, nemanjai
Differential Revision: https://reviews.llvm.org/D86706
Whilst reviewing some internal testing, I noticed a couple of holes in
coverage of mergeable sections containing symbols. This patch addresses
these holes:
1) Show that mid-piece symbols have their values updated properly when
pieces are merged.
2) Show the behaviour of symbols in mergeable pieces when --gc-sections
is enabled.
Reviewed by: grimar, MaskRay
Differential Revision: https://reviews.llvm.org/D86543
Currently, when a program header type is unknown, we dont print anything:
```
ProgramHeader {
Type: (0x60000000)
```
With this patch the output will be:
```
ProgramHeader {
Type: Unknown (0x60000000)
```
It was discussed in D85526 and consistent with what we print for
'--sections' already, e.g.:
```
Section {
Name: .sec
Type: Unknown (0x7FFFFFFF)
}
```
Differential revision: https://reviews.llvm.org/D86213
The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage.
It needs to have two relocations on it.
One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC.
The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed.
In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem.
This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D85994
PR46970: for `alias = aliasee`, the alias can be used in relocation processing
and on ARM st_type does affect Thumb interworking. It is thus desirable for the
alias to get the same st_type.
Note that the st_size field should not be inherited because some tools use
st_size=0 as a heuristic to detect aliases. Retaining st_size can thwart such
heuristics and cause aliases to be preferred over the original symbols.
Differential Revision: https://reviews.llvm.org/D86263
* GNU ld places non-SHF_ALLOC sections after SHF_ALLOC sections. This has the
advantage that the file offsets of a non-SHF_ALLOC cannot be contained in
a PT_LOAD. This patch matches the behavior.
* For non-SHF_ALLOC non-orphan sections, GNU ld may assign non-zero sh_addr and
treat them similar to SHT_NOBITS (not advance location counter). This
is an alternative approach to what we have done in D85100.
By placing non-SHF_ALLOC sections at the end, we can drop special
cases in createSection and findOrphanPos added by D85100.
Different from GNU ld, we set sh_addr to 0 for non-SHF_ALLOC sections. 0
arguably is better because non-SHF_ALLOC sections don't appear in the memory
image.
ELF spec says:
> sh_addr - If the section will appear in the memory image of a process, this
> member gives the address at which the section's first byte should
> reside. Otherwise, the member contains 0.
D85100 appeared to take a detour. If we take a combined view on D85100 and this
patch, the overall complexity slightly increases (one more 3-line loop) and
compatibility with GNU ld improves.
The behavior we don't want to match is the special treatment of .symtab
.shstrtab .strtab: they can be matched in LLD but not in GNU ld.
Reviewed By: jhenderson, psmith
Differential Revision: https://reviews.llvm.org/D85867
LLD currently does not allow non-contiguous SHF_LINK_ORDER components in an
output section. This makes it infeasible to add SHF_LINK_ORDER to an existing
metadata section if backward compatibility with older object files are
concerned.
We did not allow mixed components (like GNU ld) and D77007 relaxed to allow
non-contiguous SHF_LINK_ORDER components. This patch allows arbitrary mix, with
sorting performed within an InputSectionDescription. For example,
`.rodata : {*(.rodata.foo) *(.rodata.bar)}`, has two InputSectionDescription's.
If there is at least one SHF_LINK_ORDER and at least one non-SHF_LINK_ORDER in
.rodata.foo, they are ordered within `*(.rodata.foo)`: we arbitrarily place
SHF_LINK_ORDER components before non-SHF_LINK_ORDER components (like Solaris ld).
`*(.rodata.bar)` is ordered similarly, but the two InputSectionDescription's
don't interact. It can be argued that this is more reasonable than the previous
behavior where written order was not respected.
It would be nice if the two different semantics (ordering requirement & garbage
collection) were not overloaded on one section flag, however, it is probably
difficult to obtain a generic flag at this point
(https://groups.google.com/forum/#!topic/generic-abi/hgx_m1aXqUo
"SHF_LINK_ORDER's original semantics make upgrade difficult").
(Actually, without the GC semantics, SHF_LINK_ORDER would still have the
sh_link!=0 & sh_link=0 issue. It is just that people find the GC semantics more
useful and tend to use the feature more often.)
GNU ld feature request: https://sourceware.org/bugzilla/show_bug.cgi?id=16833
Differential Revision: https://reviews.llvm.org/D84001
This patch implements the handling for the R_PPC64_PCREL_OPT relocation as well
as the GOT relocation for the associated R_PPC64_GOT_PCREL34 relocation.
On Power10 targets with PC-Relative addressing, the linker can relax
GOT-relative accesses to PC-Relative under some conditions. Since the sequence
consists of a prefixed load, followed by a non-prefixed access (load or store),
the linker needs to replace the first instruction (as the replacement
instruction will be prefixed). The compiler communicates to the linker that
this optimization is safe by placing the two aforementioned relocations on the
GOT load (of the address).
The linker then does two things:
- Convert the load from the got into a PC-Relative add to compute the address
relative to the PC
- Find the instruction referred to by the second relocation (R_PPC64_PCREL_OPT)
and replace the first with the PC-Relative version of it
It is important to synchronize the mapping from legacy memory instructions to
their PC-Relative form. Hence, this patch adds a file to be included by both
the compiler and the linker so they're always in agreement.
Differential revision: https://reviews.llvm.org/D84360
Thunk alignment is added in thie patch when using pc-rel instructions
to avoid crossing the 64 byte boundary.
Patched by: nemanjai, NeHuang
Reviewed By: sfertile, MaskRay
Differential Revision: https://reviews.llvm.org/D85973
-gdwarf-5 -fdebug-types-section may produce multiple .debug_info sections. All
except one are type units (.debug_types before DWARF v5). When constructing
.gdb_index, we should ignore these type units. We use a simple heuristic: the
compile unit does not have the SHF_GROUP flag. (This needs to be revisited if
people place compile unit .debug_info in COMDAT groups.)
This issue manifests as a data race: because an object file may have multiple
.debug_info sections, we may concurrently construct `LLDDwarfObj` for the same
file in multiple threads. The threads may access `InputSectionBase::data()`
concurrently on the same input section. `InputSectionBase::data()` does a lazy
uncompress() and rewrites the member variable `rawData`. A thread running zlib
`inflate()` (transitively called by uncompress()) on a buffer with `rawData`
tampered by another thread may fail with `uncompress failed: zlib error: Z_DATA_ERROR`.
Even if no data race occurred in an optimistic run, if there are N .debug_info,
one CU entry and its address ranges will be replicated N times. The result
.gdb_index can be much larger than a correct one.
The new test gdb-index-dwarf5-type-unit.s actually has two compile units. This
cannot be produced with regular approaches (it can be produced with -r
--unique). This is used to demonstrate that the .gdb_index construction code
only considers the last non-SHF_GROUP .debug_info
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D85579
* For .cfi_*, GCC/GNU as emits SHT_PROGBITS type .eh_frame sections.
* Since rL252300, clang emits SHT_X86_64_UNWIND type .eh_frame sections
(originated from Solaris, documented in the x86-64 psABI).
* Some assembly use `.section .eh_frame,"a",@unwind` to generate
SHT_X86_64_UNWIND .eh_frame sections.
In a non-relocatable link, input .eh_frame are combined and there is
only one SyntheticSection .eh_frame in the output section, so the
"section type mismatch" diagnostic does not fire.
In a relocatable link, there is no SyntheticSection .eh_frame. .eh_frame of
mixed types can trigger the diagnostic. This patch fixes it by adding another
special case 0x70000001 (= SHT_X86_64_UNWIND) to canMergeToProgbits().
ld.lld -r gcc.o clang.o => error: section type mismatch for .eh_frame
There was a discussion "RFC: Usefulness of SHT_X86_64_UNWIND" on the x86-64-abi
mailing list. Folks are not wild about making the psABI value 0x70000001 into
gABI, but a few think defining 0x70000001 for .eh_frame may be a good idea for a
new architecture.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D85785
For an InputSection, the `buf` argument of `InputSectionBase::relocate` points
to the content of the containing OutputSection, instead of the content of the
InputSection itself, so `outSecOff` needs to be added in its callees. This is
counter-intuitive and leads to many `- outSecOff` and `+ outSecOff`.
This patch makes `InputSection::writeTo` call `InputSectionBase::relocate` with
`outSecOff` added. relocAlloc/relocNonAlloc/relocateNonAllocForRelocatable can
thus be simplified now.
Updated test:
* non-abs-reloc.s: A minor offset bug is fixed for a diagnostic in `relocateNonAlloc`
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D85618
It turns that gnu-ifunc-plt-i386.s and gnu-ifunc-plt.s tests are broken.
Initially they were implemented in D27581 and tested that `IRELATIVE` relocations
are placed after other relocations in `.rel.plt`.
Later, we started to place `IRELATIVE` relocations to `.rela.dyn` (D65651).
Also, at some point `.plt` was renamed to `.iplt` (D71520).
Now, `gnu-ifunc*` tests mentioned do not test what they intended to test initially:
they should test that `IRELATIVE` relocations are placed after other ones in
`.rela.dyn`. Also, comments needs to be updated accordingly after changes performed.
This patch updates them.
Differential revision: https://reviews.llvm.org/D85642
Currently both sections will be placed in the same PT_LOAD and therefore
lld generates a contiguous output file containing both sections.
By using AT(0xffff0000) the .vectors is placed a separate PT_LOAD and the
resulting file is now only a few kilobytes.
Reviewed By: psmith
Differential Revision: https://reviews.llvm.org/D85661
glibc/sysdeps/unix/sysv/linux/x86_64/sigaction.c libc.a(sigaction.o) has a CIE
with the augmentation string "zRS". Support 'S' to allow --icf={safe,all}.
Konstantin Zhuravlyov