clang may produce `movl x@GOTPCREL+4(%rip), %eax` when loading the high 32 bits
of the address of a global variable in -fpic/-fpie mode.
If assembled by GNU as, the fixup emits an R_X86_64_GOTPCRELX with an
addend != -4. The instruction loads from the GOT entry with an offset
and thus it is incorrect to relax the instruction.
If assembled by the integrated assembler, we emit R_X86_64_GOTPCREL for
relocations that definitely cannot be relaxed (D92114), so this patch is not
needed.
This patch disables the relaxation, which is compatible with the implementation in GNU ld
("Add R_X86_64_[REX_]GOTPCRELX support to gas and ld").
Reviewed By: grimar, jhenderson
Differential Revision: https://reviews.llvm.org/D91993
This adds support for ld.lld's --reproduce / lld-link's /reproduce:
flag to the MachO port. This flag can be added to a link command
to make the link write a tar file containing all inputs to the link
and a response file containing the link command. This can be used
to reproduce the link on another machine, which is useful for sharing
bug report inputs or performance test loads.
Since the linker is usually called through the clang driver and
adding linker flags can be a bit cumbersome, setting the env var
`LLD_REPRODUCE=foo.tar` triggers the feature as well.
The file response.txt in the archive can be used with
`ld64.lld.darwinnew $(cat response.txt)` as long as the contents are
smaller than the command-line limit, or with `ld64.lld.darwinnew
@response.txt` once D92149 is in.
The support in this patch is sufficient to create a tar file for
Chromium's base_unittests that can link after unpacking on a different
machine.
Differential Revision: https://reviews.llvm.org/D92274
For --gc-sections, SmallVector<InputSection *, 256> -> SmallVector<InputSection *, 0> because the code bloat (1296 bytes) is not worthwhile (the saved reallocation is negligible).
For OutputSection::compressedData, N=1 is useless (for a compressed .debug_*, the size is always larger than 1).
Also sync help texts for the option between elf and coff ports.
Decisions:
- Do this even if /lldignoreenv is passed. /reproduce: does not affect
the main output, and this makes the env var more convenient to use.
(On the other hand, it's now possible to set this env var and forget
about it, and all future builds in the same shell will be much slower.
That's true for ld.lld, but posix shells have an easy way to set an
env var for a single command; in cmd.exe this is not possible without
contortions. Then again, lld-link runs in posix shells too.)
Original patch rebased across D68378 and D68381.
Differential Revision: https://reviews.llvm.org/D67707
With this change, `TargetInfo::adjustRelaxExpr` is only related to TLS
relaxations and a subsequent clean-up can delete the `data` parameter.
Differential Revision: https://reviews.llvm.org/D92079
Enables overriding earlier --lto-whole-program-visibility.
Variant of D91583 while discussing alternate ways to identify and
handle the --export-dynamic case.
Differential Revision: https://reviews.llvm.org/D92060
Also use "unknown flag 'flag'" instead of "unknown flag: flag" for
consistency with the other ports.
Differential Revision: https://reviews.llvm.org/D91970
This allows to reuse the RelocationResolver from the code
that doesn't want to deal with `RelocationRef` class.
I am going to use it in llvm-readobj. See the description
of D91530 for more details.
Differential revision: https://reviews.llvm.org/D91533
As mentioned in https://reviews.llvm.org/D67479#1667256 ,
* `--[no-]allow-shlib-undefined` control the diagnostic for an unresolved symbol in a shared object
* `-z defs/-z undefs` control the diagnostic for an unresolved symbol in a regular object file
* `--unresolved-symbols=` controls both bits.
In addition, make --warn-unresolved-symbols affect --no-allow-shlib-undefined.
This patch makes the behavior match GNU ld.
Reviewed By: psmith
Differential Revision: https://reviews.llvm.org/D91510
This adds `--[no-]color-diagnostics[=auto,never,always]` to
the MachO port and harmonizes the flag in the other ports:
- Consistently use MetaVarName
- Consistently document the non-eq version as alias of the eq version
- Use B<> in the ports that have it (no-op, shorter)
- Fix oversight in COFF port that made the --no flag have the wrong
prefix
Differential Revision: https://reviews.llvm.org/D91640
`try ... catch` in an inline function produces `.gcc_except_table.*` in a COMDAT
group with GCC or newer Clang (since D83655). For --gc-sections, currently we
scan `.eh_frame` pieces and mark liveness of such a `.gcc_except_table.*` and
then the associated `.text.*` (if a member in a section group is retained, the
others should be retained as well).
Essentially all `.text.*` and `.gcc_except_table.*` compiled from inline
functions with `try ... catch` cannot be discarded by the imprecise
--gc-sections. Compared with the state before D83655, the output
`.gcc_except_table` is smaller (non-prevailing copies in COMDAT groups can now
be discarded) but `.text` may be larger, i.e. size regression.
This patch teaches the .eh_frame piece scanning code to not mark
`.gcc_except_table` in a section group, thus allow unused `.text.*` and
`.gcc_except_table.*` in a section group to be discarded.
Note, non-group `.gcc_except_table` can still not be discarded. That is the status quo.
Reviewed By: grimar, echristo
Differential Revision: https://reviews.llvm.org/D91579
Fixes PR48071
* The Rust compiler produces SHF_ALLOC `.debug_gdb_scripts` (which normally does not have the flag)
* `.debug_gdb_scripts` sections are removed from `inputSections` due to --strip-debug/--strip-all
* When processing --gc-sections, pieces of a SHF_MERGE section can be marked live separately
`=>` segfault when marking liveness of a `.debug_gdb_scripts` which is not split into pieces (because it is not in `inputSections`)
This patch circumvents the problem by not treating SHF_ALLOC ".debug*" as debug sections (to prevent --strip-debug's stripping)
(which is still useful on its own).
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D91291
Input sections `.ctors/.ctors.N` may go to either the output section `.init_array` or the output section `.ctors`:
* output `.ctors`: currently we sort them by name. This patch changes to sort by priority from high to low. If N in `.ctors.N` is in the form of %05u, there is no semantic difference. Actually GCC and Clang do use %05u. (In the test `ctors_dtors_priority.s` and Gold's test `gold/testsuite/script_test_14.s`, we can see %03u, but they are not really produced by compilers.)
* output `.init_array`: users can provide an input section description `SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*)` to mix `.init_array.*` and `.ctors.*`. This can make .init_array.N and .ctors.(65535-N) interchangeable.
With this change, users can mix `.ctors.N` and `.init_array.N` in `.init_array` (PR44698 and PR48096) with linker scripts. As an example:
```
SECTIONS {
.init_array : {
*(SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*))
*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors)
}
} INSERT AFTER .fini_array;
SECTIONS {
.fini_array : {
*(SORT_BY_INIT_PRIORITY(.fini_array.* .dtors.*))
*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors)
}
} INSERT BEFORE .init_array;
```
Reviewed By: psmith
Differential Revision: https://reviews.llvm.org/D91187
According to
https://sourceware.org/binutils/docs/ld/Input-Section-Basics.html#Input-Section-Basics
for `*(.a .b)`, the order should match the input order:
* for `ld 1.o 2.o`, sections from 1.o precede sections from 2.o
* within a file, `.a` and `.b` appear in the section header table order
This patch implements the behavior. The interaction with `SORT*` and --sort-section is:
Matched sections are ordered by radix sort with the keys being `(SORT*, --sort-section, input order)`,
where `SORT*` (if present) is most significant.
> Note, multiple `SORT*` within an input section description has undocumented and
> confusing behaviors in GNU ld:
> https://sourceware.org/pipermail/binutils/2020-November/114083.html
> Therefore multiple `SORT*` is not the focus for this patch but
> this patch still strives to have an explainable behavior.
As an example, we partition `SORT(a.*) b.* c.* SORT(d.*)`, into
`SORT(a.*) | b.* c.* | SORT(d.*)` and perform sorting within groups. Sections
matched by patterns between two `SORT*` are sorted by input order. If
--sort-alignment is given, they are sorted by --sort-alignment, breaking tie by
input order.
This patch also allows a section to be matched by multiple patterns, previously
duplicated sections could occupy more space in the output and had erroneous zero bytes.
The patch is in preparation for support for
`*(SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*)) *(.init_array .ctors)`,
which will allow LLD to mix .ctors*/.init_array* like GNU ld (gold's --ctors-in-init-array)
PR44698 and PR48096
Reviewed By: grimar, psmith
Differential Revision: https://reviews.llvm.org/D91127
The second `SORT` in `*(SORT(...) SORT(...))` is incorrectly parsed as a file pattern.
Fix the bug by stopping at `SORT*` in `readInputSectionsList`.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D91180
I noticed when running a large link with the --time-trace option that
there were several areas which were missing any specific time trace
categories (aside from the generic link/ExecuteLinker categories). This
patch adds new categories to fill most of the "gaps", or to provide more
detail than was previously provided.
Reviewed by: MaskRay, grimar, russell.gallop
Differential Revision: https://reviews.llvm.org/D90686
On LP64/Windows platforms, this decreases sizeof(InputSection) from 208 (larger
on Windows) to 184.
For a large executable (7.6GiB, inputSections.size()=5105122,
make<InputSection> called 4835760 times), this decreases cgroup
memory.max_usage_in_bytes by 0.6%
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D91018
Make it possible for lld users to provide a custom script that would help to
find missing libraries. A possible scenario could be:
% clang /tmp/a.c -fuse-ld=lld -loauth -Wl,--error-handling-script=/tmp/addLibrary.py
unable to find library -loauth
looking for relevant packages to provides that library
liboauth-0.9.7-4.el7.i686
liboauth-devel-0.9.7-4.el7.i686
liboauth-0.9.7-4.el7.x86_64
liboauth-devel-0.9.7-4.el7.x86_64
pix-1.6.1-3.el7.x86_64
Where addLibrary would be called with the missing library name as first argument
(in that case addLibrary.py oauth)
Differential Revision: https://reviews.llvm.org/D87758
In the presence of a gap, the st_value field of a STT_SECTION symbol is the
address of the first input section (incorrect if there is a gap). Set it to the
output section address instead.
In -r mode, this bug can cause an incorrect non-zero st_value of a STT_SECTION
symbol (while output sections have zero addresses, input sections may have
non-zero outSecOff). The non-zero st_value can cause the final link to have
incorrect relocation computation (both GNU ld and LLD add st_value of the
STT_SECTION symbol to the output section address).
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D90520
While MC did not produce R_X86_64_GOTPCRELX for test/binop instructions
(movl/adcl/addl/andl/...) before the previous commit, this code path has been
exercised by -fno-integrated-as for GNU as since 2016: -no-pie relaxing
may incorrectly access loc[-3] and produce a corrupted instruction.
Simply handle test/binop R_X86_64_GOTPCRELX like R_X86_64_GOTPCREL.
This partially reverts D85994.
In glibc, elf/dl-sym.c calls the raw `__tls_get_addr` by specifying the
tls_index parameter. Such a call does not have a pairing R_PPC64_TLSGD/R_PPC64_TLSLD.
This is legitimate. Since we cannot distinguish the benign case from cases due
to toolchain issues, we have to be permissive.
Acked by Stefan Pintilie
Add support to LLD for PC Relative Thread Local Storage for Local Dynamic.
This patch adds support for two relocations: R_PPC64_GOT_TLSLD_PCREL34 and
R_PPC64_DTPREL34.
The Local Dynamic code is:
```
pla r3, x@got@tlsld@pcrel R_PPC64_GOT_TLSLD_PCREL34
bl __tls_get_addr@notoc(x@tlsld) R_PPC64_TLSLD
R_PPC64_REL24_NOTOC
...
paddi r9, r3, x@dtprel R_PPC64_DTPREL34
```
After relaxation to Local Exec:
```
paddi r3, r13, 0x1000
nop
...
paddi r9, r3, x@dtprel R_PPC64_DTPREL34
```
Reviewed By: NeHuang, sfertile
Differential Revision: https://reviews.llvm.org/D87504
For a diagnostic `A refers to B` where B refers to a bitcode file, if the
symbol gets optimized out, the user may see `A refers to <internal>`; if the
symbol is retained, the user may see `A refers to lto.tmp`.
Save the reference InputFile * in the DenseMap so that the original filename is
available in reportBackrefs().
The ELF spec says
> If the sh_flags field for this section header includes the attribute SHF_INFO_LINK, then this member represents a section header table index.
Set SHF_INFO_LINK so that binary manipulation tools know that sh_info is
a section header table index instead of (the number of local symbols in the case of SHT_SYMTAB/SHT_DYNSYM).
We have already added SHF_INFO_LINK for --emit-relocs retained SHT_REL[A].
For example, we can teach llvm-objcopy to preserve the section index of the sh_info referenced section if
SHF_INFO_LINK is set. (GNU objcopy recognizes .rel[a].plt and updates
sh_info even if SHF_INFO_LINK is not set).
Reviewed By: grimar, psmith
Differential Revision: https://reviews.llvm.org/D89828
The combination has not been tested before. In the case of ICF,
`e.section->getVA(0)` equals the start address of the output section.
This can cause incorrect overlapping with the actual function at the
start of the output section and potentially trigger a GDB internal error
in `dw2_find_pc_sect_compunit_symtab` (presumably because:
if a short address range incorrectly starts at the start address of the
output section, GDB may pick it instead of the correct longer address
range. When mapping an address within the long address range but
out of the scope of the short address range, the routine may find
nothing - while the code asserts that it can find something).
Note that in the case of ICF there may be duplicate address range entries,
but GDB appears to be fine with them.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D89751
ICF was not able to merge equivalent sections because of relocations to
sections ineligible for ICF that use alternative symbols, e.g. symbol
aliases or section relative relocations.
Merging in this scenario has been enabled by giving the sections that
are ineligible for ICF a unique ID, i.e. an equivalence class of their
own. This approach also provides another benefit as it improves the
hashing that is used to perform the initial equivalance grouping for
ICF. This is because the ICF ineligible sections can now contribute a
unique value towards the hashes instead of the same value of zero. This
has been seen to reduce link time with ICF by ~68% for objects compiled
with -fprofile-instr-generate.
In order to facilitate this use of a unique ID, the existing
inconsistent approach to the setting of the InputSection eqClass in ICF
has been changed so that there is a clear distinction between the
eqClass values of ICF eligible sections and those of the ineligible
sections that have a unique ID. This inconsistency could have caused
incorrect equivalence class equality in the past, although it appears
that no issues were encountered in actual use.
Differential Revision: https://reviews.llvm.org/D88830
In ELF/InputFiles.cpp, getBitcodeMachineKind() is limited to uint8_t return
type. This works as long as EM_xxx is < 256, which is true for common
architectures, but not for some newly assigned or unofficial EM_* values.
The corresponding ELF field (e_machine) can hold uint16_t.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D89185
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
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
Library users should not need to call errorHandler().reset() explicitly.
google/iree calls lld:🧝:link and without the patch some global
variables are not cleaned up in the next invocation.
".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
In lit tests, we run each LLD invocation twice (LLD_IN_TEST=2), without shutting down the process in-between. This ensures a full cleanup is properly done between runs.
Only active for the COFF driver for now. Other drivers still use LLD_IN_TEST=1 which executes just one iteration with full cleanup, like before.
When the environment variable LLD_IN_TEST is unset, a shortcut is taken, only one iteration is executed, no cleanup for faster exit, like before.
A public API, lld::safeLldMain(), is also available when using LLD as a library.
Differential Revision: https://reviews.llvm.org/D70378
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
Fangrui Song