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https://reviews.llvm.org/D150510 places .lrodata before .rodata to
minimize the number of permission transitions in the memory image.
However, this layout is less ideal for -fno-pic code (which is still
important).
Small code model -fno-pic code has R_X86_64_32S relocations with a range
of `[0,2**31)` (if we ignore the negative area). Placing `.lrodata`
earlier exerts relocation pressure on such code. Non-x86 64-bit
architectures generally have a similar `[0,2**31)` limitation if they
don't use PC-relative relocations.
If we place .lrodata later, we will need one extra PT_LOAD. Two layouts
are appealing:
* .bss/.lbss/.lrodata/.ldata (GNU ld)
* .bss/.ldata/.lbss/.lrodata
The GNU ld layout has the nice property that there is only one BSS
(except .tbss/.relro_padding). Add -z lrodata-after-bss to support
this layout.
Since a read-only PT_LOAD segment (for large data sections) may appear
after RW PT_LOAD segments. The placement of `_etext` has to be adjusted.
Pull Request: https://github.com/llvm/llvm-project/pull/81224
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errorOrWarn is more conventional for recoverable errors. This error
message does not have to use `fatal`, and we try to remove such uses in
parallel code paths.
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In WebAssembly, we have `WASM_SYMBOL_NO_STRIP` symbol flag to mark the
referenced content as retained. However, the flag is not enough to
express retained data that is not referenced by any symbol. This patch
adds a new segment flag`WASM_SEG_FLAG_RETAIN` to support "private"
linkage data that is retained by llvm.used.
This kind of data that is not referenced but must be retained is usually
used with encapsulation symbols (__start/__stop). Swift runtime uses
this technique and depends on the fact "all metadata sections in live
objects are retained", which was not guaranteed with `--gc-sections`
before this patch.
This is a revised version of https://reviews.llvm.org/D126950 (has been
reverted) based on @MaskRay's comments
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This caused links to fail with:
lld/MachO/Symbols.cpp:97:
virtual uint64_t lld::macho::Defined::getVA() const:
Assertion `target->usesThunks()' failed.
or crash when asserts are disabled. See comment on
https://github.com/llvm/llvm-project/pull/79894
> Enable chained fixups in lld when all platform and version criteria are
> met. This is an attempt at simplifying the logic used in ld 907:
>
> https://github.com/apple-oss-distributions/ld64/blob/93d74eafc37c0558b4ffb88a8bc15c17bed44a20/src/ld/Options.cpp#L5458-L5549
>
> Some changes were made to simplify the logic:
> - only enable chained fixups for macOS from 13.0 to avoid the arch check
> - only enable chained fixups for iphonesimulator from 16.0 to avoid the
> arch check
> - don't enable chained fixups for not specifically listed platforms
> - don't enable chained fixups for arm64_32
This reverts commit 775c2856fb32868f357a3ce3f2b4139541e12578.
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When the data-in-code entries are in separate sections, they are not
guaranteed to be sorted. In particular, 68b1cc36f3df marked some libc++
string functions as noinline, which leads to global ctors involving
strings now producing data-in-code sections in __TEXT,__StaticInit,
which is why this now happens in practice.
Since data-in-code entries are relatively rare and small, just sort
them. No observed performance impact.
See also crbug.com/41487860
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With the new SystemZ port we noticed that -pie executables generated
from files containing R_390_TLS_IEENT relocations will have unnecessary
relocations in their GOT:
9e8d8: R_390_TLS_TPOFF *ABS*+0x18
This is caused by the config->isPic conditon in addTpOffsetGotEntry:
static void addTpOffsetGotEntry(Symbol &sym) {
in.got->addEntry(sym);
uint64_t off = sym.getGotOffset();
if (!sym.isPreemptible && !config->isPic) {
in.got->addConstant({R_TPREL, target->symbolicRel, off, 0, &sym});
return;
}
It is correct that we need to retain a TPOFF relocation if the target
symbol is preemptible or if we're building a shared library. But when
building a -pie executable, those values are fixed at link time and
there's no need for any remaining dynamic relocation.
Note that the equivalent MIPS-specific code in MipsGotSection::build
checks for config->shared instead of config->isPic; we should use the
same check here. (Note also that on many other platforms we're not even
using addTpOffsetGotEntry in this case as an IE->LE relaxation is
applied before; we don't have this type of relaxation on SystemZ.)
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(#81600)
It's not interesting for majority of downstream users.
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This patch adds full support for linking SystemZ (ELF s390x) object
files. Support should be generally complete:
- All relocation types are supported.
- Full shared library support (DYNAMIC, GOT, PLT, ifunc).
- Relaxation of TLS and GOT relocations where appropriate.
- Platform-specific test cases.
In addition to new platform code and the obvious changes, there were a
few additional changes to common code:
- Add three new RelExpr members (R_GOTPLT_OFF, R_GOTPLT_PC, and
R_PLT_GOTREL) needed to support certain s390x relocations. I chose not
to use a platform-specific name since nothing in the definition of these
relocs is actually platform-specific; it is well possible that other
platforms will need the same.
- A couple of tweaks to TLS relocation handling, as the particular
semantics of the s390x versions differ slightly. See comments in the
code.
This was tested by building and testing >1500 Fedora packages, with only
a handful of failures; as these also have issues when building with LLD
on other architectures, they seem unrelated.
Co-authored-by: Tulio Magno Quites Machado Filho <tuliom@redhat.com>
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(#81475)
These were implemented in the COFF linker in
3923e61b96cf90123762f0e0381504efaba2d77a and
d12b99a4313816cf99e97cb5f579e2d51ba72b0b.
This matches the corresponding options in the ELF linker.
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This minor issue is identified while working on #81224.
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Fix an incorrect llvm_unreachable.
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This can be used to create import libraries that contain both ARM64EC
and native exports. The implementation follows observed MSVC lib.exe
behaviour. It's ignored on targets other than ARM64EC.
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If llvm-readobj is built with a 32 bit time_t, it can't print such
timestamps correctly.
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The SOURCE_DATE_EPOCH environment variable can be set in order to get
reproducible build.
When linking PE/COFF modules with LLD, the timestamp field is set to the
current time, unless either the /timestamp: or /Brepro option is set. If
neither of them is set, check the SOURCE_DATE_EPOCH variable, before
resorting to using the actual current date and time.
See https://reproducible-builds.org/docs/source-date-epoch/ for reference
on the use of this variable.
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This makes it easier to run the tests in a containerized environment.
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Once we move `.lrodata` after .bss (#78521), or if we use `SECTIONS`
commands, certain read-only sections may be in their own PT_LOAD, not in
the traditional "text segment". Current --no-rosegment code may
unnecessarily mark read-only PT_LOAD executable. Fix it.
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Notably, test that --ro-rosegment with a linker script may unnecessarily
make a read-only PT_LOAD executable.
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This fixes:
```
[193/3517] Building CXX object
tools\lld\ELF\CMakeFiles\lldELF.dir\Arch\LoongArch.cpp.obj
C:\git\llvm-project\lld\ELF\Arch\LoongArch.cpp(683): warning C4334:
'<<': result of 32-bit shift implicitly converted to 64 bits (was 64-bit
shift intended?
```
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(#80529)
Wasm has no unified virtual memory space as other object formats and
architectures do, so previously WasmObjectFile reported 0 for all
section addresses, and until 428cf71ff used section offsets for function
symbols. Now we use file offsets for function symbols, and this change
switches section addresses to do the same (in linked files). The main
result of this is that objdump now reports VMAs in section listings, and
also uses file offets rather than section offsets when disassembling
linked binaries (matching the behavior of other disassemblers and stack
traces produced by browwsers). To make this work, this PR also updates
objdump's generation of synthetics fallback symbols to match lib/Object
and also correctly plumbs symbol types for regular and dummy symbols
through to the backend to avoid needing special knowledge of address 0.
This also paves the way for generating symbols from name sections rather
than symbol tables or imports (see #76107) by allowing the
disassembler's synthetic fallback symbols match the name-section
generated symbols (in a followup PR).
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(#78769)
getExportName implementation is based on lld-link. In its current form,
it's mostly about convenience, but it will be more useful for EXPORTAS
support, for which export name is not possible to deduce from other
printed properties.
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Refer to commit 6611d58f5bbc ("Relax R_RISCV_ALIGN"), we can relax
R_LARCH_ALIGN by same way. Reuse `SymbolAnchor`, `RISCVRelaxAux` and
`initSymbolAnchors` to simplify codes. As `riscvFinalizeRelax` is an
arch-specific function, put it override on `TargetInfo::finalizeRelax`,
so that LoongArch can override it, too.
The flow of relax R_LARCH_ALIGN is almost consistent with RISCV. The
difference is that LoongArch only has 4-bytes NOP and all executable
insn is 4-bytes aligned. So LoongArch not need rewrite NOP sequence.
Alignment maxBytesEmit parameter is supported in psABI v2.30.
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Introduce Code Object V6 in Clang, LLD, Flang and LLVM. This is the same
as V5 except a new "generic version" flag can be present in EFLAGS. This
is related to new generic targets that'll be added in a follow-up patch.
It's also likely V6 will have new changes (possibly new metadata
entries) added later.
Docs change are part of the follow-up patch #76955
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Move the WasmSymbolInfos from their own vector on the WasmLinkingData
directly into the WasmSymbol object. Removing the const-ref to an
external object allows the vector of WasmSymbols to be safely
expanded/reallocated; generating symbol info from the name section will
require this, as the numbers of function and data segment names are
stored separately.
This is a step toward generating symbol information from name sections
for #76107
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sectionCommands are non-contiguous
In a `--defsym y0=0 -T a.lds` link where a.lds contains only INSERT
commands, the `script->sectionCommands` layout may be:
```
orphan sections
SymbolAssignment due to --defsym
sections created by INSERT commands
```
The `OutputDesc` objects are not contiguous in sortInputSections, and
`compareSections` will be called with a SymbolAssignment argument,
leading to an assertion failure.
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together by decoupling the handling of the two features. (#74128)
Today `-split-machine-functions` and `-fbasic-block-sections={all,list}`
cannot be combined with `-basic-block-sections=labels` (the labels
option will be ignored).
The inconsistency comes from the way basic block address map -- the
underlying mechanism for basic block labels -- encodes basic block
addresses
(https://lists.llvm.org/pipermail/llvm-dev/2020-July/143512.html).
Specifically, basic block offsets are computed relative to the function
begin symbol. This relies on functions being contiguous which is not the
case for MFS and basic block section binaries. This means Propeller
cannot use binary profiles collected from these binaries, which limits
the applicability of Propeller for iterative optimization.
To make the `SHT_LLVM_BB_ADDR_MAP` feature work with basic block section
binaries, we propose modifying the encoding of this section as follows.
First let us review the current encoding which emits the address of each
function and its number of basic blocks, followed by basic block entries
for each basic block.
| | |
|--|--|
| Address of the function | Function Address |
| Number of basic blocks in this function | NumBlocks |
| BB entry 1
| BB entry 2
| ...
| BB entry #NumBlocks
To make this work for basic block sections, we treat each basic block
section similar to a function, except that basic block sections of the
same function must be encapsulated in the same structure so we can map
all of them to their single function.
We modify the encoding to first emit the number of basic block sections
(BB ranges) in the function. Then we emit the address map of each basic
block section section as before: the base address of the section, its
number of blocks, and BB entries for its basic block. The first section
in the BB address map is always the function entry section.
| | |
|--|--|
| Number of sections for this function | NumBBRanges |
| Section 1 begin address | BaseAddress[1] |
| Number of basic blocks in section 1 | NumBlocks[1] |
| BB entries for Section 1
|..................|
| Section #NumBBRanges begin address | BaseAddress[NumBBRanges] |
| Number of basic blocks in section #NumBBRanges |
NumBlocks[NumBBRanges] |
| BB entries for Section #NumBBRanges
The encoding of basic block entries remains as before with the minor
change that each basic block offset is now computed relative to the
begin symbol of its containing BB section.
This patch adds a new boolean codegen option `-basic-block-address-map`.
Correspondingly, the front-end flag `-fbasic-block-address-map` and LLD
flag `--lto-basic-block-address-map` are introduced.
Analogously, we add a new TargetOption field `BBAddrMap`. This means BB
address maps are either generated for all functions in the compiling
unit, or for none (depending on `TargetOptions::BBAddrMap`).
This patch keeps the functionality of the old
`-fbasic-block-sections=labels` option but does not remove it. A
subsequent patch will remove the obsolete option.
We refactor the `BasicBlockSections` pass by separating the BB address
map and BB sections handing to their own functions (named
`handleBBAddrMap` and `handleBBSections`). `handleBBSections` renumbers
basic blocks and places them in their assigned sections.
`handleBBAddrMap` is invoked after `handleBBSections` (if requested) and
only renumbers the blocks.
- New tests added:
- Two tests basic-block-address-map-with-basic-block-sections.ll and
basic-block-address-map-with-mfs.ll to exercise the combination of
`-basic-block-address-map` with `-basic-block-sections=list` and
'-split-machine-functions`.
- A driver sanity test for the `-fbasic-block-address-map` option
(basic-block-address-map.c).
- An LLD test for testing the `--lto-basic-block-address-map` option.
This reuses the LLVM IR from `lld/test/ELF/lto/basic-block-sections.ll`.
- Renamed and modified the two existing codegen tests for basic block
address map (`basic-block-sections-labels-functions-sections.ll` and
`basic-block-sections-labels.ll`)
- Removed `SHT_LLVM_BB_ADDR_MAP_V0` tests. Full deprecation of
`SHT_LLVM_BB_ADDR_MAP_V0` and `SHT_LLVM_BB_ADDR_MAP` version less than 2
will happen in a separate PR in a few months.
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This supports icf for objc stubs.
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category (#80221)
When printing category conflicts in the ObjC category checker, also
print the source file name of the problematic categories. Currently we
only print the object file name. This change is mostly useful only for
thinLTO builds, where the object file name will be of form
999.arm64.lto.o and thus does not reveal any information about the
original source file.
---------
Co-authored-by: Alex Borcan <alexborcan@meta.com>
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Enable chained fixups in lld when all platform and version criteria are
met. This is an attempt at simplifying the logic used in ld 907:
https://github.com/apple-oss-distributions/ld64/blob/93d74eafc37c0558b4ffb88a8bc15c17bed44a20/src/ld/Options.cpp#L5458-L5549
Some changes were made to simplify the logic:
- only enable chained fixups for macOS from 13.0 to avoid the arch check
- only enable chained fixups for iphonesimulator from 16.0 to avoid the
arch check
- don't enable chained fixups for not specifically listed platforms
- don't enable chained fixups for arm64_32
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The loader can usually handle an unaligned import dir chunk, but It's not
optimal and it's not what MSVC link.exe does.
Windows refuses to load ARM64X binaries with unaligned import directory.
aarch64 and arm64ec imports are shared in such binaries as much as
possible. As long as they use the same set of functions from given import
directory, both the directory and import addresses chunk are just shared.
When used set of functions differs, ARM64X dynamic relocations are used
to modify import dir to point to different names and import addresses for
its EC view. I suspect that the loader expects some alignment on ARM64X
dynamic relocation offset and may not be the case when relocated import
dir is not aligned.
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'arm64ecpe' was chosen arbitrarily as gcc MinGW doesn't provide EC
support.
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This supports dead-strip for objc stubs.
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The interaction between --warn-backrefs was not tested, but if
--defsym-created reference causes archive member extraction, it seems
reasonable to suppress the diagnostic, which was the behavior before #78944.
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A distinction that doesn't _usually_ matter is that the
MachO::SymbolKind is really a mapping of entries in TBD files not
symbols. To better understand this, rename the enum so it represents an
encoding mapped to TBDs as opposed to symbols alone.
For example, it can be a bit confusing that "GlobalSymbol" is a enum
value when all of those values can represent a GlobalSymbol.
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Clarify a comment after #78944.
All uses of `getFile()` assert `file` is non-null. `getFile` is not used
with a
synthetic section. Replace `cast_or_null` with `cast`.
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Support
R_RISCV_TLSDESC_HI20/R_RISCV_TLSDESC_LOAD_LO12/R_RISCV_TLSDESC_ADD_LO12/R_RISCV_TLSDESC_CALL.
LOAD_LO12/ADD_LO12/CALL relocations reference a label at the HI20
location, which requires special handling. We save the value of HI20 to
be reused. Two interleaved TLSDESC code sequences, which compilers do
not generate, are unsupported.
For -no-pie/-pie links, TLSDESC to initial-exec or local-exec
optimizations are eligible. Implement the relevant hooks
(R_RELAX_TLS_GD_TO_LE, R_RELAX_TLS_GD_TO_IE): the first two instructions
are converted to NOP while the latter two are converted to a GOT load or
a lui+addi.
The first two instructions, which would be converted to NOP, are removed
instead in the presence of relaxation. Relaxation is eligible as long as
the R_RISCV_TLSDESC_HI20 relocation has a pairing R_RISCV_RELAX,
regardless of whether the following instructions have a R_RISCV_RELAX.
In addition, for the TLSDESC to LE optimization (`lui a0,<hi20>; addi a0,a0,<lo12>`),
`lui` can be removed (i.e. use the short form) if hi20 is 0.
```
// TLSDESC to LE/IE optimization
.Ltlsdesc_hi2:
auipc a4, %tlsdesc_hi(c) # if relax: remove; otherwise, NOP
load a5, %tlsdesc_load_lo(.Ltlsdesc_hi2)(a4) # if relax: remove; otherwise, NOP
addi a0, a4, %tlsdesc_add_lo(.Ltlsdesc_hi2) # if LE && !hi20 {if relax: remove; otherwise, NOP}
jalr t0, 0(a5), %tlsdesc_call(.Ltlsdesc_hi2)
add a0, a0, tp
```
The implementation carefully ensures that an instruction unrelated to
the current TLSDESC code sequence, if immediately follows a removable
instruction (HI20 or LOAD_LO12 OR (LE-specific) ADD_LO12), is not
converted to NOP.
* `riscv64-tlsdesc.s` is inspired by `i386-tlsdesc-gd.s` (https://reviews.llvm.org/D112582).
* `riscv64-tlsdesc-relax.s` tests linker relaxation.
* `riscv-tlsdesc-gd-mixed.s` is inspired by `x86-64-tlsdesc-gd-mixed.s` (https://reviews.llvm.org/D116900).
Link: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/373
Reviewed By: ilovepi
Pull Request: https://github.com/llvm/llvm-project/pull/79239
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This change allows a WasmObjectFile to be created from a wasm file even
if it uses typed funcrefs and GC types. It does not significantly change how
lib/Object models its various internal types (e.g. WasmSignature,
WasmElemSegment), so LLVM does not really "support" or understand such
files, but it is sufficient to parse the type, global and element sections, discarding
types that are not understood. This is useful for low-level binary tools such as
nm and objcopy, which use only limited aspects of the binary (such as function
definitions) or deal with sections as opaque blobs.
This is done by allowing `WasmValType` to have a value of `OTHERREF`
(representing any unmodeled reference type), and adding a field to
`WasmSignature` indicating it's a placeholder for an unmodeled reference
type (since there is a 1:1 correspondence between WasmSignature objects
and types in the type section).
Then the object file parsers for the type and element sections are expanded
to parse encoded reference types and discard any unmodeled fields.
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This fixes:
```
[5839/7452] Building CXX object tools\lld\ELF\CMakeFiles\lldELF.dir\MapFile.cpp.obj
C:\git\llvm-project\lld\ELF\MapFile.cpp(124,38): warning: comparison of integers of different signs: 'uint32_t' (aka 'unsigned int') and 'const ssize_t' (aka 'const int') [-Wsign-compare]
124 | last.outputOff + last.size == p.outputOff) {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~
1 warning generated.
```
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This fixes:
```
[5383/6995] Building CXX object tools\lld\COFF\CMakeFiles\lldCOFF.dir\PDB.cpp.obj
C:\git\llvm-project\lld\COFF\PDB.cpp(835): warning C4018: '>=': signed/unsigned mismatch
```
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Here is the list of the renamed passes:
- `callbrprepare` -> `callbr-prepare`
- `dwarfehprepare` -> `dwarf-eh-prepare`
- `flattencfg` -> `flatten-cfg`
- `loweratomic` -> `lower-atomic`
- `lowerinvoke` -> `lower-invoke`
- `lowerswitch` -> `lower-switch`
- `winehprepare` -> `win-eh-prepare`
- `targetir` -> `target-ir`
- `targetlibinfo` -> `target-lib-info`
Legacy passes are not affected.
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non-SHF_ALLOC sections (#79238)
A SHN_ABS symbol has never been considered for
InputSection::relocateNonAlloc.
Before #74686, the code did made it work in the absence of `-z
dead-reloc-in-nonalloc=`.
There is now a report about such SHN_ABS uses
(https://github.com/llvm/llvm-project/pull/74686#issuecomment-1904101711)
and I think it makes sense for non-SHF_ALLOC to support SHN_ABS, like
SHF_ALLOC sections do.
```
// clang -g
__attribute__((weak)) int symbol;
int *foo() { return &symbol; }
0x00000023: DW_TAG_variable [2] (0x0000000c)
...
DW_AT_location [DW_FORM_exprloc] (DW_OP_addrx 0x0)
```
.debug_addr references `symbol`, which can be redefined by a symbol
assignment or --defsym to become a SHN_ABS symbol.
The problem is that `!sym.getOutputSection()` cannot discern SHN_ABS
from a symbol whose section has been discarded. Since commit
1981b1b6b92f7579a30c9ed32dbdf3bc749c1b40, a symbol relative to a
discarded section is changed to `Undefined`, so the `SHN_ABS` check
become trivial.
We currently apply tombstone for a relocation referencing
`SharedSymbol`. This patch does not change the behavior.
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Test an absolute relocation referencing a DSO symbol, relocating a
non-SHF_ALLOC section. Also test --gc-sections.
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