The R_ARM_SBREL32 relocation is used in debug info for ARM RWPI
(read-write position independent) code. Compiler-generated DWARF info
will use an expression to add the relocated value to the actual value of
the static base (held in r9) at run-time, so it should be relocated as
if the static base is at address 0.
Move `sectionKind` outside the bitfield and move bss/keepUnique to
InputSectionBase.
* sizeof(InputSection) decreases from 160 to 152 on 64-bit systems.
* The numerous `sectionKind` accesses are faster.
SectionBase, InputSectionBase, InputSection, MergeInputSection, and
OutputSection have different member orders. Make them consistent and
adopt the order similar to the raw Elf64_Shdr.
so that we can remove the global `ctx` from toString implementations.
Rename lld::toString (to lld:🧝:toStr) to simplify name lookup (we
have many llvm::toString and another lld::toString(const llvm::opt::Arg
&)).
Since Ctx &ctx is a member variable,
1f391a75af8685e6bba89421443d72ac6a186599
7a5b9ef54eb96abd8415fd893576c42e51fd95db
e2f0ec3a3a8a2981be8a1aac2004cfb9064c61e8 can be reverted.
The RISC-V psABI states that "The `R_RISCV_PCREL_LO12_I` or
`R_RISCV_PCREL_LO12_S` relocations contain a label pointing to an
instruction in the same section with an `R_RISCV_PCREL_HI20` relocation
entry that points to the target symbol."
Without this patch, GNU ld errors, but LLD does not -- I think because LLD is
doing the right thing, certainly in the testcase provided.
Nonetheless, I think an error is good here to bring LLD in line with
what GNU ld is doing in showing that the object the user provided is not
following the psABI as written.
Fixes#107304
Remove the global variable `symtab` and add a member variable
(`std::unique_ptr<SymbolTable>`) to `Ctx` instead.
This is one step toward eliminating global states.
Pull Request: https://github.com/llvm/llvm-project/pull/109612
Similar to commit 686cff17cc310884e48ae963bf7507f96950cc90 for SHT_REL (#57693).
CREL hasn't been tested with ICF before.
And avoid a pitfall that eqClass[0] might interfere with ICF.
Ctx was introduced in March 2022 as a more suitable place for such
singletons.
llvm/Support/thread.h includes <thread>, which transitively includes
sstream in libc++ and uses ios_base::in, so we cannot use `#define in ctx.sec`.
`symtab, config, ctx` are now the only variables using
LLVM_LIBRARY_VISIBILITY.
so that --noinhibit-exec downgrades the error to a warning, which helps
debugging when `PHDRS` is specified without `PT_TLS`. Also update the
message to make it accurate: STT_TLS may exist in the absence of PT_TLS.
In addition, invoking `exitLld(1)` (through `fatal`) is problematic
(#66974): When a thread is `exitLld(1)`, triggering `llvm_shutdown`,
another thread may be at `relocateAlloc`, accessing `sec.relocs()` which
got destroyed(tampered?), leading to
incorrect `llvm_unreachable("invalid expression")`.
This allows the input section matching algorithm to be separated from
output section descriptions. This allows a group of sections to be
assigned to multiple output sections, providing an explicit version of
--enable-non-contiguous-regions's spilling that doesn't require altering
global linker script matching behavior with a flag. It also makes the
linker script language more expressive even if spilling is not intended,
since input section matching can be done in a different order than
sections are placed in an output section.
The implementation reuses the backend mechanism provided by
--enable-non-contiguous-regions, so it has roughly similar semantics and
limitations. In particular, sections cannot be spilled into or out of
INSERT, OVERWRITE_SECTIONS, or /DISCARD/. The former two aren't
intrinsic, so it may be possible to relax those restrictions later.
Ctx was introduced in March 2022 as a more suitable place for such
singletons. ctx's hidden visibility optimizes generated instructions.
This change fixes a pitfall: certain ElfSym members (e.g.
globalOffsetTable, tlsModuleBase) were not zeroed and might be stale
when lld:🧝:link was invoked the second time.
Ctx was introduced in March 2022 as a more suitable place for such
singletons. ctx's hidden visibility optimizes generated instructions.
bufferStart and tlsPhdr, which are not OutputSection, can now be moved
outside of `Out`.
... using the temporary section type code 0x40000020
(`clang -c -Wa,--crel,--allow-experimental-crel`). LLVM will change the
code and break compatibility (Clang and lld of different versions are
not guaranteed to cooperate, unlike other features). CREL with implicit
addends are not supported.
---
Introduce `RelsOrRelas::crels` to iterate over SHT_CREL sections and
update users to check `crels`.
(The decoding performance is critical and error checking is difficult.
Follow `skipLeb` and `R_*LEB128` handling, do not use
`llvm::decodeULEB128`, whichs compiles to a lot of code.)
A few users (e.g. .eh_frame, LLDDwarfObj, s390x) require random access. Pass
`/*supportsCrel=*/false` to `relsOrRelas` to allocate a buffer and
convert CREL to RELA (`relas` instead of `crels` will be used). Since
allocating a buffer increases, the conversion is only performed when
absolutely necessary.
---
Non-alloc SHT_CREL sections may be created in -r and --emit-relocs
links. SHT_CREL and SHT_RELA components need reencoding since
r_offset/r_symidx/r_type/r_addend may change. (r_type may change because
relocations referencing a symbol in a discarded section are converted to
`R_*_NONE`).
* SHT_CREL components: decode with `RelsOrRelas` and re-encode (`OutputSection::finalizeNonAllocCrel`)
* SHT_RELA components: convert to CREL (`relToCrel`). An output section can only have one relocation section.
* SHT_REL components: print an error for now.
SHT_REL to SHT_CREL conversion for -r/--emit-relocs is complex and
unsupported yet.
Link: https://discourse.llvm.org/t/rfc-crel-a-compact-relocation-format-for-elf/77600
Pull Request: https://github.com/llvm/llvm-project/pull/98115
