[Support] Change compression::zlib::{compress,uncompress} to use uint8_t *

It's more natural to use uint8_t * (std::byte needs C++17 and llvm has
too much uint8_t *) and most callers use uint8_t * i

[Support] Change compression::zlib::{compress,uncompress} to use uint8_t *

It's more natural to use uint8_t * (std::byte needs C++17 and llvm has
too much uint8_t *) and most callers use uint8_t * instead of char *.
The functions are recently moved into `llvm::compression::zlib::`, so
downstream projects need to make adaption anyway.

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[ELF] Refactor ELFCOMPRESS_ZLIB handling and improve diagnostics

And add some tests.

[NFC] Refactor llvm::zlib namespace

* Refactor compression namespaces across the project, making way for a possible
introduction of alternatives to zlib compression.
Changes are as follows:
*

[NFC] Refactor llvm::zlib namespace

* Refactor compression namespaces across the project, making way for a possible
introduction of alternatives to zlib compression.
Changes are as follows:
* Relocate the `llvm::zlib` namespace to `llvm::compression::zlib`.

Reviewed By: MaskRay, leonardchan, phosek

Differential Revision: https://reviews.llvm.org/D128953

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[ELF] Relax R_RISCV_ALIGN

Alternative to D125036. Implement R_RISCV_ALIGN relaxation so that we can handle
-mrelax object files (i.e. -mno-relax is no longer needed) and creates a
framework for futu

[ELF] Relax R_RISCV_ALIGN

Alternative to D125036. Implement R_RISCV_ALIGN relaxation so that we can handle
-mrelax object files (i.e. -mno-relax is no longer needed) and creates a
framework for future relaxation.

`relaxAux` is placed in a union with InputSectionBase::jumpInstrMod, storing
auxiliary information for relaxation. In the first pass, `relaxAux` is allocated.
The main data structure is `relocDeltas`: when referencing `relocations[i]`, the
actual offset is `r_offset - (i ? relocDeltas[i-1] : 0)`.

`relaxOnce` performs one relaxation pass. It computes `relocDeltas` for all text
section. Then, adjust st_value/st_size for symbols relative to this section
based on `SymbolAnchor`. `bytesDropped` is set so that `assignAddresses` knows
that the size has changed.

Run `relaxOnce` in the `finalizeAddressDependentContent` loop to wait for
convergence of text sections and other address dependent sections (e.g.
SHT_RELR). Note: extrating `relaxOnce` into a separate loop works for many cases
but has issues in some linker script edge cases.

After convergence, compute section contents: shrink the NOP sequence of each
R_RISCV_ALIGN as appropriate. Instead of deleting bytes, we run a sequence of
memcpy on the content delimitered by relocation locations. For R_RISCV_ALIGN let
the next memcpy skip the desired number of bytes. Section content computation is
parallelizable, but let's ensure the implementation is mature before
optimizations. Technically we can save a copy if we interleave some code with
`OutputSection::writeTo`, but let's not pollute the generic code (we don't have
templated relocation resolving, so using conditions can impose overhead to
non-RISCV.)

Tested:
`make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- LLVM=1 defconfig all` built Linux kernel using -mrelax is bootable.
FreeBSD RISCV64 system using -mrelax is bootable.
bash/curl/firefox/libevent/vim/tmux using -mrelax works.

Differential Revision: https://reviews.llvm.org/D127581

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[ELF] Change getRISCVPCRelHi20 error to conventional errorOrWarn

[ELF] Remove support for legacy .zdebug sections

.zdebug is unlikely used any longer: gcc -gz switched from legacy
.zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been
several years.

[ELF] Remove support for legacy .zdebug sections

.zdebug is unlikely used any longer: gcc -gz switched from legacy
.zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been
several years. clang 14 dropped -gz=zlib-gnu support. According to
Debian Code Search (`gz=zlib-gnu`), no project uses -gz=zlib-gnu.

Remove .zdebug support to (a) simplify code and (b) allow removal of llvm-mc's
--compress-debug-sections=zlib-gnu.

In case the old object file `a.o` uses .zdebug, run `objcopy --decompress-debug-sections a.o`

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D126793

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[LLD][ELF] Drop the string null terminator from the hash in splitStrings

Differential Revision: https://reviews.llvm.org/D126484

[ELF][AArch64] Fix unneeded thunk for branches to hidden undefined weak

Similar to D119787 for PPC64.

A hidden undefined weak may change its binding to local before some
`isUndefinedWeak` code, so

[ELF][AArch64] Fix unneeded thunk for branches to hidden undefined weak

Similar to D119787 for PPC64.

A hidden undefined weak may change its binding to local before some
`isUndefinedWeak` code, so some `isUndefinedWeak` code needs to be changed to
`isUndefined`. The undefined non-weak case has been errored, so just using
`isUndefined` is fine.

The Linux kernel recently has a usage that a branch from 0xffff800008491ee0
references a hidden undefined weak symbol `vfio_group_set_kvm`.
It relies on the behavior that a branch to undefined weak resolving to the next
instruction, otherwise it'd see spurious relocation out of range errors.

Fixes https://github.com/ClangBuiltLinux/linux/issues/1624

Differential Revision: https://reviews.llvm.org/D123750

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[ELF] --emit-relocs: adjust offsets of .rel[a].eh_frame relocations

Two code paths may reach the EHFrame case in SectionBase::getOffset:

* .eh_frame reference
* relocation copy for --emit-relocs

T

[ELF] --emit-relocs: adjust offsets of .rel[a].eh_frame relocations

Two code paths may reach the EHFrame case in SectionBase::getOffset:

* .eh_frame reference
* relocation copy for --emit-relocs

The first may be used by clang_rt.crtbegin.o and GCC crtbeginT.o to get the
start address of the output .eh_frame. The relocation has an offset of 0 or
(x86-64 PC-relative leaq for clang_rt.crtbegin.o) -4. The current code just
returns `offset`, which handles this case well.

The second is related to InputSection::copyRelocations on .eh_frame (used by
--emit-relocs). .eh_frame pieces may be dropped due to GC/ICF, so we should
convert the input offset to the output offset. Use the same way as
MergeInputSection with a special case handling outSecOff==-1 for an invalid
piece (see eh-frame-marker.s).

This exposes an issue in mips64-eh-abs-reloc.s that we don't reliably
handle anyway. Just add --no-check-dynamic-relocations to paper over it.

Differential Revision: https://reviews.llvm.org/D122459

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Revert D122459 "[ELF] --emit-relocs: adjust offsets of .rel[a].eh_frame relocations"

This reverts commit 6faba31e0d88ce71e87567ddb51d2444524b8a81.

It may cause "offset is outside the section".

[ELF] --emit-relocs: adjust offsets of .rel[a].eh_frame relocations

.eh_frame pieces may be dropped due to GC/ICF. When --emit-relocs adds
relocations against .eh_frame, the offsets need to be adjus

[ELF] --emit-relocs: adjust offsets of .rel[a].eh_frame relocations

.eh_frame pieces may be dropped due to GC/ICF. When --emit-relocs adds
relocations against .eh_frame, the offsets need to be adjusted. Use the same
way as MergeInputSection with a special case handling outSecOff==-1 for an
invalid piece (see eh-frame-marker.s).

This exposes an issue in mips64-eh-abs-reloc.s that we don't reliably
handle anyway. Just add --no-check-dynamic-relocations to paper over it.

Original patch by Ayrton Muñoz

Differential Revision: https://reviews.llvm.org/D122459

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[ELF] Simplify MergeInputSection::getParentOffset. NFC

and remove overly verbose comments.

[ELF] Inline InputSection::getParent. NFC

Combined with the previous change, lld executable is ~2K smaller and some code
paths using InputSection::getParent are more efficient.

The fragmented heade

[ELF] Inline InputSection::getParent. NFC

Combined with the previous change, lld executable is ~2K smaller and some code
paths using InputSection::getParent are more efficient.

The fragmented headers lead to a design limitation that OutputSection has to be
incomplete, so we cannot use static_cast.

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Reland D119909 [ELF] Parallelize initializeLocalSymbols

ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. Thi

Reland D119909 [ELF] Parallelize initializeLocalSymbols

ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. This patch
extracts local symbol initialization and parallelizes it.

Technically the new function initializeLocalSymbols can be merged into
ObjFile::postParse, but functions like getSrcMsg may access the
uninitialized (all nullptr) local part of InputFile::symbols.

Linking chrome: 1.02x as fast with glibc malloc, 1.04x as fast with mimalloc

Depends on f456c3ae3f4182b23673929e8fe0aa18bcec4289 and D119908

Reviewed By: ikudrin

Differential Revision: https://reviews.llvm.org/D119909

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Revert "[ELF] Parallelize initializeLocalSymbols"

This reverts commit 09602d3b47ec83abb2c26efa5a199c13b72c7abf.

[ELF] Make InputSection::classof inline. NFC

[ELF] Move SyntheticSection check from InputSection::writeTo to OutputSection::writeTo. NFC

Simplify code and make the heavyweight operation to the call site so that it is
clearer how to improve the

[ELF] Move SyntheticSection check from InputSection::writeTo to OutputSection::writeTo. NFC

Simplify code and make the heavyweight operation to the call site so that it is
clearer how to improve the inefficient scheduling in the future.

show more ...

[ELF] Parallelize initializeLocalSymbols

ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. This patch
extract

[ELF] Parallelize initializeLocalSymbols

ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. This patch
extracts local symbol initialization and parallelizes it.

Technically the new function initializeLocalSymbols can be merged into
ObjFile::postParse, but functions like getSrcMsg may access the
uninitialized (all nullptr) local part of InputFile::symbols.

Linking chrome: 1.02x as fast with glibc malloc, 1.04x as fast with mimalloc

Reviewed By: ikudrin

Differential Revision: https://reviews.llvm.org/D119909

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[ELF] Replace uncompressed InputSectionBase::data() with rawData. NFC

In many call sites we know uncompression cannot happen (non-SHF_ALLOC, or the
data (even if compressed) must have been uncompres

[ELF] Replace uncompressed InputSectionBase::data() with rawData. NFC

In many call sites we know uncompression cannot happen (non-SHF_ALLOC, or the
data (even if compressed) must have been uncompressed by a previous pass).
Prefer rawData in these cases. data() increases code size and prevents
optimization on rawData.

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[ELF] Clean up headers. NFC

[lld][ELF] Add support for ADRP+ADD optimization for AArch64

This diff adds support for ADRP+ADD optimization for AArch64 described in
https://github.com/ARM-software/abi-aa/commit/d2ca58c54b8e955cf

[lld][ELF] Add support for ADRP+ADD optimization for AArch64

This diff adds support for ADRP+ADD optimization for AArch64 described in
https://github.com/ARM-software/abi-aa/commit/d2ca58c54b8e955cfef25c71822f837ae0439d73
i.e. under appropriate constraints

ADRP x0, symbol
ADD x0, x0, :lo12: symbol

can be turned into

NOP
ADR x0, symbol

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D117614

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[ELF] Simplify code with invokeELFT. NFC

[ELF] Switch split-stack to use SmallVector. NFC

My x86-64 lld executable is 1.1KiB smaller.

[ELF] splitStrings: replace entSize==1 special case with manual loop unswitch. NFC

My x86-64 lld executable is actually smaller.

[ELF] copyShtGroup: replace unordered_set<uint32_t> with DenseSet<uint32_t>. NFC

We don't need to support the empty/tombstone key section index.