mold 1.7.0

mold 1.7.0 is a new release of the high-speed linker.

Just like previous versions, you need to apply oneapi-src/oneTBB@137c1a8 to libtbb if you do not use a bundled version of OneTBB library. OneTBB has merged this patch, but the most recent release of OneTBB hasn't picked it up yet.

Licensing

I'd like to inform users that I'm seriously considering changing the mold's license from AGPL to a source-available license unless I secure big funding. The new license would be something like individuals can use it for free but corporate users have to pay. mold started as my personal project, and I've been working on this full time for two years so far. I thought that I could earn a comfortable income if mold become popular, but unfortunately, I'm still losing my money. I think I need to take an action to make the project sustainable long term. For the details, please read my post.

New features

• [m68k] mold now supports the Motorola 68000 series microprocessors. Yes, it's the processor in the original Mac or Sun workstations in the 80s. This work is sponsored by m68k hobbyist communities.

Bug fixes and compatibility improvements

• We fixed a few issues for Facebook/Meta's BOLT optimizer (#789). Starting from the next LLVM release (we need llvm/llvm-project@20204db), BOLT should work on mold-generated executables out of the box.
• We fixed a long-standing symbol resolution issue involving GNU UNIQUE symbols which caused a link failure for a few programs. (730e970)
• Previously, if a version script contains a "C++" directive, and a symbol matches a non-C++ version pattern and a C++ version pattern, a wrong version could be assigned to the symbol. This has been fixed so that the mold's behavior matches with GNU ld. (9875150)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• John Paul Adrian Glaubitz
• Mercury
• Wasmer
• BuildBuddy
• windenntw
• haukevb
• Kurt Mahan
• Thomas Müller
• disktnk
• David Brownlee
• James Le Cuirot
• neoman/titan
• Carsten Strotmann
• Krzysztof Wolf
• Santiago Pastorino
• Dougall Johnson
• Brett Slatkin
• Anonymous sponsor

mold 1.6.0

mold 1.6.0 is a new release of the high-speed linker. This release adds support for two IBM-based platforms, though we are not affiliated with IBM. We are happy to take donations and/or make support contracts. If you are interested in financially supporting the project, please visit our GitHub Sponsors page.

New features

• [ppc64] mold now supports the original 64-bit big-endian PowerPC ABI (which is also known as PPC64 ELFv1 or just ppc64), so that you can build applications for older PPC64 systems with mold. Note that this should not be confused with the modern PPC64 ELFv2 ABI (which is also known as ppc64le), which is already supported by mold.
• [s390x] Linux/s390x is now supported. Linux/s390x is the Linux environment on IBM z/Architecture mainframes. I've personally never seen a mainframe, but we wanted to support it because many Linux distros actively support that target, which in turn means there are many enterprise users who are using IBM mainframes. Speaking of the porting effort, we do not only port our linker to s390x but also found a couple of issues with the existing GCC toolchain for s390x. So, we are improving the whole IBM mainframe ecosystem!
• mold now creates smaller output files. It is most noticeable on targets with large page sizes such as PPC64 (on which the common page size is 64 KiB), but even on x86-64, it should save a few kilobytes per an output file.

Bug fixes and compatibility improvements

• [arm64] mold can now link executables with -static-pie. Previously, executables linked with that flag crashed immediately. (fc66759)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• Johan Andersson
• Markus Schirp
• Anonymous sponsor

mold 1.6.0-pre.1

This is a pre-release for those who want to test it before the official 1.6.0 release.

New features

• [ppc64] mold now supports 64-bit big-endian PowerPC ABI, which is also known as PPC64 ELFv1 or just ppc64. Older PowerPC systems using the processors in the big-endian mode are based on this ABI. Note that modern little-endian PowerPC systems are based on PPC64 ELFv2 ABI (which is also known as ppc64le), which is already supported by mold.
• [s390x] Linux/s390x is now supported. Linux/s390x is the Linux environment running on IBM z/Architecture mainframes. We do not only port our linker to s390x but also found a couple of issues in the existing GCC toolchain for s390x. So, we are improving the whole IBM mainframe ecosystem!
• mold now creates smaller output files. It is most noticeable on targets with large page sizes such as PPC64 (on which the common page size is 64 KiB), but even on x86-64, it should save a few kilobytes per an output file.

Bug fixes and compatibility improvements

• [arm64] mold can now link executables with -static-pie. Previously, executables linked with that flag crashed immediately.

mold 1.5.1

mold 1.5.1 is a new release of the high-speed linker. This version contains only the following bug fix. We recommend upgrading from 1.5.0 if you are being affected by this issue.

• We changed the memory layout to save both memory and disk space in 1.5.0. Even though the new layout works fine on most systems, the change made the linker to create unusable executables for systems with large pages. Specifically, if you specify a large number for the -z max-page-size option, the loader refused to execute it with the error while loading shared libraries: cannot apply additional memory protection after relocation: Cannot allocate memory error. We reverted our recent commits so that mold creates output files with the same memory layout as it did before 1.5.0. (e62de0b)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• Johan Andersson
• Markus Schirp
• Anonymous sponsor

mold 1.5.0

mold 1.5.0 is a new release of the high-speed linker. The highlight of this release is that we start supporting the following four new targets: PPC64LE, SPARC64, RV32BE and RV64BE. mold 1.5.0 also includes various bug fixes, performance and compatibility improvements as shown below.

Starting from this release, we recommend using cmake instead of make to build mold. We will soon stop supporting make, so please migrate early and report issues if you find any.

Note for those who create mold binary packages: if you are building mold for binary distribution, please link the bundled libtbb statically (which is default) or rebuild your distro's libtbb package with my patch so that mold's Link-Time Optimization (LTO) works reliably under heavy load.

New features

• PPC64LE and SPARC64 are now supported as new targets. They haven't yet been as well tested as other targets, but they are already able to link mold itself on these platforms. (Note that PPC64LE is very unlikely to work on the most recent POWER10 machines as we didn't have a chance to test it due to a limited availability (POWER10 was released in 2021). If you can support us on this matter, please contact us. We also accept donations, so please consider supporting our project!)
• RV32BE and RV64BE (32-bit and 64-bit big-endian RISC-V) are now supported as experimental targets. RISC-V is usually little-endian, but there exists a big-endian RISC-V as an extension. You can make gcc to emit code for big-endian RISC-V by passing -mbig-endian. mold can now link object files generated with that option.
• --compress-debug-sections=zstd is now supported. This is an option to compress debug info embedded to an output file with Zstandard compression algorithm. Compared to the existing --compress-debug-sections=zlib, zstd is faster and gives a higher compression ratio. You probably can't start using zstd compression today though, because other tools such as gdb may not be able to read zstd-compressed debug info yet. But adding this option early makes mold future-proof. (ede7a5a)
• mold no longer aligns loadable segments to page boundaries to reduce output file size. Previously, we allocated holes between loadable segments. The saving by this change is most visible for small programs. For example, a "hello world" program used to be ~18 KiB on x86-64. It's now 7.2 KiB. (2941d75)

Bug fixes and compatibility improvements

• [RISCV] We optimized code so that the link speed for RISC-V is now comparable to the other targets. As an example, linking mold itself (~150 MiB in size) for RV64 used to take ~45 seconds on a simulated 16-core machine. It now takes only ~0.25 seconds. (3ab5489)
• mold used to create more than one .rodata section under a certain condition. It's not technically wrong but confused Valgrind. This issue has been resolved. (25c7aee)
• [ARM32] Previously, mold failed to promote remaining undefined symbols to dynamic symbols if symbols are undefined weak. That caused a link failure for libxml (#660). This issue has been resolved. (72e26d9)
• mold didn't copy symbol types when creating symbol aliases for the --defsym option. (8c7f31c)

Removed features

• --compress-debug-sections=zlib-gnu has been removed. LLVM lld removed that option too as there seems to be no usage of the flag.

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• Johan Andersson
• Markus Schirp
• Anonymous sponsor

mold 1.4.2

mold 1.4.2 is a maintenance release of the high-speed linker. This release includes, but not limited to, the following improvements and bug fixes.

Note for those who create mold binary packages: if you are building mold for binary distribution, please link the bundled libtbb statically (which is default) or rebuild your distro's libtbb package with my patch so that mold's Link-Time Optimization (LTO) works reliably under heavy load.

New features and bug fixes

• [RV32] We've fixed several issues for 32-bit RISC-V. mold can now build complex programs including itself for the target.
• [ARM32] mold gained range extension thunks so that it can now link programs whose .text is larger than 16 MiB. Previously, mold couldn't link such large programs. We've also fixed general stability issues for ARM32.

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• modocache
• repi
• Anonymous sponsor

mold 1.4.1

mold 1.4.1 is a maintenance release of the high-speed linker. This release contains the following improvements and bug fixes.

Note for those who create mold binary packages: if you are building mold for binary distribution, please link the bundled libtbb statically (which is default) or rebuild your distro's libtbb package with my patch so that mold's Link-Time Optimization (LTO) works reliably under heavy load.

New features

• mold/macOS is now available as an alpha feature. We do not recommend using it for anything serious though. Starting from this version, we accept not only mold/Unix issues but also mold/macOS ones on our GitHub Issues. Feel free to file a bug if you encounter any problem.
• We started supporting CMake in addition to Make to build mold. Our long-term plan is to migrate from Make to CMake because we want to support Windows eventually and CMake provides a better Windows support than Make does. (e6a0e67)

Bug fixes and compatibility improvements

• There was a bug that mold accidentally exported a hidden symbol from an executable if a shared library linked to that executable happened to define the same symbol. This caused a build issue with Blender (#606). The bug has been fixed. (b163068)
• --hash-style=both is now the default if no --hash-style option is given. Previously, --hash-style=sysv was the default. This change shouldn't affect most users because the compiler driver (cc, gcc, clang, etc.) always passes --hash-style to the linker. We made this change because GNU ld defaults to --hash-style=both.
• Alias symbols defined by the --defsym option now have the same scope as the aliased symbols. Previously, alias symbols defined by --defsym were always hidden and never be exported as dynamic symbols. (5dd1227)
• mold now accepts foo = bar-style linker script directive to define symbol aliases. Previously, such statement was treated as a syntax error. This change was made to link mariadb-connector-c correctly (f0e1237)
• Symbols in mergeable string sections now have correct output section indices instead of SHN_UNDEF. (a595c48)
• [ARM32] Previously, calling a function from ARM code to Thumb code caused a program crash due to bug #442. This issue has been fixed. (053b90b)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• modocache
• repi
• Anonymous sponsor

mold 1.4.0

mold 1.4.0 is a new release of the high-speed linker. This release contains a few new features and general stability/compatibility improvements as shown below.

Note for those who create mold binary packages: if you are building mold for binary distribution, please link the bundled libtbb statically (which is default) or rebuild your distro's libtbb package with my patch so that mold's Link-Time Optimization (LTO) works reliably under a heavy load.

New features

• Initial support for the 32-bit RISC-V (RV32) has landed. (d9db6bc)
• mold now demangles Rust symbols in error messages thanks to @eddyb's rust-demangle.c. (22e1bba)
• --export-dynamic-symbol and --export-dynamic-symbol-list are now supported for the sake of compatibility with LLVM lld. With these options, you can specify symbols that should be exported using glob pattern. (e115aae)
• [x86-64] PLT entries created by mold now always begins with ENDBR64 instruction to improve compatibility with Intel IBT (Indirect Branch Tracking.) (e3e371d)

Bug fixes and compatibility improvements

• mold now defines __dso_handle symbol. The lack of this linker-synthesized symbol caused a link error with GCC in some environments (#507). (764d757)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• Mercury
• signal-slot
• Wei Wu
• BuildBuddy
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• modocache
• Anonymous sponsor

mold 1.3.1

mold 1.3.1 is a maintenance release of the high-speed linker. This release contains the following minor bug fixes.

Bug fixes and compatibility improvements

• mold now supports .preinit_array sections. Without this, AddressSanitizer didn't work in some environments. (3b75398)
• [ARM32] R_ARM_MOVT_PREL and R_ARM_PREL31 relocations are now handled correctly so that mold no longer emit spurious "recompile with -fPIC" errors. (5294300)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• Mercury
• 300baud
• BuildBuddy
• Wei Wu
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• daquexian
• Anonymous sponsor

mold 1.3.0

mold 1.3.0 is a new release of the high-speed linker. This release contains a few new features and general stability/compatibility improvements as shown below.

Note for those who create mold binary packages: if you are building mold for binary distribution, please link the bundled libtbb statically (which is default) or rebuild your distro's libtbb package with my patch so that mold's Link-Time Optimization (LTO) works reliably under a heavy load.

Bug fixes and compatibility improvements

• The --icf=safe option has been supported. This option enables a feature to find and deduplicate identical code that can be merged safely. For C++ programs, it typically reduces the output binary size by a few percent. --icf=safe needs to be used with a compiler that supports .llvm_addrsig section; if a compiler does not support it, --icf=safe doesn't do any harm but cannot optimize a given program at all. That section is supported by LLVM/Clang at the moment, and we are working on adding it to GCC. (#484, 27908af)
• LTO now works reliably under a heavy load. mold used to abort occasionally under such condition on Linux due to a spurious failure of pthread_create(2). (d8a8877)
• mold now prints out undefined symbol errors in a format similar to LLVM lld. (13816a1)
• mold now prints out a better error message for the disk full situation. (5969260)
• mold can now build GCC 12 with LTO. (708ad63)
• Fixed an LTO issue on 32-bits hosts such as i686. (920266b)
• mold is now AddressSanitizer and UndefinedSanitizer clean. (fafb75b, 3499ee6)
• mold used to create broken debug info on 32-bits hosts (#490). The bug has been fixed. (0abd0a4)
• mold used to accept not only a single dash but also double dashes for single-letter options. For example, --S was accidentally accepted as an alias for-S. This is unconventional, and such options are no longer accepted. (232dafa)
• --color-diagnostics is now an alias for --color-diagnostics=auto instead of --color-diagnostics=always for compatibility with LLVM lld.
• pkg-config is no longer needed to build mold.
• The --package-metadata option is supported. (#505, e9f6715)

Removed features

• An experimental --preload flag has been removed. (a85b1f5)

Acknowledgements

mold is an open-source project, and we accept donations via GitHub Sponsors and OpenCollective. We thank you to everybody who sponsors our project. In particular, we'd like to acknowledge the following organizations and people who have sponsored $32/mo or more during this release cycle:

• 300baud
• BuildBuddy
• Wei Wu
• Luke Kasz
• Will Bond
• H.T
• .-A-.
• nasa
• haze
• Anonymous sponsor

We'd also like to thank HPC Engineering at AWS to donate $5,000 AWS credits to us.