Support compiling with LLVM #510

imwints · 2023-03-22T13:39:06Z

Support LLVM as toolchain. Set CXX=clang++ to compile with LLVM instead of GCC.
Only works with Clang/LLVM 16.0.0 and higher.

This may not work on all supported variants, feedback appreciated.

Closes: #490
Closes: #508

imwints · 2023-05-23T11:07:22Z

I don't know why the CI for FreeBSD is failing.

aristocratos · 2023-05-23T11:22:50Z

@nobounce
Seems to be a Makefile issue
Makefile:51: *** ERROR: c++: Version minimum is 16.0.0. Stop.

It stops because of wrong clang version detected ignoring that a compatible gcc version is available.

A solution would be to instead increment a error counter variable and if the version checks for both clang and gcc fails, then throw an error.

aristocratos · 2023-05-23T15:55:07Z

@nobounce
I'm getting 8000 lines of undefined reference linker errors trying to compile with clang 16 on Ubuntu 22.04 with everything directly pulled from https://apt.llvm.org/

Installed packages:
clang-16 clang-tools-16 clang-16-doc libclang-common-16-dev libclang-16-dev libclang1-16 clang-format-16 python3-clang-16 clangd-16 clang-tidy-16 libc++-16-dev libc++abi-16-dev libllvm-16-ocaml-dev libllvm16 llvm-16 llvm-16-dev llvm-16-doc llvm-16-examples llvm-16-runtime

Am I missing something?

imwints · 2023-05-23T16:56:54Z

@aristocratos

Installed packages: clang-16 clang-tools-16 clang-16-doc libclang-common-16-dev libclang-16-dev libclang1-16 clang-format-16 python3-clang-16 clangd-16 clang-tidy-16 libc++-16-dev libc++abi-16-dev libllvm-16-ocaml-dev libllvm16 llvm-16 llvm-16-dev llvm-16-doc llvm-16-examples llvm-16-runtime

Am I missing something?

Seems like lld and libunwind are missing. If both are installed you can try to force Clang to use it's own tools by passing

-stdlib=libc++ -fuse-ld=lld -unwindlib=libunwind -rtlib=compiler-rt

aristocratos · 2023-05-23T19:12:24Z

@nobounce
Turns out the problem was that I was passing CXX=clang-16 instead of CXX=clang++-16 :)
lld and libunwind got pulled in as dependencies by the earlier packages.

Not sure why, but the binary compiled by clang is 2.0MiB compared to 1.5MiB by gcc, with the same optimization flags?

Will take a closer look at the changes this week, but since it's passing compile for all platforms now it's looking good. Nice work! 👍🏼

imwints · 2023-05-23T20:27:24Z

For what I know, Clang does more aggressive loop unrolling with -O2 than GCC with -O3. I'll have a look aswell.

imwints · 2023-05-23T21:10:03Z

@aristocratos

Compiler	Bytes	Opt	Libc	Static
Clang	1,690,008	-O2	Glibc	false
Clang	1,826,016	-O3	Glibc	false
GCC	1,411,432	-O2	Glibc	false
GCC	1,493,384	-O3	Glibc	false
Clang	1,691,552	-O2	musl	false
Clang	1,826,152	-O3	musl	false
Clang	2,515,832	-O2	musl	true
Clang	2,651,528	-O3	musl	true

That seems reasonable to me.
My only concern is that Clang takes 1.5x the time for compilation (08s / 12s).

check. Clang cannot handle <semaphore> being included in a namespace, which is also unadvised see: https://softwareengineering.stackexchange.com/a/335261. Using the fallback <semaphore.h> is only meant for GCC 10, but Clang defines `__GNUC__ = 4` so exclude Clang.

On my musl system statvfs64 is not exposed by default. The musl FAQ recommends against using type64_t types, see: https://wiki.musl-libc.org/faq.html#Q:-Do-I-need-to-define-%3Ccode%3E_LARGEFILE64_SOURCE%3C/code%3E-to-get-64bit-%3Ccode%3Eoff_t%3C/code%3E?. Defining `_FILE_OFFSET_BITS=64` and using type_t lets type_t use the 64 bit interface, see: https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html#index-_005fFILE_005fOFFSET_005fBITS.

Returning from the thread this way prevents local variables to be destructed correctly since pthread_exit is marked noreturn. This fixes a segmentation fault with glibc and llvm-libunwind on exit.

Clang 16.0.0 or later can now be used to compile btop. Simply call `CXX=clang++` make. If the CXX variable contains an incompatible Clang version try to fallback to GCC.

imwints · 2023-06-14T21:34:54Z

@aristocratos
Did you have the time to look at this?
It would be great if that can land in main. Maybe coupled with a new release so (source-based-)distros can take advantage of this and remove gcc as a dependency :)

aristocratos

Maybe coupled with a new release so (source-based-)distros can take advantage of this and remove gcc as a dependency :)

I can't imagine that many distros have clang16 included by default yet?

Gpu support should be done in a little while, and are planning to do a release with a minor version bump then.

imwints · 2023-06-15T16:10:29Z

@aristocratos

I can't imagine that many distros have clang16 included by default yet?

Yeah, probably not many :)
I'm running Gentoo on my machine and a server, and the server only has Clang as a compiler. Bothers be that the current version has a hard dependency on GCC (Compiling GCC takes a couple of hours). That's why I made the PR in the first place. A small version bump might not hurt but in the mean time I can at least run the "official" git version.

vimproved · 2023-06-18T16:46:47Z

FYI, Gentoo has clang 16, but only on the testing branch. LLVM 16 is not yet stabilized because of those various issues.

imwints force-pushed the LLVM branch from 0774135 to cd27ae6 Compare May 4, 2023 11:43

imwints force-pushed the LLVM branch 3 times, most recently from 3ae6d65 to 37bc27e Compare May 23, 2023 13:49

imwints force-pushed the LLVM branch from caf781c to 9509b28 Compare May 23, 2023 20:40

imwints added 6 commits May 25, 2023 23:00

Insert std:: for warning unqualified call to std::move.

922b647

Include <codecvt> required by Clang.

7dac850

Remove pthread_exit().

a5e4969

Returning from the thread this way prevents local variables to be destructed correctly since pthread_exit is marked noreturn. This fixes a segmentation fault with glibc and llvm-libunwind on exit.

Enable Clang as a compiler.

dec9fa1

Clang 16.0.0 or later can now be used to compile btop. Simply call `CXX=clang++` make. If the CXX variable contains an incompatible Clang version try to fallback to GCC.

imwints force-pushed the LLVM branch from 9509b28 to dec9fa1 Compare May 25, 2023 21:07

imwints mentioned this pull request Jun 15, 2023

ensure statvfs64 is declared #556

Closed

aristocratos approved these changes Jun 15, 2023

View reviewed changes

aristocratos merged commit 7e50b03 into aristocratos:main Jun 15, 2023

imwints deleted the LLVM branch June 15, 2023 16:10

imwints mentioned this pull request Jun 20, 2023

[REQUEST] Clang support #324

Closed

aristocratos mentioned this pull request Jun 23, 2023

[REQUEST] Testing of compilers other than GCC #561

Closed

Samasaur1 mentioned this pull request Jan 27, 2024

btop: update to 1.3.0, cleanup portfile macports/macports-ports#22412

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Support compiling with LLVM #510

Support compiling with LLVM #510

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Support compiling with LLVM #510

Support compiling with LLVM #510

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