thirdparty: fix tcc __atomic_thread_fence#26185

kbkpbot · 2025-12-28T02:39:11Z

Fix issue #25856
Fix issue #26158

This bug is caused by on aarch64, tcc remove the prefix __ from __atomic_thread_fence, so a workaround needed here.
Maybe a tcc fix is needed for upstream.

ping @spytheman would you please help me verify that the test file is written in a correct format ? I just want to check it can be compiled under tcc/arm64. Do it need to set a VFLAGS = -no-retry-compilation?

spytheman · 2025-12-28T06:28:38Z

@kbkpbot I think it should be fine now; I'll test on macos to be sure and in a VM asap.

kbkpbot · 2025-12-28T07:18:44Z

Thank you @spytheman

tankf33der · 2025-12-28T07:52:51Z

Also will fix #25856

spytheman

Excellent work 🙇🏻 .
@tankf33der what do you think?

tankf33der · 2025-12-29T14:36:02Z

Since all checks have passed this should be merged.
I will check everywhere and comment here.

tankf33der · 2025-12-29T15:36:26Z

@spytheman - i take my words back. do not merge. i am testing.

tankf33der · 2025-12-29T15:37:32Z

During the pause, I decided to check that the patch works.

tankf33der · 2025-12-29T16:00:53Z

x64 alpine - ok

tankf33der · 2025-12-29T16:01:27Z

some fail on one of the ARM

tankf33der@cfarm103:~/v$ gmake
cd ./vc && git clean -xf && git pull --quiet
cd ./thirdparty/tcc && git clean -xf && git pull --quiet
cc  -std=c99 -w -o v1 ./vc/v.c -lm -lpthread  || cmd/tools/cc_compilation_failed_non_windows.sh
./v1 -no-parallel -o v2 -no-retry-compilation -no-parallel cmd/v
================== C compilation error (from /home/tankf33der/v/thirdparty/tcc/tcc.exe): ==============
cc: /tmp/v_62104/v2.01KDNDDK4KEKCD1649CT8Z8KR5.tmp.c:1223: error: ARM asm not implemented.
=======================================================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
gmake: *** [GNUmakefile:115: all] Error 1

spytheman · 2025-12-29T17:42:26Z

what is on line /tmp/v_62104/v2.01KDNDDK4KEKCD1649CT8Z8KR5.tmp.c:1223 ?

tankf33der · 2025-12-29T18:14:27Z

what is on line /tmp/v_62104/v2.01KDNDDK4KEKCD1649CT8Z8KR5.tmp.c:1223 ?

@spytheman @kbkpbot

Some line from patch of this PR

kbkpbot · 2025-12-30T07:32:34Z

Yes, due to tcc does not support arm asm right now, this should not work as inline asm.
Maybe a .s file will work.
But I am not sure we can have a .s in the thirdparty directory.

spytheman · 2025-12-30T09:49:42Z

Afaik, there is no policy restriction for .s files in thirdparty/ , but I am not sure if there will not be technical ones 🤔 . I have not tried using separate .s files till now.

spytheman · 2025-12-30T09:53:27Z

thirdparty/libatomic_ops/atomic_ops.h:293 has a AO_compiler_barrier() macro.
Can it be used instead?

kbkpbot · 2025-12-30T10:31:47Z

thirdparty/libatomic_ops/atomic_ops.h:293 has a AO_compiler_barrier() macro. Can it be used instead?

no.
I just created a c file,
c.c

#include <stdio.h>

void main() {
        __asm__ __volatile__("" : : : "memory")
}

$ ./tcc.exe c.c -o c -I ./include -I ./lib/tcc/include
c.c:4: error: ARM asm not implemented.

…flag directives (needed for #26185) (#26211)

tankf33der · 2026-01-01T11:19:05Z

@spytheman let me know when i should start manual testing.

spytheman

Excellent work.
Thank you @kbkpbot .

spytheman · 2026-01-02T09:12:45Z

@tankf33der I think it is ready to be tested (and merged).

tankf33der · 2026-01-02T09:15:13Z

@tankf33der I think it is ready to be tested (and merged).

I will start testing in 90mins.

tankf33der · 2026-01-02T11:38:05Z

@spytheman @kbkpbot

CPU	Distro	Status
X64	Apine	compilation failed
X64	Debian	Passed
ARM64	Debian	Passed
ARM64	Debian	Passed
RISCV64	Alpine	compilation failed
RISCV64	Debian	Passed
PPC64LE	Debian	Passed

compilation failed text will be on next comments.
When i say Passed it means - that after patching v, v list and VTEST=ONLY=closure ./v test vlib/ works.

tankf33der · 2026-01-02T11:40:14Z

X64 on Alpine failed this way with patch.
v compiled, v list failed. Note it worked on prev. testing, see above.

lambda:~/v$ v list
cannot compile `/home/mpech/v/cmd/tools/vpm`: 1
================== C compilation error (from tcc): ==============
cc: tcc: error: undefined symbol '__atomic_thread_fence'
=================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

tankf33der · 2026-01-02T11:41:26Z

RISCV64 on Alpine v compilation failed this way with or without patch:

cfarm94:~/v$ gmake
cd ./vc && git clean -xf && git pull --quiet
cd ./thirdparty/tcc && git clean -xf && git pull --quiet
cc  -std=c99 -w -o v1 ./vc/v.c -lm -lpthread  || cmd/tools/cc_compilation_failed_non_windows.sh
./v1 -no-parallel -o v2  cmd/v
./v2 -nocache -o ./v  cmd/v
rm -rf v1 v2
================== C compilation error (from cc): ==============
cc: /usr/lib/gcc/riscv64-alpine-linux-musl/14.2.0/../../../../riscv64-alpine-linux-musl/bin/ld: cannot find /home/tankf33der/v/thirdparty/tcc/lib/libgc.a: No such file or directory
cc: collect2: error: ld returned 1 exit status
================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
gmake: *** [GNUmakefile:118: all] Error 1

kbkpbot · 2026-01-02T13:32:05Z

X64 on Alpine failed this way with patch. v compiled, v list failed. Note it worked on prev. testing, see above.

lambda:~/v$ v list
cannot compile `/home/mpech/v/cmd/tools/vpm`: 1
================== C compilation error (from tcc): ==============
cc: tcc: error: undefined symbol '__atomic_thread_fence'
=================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

I need more info to find out what is really going on.
Do you upgrade master to latest git before this test?

please provide more info about your tcc version.

kbkpbot · 2026-01-02T13:34:48Z

RISCV64 on Alpine v compilation failed this way with or without patch:

cfarm94:~/v$ gmake
cd ./vc && git clean -xf && git pull --quiet
cd ./thirdparty/tcc && git clean -xf && git pull --quiet
cc  -std=c99 -w -o v1 ./vc/v.c -lm -lpthread  || cmd/tools/cc_compilation_failed_non_windows.sh
./v1 -no-parallel -o v2  cmd/v
./v2 -nocache -o ./v  cmd/v
rm -rf v1 v2
================== C compilation error (from cc): ==============
cc: /usr/lib/gcc/riscv64-alpine-linux-musl/14.2.0/../../../../riscv64-alpine-linux-musl/bin/ld: cannot find /home/tankf33der/v/thirdparty/tcc/lib/libgc.a: No such file or directory
cc: collect2: error: ld returned 1 exit status
================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
gmake: *** [GNUmakefile:118: all] Error 1

It seems you miss a prebuilt libgc.a at that location.

…lpine X64

spytheman · 2026-01-02T13:44:49Z

I've checked in a Docker container with Alpine x64 , v -no-retry-compilation -cc tcc cmd/tools/vpm (which v list does invoke, to compile vpm), failed with tcc: error: undefined symbol '__atomic_thread_fence' .

386deb8 fixes it for me, by adding a flag for the .S file, and changing _V_atomic_thread_fence for that case to __atomic_thread_fence .

spytheman · 2026-01-02T13:47:02Z

For the Alpine X64 case, make does:

git clone --filter=blob:none --quiet --branch thirdparty-linuxmusl-amd64 https://github.com/vlang/tccbin ./thirdparty/tcc

and for that clone:

/src # ./thirdparty/tcc/tcc.exe --version
tcc version 0.9.27 mob:d3e940c (x86_64 Linux)

spytheman · 2026-01-02T13:49:42Z

tcc d3e940c is from 2022-04-28 . We should update it indeed. It is currently 499 commits behind the tip of the mob branch of git://repo.or.cz/tinycc.git .

spytheman · 2026-01-02T13:52:36Z

Can we provide both _V_atomic_thread_fence and __atomic_thread_fence symbols in the same .S file?

kbkpbot · 2026-01-02T14:02:50Z

Can we provide both _V_atomic_thread_fence and __atomic_thread_fence symbols in the same .S file?

I am not sure it can pass vtcc test, as vtcc already provide a symbol __atomic_thread_fence
https://github.com/felipensp/vtcc/blob/78da82675cf56e2a4c36e1d006bb19265114bd81/lib/libtcc1/stdatomic.v#L14-L17

spytheman · 2026-01-02T14:10:08Z

hm, if there is a pure V implementation (well with inline assembly), why do we need a separate .S file ?

spytheman · 2026-01-02T14:11:24Z

the vtcc implementation does not use a memory barrier 🤔

kbkpbot · 2026-01-02T14:13:36Z

hm, if there is a pure V implementation (well with inline assembly), why do we need a separate .S file ?

That is for vtcc only, not for tcc.
And I think vtcc is compiled by gcc not by tcc, as gcc support inline asm for arm64.

spytheman · 2026-01-02T14:32:00Z

vtcc can be compiled with the PR from here on Alpine, just checked:

/src/vtcc # v run make.vsh /src/vtcc
building bt-log.o (tcc_backtrace symbol): ok
building bcheck.o: : ok
building bt-exe.o: : ok
building dso.o: : ok
buildind libtcc1.o: : ok
building vtcc.o: : ok
building libtcc1.a: : ok
buildind vtcc: : ok
/src/vtcc # ./vtcc --version
tcc version 0.9.28rc (x86_64 Linux)
/src/vtcc # ./vtcc -c hello.c -o hello.o
/src/vtcc # ls -la hello.o
-rw-r--r--    1 root     root           976 Jan  2 14:30 hello.o
/src/vtcc #
/src/vtcc #
/src/vtcc # ./vtcc hello.c
tcc: error: file 'crt1.o' not found
tcc: error: file 'crti.o' not found
tcc: error: file 'crtn.o' not found
/src/vtcc #

The last compilation fails because of unrelated reasons - it is tuned to work on a glibc system, and imho making it work on a musl one, is out of scope for this PR.

spytheman · 2026-01-02T14:34:44Z

If the new docker-alpine-musl-tcc CI job passes here, I intend to merge this as it is. We can improve the RISCV64 Alpine case later.

spytheman · 2026-01-03T06:27:47Z

The sanitized CI jobs failed due to an unrelated problem, that is fixed on master.

spytheman · 2026-01-03T06:29:08Z

Thank you @kbkpbot 🙇🏻 .
Thank you @tankf33der.

thirdparty: fix tcc __atomic_thread_fence

041ff8b

spytheman reviewed Dec 28, 2025

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Comment thread vlib/v/tests/tcc_arm64_atomic_fence_test.v Outdated

Apply suggestion from @spytheman

3aefda5

kbkpbot marked this pull request as draft December 29, 2025 04:12

kbkpbot added 4 commits December 29, 2025 12:42

fix

e1cba85

remove #warning as it can't pass -cstrict

ae03f14

add impl

92ae908

fix asm

d0fafe4

kbkpbot marked this pull request as ready for review December 29, 2025 11:29

spytheman approved these changes Dec 29, 2025

View reviewed changes

kbkpbot marked this pull request as draft December 30, 2025 07:33

kbkpbot mentioned this pull request Dec 30, 2025

v.builder: add compile asm file support #26211

Merged

spytheman pushed a commit that referenced this pull request Dec 31, 2025

v.builder: support compiling asm .S files to .o files, mentioned in #…

e97dfaa

…flag directives (needed for #26185) (#26211)

kbkpbot added 3 commits December 31, 2025 16:40

Merge branch 'master' into fix-tcc-arm64-atomic-fence

17fbd80

Merge branch 'master' into fix-tcc-arm64-atomic-fence

b09b10c

add atomic.S

a9475f4

kbkpbot added 2 commits December 31, 2025 19:20

add asm

cb38797

fix path, only apply for tcc aarch64

ed04f72

kbkpbot marked this pull request as ready for review January 1, 2026 00:46

spytheman reviewed Jan 1, 2026

View reviewed changes

Comment thread vlib/v/builder/cc.v

spytheman approved these changes Jan 2, 2026

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spytheman reviewed Jan 2, 2026

View reviewed changes

Comment thread thirdparty/stdatomic/nix/atomic.S

fix v -no-retry-compilation -cc tcc cmd/tools/vpm and v list on A…

386deb8

…lpine X64

ci: add a simplified docker-alpine-musl-tcc job

9ba743d

spytheman merged commit 8018dde into vlang:master Jan 3, 2026
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