Test vlib/v/slow_tests/assembly/asm_test.amd64.v fails on OpenBSD with tcc

[lcheylus]

Describe the bug

On OpenBSD current/amd64, test vlib/v/slow_tests/assembly/asm_test.amd64.v fails with tcc compiler ; no error when run with Clang (version 19.1.7) compiler.

Reproduction Steps

• Build V from Git repository on OpenBSD/amd64 with gmake rebuild
• Run test with command ./v test vlib/v/slow_tests/assembly/asm_test.amd64.v

Expected Behavior

No compilation error and success for test vlib/v/slow_tests/assembly/asm_test.amd64.v

Current Behavior

• Error when test run vlib/v/slow_tests/assembly/asm_test.amd64.v

$ ./v test vlib/v/slow_tests/assembly/asm_test.amd64.v
---- Testing... ----
 FAIL     0.000 ms vlib/v/slow_tests/assembly/asm_test.amd64.v
>> compilation failed:
================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/tsession_2d54c8508_01KFXPRKE8Q7Q3QANSZXPAV6J4/asm_test.amd64.01KFXPRPCQDVE0KJFTE0WPAETB.tmp.c:8692: error: unknown constraint '*'
=================================================================
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 .

----
To reproduce just failure 1 run:    '/home/fox/dev/vlang.git/v'  '/home/fox/dev/vlang.git/vlib/v/slow_tests/assembly/asm_test.amd64.v'
Summary for all V _test.v files: 1 failed, 1 total. Elapsed time: 4464 ms, on 1 job. Comptime: 4382 ms. Runtime: 0 ms.

• Full output for v test with -showcc and -show-c-output

$ ./v -showcc -show-c-output run vlib/v/slow_tests/assembly/asm_test.amd64.v
> C compiler cmd: '/home/fox/dev/vlang.git/thirdparty/tcc/tcc.exe' '@/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c.rsp'
> C compiler response file "/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c.rsp":
  -fwrapv -o "/home/fox/dev/vlang.git/vlib/v/slow_tests/assembly/asm_test.amd64" -D GC_THREADS=1 -D GC_BUILTIN_ATOMIC=1 -I "/usr/local/include" "/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c" -std=c99 -D_DEFAULT_SOURCE -bt25 "/usr/local/lib/libgc.a" -lgc -lpthread
======== Output of the C Compiler (/home/fox/dev/vlang.git/thirdparty/tcc/tcc.exe) ========
/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c:8692: error: unknown constraint '*'
===========================================================================================
> C compiler cmd: 'cc' '@/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c.rsp'
> C compiler response file "/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c.rsp":
  -fwrapv -o '/home/fox/dev/vlang.git/vlib/v/slow_tests/assembly/asm_test.amd64' -D GC_THREADS=1 -D GC_BUILTIN_ATOMIC=1 -I "/usr/local/include" "/tmp/v_1000/asm_test.amd64.01KFXQ0BCZ4FA527XZSGSSA6R4.tmp.c" -std=c99 -D_DEFAULT_SOURCE "/usr/local/lib/libgc.a" -lgc -lpthread 
======== Output of the C Compiler (cc) ========
ld: error: unable to find library -lgc
cc: error: linker command failed with exit code 1 (use -v to see invocation)
===============================================
No such file or directory; code: 2

Possible Solution

During link with tcc / ld, error ld: error: unable to find library -lgc => problem to find path for libgc

In vlib/builtin/builtin_d_gcboehm.c.v, line 95 and beyond: case for OpenBSD OS and tcc compiler (without define dynamic_boehm), there is no flag -L to define path for libgc (/usr/local/lib/ after installation of OpenBSD package boehm-gc).

$ pkg-config --libs --cflags bdw-gc
-I/usr/local/include -L/usr/local/lib -lgc -pthread

=> need to add #flag -L/usr/local/lib/ for OpenBSD && tcc case.

Additional Information/Context

No response

V version

V 0.5.0 f479e98

Environment details (OS name and version, etc.)

V full version	V 0.5.0 f479e98
OS	openbsd, 7.8, GENERIC.MP#217
Processor	4 cpus, 64bit, little endian
Memory	2.2GB/3.98GB
V executable	/home/fox/dev/vlang.git/v
V last modified time	2026-01-26 17:48:25
V home dir	OK, value: /home/fox/dev/vlang.git
VMODULES	OK, value: /home/fox/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/fox/dev/vlang.git
Git version	git version 2.52.0
V git status	weekly.2026.05-5-gf479e989
.git/config present	true
cc version	OpenBSD clang version 19.1.7
gcc version	egcc (GCC) 11.2.0
clang version	OpenBSD clang version 19.1.7
tcc version	tcc version 0.9.28rc 2025-05-27 HEAD@cb39bc4c (x86_64 OpenBSD)
tcc git status	thirdparty-openbsd-amd64 200e7752
emcc version	N/A
glibc version	N/A

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