From: https://github.com/lz4/lz4/pull/1468

commit 63267a77d863f63826d8b13ddb8c190d3a4c01c5
Author: Holger Hoffstätte <holger@applied-asynchrony.com>
Date:   Mon Jul 22 22:11:19 2024 +0200

    Fix stack alignment of _start() in freestanding test
    
    When the freestanding test is built with any kind of optimization
    that enables vectorized loops, special care must be taken to align
    the stack for _start() at a 16-byte boundary.

diff --git a/tests/freestanding.c b/tests/freestanding.c
index 6109aa7..96de9d3 100644
--- a/tests/freestanding.c
+++ b/tests/freestanding.c
@@ -225,7 +225,7 @@ EXTERN_C int memcmp(const void *s1, const void *s2, size_t n) {
 
 
 //
-EXTERN_C void _start(void) {
+EXTERN_C void __attribute__((force_align_arg_pointer)) _start(void) {
     test();
     MY_exit(0);
 }

Disable the stack protector to allow building with clang.
See https://bugs.gentoo.org/936480

diff -up lz4-1.10.0/build/meson/meson/tests/meson.build lz4-1.10.0/build/meson/meson/tests/meson.build
--- lz4-1.10.0/build/meson/meson/tests/meson.build	2024-07-21 19:29:49.000000000 +0200
+++ lz4-1.10.0/build/meson/meson/tests/meson.build	2024-07-23 01:26:40.561113031 +0200
@@ -47,7 +47,7 @@ test_exes = {
   },
   'freestanding': {
     'sources': files(lz4_source_root / 'tests/freestanding.c'),
-    'c_args': ['-ffreestanding', '-Wno-unused-parameter', '-Wno-declaration-after-statement'],
+    'c_args': ['-ffreestanding', '-fno-stack-protector', '-Wno-unused-parameter', '-Wno-declaration-after-statement'],
     'link_args': ['-nostdlib'],
     'build': cc.get_id() in ['gcc', 'clang'] and
       host_machine.system() == 'linux' and host_machine.cpu_family() == 'x86_64',