atomic failure linking with --enable-sanitizers on 32-bit Linux hosts

[Philippe Mathieu-Daudé]

As of commit 50536341b47, using --enable-sanitizers on 32-bit Linux host:
- displays various warnings
- fails linking

Using Ubuntu 18.04 (release 20201211.1) and Clang10 on i386:

[139/675] Compiling C object softmmu.fa.p/softmmu_icount.c.o
In file included from ../softmmu/icount.c:31:
In file included from include/exec/exec-all.h:23:
In file included from ../target/mips/cpu.h:4:
In file included from ../target/mips/cpu-qom.h:23:
In file included from include/hw/core/cpu.h:23:
In file included from include/hw/qdev-core.h:5:
In file included from include/qemu/bitmap.h:16:
In file included from include/qemu/bitops.h:17:
include/qemu/atomic.h:463:12: warning: misaligned atomic operation may
incur significant performance penalty [-Watomic-alignment]
    return qatomic_read__nocheck(ptr);
           ^
include/qemu/atomic.h:129:5: note: expanded from macro
'qatomic_read__nocheck'
    __atomic_load_n(ptr, __ATOMIC_RELAXED)
    ^
include/qemu/atomic.h:473:5: warning: misaligned atomic operation may
incur significant performance penalty [-Watomic-alignment]
    qatomic_set__nocheck(ptr, val);
    ^
include/qemu/atomic.h:138:5: note: expanded from macro
'qatomic_set__nocheck'
    __atomic_store_n(ptr, i, __ATOMIC_RELAXED)
    ^
2 warnings generated.
[...]

[850/2216] Linking target tests/test-hbitmap
FAILED: tests/test-hbitmap
clang -o tests/test-hbitmap tests/test-hbitmap.p/test-hbitmap.c.o
tests/test-hbitmap.p/iothread.c.o -Wl,--as-needed -Wl,--no-undefined
-pie -Wl,--whole-archive libblock.fa libcrypto.fa libauthz.fa libqom.fa
libio.fa -Wl,--no-whole-archive -Wl,--warn-common -fsanitize=undefined
-fsanitize=address -Wl,-z,relro -Wl,-z,now -m32 -ggdb
-fstack-protector-strong -Wl,--start-group libqemuutil.a
subprojects/libvhost-user/libvhost-user-glib.a
subprojects/libvhost-user/libvhost-user.a libblock.fa libcrypto.fa
libauthz.fa libqom.fa libio.fa @block.syms -lgio-2.0 -lgobject-2.0
-lglib-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0 -pthread -lutil -lgnutls
-lm -lgthread-2.0 -lglib-2.0 /usr/lib/i386-linux-gnu/libglib-2.0.so
-liscsi -lgthread-2.0 -lglib-2.0 -laio -lcurl
/usr/lib/i386-linux-gnu/libz.so -lrbd -lrados -lnettle -lgnutls
-Wl,--end-group
libblock.fa(block_io.c.o): In function `stat64_max':
include/qemu/stats64.h:58: undefined reference to `__atomic_load_8'
include/qemu/stats64.h:60: undefined reference to
`__atomic_compare_exchange_8'
libblock.fa(block_qapi.c.o): In function `stat64_get':
include/qemu/stats64.h:40: undefined reference to `__atomic_load_8'
libqemuutil.a(util_qsp.c.o): In function `qatomic_set_u64':
include/qemu/atomic.h:478: undefined reference to `__atomic_store_8'
libqemuutil.a(util_qsp.c.o): In function `qatomic_read_u64':
include/qemu/atomic.h:468: undefined reference to `__atomic_load_8'
clang: error: linker command failed with exit code 1 (use -v to see
invocation)

Issue previously reported on the list here:
https://<email address hidden>/msg770128.html

[Philippe Mathieu-Daudé (philmd)]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'invalid' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/235