I see the following warnings issued by the compiler (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.2) on a AArch64 machine:
/usr/bin/cc -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE -std=gnu99 -pedantic -Wall -W -Wundef -Wendif-labels -Wshadow -Wpointer-arith -Wcast-align -Wcast-qual -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wdisabled-optimization -fstrict-aliasing -O2 -pipe -Wno-parentheses -fPIC -I/home/ubuntu/src/git/ck/include -I/home/ubuntu/src/git/ck/include -c -o /home/ubuntu/src/git/ck/src/ck_epoch.o /home/ubuntu/src/git/ck/src/ck_epoch.c
In file included from /home/ubuntu/src/git/ck/include/ck_pr.h:51:0,
from /home/ubuntu/src/git/ck/include/ck_backoff.h:31,
from /home/ubuntu/src/git/ck/src/ck_epoch.c:33:
/home/ubuntu/src/git/ck/src/ck_epoch.c: In function ‘ck_pr_cas_ptr_value’:
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘previous’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:242:5: note: ‘previous’ was declared here
T previous; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:282:1: note: in expansion of macro ‘CK_PR_CAS’
CK_PR_CAS(ptr, void, void *, "", "")
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘tmp’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:243:5: note: ‘tmp’ was declared here
T tmp; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:282:1: note: in expansion of macro ‘CK_PR_CAS’
CK_PR_CAS(ptr, void, void *, "", "")
^
/home/ubuntu/src/git/ck/src/ck_epoch.c: In function ‘ck_pr_cas_uint_value’:
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘previous’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:242:5: note: ‘previous’ was declared here
T previous; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:284:33: note: in expansion of macro ‘CK_PR_CAS’
#define CK_PR_CAS_S(N, M, W, R) CK_PR_CAS(N, M, M, W, R)
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:288:1: note: in expansion of macro ‘CK_PR_CAS_S’
CK_PR_CAS_S(uint, unsigned int, "", "w")
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘tmp’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:243:5: note: ‘tmp’ was declared here
T tmp; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:284:33: note: in expansion of macro ‘CK_PR_CAS’
#define CK_PR_CAS_S(N, M, W, R) CK_PR_CAS(N, M, M, W, R)
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:288:1: note: in expansion of macro ‘CK_PR_CAS_S’
CK_PR_CAS_S(uint, unsigned int, "", "w")
^
/usr/bin/cc -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE -std=gnu99 -pedantic -Wall -W -Wundef -Wendif-labels -Wshadow -Wpointer-arith -Wcast-align -Wcast-qual -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wdisabled-optimization -fstrict-aliasing -O2 -pipe -Wno-parentheses -fPIC -I/home/ubuntu/src/git/ck/include -I/home/ubuntu/src/git/ck/include -c -o /home/ubuntu/src/git/ck/src/ck_ht.o /home/ubuntu/src/git/ck/src/ck_ht.c
/usr/bin/cc -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE -std=gnu99 -pedantic -Wall -W -Wundef -Wendif-labels -Wshadow -Wpointer-arith -Wcast-align -Wcast-qual -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wdisabled-optimization -fstrict-aliasing -O2 -pipe -Wno-parentheses -fPIC -I/home/ubuntu/src/git/ck/include -I/home/ubuntu/src/git/ck/include -c -o /home/ubuntu/src/git/ck/src/ck_hp.o /home/ubuntu/src/git/ck/src/ck_hp.c
In file included from /home/ubuntu/src/git/ck/include/ck_pr.h:51:0,
from /home/ubuntu/src/git/ck/include/ck_backoff.h:31,
from /home/ubuntu/src/git/ck/src/ck_hp.c:54:
/home/ubuntu/src/git/ck/src/ck_hp.c: In function ‘ck_pr_cas_ptr_value’:
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘previous’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:242:5: note: ‘previous’ was declared here
T previous; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:282:1: note: in expansion of macro ‘CK_PR_CAS’
CK_PR_CAS(ptr, void, void *, "", "")
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:244:3: warning: ‘tmp’ is used uninitialized in this function [-Wuninitialized]
__asm__ __volatile__("1:" \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:243:5: note: ‘tmp’ was declared here
T tmp; \
^
/home/ubuntu/src/git/ck/include/gcc/aarch64/ck_pr.h:282:1: note: in expansion of macro ‘CK_PR_CAS’
CK_PR_CAS(ptr, void, void *, "", "")
^