| Message ID | 117f3c2fdc17c319b0e04014bbd7e0c94992c197.1678733663.git.quic_mathbern@quicinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | migration/xbzrle: fix two avx512 runtime issues | expand |
* Matheus Tavares Bernardino (quic_mathbern@quicinc.com) wrote: > __builtin_ctzll() produces undefined results when the argument is 0. > This can be seen through test-xbzrle, which produces the following > warning: > > ../migration/xbzrle.c:265: runtime error: passing zero to ctz(), which is not a valid argument > > Replace __builtin_ctzll() with our ctz64() wrapper which properly > handles 0. > > Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/xbzrle.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/migration/xbzrle.c b/migration/xbzrle.c > index 05366e86c0..21b92d4eae 100644 > --- a/migration/xbzrle.c > +++ b/migration/xbzrle.c > @@ -12,6 +12,7 @@ > */ > #include "qemu/osdep.h" > #include "qemu/cutils.h" > +#include "qemu/host-utils.h" > #include "xbzrle.h" > > /* > @@ -233,7 +234,7 @@ int xbzrle_encode_buffer_avx512(uint8_t *old_buf, uint8_t *new_buf, int slen, > break; > } > never_same = false; > - num = __builtin_ctzll(~comp); > + num = ctz64(~comp); > num = (num < bytes_to_check) ? num : bytes_to_check; > zrun_len += num; > bytes_to_check -= num; > @@ -262,7 +263,7 @@ int xbzrle_encode_buffer_avx512(uint8_t *old_buf, uint8_t *new_buf, int slen, > nzrun_len += 64; > break; > } > - num = __builtin_ctzll(comp); > + num = ctz64(comp); > num = (num < bytes_to_check) ? num : bytes_to_check; > nzrun_len += num; > bytes_to_check -= num; > -- > 2.39.1 >
Matheus Tavares Bernardino <quic_mathbern@quicinc.com> wrote: > __builtin_ctzll() produces undefined results when the argument is 0. > This can be seen through test-xbzrle, which produces the following > warning: > > ../migration/xbzrle.c:265: runtime error: passing zero to ctz(), which is not a valid argument > > Replace __builtin_ctzll() with our ctz64() wrapper which properly > handles 0. > > Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com> Reviewed-by: Juan Quintela <quintela@redhat.com> queued.
diff --git a/migration/xbzrle.c b/migration/xbzrle.c index 05366e86c0..21b92d4eae 100644 --- a/migration/xbzrle.c +++ b/migration/xbzrle.c @@ -12,6 +12,7 @@ */ #include "qemu/osdep.h" #include "qemu/cutils.h" +#include "qemu/host-utils.h" #include "xbzrle.h" /* @@ -233,7 +234,7 @@ int xbzrle_encode_buffer_avx512(uint8_t *old_buf, uint8_t *new_buf, int slen, break; } never_same = false; - num = __builtin_ctzll(~comp); + num = ctz64(~comp); num = (num < bytes_to_check) ? num : bytes_to_check; zrun_len += num; bytes_to_check -= num; @@ -262,7 +263,7 @@ int xbzrle_encode_buffer_avx512(uint8_t *old_buf, uint8_t *new_buf, int slen, nzrun_len += 64; break; } - num = __builtin_ctzll(comp); + num = ctz64(comp); num = (num < bytes_to_check) ? num : bytes_to_check; nzrun_len += num; bytes_to_check -= num;
__builtin_ctzll() produces undefined results when the argument is 0. This can be seen through test-xbzrle, which produces the following warning: ../migration/xbzrle.c:265: runtime error: passing zero to ctz(), which is not a valid argument Replace __builtin_ctzll() with our ctz64() wrapper which properly handles 0. Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com> --- migration/xbzrle.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)