From d84a78d15d3af9ff28ceec6906a4b101bd545b55 Mon Sep 17 00:00:00 2001 From: Matheus Tavares Bernardino Date: Mon, 13 Mar 2023 15:58:19 -0300 Subject: [PATCH] migration/xbzrle: use ctz64 to avoid undefined result __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 Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- 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;