https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88223
Bug ID: 88223
Summary: Wrong code for intrinsic memmove
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: fuz at fuz dot su
Target Milestone: ---
Created attachment 45103
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45103&action=edit
preprocessed test case
A user on reddit has pointed out that gcc 8 generates wrong code
for intrinsic memmove() when compiling with optimisations:
https://www.reddit.com/r/C_Programming/comments/a0tdux
The following minimal reproduction was provided:
char s[] = "12345";
memmove(s + 1, s, 4); /* 11234 */
memmove(s + 1, s, 4); /* 11123 */
memmove(s + 1, s, 4); /* 11112 */
puts(s);
Without optimisations, this prints "11112" as expected whereas
with optimisations, it prints "11123".
I was able to reproduce this problem on FreeBSD with gcc 8.2.0.
The relevant files are attached.
