https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112748
Bug ID: 112748
Summary: memmove(ptr, ptr, n) call optimized out even at -O0
with -fsanitize=undefined
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: tavianator at gmail dot com
Target Milestone: ---
This is counter-productive, as I wrote the memmove() specifically to get the
sanitizers to check that ptr really points to a big enough allocation.
$ cat foo.c
typedef __SIZE_TYPE__ size_t;
void *memmove(void *dest, void *src, size_t n);
void foo(void *ptr, size_t n) {
memmove(ptr, ptr, n);
}
$ gcc -O0 -fsanitize=undefined -S foo.c
$ cat foo.s
.file "foo.c"
.text
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
movq %rdi, -8(%rbp)
movq %rsi, -16(%rbp)
nop
popq %rbp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 13.2.1 20230801"
.section .note.GNU-stack,"",@progbits
