https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113164
Bug ID: 113164
Summary: [missed optimization] struct fields should not alias
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: powerboat9.gamer at gmail dot com
Target Milestone: ---
I have the following code
> struct sss {
> int a;
> int b;
> };
>
> int foo(struct sss *a, struct sss *b) {
> return &a->a == &b->b;
> }
When I compile it with
> gcc -c -O3 -Wall -Wextra test.c
I get
> 0000000000000000 <foo>:
> 0: 48 83 c6 04 add $0x4,%rsi
> 4: 31 c0 xor %eax,%eax
> 6: 48 39 fe cmp %rdi,%rsi
> 9: 0f 94 c0 sete %al
> c: c3 ret
, but GCC should be able to infer that the two pointers being compared can not
alias.
