https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110137
user202729 <user202729 at protonmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |user202729 at protonmail dot
com
--- Comment #6 from user202729 <user202729 at protonmail dot com> ---
Created attachment 58293
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58293&action=edit
Proposed implementation.
I've implement it. (Attached patch) It would be helpful if someone can review
it.
Some notes:
1. Clang's documentation says the effect of `-fassume-sane-operator-new` is to
assume no-alias, but it is pointed out that Clang also assumes no-side-effect.
So I explicitly state that in the documentation.
2. The original intent is to fix
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110035 .
While this patch alone is insufficient to fix that (as explained in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110035#c17 ), it would be
sufficient to improve the performance of the following (to only load from
global memory once):
```
int a;
// Prevent optimization
void sink(void *m) {
asm volatile("" : : "g"(m) : "memory");
}
int f(){
int x=a;
float* z=new float;
int y=a;
int result=x+y;
sink(z);
return result;
}
```
3. I'm not sure which additional optimizations can be done if we know something
is pure, but this would improve that one case. Other cases can be added later
on.
