[Bug tree-optimization/107263] New: Memcpy not elided when initializing struct

[jmuizelaar at mozilla dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107263

            Bug ID: 107263
           Summary: Memcpy not elided when initializing struct
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jmuizelaar at mozilla dot com
  Target Milestone: ---

With the following code

struct Foo {
    Foo* next;
    char arr[580];
};

void ctx_push(Foo* f) {
    Foo tmp = { f->next };
    *f = tmp;
}

Clang is able to generate code that just memsets `arr`. GCC instead initializes
the entire struct on the stack and then copies it into `f`.

https://gcc.godbolt.org/z/Yzcbs4G71