https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61982
Bug ID: 61982
Summary: Optimizer does not eliminate stores to destroyed
objects
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: a...@cloudius-systems.com
After a destructor is run, access to the object is forbidden; the object is
turned into a pile of bytes. Yet the generated code for:
struct X {
int i;
void clear() { i = 0; }
};
void f(X* x) {
x->clear();
x->~X();
}
void g(X* x) {
x->clear();
delete x;
}
contains a store for each of f() and g(), stores that should have been
eliminated:
0000000000000000 <f(X*)>:
0: c7 07 00 00 00 00 movl $0x0,(%rdi)
6: c3 retq
7: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
e: 00 00
0000000000000010 <g(X*)>:
10: c7 07 00 00 00 00 movl $0x0,(%rdi)
16: e9 00 00 00 00 jmpq 1b <g(X*)+0xb>
17: R_X86_64_PC32 operator delete(void*)-0x4
To be clear, the generated code is correct, but not optimal.
