https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102221
Bug ID: 102221
Summary: Missed optimizations for algorithms over
std::unique_ptr
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: dangelog at gmail dot com
Target Milestone: ---
Sorting/heaping/etc. an array/vector of unique_ptr generates worse codegen than
the equivalent code on an array of raw pointers. This is a missed optimization,
as the operations involved should just be mere swaps.
For instance:
#include <memory>
#include <algorithm>
#if defined(SMART)
using ptr = std::unique_ptr<int>;
#else
using ptr = int*;
#endif
void f()
{
extern ptr *data;
const auto cmp = [](const auto &a, const auto &b) { return *a < *b; };
std::sort(data, data+1000, cmp);
}
https://gcc.godbolt.org/z/7zPYxr9q7
This generates quite some extra code (including calls to operator delete); the
result is that such a sort is slower than the countepart with a raw pointer.
