https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104601
Bug ID: 104601
Summary: [11 Regression] Invalid branch elimination at -O2
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: markus.boeck02 at gmail dot com
Target Milestone: ---
Following code has been produced via reduction with `creduce`.
When compiled with `-O2`, GCC 11 and later versions will incorrectly print `f`,
while if `-O1` or lower, or an older version of GCC is used, it will correctly
print 't'.
#include <algorithm>
#include <cstdio>
#include <optional>
inline std::optional<int> a(std::vector<int>::iterator b,
std::vector<int>::iterator c,
std::optional<int> h(int)) {
std::optional<int> d;
find_if(b, c, [&](auto e) {
d = h(e);
return d;
});
return d;
}
std::optional<int> f(int) { return 1; }
main() {
std::vector<int> g(100);
auto e = a(g.begin(), g.end(), f);
printf("%c", e ? 't' : 'f');
}
For the sake of completion, this was the original code:
https://godbolt.org/z/enx19v7E5
