https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117279
Bug ID: 117279
Summary: std::string bounds check from -D_GLIBCXX_ASSERTIONS
not optimised out
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: sjames at gcc dot gnu.org
Target Milestone: ---
Even at -O3, we (and Clang) don't seem to optimise out the unnecessary bounds
checks from -D_GLIBCXX_ASSERTIONS for this using `-O3 -D_GLIBCXX_ASSERTIONS`:
```
#include <string>
int foo(int index) {
if (index < 0 || index > 4) {
return 0;
}
std::string p = "Hello world";
__builtin_printf("%c\n", p[index]);
return p[index];
}
```
If we rewrite it as this, we can as well as Clang:
```
#include <string>
void foo(int index) {
if (index < 0 || index > 4) {
return;
}
std::string p = "Hello world";
__builtin_printf("%c\n", p[index]);
}
```
https://godbolt.org/z/6PGf4WKnK
