https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109931
--- Comment #3 from Antony Polukhin <antoshkka at gmail dot com> ---
> But that's because nothing in the function asserts this? Without fully
> specializing and unrolling on the constant "hello" argument at least.
Yes, I was hoping for that unrolling to happen
Probably a more simplified case:
constexpr bool EqualICase(const char* lowercase, const char* y) noexcept {
for (;;) {
const auto lowercase_c = *lowercase;
if (!lowercase_c) return true;
if (lowercase_c != *y) {
return false;
}
++lowercase;
++y;
}
}
bool test2(const char* y) {
return EqualICase("he", y);
}
With range info for loads from read-only constants I'd expect this to become
just a
test2(char const*):
cmp BYTE PTR [rdi], 104
jne .L3
cmp BYTE PTR [rdi+1], 101
sete al
ret
.L3:
xor eax, eax
ret
rather than a fair loop with checks for \0
Godbolt: https://godbolt.org/z/z6rTYEzWx
