https://bugs.kde.org/show_bug.cgi?id=492549
--- Comment #5 from martin.lu...@ohb.de ---
It seems that the behaviour of __builtin_memchr depends on where the source
string is stored. The following two programs have different output with massif,
but otherwise the same output:
Always says 0 (= not found):
#include <string>
#include <iostream>
int main()
{
std::cout << (void*) __builtin_memchr("haystack", 'x', 1) << std::endl;
}
Says 0 normally, but 0x1fff000120 (a heap address?) with massif:
#include <string>
#include <iostream>
int main()
{
std::string s = "haystack";
std::cout << (void*) __builtin_memchr(s.c_str(), 'x', 1) << std::endl;
}
But it looks like the same happens on the stack, massif returns 0x1fff000147
here again, but normal run returns 0:
#include <string>
#include <iostream>
int main()
{
char sample[] = { 'h', 'a', 'y', 's', 't', 'a', 'c', 'k', 0 };
std::cout << (void*) __builtin_memchr(sample, 'x', 1) << std::endl;
}
However, just making sample a const char works:
#include <string>
#include <iostream>
int main()
{
const char sample[] = { 'h', 'a', 'y', 's', 't', 'a', 'c', 'k', 0 };
std::cout << (void*) __builtin_memchr(sample, 'x', 1) << std::endl;
}
~ $ ./a.out
0
~ $ valgrind -q --tool=massif ./a.out
0
--
You are receiving this mail because:
You are watching all bug changes.
