Maybe I'm using the wrong terminology then or am possibly confused. I am
under the impression that std::allocator points to std::new_allocator by
default. In fact, in debugging with gdb, I've gotten into
new_allocator.h. At any rate, in trying to contrive the smallest
possible test program, I learned some new things that in my original
pass, I mistook.
It turns out that std::vector seems to work fine with -O2 or without it.
std::ostringstream however does not call my new OR delete with no
optimization. With -O2, it calls only my delete.
If I do not attempt to wrap malloc and free, I get the same result.
std::vector calls my new and delete, ostringstream calls neither.
The command line I used to compile it is:
g++ -g -O2 --std=c++14 -Wl,-wrap,malloc -Wl,-wrap,free Test.c -o test.exe
Test.c:
#include <sstream>
#include <iostream>
#include <vector>
extern "C" void *__real_malloc(size_t);
extern "C" void __real_free(void *);
extern "C" void *__wrap_malloc(size_t nbytes) {
printf("wrap_malloc: %ld bytes\n", nbytes);
void * foo = __real_malloc(nbytes);
printf("wrap_malloc address: %ld\n", foo);
return foo;
}
extern "C" void __wrap_free(void *ptr) {
printf("wrap_free: %ld\n", ptr);
__real_free(ptr);
}
void* operator new (std::size_t size) throw (std::bad_alloc) {
printf("new: %ld bytes\n", size);
void *p = __wrap_malloc(size);
printf("new address: %ld\n", p);
return p;
}
void operator delete (void *p) {
printf("delete: %ld\n", p);
__wrap_free(p);
}
void operator delete (void *p, std::size_t) {
printf("delete with size: %ld\n", p);
__wrap_free(p);
}
int main(int argc, char ** argv) {
printf("Creating new vector\n\n");
std::vector<int> foo;
printf("pushing an element\n\n");
foo.push_back(5);
printf("Creating new ostringstream\n\n");
std::ostringstream msg2;
printf("pushing once\n\n");
msg2 << "Blah blah blah ";
printf("pushing twice\n\n");
msg2 << "boo dee doo" << std::endl;
printf("printing it out\n\n");
std::cout << msg2.str();
}
On 09/27/2016 01:10 PM, Jonathan Wakely wrote:
* Nikolaus Dunn:
I've run into an issue where turning on compiler optimization using
-O1 or higher causes an issue in my program. Specifically, I am
replacing the new and delete operators globally to perform some real
time allocation tracking. When I compile with -O1 or -O2, my
implementation of new is not being called by STL classes, via the
std::allocator. My version of delete IS being called.
That doesn't make much sense, because std::allocator<T> doesn't use
new or delete for objects of type T, so neither should be called.
Instead std::allocator<T> allocates untyped memory (e.g. via malloc)
and then constructs objects into it with placement new-expressions.
What do you replacement new and delete operators look like?
