https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94671
Bug ID: 94671
Summary: Wrong behavior with operator new overloading when
using O2 for optimization
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: b...@odd-e.com
Target Milestone: ---
This bug is a similar bug as an earlier reported in clang:
https://bugs.llvm.org/show_bug.cgi?id=15541
When having the overloaded new operator defined in other cpp or in a lib, g++
with O2 optimizes a new operation without assignment (or assignment to local or
static), and it will not call the overloaded new at all.
The following code will reproduce the problem.
---------------
test.cpp:
---------------
#include <iostream>
#define CHECK(expect, actual) std::cout << "EXPECT:" << expect <<
"\tACTUAL:"<<actual << std::endl
extern bool newCalled;
void testNewWithoutAssignment() {
newCalled = false;
new char;
CHECK(1, newCalled);
}
static char* somechar;
void testNewWithAssignmentToStatic() {
newCalled = false;
somechar = new char;
CHECK(1, newCalled);
}
char *p;
void testNewWithAssignment() {
newCalled = false;
p = new char;
CHECK(1, newCalled);
}
int main() {
testNewWithoutAssignment();
testNewWithAssignmentToStatic();
testNewWithAssignment();
return 0;
}
---------------
new.cpp:
---------------
#include <exception>
#include <new>
#include <cstdlib>
extern bool newCalled;
bool newCalled = false;
void* operator new (size_t size) throw (std::bad_alloc)
{
newCalled = true;
return malloc(size);
}
-----------
I know this is an optimization (it doesn't happen with -O0)... but it does
break the C++ standard.
