::operator new[] overloading.

Let's try to run Foo and Bar classes under ARM Linux platform:

// Foo class class Foo { public: Foo() { vec = my_value; } float32x4_t vec; }; // Bar class class Bar { public: Bar() { vec = my_value; } ~Bar() { } // this destructor is important float32x4_t vec; }; // 16-byte alignment allocation // this approach will work on all platforms! void *operator new(size_t size) { return memalign(16,size); } void *operator new[](size_t size) { return memalign(16,size); } // everything is OK... Foo *f0 = new Foo(); Bar *b0 = new Bar(); Foo *f1 = new Foo[1]; // Hello SIGBUS! where are you from? Bar *b1 = new Bar[1]; // I'm from 8-byte cookie.

The f1 pointer has 16-byte alignment. But b1 pointer has 8-byte alignment. For a Bar class with non-default destructor compiler will save allocation size and class size inside the cookie.
The cookie size on non-__ARM_EABI__ platforms is max(sizeof(size_t) * 2,sizeof(Foo)).
The cookie size of __ARM_EABI__ platform is sizeof(size_t) * 2 and we can't change it.

We you should do with all your code which is using this approach on __ARB_EABI__??
The stupid straightforward solution is to return the wrong 8-byte alignment instead of 16-byte one for all Bar classes:

void *operator new[](size_t size) { #if defined(_LINUX) && defined(__ARM_EABI__) if(sizeof(size_t) == 4 && !IS_ALIGNED16(size)) { size += sizeof(size_t) * 2; return static_cast<size_t*>(memalign(16,size)) + 2; } #endif return memalign(16,size); } void operator delete(void *ptr) { #if defined(_LINUX) && defined(__ARM_EABI__) if(sizeof(size_t) == 4 && !IS_ALIGNED16(ptr)) { return free(static_cast<size_t*>(ptr) - 2); } #endif free(ptr); }