C / C++ / MFC

Vaclav_ wrote:

Here is the entire test code

struct small_obj {
   char description[16];
   int count;
};  // size = 20 bytes

struct large_obj {
    char text[1024][1024];
    double factor[1024][1024];
}; // size = 9 MB

void f1(small_obj arg);  // OK, puts 20 bytes on the stack, f1 gets a copy
                                // of the struct. Any modifications to the struct are
                                // local ot f1

void f2(small_obj* arg);  // stack is 4 bytes only. changes to f2 members will not
                                 // be seen by caller

void f3(const small_obj *arg); // stack is 4 bytes only. attempts within f3 to modify members
                               // should produce compiler warnings

void f4(small_obj& arg);   // similar to f2(), but uses C++ reference type

void f5(const small_obj& arg);   // similar to f3, but uses C++ reference type

void f6(large_obj arg);   // questionable.  This copys 9 MB onto the stack, which might
                          // be more than the OS can handle, and might incur performance
                          // penalties you can avoid by passing as a pointer or reference

Quote:

I can highly recommend learning the whole process on a simple software renderer

• instlatx64
• uops.info - Table
• Software optimization resources (item 4: instruction tables)

CBitmap myBitmap;
myBitmap.LoadBitmap(IDB_STOP);