Question

I have compared gcc assembler output of

do { 

// some code 

} while (0);

with

do {
 
    // some code

    break; 
} while (1);

The output is equal, with or without optimization but..

It’s always that way?

No experiment can prove theories, they can only show they are wrong

Answer 1

There is a slight difference:

do {
  // code
  if ( condition )
    continue;
  // code
  break;
} while(1);

Will restart the loop when condition is true, whereas in the } while(0); version, the continue will be equivalent to break.

If no continue is present, then they should produce exactly the same code.