Re: Using __builtin_expect (likely/unlikely macros)

[Paul Eggert]

Eli Zaretskii wrote:
> > In this case the patch not only improved performance, it also made
> > the code smaller and in my opinion more readable: the total source
> > code size shrank by 1775 bytes.
> I meant code in C, not the produced machine code

Yes, that's what I meant too. That is, the patch made the C code shorter.

> I'm not sure how do you see that the code became more readable

It's more readable to me partly because the common case is shorter, e.g.:

-static _Noreturn void module_abort (const char *format, ...)
-  ATTRIBUTE_FORMAT_PRINTF(1, 2);
+static AVOID module_abort (const char *, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);

and partly because the unusual case is more obviously unusual. For example, in:

-static _Noreturn void
+static AVOID
 x_connection_closed (Display *dpy, const char *error_message, bool ioerror)
...
-static _Noreturn int
+static _Noreturn ATTRIBUTE_COLD int
 x_io_error_quitter (Display *display)

the x_connection_closed closed is obviously typical (it uses the now-common 
"AVOID"), whereas the x_io_error_quitter is obviously atypical (one normally 
doesn't see ATTRIBUTE_COLD in .c files), and this lets the reader more-easily 
see that x_io_error_quitter (a) returns 'int' and (b) never returns anything, 
which makes it even more of an oddball than the usual AVOID functions are.