I'm implementing a computer simulator in C with the challenge not to use conditionals (ie no if/else, switch/case, while/for, etc.). There are a lot of muxes in the hardware I'm simulating, so it would be nice if I could use the conditional ternary logic operators. So, my question: do C compilers create MUX logic from ternary logic operators, or do they create branches?
Example:
int a, b, q, r;
/* Ternary logic */
r = q ? a : b;
/* MUX equivalent logic */
r = ( q & a ) | ( (~q) & b )
/* Branch equivalent logic */
if (q) r = a; else r = b;
The ternary operator is equivalent to a branch: i.e. the value not returned is not evaluated.
I don't know how much you are constrained, so note that boolean operators && and || don't evaluate their second argument is the result can be determined from the first.
(And note that you line "MUX" doesn't something very different from the other two expressions: it select bits from a or b depending on the value of corresponding bit in q, it doesn't select a or b depending if q is null or not; Edit: it is worse: you are using !q and not ~q...).