I just compiled your code on a VAX (VMS) both with and without optimization enabled. In each case, both routines generated identical code.

To me, the ternary operator is most useful when used in a function call argument list or other complex expression where one element needs to change based on some condition. These become much easier and concise to express with a ternary operator than with two separate statements within an if/else construct.

Contrived example:

    printf("File name: %s\n", (ptr == NULL) ? "<unspecified>" : ptr);
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...or...

    char *s;
    if (ptr == NULL)
        s = "<unspecified>";
    else
        s = ptr;
    printf("File name: %s\n", s);
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What it boils down to is that the ternary operator presents an expression and can be used anywhere an expression can be used. if/else is a (compound) statement and is much more restrictive about where it can be used.

# trinary
movl    %eax, -28(%ebp) #  to_return

# ifelse
movl    $1, -28(%ebp)   #  to_return
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The trinary function is handling the variable between registers, whereas ifelse is using a memory location. This is another boost to the trinary operator.

Doesn't the $1 notation mean that the value 1 is encoded in the instruction itself (immediate value)? You seem to imply that it is referencing a variable somewhere else in memory.