[ILUG] a quick gcc microoptimisation question

[Justin Mason]

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HiLUG,

quickie: when using gcc's -O switches, what is more efficient:

    if (condition) {
      /* more common case */
    } else {
      /* less common case */
    }

or 

    if (condition) {
      /* less common case */
    } else {
      /* more common case */
    }

??

I know there is/was a tool that using coverage/profile data to optimise
branching and cache locality of code, but is there a technique to do this
efficiently without requiring that and the profiling runs it'd require?
In other words, with gcc optimisation, is the branch instruction used for
the "if" case or the "else" case by default?

- --j.
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