[Openais] [patch] Unnecessary `else' in assembly code of totempg

[Masatake YAMATO]

> On Sun, 2009-02-15 at 02:05 +0900, Masatake YAMATO wrote:
> > Hi,
> > 
> > Could you merge this patch if it is correct?
> > 
> 
> The optimizer benefits from the else on some archs/compilers and it
> doesn't cause any harm so I am inclined to leave it the way it is.

I think the 'else' causes harm.

Look at the local variable `start'.

`start' is initialized to 0.
Then `start' is set to 1 in "if (throw_away_mode == THROW_AWAY_ACTIVE) {}" block.

The value of `start' is refereed in "if (throw_away_mode ==
THROW_AWAY_INACTIVE) {}" block.

If the "else" is there, start is always 0 in 
"if (throw_away_mode == THROW_AWAY_INACTIVE) {}".
I could not understand why `start' is set to 1 in 
"if (throw_away_mode == THROW_AWAY_ACTIVE) {}"

Masatake YAMATO


    static void totempg_deliver_fn (
	    unsigned int nodeid,
	    struct iovec *iovec,
	    int iov_len,
	    int endian_conversion_required)
    {
	    struct totempg_mcast *mcast;
	    unsigned short *msg_lens;
	    int i;
	    struct assembly *assembly;
	    char header[FRAME_SIZE_MAX];
	    int h_index;
	    int a_i = 0;
	    int msg_count;
	    int continuation;
	    int start;

	    /*
	     * Make sure that if this message is a continuation, that it
	     * matches the sequence number of the previous fragment.
	     * Also, if the first packed message is a continuation
	     * of a previous message, but the assembly buffer
	     * is empty, then we need to discard it since we can't
	     * assemble a complete message. Likewise, if this message isn't a 
	     * continuation and the assembly buffer is empty, we have to discard
	     * the continued message.
	     */
	    start = 0;

	    if (throw_away_mode == THROW_AWAY_ACTIVE) {
		     /* Throw away the first msg block */
		    if (mcast->fragmented == 0 || mcast->fragmented == 1) {
			    throw_away_mode = THROW_AWAY_INACTIVE;

			    assembly->index += msg_lens[0];
			    iov_delv.iov_base = &assembly->data[assembly->index];
			    iov_delv.iov_len = msg_lens[1];
			    start = 1;
		    }
	    } else 
	    if (throw_away_mode == THROW_AWAY_INACTIVE) {
		    if (continuation == assembly->last_frag_num) {
			    assembly->last_frag_num = mcast->fragmented;
			    for  (i = start; i < msg_count; i++) {