RDMA/ocrdma: Help gcc generate better code for ocrdma_srq_toggle_bit
gcc emits a surprising amount of code in order to flip a bit. One
would think that a single instruction is enough.
$ scripts/bloat-o-meter /tmp/ocrdma_verbs.o drivers/infiniband/hw/ocrdma/ocrdma_verbs.o
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-142 (-142)
function old new delta
ocrdma_post_srq_recv 498 460 -38
ocrdma_poll_cq 2010 1962 -48
ocrdma_discard_cqes 495 439 -56
All three calls of ocrdma_srq_toggle_bit happen within spinlocks, so
saving a few useless instructions might be worthwhile.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Selvin Xavier <selvin.xavier@emulex.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
index 5f656b9..c1e9f96 100644
--- a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
+++ b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
@@ -1591,10 +1591,7 @@
int i = idx / 32;
unsigned int mask = (1 << (idx % 32));
- if (srq->idx_bit_fields[i] & mask)
- srq->idx_bit_fields[i] &= ~mask;
- else
- srq->idx_bit_fields[i] |= mask;
+ srq->idx_bit_fields[i] ^= mask;
}
static int ocrdma_hwq_free_cnt(struct ocrdma_qp_hwq_info *q)