Hi Jiangning
On 3/15/19 4:46 AM, JiangNing OS wrote:
This patch is to fix a missing ifcvt opportunity in back-end. For the
simple case below,
if (...)
x = a; /* x is memory */
/* no else */
We can generate conditional move and remove the branch as below if the
target cost is acceptable.
r1 = x
r2 = a
cmp ...
csel r3, r1, r2, cond
x = r3
This could be safe if x is a stack variable, and there isn't any
address taken in current function, so the store speculation can be
avoided.
In practice, this optimization can improve a real application
performance by %4 on aarch64.
Now that GCC 10 development is open, this should appropriate for
considering.
I've cc'ed folks who are either listed maintainers in this area or have
reviewed patches in this area in my recent memory.
Thanks,
Kyrill
Thanks,
-Jiangning
