We can now hoist the check in:
for (i = start; i != end; ++i)
a[i] = ...
or
for i in start ..< end
a[i] = ...
We will also hoist invariant checks as in
k =
for i in start ..< end
a[k] = ...
We will also hoists the overflow check for "++i" out of the loop.
The only thing blocking vectorization of memset loops is the fact that we are
overflow checking the type size muliplication of array accesses. "a[i]" is
translated to "a + sizeof(T) * i" and this multiplication is still overflow
checked.
We can remove bounds checks in PrimeNum, XorLoop, Hash, MemSet, NBody, Walsh.
Memset , 2371.00 , 1180.00 , 1179.00 , 99.9%
XorLoop , 1403.00 , 1255.00 , 149.00 , 11.9%
rdar://14757945
Swift SVN r21182
Implements redundant bounds check elimination for basic blocks and along the
dominator tree of loops.
No induction variable based hoisting yet.
O3:
NBody , 473.00 , 122.00 , 294.2%
QuickSort , 477.00 , 310.00 , 53.9%
RC4 , 1022.00 , 736.00 , 38.6%
Walsh , 1781.00 , 1142.00 , 55.5%
No effect on Ofast.
Disabled for now.
Swift SVN r20199
