This is being disabled because it is no longer needed for
performance. It is only used by postRAscheduler which is also planned
for removal, and it is implemented with an out-dated view of register
liveness. It consideres aliases instead of register units, assumes
valid kill flags, and assumes implicit uses on partial register
defs. Kill flags and implicit operands are error prone and impossible
to verify. We should gradually eliminate dependence on them in the
postRA phases.
Targets that still benefit from this should move to the MI
scheduler. If that doesn't solve the problem, then we should add a
hook to regalloc to optimize reload placement.
llvm-svn: 191348
1. Teach it to use overlapping unaligned load / store to copy / set the trailing
bytes. e.g. On 86, use two pairs of movups / movaps for 17 - 31 byte copies.
2. Use f64 for memcpy / memset on targets where i64 is not legal but f64 is. e.g.
x86 and ARM.
3. When memcpy from a constant string, do *not* replace the load with a constant
if it's not possible to materialize an integer immediate with a single
instruction (required a new target hook: TLI.isIntImmLegal()).
4. Use unaligned load / stores more aggressively if target hooks indicates they
are "fast".
5. Update ARM target hooks to use unaligned load / stores. e.g. vld1.8 / vst1.8.
Also increase the threshold to something reasonable (8 for memset, 4 pairs
for memcpy).
This significantly improves Dhrystone, up to 50% on ARM iOS devices.
rdar://12760078
llvm-svn: 169791
aligned address. Based on patch by David Peixotto.
Also use vld1.64 / vst1.64 with 128-bit alignment to take advantage of alignment
hints. rdar://12090772, rdar://12238782
llvm-svn: 164089
