llvm-6502/test/Transforms/SROA
Chandler Carruth 4f9a7277d1 [SROA] Apply a somewhat heavy and unpleasant hammer to fix PR22093, an
assert out of the new pre-splitting in SROA.

This fix makes the code do what was originally intended -- when we have
a store of a load both dealing in the same alloca, we force them to both
be pre-split with identical offsets. This is really quite hard to do
because we can keep discovering problems as we go along. We have to
track every load over the current alloca which for any resaon becomes
invalid for pre-splitting, and go back to remove all stores of those
loads. I've included a couple of test cases derived from PR22093 that
cover the different ways this can happen. While that PR only really
triggered the first of these two, its the same fundamental issue.

The other challenge here is documented in a FIXME now. We end up being
quite a bit more aggressive for pre-splitting when loads and stores
don't refer to the same alloca. This aggressiveness comes at the cost of
introducing potentially redundant loads. It isn't clear that this is the
right balance. It might be considerably better to require that we only
do pre-splitting when we can presplit every load and store involved in
the entire operation. That would give more consistent if conservative
results. Unfortunately, it requires a non-trivial change to the actual
pre-splitting operation in order to correctly handle cases where we end
up pre-splitting stores out-of-order. And it isn't 100% clear that this
is the right direction, although I'm starting to suspect that it is.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225149 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-05 04:17:53 +00:00
..
address-spaces.ll
alignment.ll [SROA] Teach SROA to be more aggressive in splitting now that we have 2015-01-02 03:55:54 +00:00
basictest.ll [SROA] Apply a somewhat heavy and unpleasant hammer to fix PR22093, an 2015-01-05 04:17:53 +00:00
big-endian.ll [SROA] Teach SROA to be more aggressive in splitting now that we have 2015-01-02 03:55:54 +00:00
fca.ll
phi-and-select.ll
slice-order-independence.ll
slice-width.ll
vector-conversion.ll
vector-lifetime-intrinsic.ll
vector-promotion.ll
vectors-of-pointers.ll