Currently loop cache analysis uses following formula to evaluate cost of
an RefGroup for a consecutive memory access:
`RefCost=(TripCount*Stride)/CLS`
This cost evaluates to zero when `TripCount*Stride` is smaller than
cache-line-size. This results in wrong cost value for a loop and
misleads loopInterchange decisions as shown in [this
case](https://llvm.godbolt.org/z/jTz1vn4hn).
This patch fixes the problem by rounding the cost to 1 once this problem
happens.
In this patch we change test cases from using "CHECK" to using
"CHECK-NEXT", which is to ensure the order of loops output by
loop cache analysis is correct. After D124725 we fixed the
non-deterministic output order hence we did not use "CHECK-DAG"
anymore, and now we should really use "CHECK-NEXT" to make sure
the loops in the output loop vector follow the right order.
Reviewed By: bmahjour, #loopoptwg
Differential Revision: https://reviews.llvm.org/D124984
The print output of loop cache analysis sometimes has a non-deterministic order
and therefore we have been using `CHECK-DAG` in its lit tests. This patch changes
the sorting of LoopCosts to llvm::stable_sort() where we compare loop cost numbers
and sort the loops. In case of the same loop cost numbers, llvm::stable_sort() now
would output a deterministic loop order.
Reviewed By: Meinersbur, fhahn, #loopoptwg
Differential Revision: https://reviews.llvm.org/D124725
Currently loop cache cost (LCC) cannot analyze fix-sized arrays
since it cannot delinearize them. This patch adds the capability
to delinearize fix-sized arrays to LCC. Most of the code is ported
from DependenceAnalysis.cpp and some refactoring will be done in a
next patch.
Reviewed By: #loopoptwg, Meinersbur
Differential Revision: https://reviews.llvm.org/D122857
