mem-cache: Create Tree-PLRU replacement policy

Implementation of a Tree-PLRU replacement policy. It is based on
the assumption that a set associative cache is used.

Change-Id: I74b227e88fd6c93aab5bb2cd0e8730376db28f52
Reviewed-on: https://gem5-review.googlesource.com/c/11106
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

mem-cache: Create Second-Chance replacement policy

Implementation of a Second-Chance replacement policy. Similar to FIFO,
but every block is given a second chance if it has been touched.

Change-Id: Id4d52b698d0045a4914a4d848fdf9c3c00a28508
Reviewed-on: https://gem5-review.googlesource.com/9441
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: ReplacementPolicy specific replacement data

Replacement data is specific for each replacement policy, and thus
should be instantiated differently by each policy.

Touch() and reset() do not need to be aware of CacheBlk, as they
only update its ReplacementData.

Invalidate() makes replacement policies independent of cache blocks,
by removing the awareness of the valid state.

An inheritable base ReplaceableEntry class was created to allow usage
of replacement policies with any table-like structure.

Change-Id: I998917d800fa48504ed95abffa2f1b7bfd68522b
Reviewed-on: https://gem5-review.googlesource.com/9421
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create BIP Replacement Policy

Implementation of a Bimodal Insertion Policy replacement policy.

Change-Id: Ife058d0d4310dbcb35858348006189f0b2bf7c37
Reviewed-on: https://gem5-review.googlesource.com/9003
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create LFU replacement policy

Implementation of a Least Frequently Used replacement policy.

Change-Id: I772afccd3a7955777e53d59341e922718db44e5c
Reviewed-on: https://gem5-review.googlesource.com/8890
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create BRRIP replacement policy

Implementation of a Bimodal Re-Reference Interval Prediction
replacement policy.

Change-Id: I25d4a59a60ef7ac496c66852e394fd6cbaf50912
Reviewed-on: https://gem5-review.googlesource.com/8891
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create FIFO replacement policy

Implementation of a First-In, First-Out replacement policy.

Change-Id: Id234ec9d29c092dd4516e609da14b8a75a96b5e4
Reviewed-on: https://gem5-review.googlesource.com/8888
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create MRU replacement policy

Implementation of a Most Recently Used replacement policy.

Change-Id: Id52cb247ca25d4523dcc53490d113695dac6a3f1
Reviewed-on: https://gem5-review.googlesource.com/8889
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Split array indexing and replacement policies.

Replacement policies (LRU, Random) are currently considered as array
indexing methods, but have completely different functionalities:

- Array indexers determine the possible locations for block allocation.
This information is used to generate replacement candidates when
conflicts happen.
- Replacement policies determine which of the replacement candidates
should be evicted to make room for new allocations.

For this reason, they were split into different classes. Advantages:

- Easier and more straightforward to implement other replacement
policies (RRIP, LFU, ARC, ...)
- Allow easier future implementation of cache organization schemes

As now we can't assure the use of sets, the previous way to create a
true LRU is not viable. Now a timestamp_bits parameter controls how
many bits are dedicated for the timestamp, and a true LRU can be
achieved through an infinite number of bits (although a few bits suffice
in practice).

Change-Id: I23750db121f1474d17831137e6ff618beb2b3eda
Reviewed-on: https://gem5-review.googlesource.com/8501
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>