mem-cache: Create CacheComp debug flag

Create a debug flag for cache compression.

Change-Id: Id4b8e86d658d3aa550906ee0f8da3b54f4cdab7d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/11104
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

mem-cache: Move sector_blks to tags folder

Move sector_blks.hh and sector_blks.cc to the tags folder,
as its usage scope is restricted to the tags, and caches
should not be aware of them.

Change-Id: Ia7a71f51ec251d827872daf108c87da543a0ba57
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/13417
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Rename blk.cc/hh to cache_blk.cc/hh

Rename the files blk.cc and blk.hh to cache_blk.cc and cache_blk.hh
to comply with the usual file-class naming rules.

Change-Id: I8af45df3e4b8dd934fd9929ec914fb230cb2cb09
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/13416
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create Sector Cache

Implementation of Sector Caches, i.e., a cache with multiple
sequential data entries per tag entry for Set Associtive
placement policies.

Change-Id: I8e1e9448fa44ba308ccb16cd5bcc5fd36c988feb
Reviewed-on: https://gem5-review.googlesource.com/9741
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Add a non-coherent cache

The class re-uses the existing MSHR and write queue. At the moment
every single access is handled by the cache, even uncacheable
accesses, and nothing is forwarded.

This is a modified version of a changeset put together by Andreas
Hansson <andreas.hansson@arm.com>

Change-Id: I41f7f9c2b8c7fa5ec23712a4446e8adb1c9a336a
Reviewed-on: https://gem5-review.googlesource.com/8291
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

mem: Create a separate class for the cache write buffer

This patch breaks out the cache write buffer into a separate class,
without affecting any stats. The goal of the patch is to avoid
encumbering the much-simpler write queue with the complex MSHR
handling. In a follow on patch this simplification allows us to
implement write combining.

The WriteQueue gets its own class, but shares a common ancestor, the
generic Queue, with the MSHRQueue.

mem: add CacheVerbose debug flag, filter noisy DPRINTFs

Some of the DPRINTFs added to the classic cache in cset 45df88079f04,
while useful to those unfamiliar with the cache code, end up being
noise when you're familiar with the code but are trying to debug tricky
protocol issues. (Particularly getting two messages from each cache
as it receives a snoop request then declares that there was no match.)

This patch introduces a CacheVerbose debug flag, and moves a subset of
the added DPRINTFs into that category, so that Cache by itself returns
to being a more succinct summary of cache activity.

Also added a CacheAll compound flag to turn on all the cache-related
debug flags (other than CacheTags, which you *really* have to want badly
to turn it on, IMO).

mem: Add explicit Cache subclass and make BaseCache abstract

Open up for other subclasses to BaseCache and transition to using the
explicit Cache subclass.

arch: Resurrect the NOISA build target and rename it NULL

This patch makes it possible to once again build gem5 without any
ISA. The main purpose is to enable work around the interconnect and
memory system without having to build any CPU models or device models.

The regress script is updated to include the NULL ISA target. Currently
no regressions make use of it, but all the testers could (and perhaps
should) transition to it.

mem: Remove the cache builder

This patch removes the redundant cache builder class.

mem: Adding verbose debug output in the memory system

This patch provides useful printouts throughut the memory system. This
includes pretty-printed cache tags and function call messages
(call-stack like).

scons: rename TraceFlags to DebugFlags

SCons: Support building without an ISA

Rename cache files for brevity and consistency with rest of tree.

Add functional PrintReq command for memory-system debugging.

Traceflags: Add SCons function to created a traceflag instead of having one file with them all.

Move SimObject python files alongside the C++ and fix
the SConscript files so that only the objects that are
actually available in a given build are compiled in.
Remove a bunch of files that aren't used anymore.

Rework the way SCons recurses into subdirectories, making it
automatic. The point is that now a subdirectory can be added
to the build process just by creating a SConscript file in it.
The process has two passes. On the first pass, all subdirs
of the root of the tree are searched for SConsopts files.
These files contain any command line options that ought to be
added for a particular subdirectory. On the second pass,
all subdirs of the src directory are searched for SConscript
files. These files describe how to build any given subdirectory.
I have added a Source() function. Any file (relative to the
directory in which the SConscript resides) passed to that
function is added to the build. Clean up everything to take
advantage of Source().
function is added to the list of files to be built.