arch, base, cpu, gpu, sim: Merge getMemProxy and getVirtProxy.

These two functions were performing the same function but had two
different names for historical reasons. This change merges them
together, keeping the getVirtProxy name to be consistent with the
getPhysProxy method used to get a non-translating proxy port.

Change-Id: Idd83c6b899f9343795075b030ccbc723a79e52a4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18581
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

cpu, sim: Return PortProxy &s from all the proxy accessors.

This is a step towards merging the accessors for SE and FS modes.

Change-Id: I76818ab88b97097ac363e243be9cc1911b283090
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18579
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

cpu: Add a memory access predicate

This changeset introduces a new predicate to guard memory accesses.
The most immediate use for this is to allow proper handling of
predicated-false vector contiguous loads and predicated-false
micro-ops of vector gather loads (added in separate changesets).

Change-Id: Ice6894fe150faec2f2f7ab796a00c99ac843810a
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17991
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bradley Wang <radwang@ucdavis.edu>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

cpu: alpha: Delete all occurrances of the simPalCheck function.

This is now handled within the ISA description.

Change-Id: Ie409bb46d102e59d4eb41408d9196fe235626d32
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18434
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

cpu: Remove hwrei from the generic interfaces.

This mechanism is specific to Alpha and doesn't belong sprinkled around
the CPU's generic mechanisms.

Change-Id: I87904d1a08df2b03eb770205e2c4b94db25201a1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18432
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch: cpu: Track kernel stats using the base ISA agnostic type.

Then cast to the ISA specific type when necessary. This removes
(mostly) an ISA specific aspect to some of the interfaces. The ISA
specific version of the kernel stats still needs to be constructed and
stored in a few places which means that kernel_stats.hh still needs to
be a switching arch header, for instance.

In the future, I'd like to make the kernel its own object like the
Process objects in SE mode, and then it would be able to instantiate
and maintain its own stats.

Change-Id: I8309d49019124f6bea1482aaea5b5b34e8c97433
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18429
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

cpu,mem: missing override specifier

Change-Id: I731d3ef021596450ac307461f215760a148bb28a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18348
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

cpu: Eliminate the ProxyThreadContext class.

Replace it with direct inheritance from the ThreadContext class in the
SimpleThread class which was the only place it was used.

Also take the opportunity to use some specialized types instead of
ints, etc., add some consts, and fix some style issues.

Change-Id: I5d2cfa87b20dc43615e33e6755c9d016564e9c0e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18048
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

cpu: Add ISA* getter in Thread interface

This patch is adding a ISA* getter to the TC interface

Change-Id: Ib8ddc5d8fdd44e782f50a2ad15878a6bcf931e58
Reviewed-on: https://gem5-review.googlesource.com/c/16462
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>

cpu, arch: Replace the CCReg type with RegVal.

Most architectures weren't using the CCReg type, and in x86 and arm
it was already a uint64_t.

Change-Id: I0b3d5e690e6b31db6f2627f449c89bde0f6750a6
Reviewed-on: https://gem5-review.googlesource.com/c/14515
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch: cpu: Rename *FloatRegBits* to *FloatReg*.

Now that there's no plain FloatReg, there's no reason to distinguish
FloatRegBits with a special suffix since it's the only way to read or
write FP registers.

Change-Id: I3a60168c1d4302aed55223ea8e37b421f21efded
Reviewed-on: https://gem5-review.googlesource.com/c/14460
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch,cpu: Add vector predicate registers

Latest-gen. vector/SIMD extensions, including the Arm Scalable Vector
Extension (SVE), introduce the notion of a predicate register file.
This changeset adds this feature across architectures and CPU models.

Change-Id: Iebcadbad89c0a582ff8b1b70de353305db603946
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13715
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

arch: cpu: Stop passing around misc registers by reference.

These values are all basic integers (specifically uint64_t now), and
so passing them by const & is actually less efficient since there's a
extra level of indirection and an extra value, and the same sized value
(a 64 bit pointer vs. a 64 bit int) is being passed around.

Change-Id: Ie9956b8dc4c225068ab1afaba233ec2b42b76da3
Reviewed-on: https://gem5-review.googlesource.com/c/13626
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

cpu: dev: sim: gpu-compute: Banish some ISA specific register types.

These types are IntReg, FloatReg, FloatRegBits, and MiscReg. There are
some remaining types, specifically the vector registers and the CCReg.
I'm less familiar with these new types of registers, and so will look
at getting rid of them at some later time.

Change-Id: Ide8f76b15c531286f61427330053b44074b8ac9b
Reviewed-on: https://gem5-review.googlesource.com/c/13624
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

cpu: Stop using unions to store FP registers.

These are now accessed only as integer values.

Change-Id: I21ae6537ebbcbaa02890384194ee1ce001c092bb
Reviewed-on: https://gem5-review.googlesource.com/c/14458
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch, cpu: Remove float type accessors.

Use the binary accessors instead.

Change-Id: Iff1877e92c79df02b3d13635391a8c2f025776a2
Reviewed-on: https://gem5-review.googlesource.com/c/14457
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch,cpu: "virtualize" the TLB interface.

CPUs have historically instantiated the architecture specific version
of the TLBs to avoid a virtual function call, making them a little bit
more dependent on what the current ISA is. Some simple performance
measurement, the x86 twolf regression on the atomic CPU, shows that
there isn't actually any performance benefit, and if anything the
simulator goes slightly faster (although still within margin of error)
when the TLB functions are virtual.

This change switches everything outside of the architectures themselves
to use the generic BaseTLB type, and then inside the ISA for them to
cast that to their architecture specific type to call into architecture
specific interfaces.

The ARM TLB needed the most adjustment since it was using non-standard
translation function signatures. Specifically, they all took an extra
"type" parameter which defaulted to normal, and translateTiming
returned a Fault. translateTiming actually doesn't need to return a
Fault because everywhere that consumed it just stored it into a
structure which it then deleted(?), and the fault is stored in the
Translation object when the translation is done.

A little more work is needed to fully obviate the arch/tlb.hh header,
so the TheISA::TLB type is still visible outside of the ISAs.
Specifically, the TlbEntry type is used in the generic PageTable which
lives in src/mem.

Change-Id: I51b68ee74411f9af778317eff222f9349d2ed575
Reviewed-on: https://gem5-review.googlesource.com/6921
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

cpu: Added interface for vector reg file

This patch adds some more functionality to the cpu model and the arch to
interface with the vector register file.

This change consists mainly of augmenting ThreadContexts and ExecContexts
with calls to get/set full vectors, underlying microarchitectural elements
or lanes. Those are meant to interface with the vector register file. All
classes that implement this interface also get an appropriate implementation.

This requires implementing the vector register file for the different
models using the VecRegContainer class.

This change set also updates the Result abstraction to contemplate the
possibility of having a vector as result.

The changes also affect how the remote_gdb connection works.

There are some (nasty) side effects, such as the need to define dummy
numPhysVecRegs parameter values for architectures that do not implement
vector extensions.

Nathanael Premillieu's work with an increasing number of fixes and
improvements of mine.

Change-Id: Iee65f4e8b03abfe1e94e6940a51b68d0977fd5bb
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[ Fix RISCV build issues and CC reg free list initialisation ]
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2705

cpu: Simplify the rename interface and use RegId

With the hierarchical RegId there are a lot of functions that are
redundant now.

The idea behind the simplification is that instead of having the regId,
telling which kind of register read/write/rename/lookup/etc. and then
the function panic_if'ing if the regId is not of the appropriate type,
we provide an interface that decides what kind of register to read
depending on the register type of the given regId.

Change-Id: I7d52e9e21fc01205ae365d86921a4ceb67a57178
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[ Fix RISCV build issues ]
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2702

syscall_emul: [PATCH 15/22] add clone/execve for threading and multiprocess simulations

Modifies the clone system call and adds execve system call. Requires allowing
processes to steal thread contexts from other processes in the same system
object and the ability to detach pieces of process state (such as MemState)
to allow dynamic sharing.

syscall_emul: [patch 13/22] add system call retry capability

This changeset adds functionality that allows system calls to retry without
affecting thread context state such as the program counter or register values
for the associated thread context (when system calls return with a retry
fault).

This functionality is needed to solve problems with blocking system calls
in multi-process or multi-threaded simulations where information is passed
between processes/threads. Blocking system calls can cause deadlock because
the simulator itself is single threaded. There is only a single thread
servicing the event queue which can cause deadlock if the thread hits a
blocking system call instruction.

To illustrate the problem, consider two processes using the producer/consumer
sharing model. The processes can use file descriptors and the read and write
calls to pass information to one another. If the consumer calls the blocking
read system call before the producer has produced anything, the call will
block the event queue (while executing the system call instruction) and
deadlock the simulation.

The solution implemented in this changeset is to recognize that the system
calls will block and then generate a special retry fault. The fault will
be sent back up through the function call chain until it is exposed to the
cpu model's pipeline where the fault becomes visible. The fault will trigger
the cpu model to replay the instruction at a future tick where the call has
a chance to succeed without actually going into a blocking state.

In subsequent patches, we recognize that a syscall will block by calling a
non-blocking poll (from inside the system call implementation) and checking
for events. When events show up during the poll, it signifies that the call
would not have blocked and the syscall is allowed to proceed (calling an
underlying host system call if necessary). If no events are returned from the
poll, we generate the fault and try the instruction for the thread context
at a distant tick. Note that retrying every tick is not efficient.

As an aside, the simulator has some multi-threading support for the event
queue, but it is not used by default and needs work. Even if the event queue
was completely multi-threaded, meaning that there is a hardware thread on
the host servicing a single simulator thread contexts with a 1:1 mapping
between them, it's still possible to run into deadlock due to the event queue
barriers on quantum boundaries. The solution of replaying at a later tick
is the simplest solution and solves the problem generally.

misc: Remove redundant compiler-specific defines

This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap
(and similar) abstractions, as these are no longer needed with gcc 4.7
and clang 3.1 as minimum compiler versions.

revert 5af8f40d8f2c

cpu: implements vector registers

This adds a vector register type. The type is defined as a std::array of a
fixed number of uint64_ts. The isa_parser.py has been modified to parse vector
register operands and generate the required code. Different cpus have vector
register files now.

sim: Refactor the serialization base class

Objects that are can be serialized are supposed to inherit from the
Serializable class. This class is meant to provide a unified API for
such objects. However, so far it has mainly been used by SimObjects
due to some fundamental design limitations. This changeset redesigns
to the serialization interface to make it more generic and hide the
underlying checkpoint storage. Specifically:

* Add a set of APIs to serialize into a subsection of the current
object. Previously, objects that needed this functionality would
use ad-hoc solutions using nameOut() and section name
generation. In the new world, an object that implements the
interface has the methods serializeSection() and
unserializeSection() that serialize into a named /subsection/ of
the current object. Calling serialize() serializes an object into
the current section.

* Move the name() method from Serializable to SimObject as it is no
longer needed for serialization. The fully qualified section name
is generated by the main serialization code on the fly as objects
serialize sub-objects.

* Add a scoped ScopedCheckpointSection helper class. Some objects
need to serialize data structures, that are not deriving from
Serializable, into subsections. Previously, this was done using
nameOut() and manual section name generation. To simplify this,
this changeset introduces a ScopedCheckpointSection() helper
class. When this class is instantiated, it adds a new /subsection/
and subsequent serialization calls during the lifetime of this
helper class happen inside this section (or a subsection in case
of nested sections).

* The serialize() call is now const which prevents accidental state
manipulation during serialization. Objects that rely on modifying
state can use the serializeOld() call instead. The default
implementation simply calls serialize(). Note: The old-style calls
need to be explicitly called using the
serializeOld()/serializeSectionOld() style APIs. These are used by
default when serializing SimObjects.

* Both the input and output checkpoints now use their own named
types. This hides underlying checkpoint implementation from
objects that need checkpointing and makes it easier to change the
underlying checkpoint storage code.

arch: Make readMiscRegNoEffect const throughout

Finally took the plunge and made this apply to all ISAs, not just ARM.

cpu: Remove all notion that we know when the cpu is misspeculating.

We have no way of knowing if a CPU model is on the wrong path with
our execute-in-execute CPU models. Don't pretend that we do.

alpha,arm,mips,power,x86,cpu,sim: Cleanup activate/deactivate

activate(), suspend(), and halt() used on thread contexts had an optional
delay parameter. However this parameter was often ignored. Also, when used,
the delay was seemily arbitrarily set to 0 or 1 cycle (no other delays were
ever specified). This patch removes the delay parameter and 'Events'
associated with them across all ISAs and cores. Unused activate logic
is also removed.

arm: use condition code registers for ARM ISA

Analogous to ee049bf (for x86). Requires a bump of the checkpoint version
and corresponding upgrader code to move the condition code register values
to the new register file.

arch, cpu: Add support for flattening misc register indexes.

With ARMv8 support the same misc register id results in accessing different
registers depending on the current mode of the processor. This patch adds
the same orthogonality to the misc register file as the others (int, float, cc).
For all the othre ISAs this is currently a null-implementation.

Additionally, a system variable is added to all the ISA objects.

cpu: add a condition-code register class

Add a third register class for condition codes,
in parallel with the integer and FP classes.
No ISAs use the CC class at this point though.

x86: Changes to decoder, corrects 9376
The changes made by the changeset 9376 were not quite correct. The patch made
changes to the code which resulted in decoder not getting initialized correctly
when the state was restored from a checkpoint.

This patch adds a startup function to each ISA object. For x86, this function
sets the required state in the decoder. For other ISAs, the function is empty
right now.

cpu: Fix broken thread context handover

The thread context handover code used to break when multiple handovers
were performed during the same quiesce period. Previously, the thread
contexts would assign the TC pointer in the old quiesce event to the
new TC. This obviously broke in cases where multiple switches were
performed within the same quiesce period, in which case the TC pointer
in the quiesce event would point to an old CPU.

The new implementation deschedules pending quiesce events in the old
TC and schedules a new quiesce event in the new TC. The code has been
refactored to remove most of the code duplication.

cpu: Unify SimpleCPU and O3 CPU serialization code

The O3 CPU used to copy its thread context to a SimpleThread in order
to do serialization. This was a bit of a hack involving two static
SimpleThread instances and a magic constructor that was only used by
the O3 CPU.

This patch moves the ThreadContext serialization code into two global
procedures that, in addition to the normal serialization parameters,
take a ThreadContext reference as a parameter. This allows us to reuse
the serialization code in all ThreadContext implementations.

cpu: Implement a flat register interface in thread contexts

Some architectures map registers differently depending on their mode
of operations. There is currently no architecture independent way of
accessing all registers. This patch introduces a flat register
interface to the ThreadContext class. This interface is useful, for
example, when serializing or copying thread contexts.

arch: Make the ISA class inherit from SimObject

The ISA class on stores the contents of ID registers on many
architectures. In order to make reset values of such registers
configurable, we make the class inherit from SimObject, which allows
us to use the normal generated parameter headers.

This patch introduces a Python helper method, BaseCPU.createThreads(),
which creates a set of ISAs for each of the threads in an SMT
system. Although it is currently only needed when creating
multi-threaded CPUs, it should always be called before instantiating
the system as this is an obvious place to configure ID registers
identifying a thread/CPU.

Clock: Add a Cycles wrapper class and use where applicable

This patch addresses the comments and feedback on the preceding patch
that reworks the clocks and now more clearly shows where cycles
(relative cycle counts) are used to express time.

Instead of bumping the existing patch I chose to make this a separate
patch, merely to try and focus the discussion around a smaller set of
changes. The two patches will be pushed together though.

This changes done as part of this patch are mostly following directly
from the introduction of the wrapper class, and change enough code to
make things compile and run again. There are definitely more places
where int/uint/Tick is still used to represent cycles, and it will
take some time to chase them all down. Similarly, a lot of parameters
should be changed from Param.Tick and Param.Unsigned to
Param.Cycles.

In addition, the use of curTick is questionable as there should not be
an absolute cycle. Potential solutions can be built on top of this
patch. There is a similar situation in the o3 CPU where
lastRunningCycle is currently counting in Cycles, and is still an
absolute time. More discussion to be had in other words.

An additional change that would be appropriate in the future is to
perform a similar wrapping of Tick and probably also introduce a
Ticks class along with suitable operators for all these classes.

Decode: Make the Decoder class defined per ISA.

gcc: Clean-up of non-C++0x compliant code, first steps

This patch cleans up a number of minor issues aiming to get closer to
compliance with the C++0x standard as interpreted by gcc and clang
(compile with std=c++0x and -pedantic-errors). In particular, the
patch cleans up enums where the last item was succeded by a comma,
namespaces closed by a curcly brace followed by a semi-colon, and the
use of the GNU-extension typeof (replaced by templated functions). It
does not address variable-length arrays, zero-size arrays, anonymous
structs, range expressions in switch statements, and the use of long
long. The generated CPU code also has a large number of issues that
remain to be fixed, mainly related to overflows in implicit constant
conversion (due to shifts).

CheckerCPU: Make CheckerCPU runtime selectable instead of compile selectable

Enables the CheckerCPU to be selected at runtime with the --checker option
from the configs/example/fs.py and configs/example/se.py configuration
files. Also merges with the SE/FS changes.

MEM: Make port proxies use references rather than pointers

This patch is adding a clearer design intent to all objects that would
not be complete without a port proxy by making the proxies members
rathen than dynamically allocated. In essence, if NULL would not be a
valid value for the proxy, then we avoid using a pointer to make this
clear.

The same approach is used for the methods using these proxies, such as
loadSections, that now use references rather than pointers to better
reflect the fact that NULL would not be an acceptable value (in fact
the code would break and that is how this patch started out).

Overall the concept of "using a reference to express unconditional
composition where a NULL pointer is never valid" could be done on a
much broader scale throughout the code base, but for now it is only
done in the locations affected by the proxies.

SE/FS: Record the system pointer all the time for the simple CPU.

This pointer was only being stored in code that came from SE mode. The system
pointer is always meaningful and available, so it should always be stored.

Merge with head, hopefully the last time for this batch.

Merge with main repository.

Merge with the main repo.

SE/FS: Get rid of includes of config/full_system.hh.

SE/FS: Get rid of FULL_SYSTEM in the CPU directory.

SE/FS: Make the functions available from the TC consistent between SE and FS.

SE/FS: Build/expose vport in SE mode.

CPU: Make physPort and getPhysPort available in SE mode.

Thread: Use inherited baseCpu rather than cpu in SimpleThread

This patch is a trivial simplification, removing the cpu pointer from
SimpleThread and relying on the baseCpu pointer in ThreadState. The
patch does not add or change any functionality, it merely cleans up
the code.

CheckerCPU: Re-factor CheckerCPU to be compatible with current gem5

Brings the CheckerCPU back to life to allow FS and SE checking of the
O3CPU. These changes have only been tested with the ARM ISA. Other
ISAs potentially require modification.

MEM: Clean-up of Functional/Virtual/TranslatingPort remnants

This patch cleans up forward declarations and a member-function
prototype that still referred to the old FunctionalPort, VirtualPort
and TranslatingPort. There is no change in functionality.

MEM: Add port proxies instead of non-structural ports

Port proxies are used to replace non-structural ports, and thus enable
all ports in the system to correspond to a structural entity. This has
the advantage of accessing memory through the normal memory subsystem
and thus allowing any constellation of distributed memories, address
maps, etc. Most accesses are done through the "system port" that is
used for loading binaries, debugging etc. For the entities that belong
to the CPU, e.g. threads and thread contexts, they wrap the CPU data
port in a port proxy.

The following replacements are made:
FunctionalPort > PortProxy
TranslatingPort > SETranslatingPortProxy
VirtualPort > FSTranslatingPortProxy

Decode: Pull instruction decoding out of the StaticInst class into its own.

This change pulls the instruction decoding machinery (including caches) out of
the StaticInst class and puts it into its own class. This has a few intrinsic
benefits. First, the StaticInst code, which has gotten to be quite large, gets
simpler. Second, the code that handles decode caching is now separated out
into its own component and can be looked at in isolation, making it easier to
understand. I took the opportunity to restructure the code a bit which will
hopefully also help.

Beyond that, this change also lays some ground work for each ISA to have its
own, potentially stateful decode object. We'd be able to include less
contextualizing information in the ExtMachInst objects since that context
would be applied at the decoder. Also, the decoder could "know" ahead of time
that all the instructions it's going to see are going to be, for instance, 64
bit mode, and it will have one less thing to check when it decodes them.
Because the decode caching mechanism has been separated out, it's now possible
to have multiple caches which correspond to different types of decoding
context. Having one cache for each element of the cross product of different
configurations may become prohibitive, so it may be desirable to clear out the
cache when relatively static state changes and not to have one for each
setting.

Because the decode function is no longer universally accessible as a static
member of the StaticInst class, a new function was added to the ThreadContexts
that returns the applicable decode object.

simple-thread: give a name() function for debugging w/the SimpleThread object

trace: reimplement the DTRACE function so it doesn't use a vector
At the same time, rename the trace flags to debug flags since they
have broader usage than simply tracing. This means that
--trace-flags is now --debug-flags and --trace-help is now --debug-help

includes: sort all includes

ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors.



This change is a low level and pervasive reorganization of how PCs are managed
in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about,
the PC and the NPC, and the lsb of the PC signaled whether or not you were in
PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next
micropc, x86 and ARM introduced variable length instruction sets, and ARM
started to keep track of mode bits in the PC. Each CPU model handled PCs in
its own custom way that needed to be updated individually to handle the new
dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack,
the complexity could be hidden in the ISA at the ISA implementation's expense.
Areas like the branch predictor hadn't been updated to handle branch delay
slots or micropcs, and it turns out that had introduced a significant (10s of
percent) performance bug in SPARC and to a lesser extend MIPS. Rather than
perpetuate the problem by reworking O3 again to handle the PC features needed
by x86, this change was introduced to rework PC handling in a more modular,
transparent, and hopefully efficient way.


PC type:

Rather than having the superset of all possible elements of PC state declared
in each of the CPU models, each ISA defines its own PCState type which has
exactly the elements it needs. A cross product of canned PCState classes are
defined in the new "generic" ISA directory for ISAs with/without delay slots
and microcode. These are either typedef-ed or subclassed by each ISA. To read
or write this structure through a *Context, you use the new pcState() accessor
which reads or writes depending on whether it has an argument. If you just
want the address of the current or next instruction or the current micro PC,
you can get those through read-only accessors on either the PCState type or
the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the
move away from readPC. That name is ambiguous since it's not clear whether or
not it should be the actual address to fetch from, or if it should have extra
bits in it like the PAL mode bit. Each class is free to define its own
functions to get at whatever values it needs however it needs to to be used in
ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the
PC and into a separate field like ARM.

These types can be reset to a particular pc (where npc = pc +
sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as
appropriate), printed, serialized, and compared. There is a branching()
function which encapsulates code in the CPU models that checked if an
instruction branched or not. Exactly what that means in the context of branch
delay slots which can skip an instruction when not taken is ambiguous, and
ideally this function and its uses can be eliminated. PCStates also generally
know how to advance themselves in various ways depending on if they point at
an instruction, a microop, or the last microop of a macroop. More on that
later.

Ideally, accessing all the PCs at once when setting them will improve
performance of M5 even though more data needs to be moved around. This is
because often all the PCs need to be manipulated together, and by getting them
all at once you avoid multiple function calls. Also, the PCs of a particular
thread will have spatial locality in the cache. Previously they were grouped
by element in arrays which spread out accesses.


Advancing the PC:

The PCs were previously managed entirely by the CPU which had to know about PC
semantics, try to figure out which dimension to increment the PC in, what to
set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction
with the PC type itself. Because most of the information about how to
increment the PC (mainly what type of instruction it refers to) is contained
in the instruction object, a new advancePC virtual function was added to the
StaticInst class. Subclasses provide an implementation that moves around the
right element of the PC with a minimal amount of decision making. In ISAs like
Alpha, the instructions always simply assign NPC to PC without having to worry
about micropcs, nnpcs, etc. The added cost of a virtual function call should
be outweighed by not having to figure out as much about what to do with the
PCs and mucking around with the extra elements.

One drawback of making the StaticInsts advance the PC is that you have to
actually have one to advance the PC. This would, superficially, seem to
require decoding an instruction before fetch could advance. This is, as far as
I can tell, realistic. fetch would advance through memory addresses, not PCs,
perhaps predicting new memory addresses using existing ones. More
sophisticated decisions about control flow would be made later on, after the
instruction was decoded, and handed back to fetch. If branching needs to
happen, some amount of decoding needs to happen to see that it's a branch,
what the target is, etc. This could get a little more complicated if that gets
done by the predecoder, but I'm choosing to ignore that for now.


Variable length instructions:

To handle variable length instructions in x86 and ARM, the predecoder now
takes in the current PC by reference to the getExtMachInst function. It can
modify the PC however it needs to (by setting NPC to be the PC + instruction
length, for instance). This could be improved since the CPU doesn't know if
the PC was modified and always has to write it back.


ISA parser:

To support the new API, all PC related operand types were removed from the
parser and replaced with a PCState type. There are two warts on this
implementation. First, as with all the other operand types, the PCState still
has to have a valid operand type even though it doesn't use it. Second, using
syntax like PCS.npc(target) doesn't work for two reasons, this looks like the
syntax for operand type overriding, and the parser can't figure out if you're
reading or writing. Instructions that use the PCS operand (which I've
consistently called it) need to first read it into a local variable,
manipulate it, and then write it back out.


Return address stack:

The return address stack needed a little extra help because, in the presence
of branch delay slots, it has to merge together elements of the return PC and
the call PC. To handle that, a buildRetPC utility function was added. There
are basically only two versions in all the ISAs, but it didn't seem short
enough to put into the generic ISA directory. Also, the branch predictor code
in O3 and InOrder were adjusted so that they always store the PC of the actual
call instruction in the RAS, not the next PC. If the call instruction is a
microop, the next PC refers to the next microop in the same macroop which is
probably not desirable. The buildRetPC function advances the PC intelligently
to the next macroop (in an ISA specific way) so that that case works.


Change in stats:

There were no change in stats except in MIPS and SPARC in the O3 model. MIPS
runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could
likely be improved further by setting call/return instruction flags and taking
advantage of the RAS.


TODO:

Add != operators to the PCState classes, defined trivially to be !(a==b).
Smooth out places where PCs are split apart, passed around, and put back
together later. I think this might happen in SPARC's fault code. Add ISA
specific constructors that allow setting PC elements without calling a bunch
of accessors. Try to eliminate the need for the branching() function. Factor
out Alpha's PAL mode pc bit into a separate flag field, and eliminate places
where it's blindly masked out or tested in the PC.

Faults: Pass the StaticInst involved, if any, to a Fault's invoke method.

Also move the "Fault" reference counted pointer type into a separate file,
sim/fault.hh. It would be better to name this less similarly to sim/faults.hh
to reduce confusion, but fault.hh matches the name of the type. We could change
Fault to FaultPtr to match other pointer types, and then changing the name of
the file would make more sense.

CPU: Print out flatten-out register index as with IntRegs/FloatRegs traceflag

ARM/O3: store the result of the predicate evaluation in DynInst or Threadstate.
THis allows the CPU to handle predicated-false instructions accordingly.
This particular patch makes loads that are predicated-false to be sent
straight to the commit stage directly, not waiting for return of the data
that was never requested since it was predicated-false.

ARM: Implement ARM CPU interrupts

Simple CPU: Make the FloatRegs trace flag do something.

arch: nuke arch/isa_specific.hh and move stuff to generated config/the_isa.hh

Simple CPU: Make the simple CPU handle the IntRegs trace flag.

Get rid of the unused get(Data|Inst)Asid and (inst|data)Asid functions.

Registers: Add a registers.hh file as an ISA switched header.
This file is for register indices, Num* constants, and register types.
copyRegs and copyMiscRegs were moved to utility.hh and utility.cc.

Registers: Eliminate the ISA defined RegFile class.

Registers: Move the PCs out of the ISAs and into the CPUs.

ARM, Simple CPU: Fix an index and add assert checks.

Registers: Eliminate the ISA defined integer register file.

Registers: Eliminate the ISA defined floating point register file.

Registers: Get rid of the float register width parameter.

Registers: Add an ISA object which replaces the MiscRegFile.
This object encapsulates (or will eventually) the identity and characteristics
of the ISA in the CPU.

types: add a type for thread IDs and try to use it everywhere

includes: sort includes again

types: Move stuff for global types into src/base/types.hh

Get rid of the Unallocated thread context state.
Basically merge it in with Halted.
Also had to get rid of a few other functions that
called ThreadContext::deallocate(), including:
- InOrderCPU's setThreadRescheduleCondition.
- ThreadContext::exit(). This function was there to avoid terminating
simulation when one thread out of a multi-thread workload exits, but we
need to find a better (non-cpu-centric) way.

tlb: Don't separate the TLB classes into an instruction TLB and a data TLB

Processes: Make getting and setting system call arguments part of a process object.

ISA: Replace the translate functions in the TLBs with translateAtomic.

CPU: Get rid of translate... functions from various interface classes.

thread_context: move getSystemPtr so SE mode can get to it.
There was really no reason that it should be FS only.

SPARC: Truncate syscall args and return values appropriately.

get rid of all instances of readTid() and getThreadNum(). Unify and eliminate
redundancies with threadId() as their replacement.

O3CPU: Undo Gabe's changes to remove hwrei and simpalcheck from O3 CPU. Removing hwrei causes
the instruction after the hwrei to be fetched before the ITB/DTB_CM register is updated in a call pal
call sys and thus the translation fails because the user is attempting to access a super page address.

Minimally, it seems as though some sort of fetch stall or refetch after a hwrei is required. I think
this works currently because the hwrei uses the exec context interface, and the o3 stalls when that occurs.

Additionally, these changes don't update the LOCK register and probably break ll/sc. Both o3 changes were
removed since a great deal of manual patching would be required to only remove the hwrei change.

Get rid of old RegContext code.

CPU: Eliminate the simPalCheck funciton.

CPU: Eliminate the hwrei function.

style: Remove non-leading tabs everywhere they shouldn't be. Developers should configure their editors to not insert tabs

Remove delVirtPort() and make getVirtPort() only return cached version.

TLB: Make a TLB base class and put a virtual demapPage function in it.

Get MIPS simple regression working. Take out unecessary functions "setShadowSet", "CacheOp"

Add in files from merge-bare-iron, get them compiling in FS and SE mode

SPARC: Fix a stupid mistake which was breaking the SPARC regressions.

X86: Put in the foundation for x87 stack based fp registers.

Address Translation: Make SE mode use an actual TLB/MMU for translation like FS.

X86: Fix argument register indexing.
Code was assuming that all argument registers followed in order from ArgumentReg0. There is now an ArgumentReg array which is indexed to find the right index. There is a constant, NumArgumentRegs, which can be used to protect against using an invalid ArgumentReg.

mips import pt. 1

src/arch/mips/SConscript:
"mips import pt.1".

Remove unnecessary include of physical.hh.

*MiscReg->*MiscRegNoEffect, *MiscRegWithEffect->*MiscReg

Merge zizzer:/bk/newmem/
into zower.eecs.umich.edu:/eecshome/m5/newmem

Flattening and syscallReturn fixes

src/cpu/o3/thread_context_impl.hh:
Use flattened indices
src/cpu/simple_thread.hh:
Use flattened indices, and pass a thread context to setSyscallReturn rather than a register file.
src/cpu/thread_context.hh:
The SyscallReturn class is no longer in arch/syscallreturn.hh

Get rid of unused lock code.

Update Virtual and Physical ports.

src/cpu/o3/alpha/cpu_impl.hh:
Handle the PhysicalPort and VirtualPort in the ThreadState.
src/cpu/o3/cpu.cc:
Initialize the thread context.
src/cpu/o3/thread_context.hh:
Add new function to initialize thread context.
src/cpu/o3/thread_context_impl.hh:
Use code now put into function.
src/cpu/simple_thread.cc:
Move code to ThreadState and use the new helper function.
src/cpu/simple_thread.hh:
Remove init() in this derived class; use init() from ThreadState base class.
src/cpu/thread_state.cc:
Move setting up of Physical and Virtual ports here. Change getMemFuncPort() to connectToMemFunc(), which connects a port to a functional port of the memory object below the CPU.
src/cpu/thread_state.hh:
Update functions.

Make an initialization pass for the thread context and set the [phys,virt]Port correctly

src/cpu/simple/atomic.cc:
src/cpu/simple/timing.cc:
Call the thread context initialization

Moved the switched version of kernel_stats.hh back to kern, and moved the base kernel_stats to base_kernel_stats

Got rid of "inPalMode". Some places are still effectively checking if they are in PAL mode, however.

Merge ktlim@zizzer:/bk/newmem
into zamp.eecs.umich.edu:/z/ktlim2/clean/newmem-busfix

Remove function that should have been deleted.

src/cpu/simple_thread.cc:
This function should have been deleted from an earlier push.
src/cpu/simple_thread.hh:
Delete this function; it's now in thread_state.hh/.cc.

Merge zizzer.eecs.umich.edu:/bk/newmem/
into zeep.eecs.umich.edu:/home/gblack/m5/newmemmemops

Adjustments for the AlphaTLB changing to AlphaISA::TLB and changing register file functions to not take faults

Move IntrFlag into the MiscRegFile and get rid of specialized accessor functions.

Put the Alpha tlb stuff into the AlphaISA namespace, and give the classes more neutral names.

Remove mem parameter. Now the translating port asks the CPU's dcache's peer for its MemObject instead of having to have a paramter for the MemObject.

configs/example/fs.py:
configs/example/se.py:
src/cpu/simple/base.cc:
src/cpu/simple/base.hh:
src/cpu/simple/timing.cc:
src/cpu/simple_thread.cc:
src/cpu/simple_thread.hh:
src/cpu/thread_state.cc:
src/cpu/thread_state.hh:
tests/configs/o3-timing-mp.py:
tests/configs/o3-timing.py:
tests/configs/simple-atomic-mp.py:
tests/configs/simple-atomic.py:
tests/configs/simple-timing-mp.py:
tests/configs/simple-timing.py:
tests/configs/tsunami-simple-atomic-dual.py:
tests/configs/tsunami-simple-atomic.py:
tests/configs/tsunami-simple-timing-dual.py:
tests/configs/tsunami-simple-timing.py:
No need for mem parameter any more.
src/cpu/checker/cpu.cc:
Use new constructor for simple thread (no more MemObject parameter).
src/cpu/checker/cpu.hh:
Remove MemObject parameter.
src/cpu/memtest/memtest.hh:
Ports now take in their MemObject owner.
src/cpu/o3/alpha/cpu_builder.cc:
Remove mem parameter.
src/cpu/o3/alpha/cpu_impl.hh:
Remove memory parameter and clean up handling of TranslatingPort.
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
src/cpu/o3/fetch.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/mips/cpu_builder.cc:
src/cpu/o3/mips/cpu_impl.hh:
src/cpu/o3/params.hh:
src/cpu/o3/thread_state.hh:
src/cpu/ozone/cpu.hh:
src/cpu/ozone/cpu_builder.cc:
src/cpu/ozone/cpu_impl.hh:
src/cpu/ozone/front_end.hh:
src/cpu/ozone/front_end_impl.hh:
src/cpu/ozone/lw_lsq.hh:
src/cpu/ozone/lw_lsq_impl.hh:
src/cpu/ozone/simple_params.hh:
src/cpu/ozone/thread_state.hh:
src/cpu/simple/atomic.cc:
Remove memory parameter.

Started implementing microcode.

Replace tests of LOCKED/UNCACHEABLE flags with isLocked()/isUncacheable().

Pushed most of constants.hh back into isa_traits.hh and regfile.hh and created a seperate file for the syscallreturn class.

Support serializing and unserializing in the O3 CPU. Also a few small fixes for draining/switching CPUs.

src/cpu/o3/commit_impl.hh:
Fix to clear drainPending variable on call to resume.
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
Support serializing and unserializing in the O3 CPU.
src/cpu/o3/lsq_impl.hh:
Be sure to say we have no stores to write back if the active thread list is empty.
src/cpu/simple_thread.cc:
src/cpu/simple_thread.hh:
Slightly change how SimpleThread is used to copy from other ThreadContexts.

Various serialization changes to make it possible for the O3CPU to checkpoint.

src/arch/alpha/regfile.hh:
Define serialize/unserialize functions on MiscRegFile itself.
src/cpu/o3/regfile.hh:
Remove old commented code.
src/cpu/simple_thread.cc:
src/cpu/simple_thread.hh:
Push common serialization code to ThreadState level. Also allow the SimpleThread to be used for checkpointing by other models.
src/cpu/thread_state.cc:
src/cpu/thread_state.hh:
Move common serialization code into ThreadState.

Reorganization/renaming of CPUExecContext. Now it is called SimpleThread in order to clear up the confusion due to the many ExecContexts. It also derives from a common ThreadState object, which holds various state common to threads across CPU models.

Following with the previous check-in, ExecContext now refers only to the interface provided to the ISA in order to access CPU state. ThreadContext refers to the interface provided to all objects outside the CPU in order to access thread state. SimpleThread provides all thread state and the interface to access it, and is suitable for simple execution models such as the SimpleCPU.

src/SConscript:
Include thread state file.
src/arch/alpha/ev5.cc:
src/cpu/checker/cpu.cc:
src/cpu/checker/cpu.hh:
src/cpu/checker/thread_context.hh:
src/cpu/memtest/memtest.cc:
src/cpu/memtest/memtest.hh:
src/cpu/o3/cpu.cc:
src/cpu/ozone/cpu_impl.hh:
src/cpu/simple/atomic.cc:
src/cpu/simple/base.cc:
src/cpu/simple/base.hh:
src/cpu/simple/timing.cc:
Rename CPUExecContext to SimpleThread.
src/cpu/base_dyn_inst.hh:
Make thread member variables protected..
src/cpu/o3/alpha_cpu.hh:
src/cpu/o3/cpu.hh:
Make various members of ThreadState protected.
src/cpu/o3/alpha_cpu_impl.hh:
Push generation of TranslatingPort into the CPU itself.
Make various members of ThreadState protected.
src/cpu/o3/thread_state.hh:
Pull a lot of common code into the base ThreadState class.
src/cpu/ozone/thread_state.hh:
Rename CPUExecContext to SimpleThread, move a lot of common code into base ThreadState class.
src/cpu/thread_state.hh:
Push a lot of common code into base ThreadState class. This goes along with renaming CPUExecContext to SimpleThread, and making it derive from ThreadState.
src/cpu/simple_thread.cc:
Rename CPUExecContext to SimpleThread, make it derive from ThreadState. This helps push a lot of common code/state into a single class that can be used by all CPUs.
src/cpu/simple_thread.hh:
Rename CPUExecContext to SimpleThread, make it derive from ThreadState.
src/kern/system_events.cc:
Rename cpu_exec_context to thread_context.
src/sim/process.hh:
Remove unused forward declaration.