misc: Removed inconsistency in O3* debug msgs

Added consistency in the DEBUG message form, to allow a better parsing.
Fixed sn/tid type parameter.
Removed some annoying newlines

Change-Id: I4761c49fc12b874a7d8b46779475b606865cad4b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17248
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

cpu: support atomic memory request type with AtomicOpFunctor

This patch enables all 4 CPU models (AtomicSimpleCPU, TimingSimpleCPU,
MinorCPU and DerivO3CPU) to issue atomic memory (AMO) requests to memory
system.

Atomic memory instruction is treated as a special store instruction in
all CPU models.

In simple CPUs, an AMO request with an associated AtomicOpFunctor is
simply sent to L1 dcache.

In MinorCPU, an AMO request bypasses store buffer and waits for any
conflicting store request(s) currently in the store buffer to retire
before the AMO request is sent to the cache. AMO requests are not buffered
in the store buffer, so their effects appear immediately in the cache.

In DerivO3CPU, an AMO request is inserted in the store buffer so that it
is delivered to the cache only after all previous stores are issued to
the cache. Data forwarding between between an outstanding AMO in the
store buffer and a subsequent load is not allowed since the AMO request
does not hold valid data until it's executed in the cache.

This implementation assumes that a target ISA implementation must insert
enough memory fences as micro-ops around an atomic instruction to
enforce a correct order of memory instructions with respect to its
memory consistency model. Without extra memory fences, this implementation
can allow AMOs and other memory instructions that do not conflict
(i.e., not target the same address) to reorder.

This implementation also assumes that atomic instructions execute within
a cache line boundary since the cache for now is not able to execute an
operation on two different cache lines in one single step. Therefore,
ISAs like x86 that require multi-cache-line atomic instructions need to
either use a pair of locking load and unlocking store or change the
cache implementation to guarantee the atomicity of an atomic
instruction.

Change-Id: Ib8a7c81868ac05b98d73afc7d16eb88486f8cf9a
Reviewed-on: https://gem5-review.googlesource.com/c/8188
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

cpu: Fix the usage of const DynInstPtr

Summary: Usage of const DynInstPtr& when possible and introduction of
move operators to RefCountingPtr.

In many places, scoped references to dynamic instructions do a copy of
the DynInstPtr when a reference would do. This is detrimental to
performance. On top of that, in case there is a need for reference
tracking for debugging, the redundant copies make the process much more
painful than it already is.

Also, from the theoretical point of view, a function/method that
defines a convenience name to access an instruction should not be
considered an owner of the data, i.e., doing a copy and not a reference
is not justified.

On a related topic, C++11 introduces move semantics, and those are
useful when, for example, there is a class modelling a HW structure that
contains a list, and has a getHeadOfList function, to prevent doing a
copy to an internal variable -> update pointer, remove from the list ->
update pointer, return value making a copy to the assined variable ->
update pointer, destroy the returned value -> update pointer.

Change-Id: I3bb46c20ef23b6873b469fd22befb251ac44d2f6
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13105
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

cpu: Add drain check functionality to IEW

IEW did not check the instQueue and memDepUnit to ensure
they were drained. This caused issues when drainSanityCheck()
did check those structures after asserting IEW was drained.

o3: Use shared_ptr for MemDepEntry

This patch transitions the o3 MemDepEntry from the ad-hoc
RefCountingPtr to the c++11 shared_ptr. There are no changes in
behaviour, and the code modifications are mainly replacing "new" with
"make_shared".

cpu: Fix cache blocked load behavior in o3 cpu

This patch fixes the load blocked/replay mechanism in the o3 cpu. Rather than
flushing the entire pipeline, this patch replays loads once the cache becomes
unblocked.

Additionally, deferred memory instructions (loads which had conflicting stores),
when replayed would not respect the number of functional units (only respected
issue width). This patch also corrects that.

Improvements over 20% have been observed on a microbenchmark designed to
exercise this behavior.

cpu: add consistent guarding to *_impl.hh files.

cpu: Rewrite O3 draining to avoid stopping in microcode

Previously, the O3 CPU could stop in the middle of a microcode
sequence. This patch makes sure that the pipeline stops when it has
committed a normal instruction or exited from a microcode
sequence. Additionally, it makes sure that the pipeline has no
instructions in flight when it is drained, which should make draining
more robust.

Draining is controlled in the commit stage, which checks if the next
PC after a committed instruction is in microcode. If this isn't the
case, it requests a squash of all instructions after that the
instruction that just committed and immediately signals a drain stall
to the fetch stage. The CPU then continues to execute until the
pipeline and all associated buffers are empty.

LSQ: Set store predictor to periodically clear itself as recommended in the storesets paper.

This patch improves performance by as much as 10% on some spec benchmarks.

LSQ: Add some better dprintfs for storeset predictor.

LSQ: Fix a few issues with the storeset predictor.

Two issues are fixed in this patch:
1. The load and store pc passed to the predictor are passed in reverse order.
2. The flag indicating that a barrier is inflight was never cleared when
the barrier was squashed instead of committed. This made all load insts
dependent on a non-existent barrier in-flight.

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

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.

style: fix sorting of includes and whitespace in some files

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

stats: fix duplicate statistics names.
This generally requires providing a more meaningful name() function for a
class.

params: Convert the CPU objects to use the auto generated param structs.
A whole bunch of stuff has been converted to use the new params stuff, but
the CPU wasn't one of them. While we're at it, make some things a bit
more stylish. Most of the work was done by Gabe, I just cleaned stuff up
a bit more at the end.

Handle status bits a little better, as well as non-speculative instructions.

src/cpu/o3/iew_impl.hh:
Allow for slightly more flexible handling of non-speculative instructions. They can be other classes now, such as loads or stores.

Also be sure to clear the state associated with squashes that are not used. i.e. if a squash due to a memory ordering violation happens on the same cycle as an older branch squashing, clear the state associated with the memory ordering violation.

Lastly don't consider uncached loads to officially be "at commit" until IEW receives the signal back from commit about the load.
src/cpu/o3/inst_queue_impl.hh:
Don't consider non-speculative instructions to be "at commit" until the IQ has received a signal from commit about the instruction. This prevents non-speculative instructions from being issued too early.
src/cpu/o3/mem_dep_unit_impl.hh:
Clear instruction's ability to issue if it's replayed.

Initialize mem dep unit properly.

src/cpu/o3/mem_dep_unit_impl.hh:
Initialize mem dep unit properly, add debug output.

Merge ktlim@zamp:./local/clean/o3-merge/m5
into zamp.eecs.umich.edu:/z/ktlim2/clean/o3-merge/newmem

configs/boot/micro_memlat.rcS:
configs/boot/micro_tlblat.rcS:
src/arch/alpha/ev5.cc:
src/arch/alpha/isa/decoder.isa:
src/arch/alpha/isa_traits.hh:
src/cpu/base.cc:
src/cpu/base.hh:
src/cpu/base_dyn_inst.hh:
src/cpu/checker/cpu.hh:
src/cpu/checker/cpu_impl.hh:
src/cpu/o3/alpha/cpu_impl.hh:
src/cpu/o3/alpha/params.hh:
src/cpu/o3/checker_builder.cc:
src/cpu/o3/commit_impl.hh:
src/cpu/o3/cpu.cc:
src/cpu/o3/decode_impl.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/iew.hh:
src/cpu/o3/iew_impl.hh:
src/cpu/o3/inst_queue.hh:
src/cpu/o3/lsq.hh:
src/cpu/o3/lsq_impl.hh:
src/cpu/o3/lsq_unit.hh:
src/cpu/o3/lsq_unit_impl.hh:
src/cpu/o3/regfile.hh:
src/cpu/o3/rename_impl.hh:
src/cpu/o3/thread_state.hh:
src/cpu/ozone/checker_builder.cc:
src/cpu/ozone/cpu.hh:
src/cpu/ozone/cpu_impl.hh:
src/cpu/ozone/front_end.hh:
src/cpu/ozone/front_end_impl.hh:
src/cpu/ozone/lw_back_end.hh:
src/cpu/ozone/lw_back_end_impl.hh:
src/cpu/ozone/lw_lsq.hh:
src/cpu/ozone/lw_lsq_impl.hh:
src/cpu/ozone/thread_state.hh:
src/cpu/simple/base.cc:
src/cpu/simple_thread.cc:
src/cpu/simple_thread.hh:
src/cpu/thread_state.hh:
src/dev/ide_disk.cc:
src/python/m5/objects/O3CPU.py:
src/python/m5/objects/Root.py:
src/python/m5/objects/System.py:
src/sim/pseudo_inst.cc:
src/sim/pseudo_inst.hh:
src/sim/system.hh:
util/m5/m5.c:
Hand merge.

Fixes to get new CPU model working for simple test case. The CPU does not yet support retrying accesses.

src/cpu/base_dyn_inst.cc:
Delete the allocated data in destructor.
src/cpu/base_dyn_inst.hh:
Only copy the addresses if the translation succeeded.
src/cpu/o3/alpha_cpu.hh:
Return actual translating port.
Don't panic on setNextNPC() as it's always called, regardless of the architecture, when the process initializes.
src/cpu/o3/alpha_cpu_impl.hh:
Pass in memobject to the thread state in SE mode.
src/cpu/o3/commit_impl.hh:
Initialize all variables.
src/cpu/o3/decode_impl.hh:
Handle early resolution of branches properly.
src/cpu/o3/fetch.hh:
Switch structure back to requests.
src/cpu/o3/fetch_impl.hh:
Initialize all variables, create/delete requests properly.
src/cpu/o3/lsq_unit.hh:
Include sender state along with the packet. Also include a more generic writeback event that's only used for stores forwarding data to loads.
src/cpu/o3/lsq_unit_impl.hh:
Redo writeback code to support the response path of the memory system.
src/cpu/o3/mem_dep_unit.cc:
src/cpu/o3/mem_dep_unit_impl.hh:
Wrap variables in #ifdefs.
src/cpu/o3/store_set.cc:
Include to get panic() function.
src/cpu/o3/thread_state.hh:
Create with MemObject as well.
src/cpu/thread_state.hh:
Have a translating port in the thread state object.
src/python/m5/objects/AlphaFullCPU.py:
Mem parameter no longer needed.

Merge ktlim@zamp:/z/ktlim2/clean/m5-o3
into zamp.eecs.umich.edu:/z/ktlim2/clean/newmem-merge

src/cpu/checker/o3_cpu_builder.cc:
src/cpu/o3/alpha_cpu.hh:
src/cpu/o3/alpha_cpu_impl.hh:
src/cpu/o3/alpha_dyn_inst_impl.hh:
src/cpu/o3/bpred_unit.cc:
src/cpu/o3/commit.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/lsq_unit.hh:
src/cpu/o3/lsq_unit_impl.hh:
src/cpu/o3/thread_state.hh:
Hand merge.

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

Updated Authors from bk prs info

Merge ktlim@zizzer:/bk/m5
into zamp.eecs.umich.edu:/z/ktlim2/clean/newmem

SConstruct:
src/SConscript:
src/arch/SConscript:
src/arch/alpha/faults.cc:
src/arch/alpha/tlb.cc:
src/base/traceflags.py:
src/cpu/SConscript:
src/cpu/base.cc:
src/cpu/base.hh:
src/cpu/base_dyn_inst.cc:
src/cpu/cpu_exec_context.cc:
src/cpu/cpu_exec_context.hh:
src/cpu/exec_context.hh:
src/cpu/o3/alpha_cpu.hh:
src/cpu/o3/alpha_cpu_impl.hh:
src/cpu/o3/alpha_dyn_inst.hh:
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
src/cpu/o3/regfile.hh:
src/cpu/ozone/cpu.hh:
src/cpu/simple/base.cc:
src/cpu/base_dyn_inst.hh:
src/cpu/o3/2bit_local_pred.cc:
src/cpu/o3/2bit_local_pred.hh:
src/cpu/o3/alpha_cpu.cc:
src/cpu/o3/alpha_cpu_builder.cc:
src/cpu/o3/alpha_dyn_inst.cc:
src/cpu/o3/alpha_dyn_inst_impl.hh:
src/cpu/o3/alpha_impl.hh:
src/cpu/o3/alpha_params.hh:
src/cpu/o3/bpred_unit.cc:
src/cpu/o3/bpred_unit.hh:
src/cpu/o3/bpred_unit_impl.hh:
src/cpu/o3/btb.cc:
src/cpu/o3/btb.hh:
src/cpu/o3/comm.hh:
src/cpu/o3/commit.cc:
src/cpu/o3/commit.hh:
src/cpu/o3/commit_impl.hh:
src/cpu/o3/cpu_policy.hh:
src/cpu/o3/decode.cc:
src/cpu/o3/decode.hh:
src/cpu/o3/decode_impl.hh:
src/cpu/o3/fetch.cc:
src/cpu/o3/fetch.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/free_list.cc:
src/cpu/o3/free_list.hh:
src/cpu/o3/iew.cc:
src/cpu/o3/iew.hh:
src/cpu/o3/iew_impl.hh:
src/cpu/o3/inst_queue.cc:
src/cpu/o3/inst_queue.hh:
src/cpu/o3/inst_queue_impl.hh:
src/cpu/o3/mem_dep_unit.cc:
src/cpu/o3/mem_dep_unit.hh:
src/cpu/o3/mem_dep_unit_impl.hh:
src/cpu/o3/ras.cc:
src/cpu/o3/ras.hh:
src/cpu/o3/rename.cc:
src/cpu/o3/rename.hh:
src/cpu/o3/rename_impl.hh:
src/cpu/o3/rename_map.cc:
src/cpu/o3/rename_map.hh:
src/cpu/o3/rob.cc:
src/cpu/o3/rob.hh:
src/cpu/o3/rob_impl.hh:
src/cpu/o3/sat_counter.cc:
src/cpu/o3/sat_counter.hh:
src/cpu/o3/store_set.cc:
src/cpu/o3/store_set.hh:
src/cpu/o3/tournament_pred.cc:
src/cpu/o3/tournament_pred.hh:
Hand merges.

New directory structure:
- simulator source now in 'src' subdirectory
- imported files from 'ext' repository
- support building in arbitrary places, including
outside of the source tree. See comment at top
of SConstruct file for more details.
Regression tests are temporarily disabled; that
syetem needs more extensive revisions.

SConstruct:
Update for new directory structure.
Modify to support build trees that are not subdirectories
of the source tree. See comment at top of file for
more details.
Regression tests are temporarily disabled.
src/arch/SConscript:
src/arch/isa_parser.py:
src/python/SConscript:
Update for new directory structure.