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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.
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This reduces the scope of those includes and makes it less likely for there to
be a dependency loop. This also moves the hashing functions associated with
ExtMachInst objects to be with the ExtMachInst definitions and out of
utility.hh.
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instructions
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kernel code.
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to compile. The fix was the simple addition of another set
of parenthesis to ensure the correct condition resolution.
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redundancies with threadId() as their replacement.
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SimObjects not yet updated:
- Process and subclasses
- BaseCPU and subclasses
The SimObject(const std::string &name) constructor was removed. Subclasses
that still rely on that behavior must call the parent initializer as
: SimObject(makeParams(name))
--HG--
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These need to be refined a little still and given parameters.
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creation and initialization now happens in python. Parameter objects
are generated and initialized by python. The .ini file is now solely for
debugging purposes and is not used in construction of the objects in any
way.
--HG--
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--HG--
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Make code compatible with new decode method.
src/arch/alpha/remote_gdb.cc:
src/cpu/base_dyn_inst_impl.hh:
src/cpu/exetrace.cc:
src/cpu/simple/base.cc:
Make code compatible with new decode method.
src/cpu/static_inst.cc:
src/cpu/static_inst.hh:
Modified instruction decode method.
--HG--
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--HG--
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src/arch/x86/isa/macroop.isa:
Make microOp vs microop and macroOp vs macroop capitilization consistent. Also fill out the emulation environment handling a little more, and use an object to pass around output code.
src/arch/x86/isa/microops/base.isa:
Make microOp vs microop and macroOp vs macroop capitilization consistent. Also adjust python to C++ bool translation.
--HG--
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--HG--
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into zower.eecs.umich.edu:/home/gblack/m5/newmem-statetrace
--HG--
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--HG--
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src/arch/alpha/predecoder.hh:
src/arch/sparc/predecoder.hh:
Put in a missing include
src/cpu/exetrace.cc:
Convert the legion lockstep stuff from makeExtMI to the predecoder object.
--HG--
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--HG--
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the traceflags infrastructure. InstExec is now just Exec
and all of the command line options are now trace options.
--HG--
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its not all that useful. Fix a few bugs with python/C++
integration.
--HG--
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fix unaligned accesses in mmaped disk device
src/arch/sparc/isa/decoder.isa:
get (ld|st)fsr ops working right. In reality the fp enable check needs to go higher up in the emitted code
src/arch/sparc/isa/formats/basic.isa:
move the cexec into the aexec field
src/cpu/exetrace.cc:
copy the exception state from legion when we get it wrong. We aren't going to get it right without an fp emulation layer
src/dev/sparc/mm_disk.cc:
src/dev/sparc/mm_disk.hh:
fix unaligned accesses in the memory mapped disk device
--HG--
extra : convert_revision : aaa33096b08cf0563fe291d984a87493a117e528
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src/arch/sparc/floatregfile.cc:
fix fp read/writing to registers... looking for suggestions on cleaner ways if anyone has them
src/arch/sparc/isa/decoder.isa:
fix some fp implementations
src/arch/sparc/isa/formats/basic.isa:
add new fp op class that 0 cexec in fsr and sets rounding mode for the up comming op
src/arch/sparc/isa/includes.isa:
include the appropriate header files for the rounding code
src/arch/sparc/miscregfile.cc:
print fsr out when it's read/written and the Sparc traceflgas in on
src/cpu/exetrace.cc:
fix printing of float registers
--HG--
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--HG--
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--HG--
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into zeep.pool:/z/saidi/work/m5.newmem
--HG--
extra : convert_revision : 7b8b791815d1fb51cc7ad085307a640b2ee51642
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make fp writes also chatty with the Sparc traceflag
src/arch/sparc/floatregfile.cc:
make fp writes also chatty with the Sparc traceflag
src/cpu/exetrace.cc:
fix comparing fp registers between legion and m5
--HG--
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into zower.eecs.umich.edu:/eecshome/m5/newmem
src/arch/sparc/isa/formats/mem/util.isa:
src/arch/sparc/isa_traits.hh:
src/arch/sparc/system.cc:
Hand Merge
--HG--
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some fixes to fp instructions to use the single precision registers
if this is an fp op emit fp check code
add fpregs to m5legion struct
src/arch/sparc/floatregfile.cc:
Make Sparc traceflag even more chatty
src/arch/sparc/isa/base.isa:
add code to check if the fpu is enabled
src/arch/sparc/isa/decoder.isa:
some fixes to fp instructions to use the single precision registers
fix smul again
fix subc/subcc/subccc condition code setting
src/arch/sparc/isa/formats/basic.isa:
src/arch/sparc/isa/formats/mem/util.isa:
if this is an fp op emit fp check code
src/cpu/exetrace.cc:
check fp regs as well as int regs
src/cpu/m5legion_interface.h:
add fpregs to m5legion struct
--HG--
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into zower.eecs.umich.edu:/eecshome/m5/newmem
--HG--
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check writability of tlb cache entry before using
update tagaccess in places I forgot to
move the tlb privileged test up since it is higher priority
src/arch/sparc/faults.cc:
save only 32 bits of PC/NPC if Pstate.am is set
src/arch/sparc/isa/decoder.isa:
return only 32 bits of PC/NPC if Pstate.am is set
increment cleanwin correctly
src/arch/sparc/tlb.cc:
check writability of cache entry
update tagaccess in a few more places
move the privileged test up since it is higher priority
src/cpu/exetrace.cc:
mask off upper bits of pc if pstate.am is set before comparing to legion
--HG--
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into ewok.(none):/home/gblack/m5/newmemo3
src/sim/byteswap.hh:
Hand Merge
--HG--
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instruction (because of a fault on the first op) we don't lose sync with legion
Only print TLB if there is a tlb difference
--HG--
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two consuctive differences since we compare stuff
at slightly different times interrupts are seen the cycle before they happen in m5 so the pc gets changed early.
--HG--
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into zower.eecs.umich.edu:/eecshome/m5/newmem
--HG--
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Only print faults instructions that aren't traps or faulting loads
src/cpu/exetrace.cc:
Compare the legion and m5 tlbs and printout any differences
Only show differences if the instruction isn't a trap and isn't a memory
operation that changes the trap level (a fault)
src/cpu/m5legion_interface.h:
update the m5<->legion interface to add tlb data
--HG--
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bugfixes and demap implementation in tlb
ignore some more differencs for one cycle
src/arch/sparc/isa/formats/mem/blockmem.isa:
twinx has 2 micro-ops
src/arch/sparc/isa/formats/mem/util.isa:
fix the fault check for twinx
src/arch/sparc/tlb.cc:
tlb bugfixes and write demapping code
src/cpu/exetrace.cc:
don't halt on a couple more instruction (ldx, stx) when things differ
beacuse of the way tlb faults are handled in legion.
--HG--
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into zower.eecs.umich.edu:/eecshome/m5/newmem
src/arch/isa_parser.py:
src/arch/sparc/isa/formats/mem/basicmem.isa:
src/arch/sparc/isa/formats/mem/blockmem.isa:
src/arch/sparc/isa/formats/mem/util.isa:
src/arch/sparc/miscregfile.cc:
src/arch/sparc/miscregfile.hh:
src/cpu/o3/iew_impl.hh:
Hand Merge
--HG--
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we can merge back with newmem.
exetrace.cc:
wrap this variable between FULL_SYSTEM #ifs
mmaped_ipr.hh:
fix for build
miscregfile.cc:
fixes for HPSTATE access during SE mode
src/arch/sparc/miscregfile.cc:
fixes for HPSTATE access during SE mode
src/arch/mips/mmaped_ipr.hh:
fix for build
src/cpu/exetrace.cc:
wrap this variable between FULL_SYSTEM #ifs
--HG--
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Deal with block initializing stores (by doing nothing, at some point we might want to do the write hint 64 like thing)
Fix tcc instruction igoner in legion-lock stuff to be correct in all cases
Have console interrupts warn rather than panicing until we figure out what to do with interrupts
src/arch/sparc/miscregfile.cc:
src/arch/sparc/miscregfile.hh:
add a magic miscreg which reads all the bits the tlb needs in one go
src/arch/sparc/tlb.cc:
initialized the context type and id to reasonable values and handle block init stores
src/arch/sparc/tlb_map.hh:
fix bug in tlb map code
src/base/range_map.hh:
fix bug in rangemap code and add range_multimap
(these are probably useful for bus range stuff)
src/cpu/exetrace.cc:
fixup tcc ignore code to be correct
src/dev/sparc/t1000.cc:
make console interrupt stuff warn instead of panicing until we get interrupt stuff figured out
src/unittest/rangemaptest.cc:
fix up the rangemap unit test to catch the missing case
--HG--
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Fix fault formating and code for traps
fix a couple of bugs in the decoder
Cleanup/fix page table entry code
Implement more mmaped iprs, fix numbered tlb insertion code, add function to dump tlb contents
Don't panic if we differ from legion on a tcc instruction because of where legion prints its data and where we print our data
src/arch/sparc/faults.cc:
Fix fault formating and code for traps
src/arch/sparc/intregfile.hh:
allocate the correct number of global registers
src/arch/sparc/isa/decoder.isa:
fix a couple of bugs in the decoder: wrasi should write asi not ccr, done/retry should get hpstate from htstate
src/arch/sparc/pagetable.hh:
cleanup/fix page table code
src/arch/sparc/tlb.cc:
implement more mmaped iprs, fix numbered insertion code, add function to dump tlb contents
src/arch/sparc/tlb.hh:
add functions to write TagAccess register on tlb miss and to dump all tlb entries for debugging
src/cpu/exetrace.cc:
dump tlb entries on error, don't consider differences the cycle we take a trap to be bad.
--HG--
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--HG--
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src/arch/sparc/asi.cc:
src/arch/sparc/asi.hh:
add sparc error asi
src/arch/sparc/faults.cc:
put a panic in if TL == MaxTL
src/arch/sparc/isa/decoder.isa:
Hpstate needs to be updated on a done too
src/arch/sparc/miscregfile.cc:
warn istead of panicing of fprs/fsr accesses
src/arch/sparc/tlb.cc:
add sparc error register code that just does nothing
fix a couple of other tlb bugs
src/arch/sparc/ua2005.cc:
fix implementation of HPSTATE write
src/cpu/exetrace.cc:
let exectrate mess up a couple of times before dying
src/python/m5/objects/T1000.py:
add l2 error status register fake devices
--HG--
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file (reducing the number of if FULL_SYSTEM defines and includes)
Protect other pieces of code so that sparc compiles SE again
src/arch/sparc/SConscript:
Add ua2005.cc back into SConscript
src/arch/sparc/miscregfile.hh:
add functions that deal with priv registers so we don't have to have a bunch of if defs and other ugliness
src/arch/sparc/mmaped_ipr.hh:
wrap handleIpr* with if full_system so it compiles under se
src/arch/sparc/ua2005.cc:
reorganize edit fs only miscreg functions
src/cpu/exetrace.cc:
protect legion code so it doesn't try to compile under se
--HG--
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correctly
--HG--
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configs/common/FSConfig.py:
seperate the hypervisor memory and the guest0 memory. In reality we're going to need a better way to do this at some point. Perhaps auto generating the hv-desc image based on the specified config.
src/arch/sparc/isa/decoder.isa:
change reads/writes to the [hs]tick(cmpr) registers to use readmiscregwitheffect
src/arch/sparc/miscregfile.cc:
For niagra stick and tick are aliased to one value (if we end up doing mps we might not want this).
Use instruction count from cpu rather than cycles because that is what legion does
we can change it back after were done with legion
src/base/bitfield.hh:
add a new function mbits() that just masks off bits of interest but doesn't shift
src/cpu/base.cc:
src/cpu/base.hh:
add instruction count to cpu
src/cpu/exetrace.cc:
src/cpu/m5legion_interface.h:
compare instruction count between legion and m5 too
src/cpu/simple/atomic.cc:
change asserts of packet success to if panics wrapped with NDEBUG defines
so we can get some more useful information when we have a bad address
src/dev/isa_fake.cc:
src/dev/isa_fake.hh:
src/python/m5/objects/Device.py:
expand isa fake a bit more having data for each size request, the ability to have writes update the data and to warn on accesses
src/python/m5/objects/System.py:
convert some tabs to spaces
src/python/m5/objects/T1000.py:
add more fake devices for each l1 bank and each memory controller
--HG--
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--HG--
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