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/gem5/src/arch/power/
H A Dutility.hhdiff 7720:65d338a8dba4 Sun Oct 31 03:07:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> 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.
diff 7693:f1db1000d957 Fri Oct 01 17:02:00 EDT 2010 Ali Saidi <Ali.Saidi@ARM.com> Debug: Implement getArgument() and function skipping for ARM.

In the process make add skipFuction() to handle isa specific function skipping
instead of ifdefs and other ugliness. For almost all ABIs, 64 bit arguments can
only start in even registers. Size is now passed to getArgument() so that 32
bit systems can make decisions about register selection for 64 bit arguments.
The number argument is now passed by reference because getArgument() will need
to change it based on the size of the argument and the current argument number.

For ARM, if the argument number is odd and a 64-bit register is requested the
number must first be incremented to because all 64 bit arguments are passed
in an even argument register. Then the number will be incremented again to
access both halves of the argument.
diff 7680:f4eda002333b Tue Sep 14 03:29:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> CPU: Trim unnecessary includes from some common files.

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.
diff 7628:d9b98534a872 Mon Aug 23 19:14:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> Power: Get rid of unused checkFpEnableFault.

This function was brought in from another ISA and doesn't actually do anything
or get used.
diff 7627:3b0c4b819651 Mon Aug 23 19:14:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ISA: Get rid of old, unused utility functions cluttering up the ISAs.
diff 7506:e76cc0ca16cc Thu Jul 22 13:47:00 EDT 2010 Timothy M. Jones <tjones1@inf.ed.ac.uk> Power: Provide a utility function to copy registers from one thread context
to another in the Power ISA.
/gem5/src/mem/ruby/network/
H A DNetwork.ccdiff 7805:f249937228b5 Thu Dec 23 00:15:00 EST 2010 Nilay Vaish<nilay@cs.wisc.edu> This patch removes the WARN_* and ERROR_* from src/mem/ruby/common/Debug.hh file. These statements have been replaced with warn(), panic() and fatal() defined in src/base/misc.hh
diff 7548:764a7401e217 Fri Aug 20 14:46:00 EDT 2010 Brad Beckmann <Brad.Beckmann@amd.com> ruby: Added bcast msg profiling to hammer and token
diff 7454:3a3e8e8cce1b Fri Jun 11 02:17:00 EDT 2010 Nathan Binkert <nate@binkert.org> ruby: get rid of Vector and use STL
add a couple of helper functions to base for deleteing all pointers in
a container and outputting containers to a stream
diff 7054:7d6862b80049 Wed Mar 31 19:56:00 EDT 2010 Nathan Binkert <nate@binkert.org> style: another ruby style pass
diff 6881:5a61a8a9009a Fri Jan 29 23:29:00 EST 2010 Brad Beckmann <Brad.Beckmann@amd.com> ruby: connects sm queues to the network
diff 6876:a658c315512c Fri Jan 29 23:29:00 EST 2010 Steve Reinhardt <steve.reinhardt@amd.com> ruby: Convert most Ruby objects to M5 SimObjects.
The necessary companion conversion of Ruby objects generated by SLICC
are converted to M5 SimObjects in the following patch, so this patch
alone does not compile.
Conversion of Garnet network models is also handled in a separate
patch; that code is temporarily disabled from compiling to allow
testing of interim code.
/gem5/src/arch/arm/isa/templates/
H A Dpred.isadiff 7646:a444dbee8c07 Wed Aug 25 20:10:00 EDT 2010 Gene WU <gene.wu@arm.com> ARM: Use fewer micro-ops for register update loads if possible.

Allow some loads that update the base register to use just two micro-ops. three
micro-ops are only used if the destination register matches the offset register
or the PC is the destination regsiter. If the PC is updated it needs to be
the last micro-op otherwise O3 will mispredict.
diff 7597:063f160e8b50 Mon Aug 23 12:18:00 EDT 2010 Min Kyu Jeong <minkyu.jeong@arm.com> 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.
diff 7422:feddb9077def Wed Jun 02 01:58:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Decode to specialized conditional/unconditional versions of instructions.

This is to avoid condition code based dependences from effectively serializing
instructions when the instruction doesn't actually use them.
diff 7408:ee6949c5bb5b Wed Jun 02 01:58:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Implement support for the IT instruction and the ITSTATE bits of CPSR.
diff 7138:5dff7c15008f Wed Jun 02 01:58:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Implement data processing instructions external to the decoder.
7133:4a1af4580b7d Wed Jun 02 01:58:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Move the templates for predicated instructions into a separate file.
This allows the templates to all be available at the same time before any of
the formats, etc. This breaks an artificial circular dependence.
/gem5/src/arch/arm/isa/insts/
H A Dneon.isadiff 7783:9b880b40ac10 Tue Dec 07 19:19:00 EST 2010 Giacomo Gabrielli <Giacomo.Gabrielli@arm.com> O3: Make all instructions that write a misc. register not perform the write until commit.

ARM instructions updating cumulative flags (ARM FP exceptions and saturation
flags) are not serialized.

Added aliases for ARM FP exceptions and saturation flags in FPSCR. Removed
write accesses to the FP condition codes for most ARM VFP instructions: only
VCMP and VCMPE instructions update the FP condition codes. Removed a potential
cause of seg. faults in the O3 model for NEON memory macro-ops (ARM).
diff 7760:e93e7e0caae1 Mon Nov 15 15:04:00 EST 2010 Giacomo Gabrielli <Giacomo.Gabrielli@arm.com> CPU/ARM: Add SIMD op classes to CPU models and ARM ISA.
diff 7644:62873d5c2bfc Wed Aug 25 20:10:00 EDT 2010 Ali Saidi <ali.saidi@arm.com> ARM: Fix VFP enabled checks for mem instructions
diff 7641:788c719d0fc8 Wed Aug 25 20:10:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Fix type comparison warnings in Neon.
diff 7640:5286a8a469c5 Wed Aug 25 20:10:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Implement CPACR register and return Undefined Instruction when FP access is disabled.
7639:8c09b7ff5b57 Wed Aug 25 20:10:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ARM: Implement all ARM SIMD instructions.
/gem5/src/mem/ruby/slicc_interface/
H A DSConscriptdiff 6882:898047a3672c Fri Jan 29 23:29:00 EST 2010 Brad Beckmann <Brad.Beckmann@amd.com> ruby: Ruby changes required to use the python config system
This patch includes the necessary changes to connect ruby objects using
the python configuration system. Mainly it consists of removing
unnecessary ruby object pointers and connecting the necessary object
pointers using the generated param objects. This patch includes the
slicc changes necessary to connect generated ruby objects together using
the python configuraiton system.
diff 6876:a658c315512c Fri Jan 29 23:29:00 EST 2010 Steve Reinhardt <steve.reinhardt@amd.com> ruby: Convert most Ruby objects to M5 SimObjects.
The necessary companion conversion of Ruby objects generated by SLICC
are converted to M5 SimObjects in the following patch, so this patch
alone does not compile.
Conversion of Garnet network models is also handled in a separate
patch; that code is temporarily disabled from compiling to allow
testing of interim code.
/gem5/src/mem/slicc/ast/
H A DMachineAST.pydiff 7542:49327b849c7f Fri Aug 20 14:46:00 EDT 2010 Brad Beckmann <Brad.Beckmann@amd.com> slicc: Consolidated the protocol stats printing

Created a separate ProfileDumper that consolidates the generated stats for
each controller of a certain type.
diff 6877:2a1a3d916ca8 Fri Jan 29 23:29:00 EST 2010 Steve Reinhardt <steve.reinhardt@amd.com> ruby: Make SLICC-generated objects SimObjects.
Also add SLICC support for state-machine parameter defaults
(passed through to Python as SimObject Param defaults).
/gem5/src/arch/arm/linux/
H A Dlinux.ccdiff 7799:5d0f62927d75 Mon Dec 20 16:24:00 EST 2010 Gabe Black <gblack@eecs.umich.edu> Style: Replace some tabs with spaces.
diff 7441:be2acdfb8bdc Wed Jun 02 01:58:00 EDT 2010 Ali Saidi <Ali.Saidi@ARM.com> ARM: Fix SPEC2000 benchmarks in SE mode. With this patch all
Spec2k benchmarks seem to run with atomic or timing mode simple
CPUs. Fixed up some constants, handling of 64 bit arguments,
and marked a few more syscalls ignoreFunc.
/gem5/src/arch/x86/
H A Dtypes.ccdiff 7660:adae3e7d325a Fri Aug 27 18:35:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Change the copyright holder to AMD.

I accidentally left myself as a placeholder copyright holder on this file when
I checked it in. Copyright should be assigned to AMD.
7624:3f32191bcf66 Mon Aug 23 12:44:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Make the x86 ExtMachInst serializable with (UN)SERIALIZE_SCALAR.
H A DX86System.pydiff 7580:6f77f379a594 Mon Aug 23 12:18:00 EDT 2010 Ali Saidi <Ali.Saidi@arm.com> Loader: Make the load address mask be a parameter of the system rather than a constant.

This allows one two different OS requirements for the same ISA to be handled.
Some OSes are compiled for a virtual address and need to be loaded into physical
memory that starts at address 0, while other bare metal tools generate
images that start at address 0.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/insts/
H A Dmicroregop.hhdiff 7620:3d8a23caa1ef Mon Aug 23 12:44:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Consolidate extra microop flags into one parameter.

This single parameter replaces the collection of bools that set up various
flavors of microops. A flag parameter also allows other flags to be set like
the serialize before/after flags, etc., without having to change the
constructor.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/isa/formats/
H A Dformats.isadiff 7715:5581d0cd2bdb Fri Oct 22 03:24:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Make nop a regular, non-microcoded instruction.

Code in the CPUs that need a nop to carry a fault can't easily deal with a
microcoded nop. This instruction format provides for one that isn't.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
H A Dcpuid.isadiff 7622:b49144029ec8 Mon Aug 23 12:44:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Mark serializing macroops and regular instructions as such.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/isa/insts/general_purpose/control_transfer/
H A Dinterrupts_and_exceptions.pydiff 7622:b49144029ec8 Mon Aug 23 12:44:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Mark serializing macroops and regular instructions as such.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
H A Dxreturn.pydiff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/isa/insts/system/
H A Dmsrs.pydiff 7622:b49144029ec8 Mon Aug 23 12:44:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> X86: Mark serializing macroops and regular instructions as such.
diff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/dev/arm/
H A Damba_fake.ccdiff 7587:177151a54462 Mon Aug 23 12:18:00 EDT 2010 Ali Saidi <Ali.Saidi@arm.com> ARM: Change how the AMBA device ID checking is done to make it more generic
7584:28ddf6d9e982 Mon Aug 23 12:18:00 EDT 2010 Ali Saidi <Ali.Saidi@arm.com> ARM: Add I/O devices for booting linux
/gem5/src/python/
H A Dimporter.pydiff 7801:f71f9634d809 Tue Dec 21 11:02:00 EST 2010 Nathan Binkert <nate@binkert.org> importer: fix error message
diff 7502:3ef7ff12c788 Wed Jul 21 18:53:00 EDT 2010 Nathan Binkert <nate@binkert.org> python: Add mechanism to override code compiled into the exectuable
If the user sets the environment variable M5_OVERRIDE_PY_SOURCE to
True, then imports that would normally find python code compiled into
the executable will instead first check in the absolute location where
the code was found during the build of the executable. This only
works for files in the src (or extras) directories, not automatically
generated files.

This is a developer feature!
/gem5/src/python/m5/internal/
H A Dparams.pydiff 7689:9d75590d7abe Wed Sep 22 11:45:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> python: get rid of internal.enums package.

Move generated enums into internal.params, which gets
imported into object.params, restoring backward
compatibility for scripts that expect to find them there.
7677:c6e283904437 Sun Sep 12 18:41:00 EDT 2010 Nathan Binkert <nate@binkert.org> swig: make all generated files go into the m5.internal package

This is necessary because versions of swig older than 1.3.39 fail to
do the right thing and try to do relative imports for everything (even
with the package= option to %module). Instead of putting params in
the m5.internal.params package, put params in the m5.internal package
and make all param modules start with param_. Same thing for
m5.internal.enums.

Also, stop importing all generated params into m5.objects. They are
not necessary and now with everything using relative imports we wound
up with pollution of the namespace (where builtin-range got overridden).
/gem5/src/python/m5/util/
H A Dcode_formatter.pydiff 7672:d609cd948ca0 Thu Sep 09 17:15:00 EDT 2010 Nathan Binkert <nate@binkert.org> code_formatter: make it easier to insert whitespace
a newline by just doing "code()". indent() and dedent() now take a
"count" parameter to indent/dedent multiple levels.
diff 6999:f226c098c393 Wed Mar 10 19:22:00 EST 2010 Nathan Binkert <nate@binkert.org> slicc: have a central mechanism for creating a code_formatter.
This makes it easier to add global variables like protocol
/gem5/src/mem/slicc/symbols/
H A DSymbolTable.pydiff 6999:f226c098c393 Wed Mar 10 19:22:00 EST 2010 Nathan Binkert <nate@binkert.org> slicc: have a central mechanism for creating a code_formatter.
This makes it easier to add global variables like protocol
diff 6877:2a1a3d916ca8 Fri Jan 29 23:29:00 EST 2010 Steve Reinhardt <steve.reinhardt@amd.com> ruby: Make SLICC-generated objects SimObjects.
Also add SLICC support for state-machine parameter defaults
(passed through to Python as SimObject Param defaults).
/gem5/src/base/stats/
H A Dinfo.hhdiff 7505:7772a8bf76ee Wed Jul 21 21:54:00 EDT 2010 Nathan Binkert <nate@binkert.org> stats: unify the two stats distribution type better
diff 7462:0c61c3cf7639 Tue Jun 15 11:34:00 EDT 2010 Nathan Binkert <nate@binkert.org> stats: rename print to display so it work in python
/gem5/src/arch/x86/bios/
H A DE820.pydiff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/isa/insts/general_purpose/arithmetic/
H A Dmultiply_and_divide.pydiff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
/gem5/src/arch/x86/isa/insts/general_purpose/input_output/
H A Dgeneral_io.pydiff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly
H A Dstring_io.pydiff 7087:fb8d5786ff30 Mon May 24 01:44:00 EDT 2010 Nathan Binkert <nate@binkert.org> copyright: Change HP copyright on x86 code to be more friendly

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