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2014-02-09cpu: simple: Add support for using branch predictorsAndreas Sandberg
This changesets adds branch predictor support to the BaseSimpleCPU. The simple CPUs normally don't need a branch predictor, however, there are at least two cases where it can be desirable: 1) A simple CPU can be used to warm the branch predictor of an O3 CPU before switching to the slower O3 model. 2) The simple CPU can be used as a quick way of evaluating/debugging new branch predictors since it exposes branch predictor statistics. Limitations: * Since the simple CPU doesn't speculate, only one instruction will be active in the branch predictor at a time (i.e., the branch predictor will never see speculative branches). * The outcome of a branch prediction does not affect the performance of the simple CPU.
2013-10-15cpu: add a condition-code register classYasuko Eckert
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.
2013-01-12base simple cpu: removes commented out code about cache opsNilay Vaish
2013-01-12x86: Changes to decoder, corrects 9376Nilay Vaish
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.
2013-01-07cpu: Unify the serialization code for all of the CPU modelsAndreas Sandberg
Cleanup the serialization code for the simple CPUs and the O3 CPU. The CPU-specific code has been replaced with a (un)serializeThread that serializes the thread state / context of a specific thread. Assuming that the thread state class uses the CPU-specific thread state uses the base thread state serialization code, this allows us to restore a checkpoint with any of the CPU models.
2013-01-07arch: Make the ISA class inherit from SimObjectAndreas Sandberg
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.
2013-01-04Decoder: Remove the thread context get/set from the decoder.Gabe Black
This interface is no longer used, and getting rid of it simplifies the decoders and code that sets up the decoders. The thread context had been used to read architectural state which was used to contextualize the instruction memory as it came in. That was changed so that the state is now sent to the decoders to keep locally if/when it changes. That's significantly more efficient. Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2012-09-19AddrRange: Transition from Range<T> to AddrRangeAndreas Hansson
This patch takes the final plunge and transitions from the templated Range class to the more specific AddrRange. In doing so it changes the obvious Range<Addr> to AddrRange, and also bumps the range_map to be AddrRangeMap. In addition to the obvious changes, including the removal of redundant includes, this patch also does some house keeping in preparing for the introduction of address interleaving support in the ranges. The Range class is also stripped of all the functionality that is never used. --HG-- rename : src/base/range.hh => src/base/addr_range.hh rename : src/base/range_map.hh => src/base/addr_range_map.hh
2012-05-26CPU: Merge the predecoder and decoder.Gabe Black
These classes are always used together, and merging them will give the ISAs more flexibility in how they cache things and manage the process. --HG-- rename : src/arch/x86/predecoder_tables.cc => src/arch/x86/decoder_tables.cc
2012-04-15CPU: Tidy up some formatting and a DPRINTF in the simple CPU base class.Gabe Black
Put the { on the same line as the if and put a space between the if and the open paren. Also, use the # format modifier which puts a 0x in front of hex values automatically. If the ExtMachInst type isn't integral and actually prints something more complicated, the # falls away harmlessly and we aren't left with a phantom 0x followed by a bunch of unrelated text.
2012-03-09CheckerCPU: Make CheckerCPU runtime selectable instead of compile selectableGeoffrey Blake
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.
2012-02-12cpu: add separate stats for insts/ops both globally and per cpu modelAnthony Gutierrez
2012-02-12mem: Add a master ID to each request object.Ali Saidi
This change adds a master id to each request object which can be used identify every device in the system that is capable of issuing a request. This is part of the way to removing the numCpus+1 stats in the cache and replacing them with the master ids. This is one of a series of changes that make way for the stats output to be changed to python.
2012-02-10SE/FS: Record the system pointer all the time for the simple CPU.Gabe Black
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.
2012-02-07Faults: Turn off arch/faults.hhGabe Black
Because there are no longer architecture independent but specialized functions in arch/XXX/faults.hh, code that isn't using the faults from a particular ISA no longer needs to be able to include them through the switching header file arch/faults.hh. By removing that header file (arch/faults.hh), the potential interface between ISA code and non ISA code is narrowed.
2012-01-31Merge with head, hopefully the last time for this batch.Gabe Black
2012-01-31clang: Enable compiling gem5 using clang 2.9 and 3.0Koan-Sin Tan
This patch adds the necessary flags to the SConstruct and SConscript files for compiling using clang 2.9 and later (on Ubuntu et al and OSX XCode 4.2), and also cleans up a bunch of compiler warnings found by clang. Most of the warnings are related to hidden virtual functions, comparisons with unsigneds >= 0, and if-statements with empty bodies. A number of mismatches between struct and class are also fixed. clang 2.8 is not working as it has problems with class names that occur in multiple namespaces (e.g. Statistics in kernel_stats.hh). clang has a bug (http://llvm.org/bugs/show_bug.cgi?id=7247) which causes confusion between the container std::set and the function Packet::set, and this is currently addressed by not including the entire namespace std, but rather selecting e.g. "using std::vector" in the appropriate places.
2012-01-31CheckerCPU: Re-factor CheckerCPU to be compatible with current gem5Geoffrey Blake
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.
2011-11-18SE/FS: Get rid of FULL_SYSTEM in the CPU directory.Gabe Black
2011-11-01SE/FS: Get rid of uses of FULL_SYSTEM in Alpha.Gabe Black
2011-11-01SE/FS: Expose the same methods on the CPUs in SE and FS modes.Gabe Black
2011-09-09Decode: Pull instruction decoding out of the StaticInst class into its own.Gabe Black
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.
2011-04-15trace: reimplement the DTRACE function so it doesn't use a vectorNathan Binkert
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
2011-04-15includes: sort all includesNathan Binkert
2011-02-06mcpat: Adds McPAT performance countersJoel Hestness
Updated patches from Rick Strong's set that modify performance counters for McPAT
2011-01-07Replace curTick global variable with accessor functions.Steve Reinhardt
This step makes it easy to replace the accessor functions (which still access a global variable) with ones that access per-thread curTick values.
2010-11-08ARM/Alpha/Cpu: Change prefetchs to be more like normal loads.Ali Saidi
This change modifies the way prefetches work. They are now like normal loads that don't writeback a register. Previously prefetches were supposed to call prefetch() on the exection context, so they executed with execute() methods instead of initiateAcc() completeAcc(). The prefetch() methods for all the CPUs are blank, meaning that they get executed, but don't actually do anything. On Alpha dead cache copy code was removed and prefetches are now normal ops. They count as executed operations, but still don't do anything and IsMemRef is not longer set on them. On ARM IsDataPrefetch or IsInstructionPreftech is now set on all prefetch instructions. The timing simple CPU doesn't try to do anything special for prefetches now and they execute with the normal memory code path.
2010-10-31ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors.Gabe Black
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.
2010-09-13CPU: Get rid of the now unnecessary getInst/setInst family of functions.Gabe Black
This code is no longer needed because of the preceeding change which adds a StaticInstPtr parameter to the fault's invoke method, obviating the only use for this pair of functions.
2010-09-13Faults: Pass the StaticInst involved, if any, to a Fault's invoke method.Gabe Black
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.
2010-06-14stats: get rid of the never-really-used event stuffNathan Binkert
2010-06-03Minor remote GDB cleanup.Steve Reinhardt
Expand the help text on the --remote-gdb-port option so people know you can use it to disable remote gdb without reading the source code, and thus don't waste any time trying to add a separate option to do that. Clean up some gdb-related cruft I found while looking for where one would add a gdb disable option, before I found the comment that told me that I didn't need to do that.
2010-06-02ARM: Implement support for the IT instruction and the ITSTATE bits of CPSR.Gabe Black
2010-06-02CPU: Reset fetch offset after a exceptionAli Saidi
2010-06-02ARM: Make the predecoder handle Thumb instructions.Gabe Black
2010-03-23cpu: fix exec tracing memory corruption bugSteve Reinhardt
Accessing traceData (to call setAddress() and/or setData()) after initiating a timing translation was causing crashes, since a failed translation could delete the traceData object before returning. It turns out that there was never a need to access traceData after initiating the translation, as the traced data was always available earlier; this ordering was merely historical. Furthermore, traceData->setAddress() and traceData->setData() were being called both from the CPU model and the ISA definition, often redundantly. This patch standardizes all setAddress and setData calls for memory instructions to be in the CPU models and not in the ISA definition. It also moves those calls above the translation calls to eliminate the crashes.
2009-09-23arch: nuke arch/isa_specific.hh and move stuff to generated config/the_isa.hhNathan Binkert
2009-08-01Fix setting of INST_FETCH flag for O3 CPU.Steve Reinhardt
It's still broken in inorder. Also enhance DPRINTFs in cache and physical memory so we can see more easily whether it's getting set or not.
2009-07-08Get rid of the unused get(Data|Inst)Asid and (inst|data)Asid functions.Gabe Black
2009-06-04types: clean up types, especially signed vs unsignedNathan Binkert
2009-05-26types: add a type for thread IDs and try to use it everywhereNathan Binkert
2009-05-17includes: sort includes againNathan Binkert
2009-05-17types: Move stuff for global types into src/base/types.hhNathan Binkert
--HG-- rename : src/sim/host.hh => src/base/types.hh
2009-04-20request: rename INST_READ to INST_FETCH.Steve Reinhardt
2009-04-15Get rid of the Unallocated thread context state.Steve Reinhardt
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.
2009-02-26CPA: Add code to automatically record function symbols as CPU executes.Ali Saidi
2009-02-25CPU: Implement translateTiming which defers to translateAtomic, and convert ↵Gabe Black
the timing simple CPU to use it.
2009-02-25ISA: Replace the translate functions in the TLBs with translateAtomic.Gabe Black
2009-02-25CPU: Get rid of translate... functions from various interface classes.Gabe Black
2009-02-01CPU: Don't always reset the micro pc on faults. Let the faults handle it.Gabe Black