| Age | Commit message (Collapse) | Author | |
|---|---|---|---|
| 2018-11-16 | cpu: Fix the usage of const DynInstPtr | Rekai Gonzalez-Alberquilla | |
| 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> | |||
| 2013-01-07 | cpu: Rewrite O3 draining to avoid stopping in microcode | Andreas Sandberg | |
| 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. | |||
| 2010-10-31 | ISA,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. | |||
| 2006-06-16 | Miscellaneous minor fixes. | Kevin Lim | |
| src/cpu/checker/cpu.cc: Add in comment. src/cpu/cpuevent.hh: Fix up comment. src/cpu/o3/bpred_unit.cc: Comment out Ozone instantiations. src/cpu/o3/dep_graph.hh: Include destructor. --HG-- extra : convert_revision : 549454ed11bc2fa49a0627f7fb8f96d00a9be303 | |||
| 2006-06-07 | Update copyright. | Kevin Lim | |
| --HG-- extra : convert_revision : 8ad012b1acfe046e6a8a5fb064891d91dadeb2e0 | |||
| 2006-06-04 | Merge ktlim@zamp:/z/ktlim2/clean/m5-o3 | Kevin Lim | |
| 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. --HG-- rename : cpu/activity.cc => src/cpu/activity.cc rename : cpu/activity.hh => src/cpu/activity.hh rename : cpu/base_dyn_inst.cc => src/cpu/base_dyn_inst.cc rename : cpu/checker/cpu.hh => src/cpu/checker/cpu.hh rename : cpu/checker/cpu_builder.cc => src/cpu/checker/cpu_builder.cc rename : cpu/checker/exec_context.hh => src/cpu/checker/exec_context.hh rename : cpu/checker/o3_cpu_builder.cc => src/cpu/checker/o3_cpu_builder.cc rename : cpu/o3/2bit_local_pred.cc => src/cpu/o3/2bit_local_pred.cc rename : cpu/o3/2bit_local_pred.hh => src/cpu/o3/2bit_local_pred.hh rename : cpu/o3/alpha_cpu.hh => src/cpu/o3/alpha_cpu.hh rename : cpu/o3/alpha_cpu_builder.cc => src/cpu/o3/alpha_cpu_builder.cc rename : cpu/o3/alpha_cpu_impl.hh => src/cpu/o3/alpha_cpu_impl.hh rename : cpu/o3/alpha_dyn_inst.hh => src/cpu/o3/alpha_dyn_inst.hh rename : cpu/o3/alpha_dyn_inst_impl.hh => src/cpu/o3/alpha_dyn_inst_impl.hh rename : cpu/o3/alpha_params.hh => src/cpu/o3/alpha_params.hh rename : cpu/o3/bpred_unit.cc => src/cpu/o3/bpred_unit.cc rename : cpu/o3/bpred_unit.hh => src/cpu/o3/bpred_unit.hh rename : cpu/o3/bpred_unit_impl.hh => src/cpu/o3/bpred_unit_impl.hh rename : cpu/o3/comm.hh => src/cpu/o3/comm.hh rename : cpu/o3/commit.hh => src/cpu/o3/commit.hh rename : cpu/o3/commit_impl.hh => src/cpu/o3/commit_impl.hh rename : cpu/o3/cpu.hh => src/cpu/o3/cpu.hh rename : cpu/o3/cpu_policy.hh => src/cpu/o3/cpu_policy.hh rename : cpu/o3/decode.hh => src/cpu/o3/decode.hh rename : cpu/o3/decode_impl.hh => src/cpu/o3/decode_impl.hh rename : cpu/o3/dep_graph.hh => src/cpu/o3/dep_graph.hh rename : cpu/o3/fetch.hh => src/cpu/o3/fetch.hh rename : cpu/o3/fetch_impl.hh => src/cpu/o3/fetch_impl.hh rename : cpu/o3/fu_pool.cc => src/cpu/o3/fu_pool.cc rename : cpu/o3/fu_pool.hh => src/cpu/o3/fu_pool.hh rename : cpu/o3/iew.hh => src/cpu/o3/iew.hh rename : cpu/o3/iew_impl.hh => src/cpu/o3/iew_impl.hh rename : cpu/o3/inst_queue.hh => src/cpu/o3/inst_queue.hh rename : cpu/o3/inst_queue_impl.hh => src/cpu/o3/inst_queue_impl.hh rename : cpu/o3/lsq.hh => src/cpu/o3/lsq.hh rename : cpu/o3/lsq_unit.hh => src/cpu/o3/lsq_unit.hh rename : cpu/o3/lsq_unit_impl.hh => src/cpu/o3/lsq_unit_impl.hh rename : cpu/o3/mem_dep_unit.hh => src/cpu/o3/mem_dep_unit.hh rename : cpu/o3/mem_dep_unit_impl.hh => src/cpu/o3/mem_dep_unit_impl.hh rename : cpu/o3/rename.hh => src/cpu/o3/rename.hh rename : cpu/o3/rename_impl.hh => src/cpu/o3/rename_impl.hh rename : cpu/o3/rename_map.hh => src/cpu/o3/rename_map.hh rename : cpu/o3/rob.hh => src/cpu/o3/rob.hh rename : cpu/o3/store_set.cc => src/cpu/o3/store_set.cc rename : cpu/o3/store_set.hh => src/cpu/o3/store_set.hh rename : cpu/o3/thread_state.hh => src/cpu/o3/thread_state.hh rename : cpu/o3/tournament_pred.cc => src/cpu/o3/tournament_pred.cc rename : cpu/o3/tournament_pred.hh => src/cpu/o3/tournament_pred.hh rename : cpu/ozone/cpu_builder.cc => src/cpu/ozone/cpu_builder.cc rename : cpu/ozone/ozone_impl.hh => src/cpu/ozone/ozone_impl.hh rename : cpu/ozone/simple_impl.hh => src/cpu/ozone/simple_impl.hh rename : cpu/ozone/simple_params.hh => src/cpu/ozone/simple_params.hh rename : python/m5/objects/AlphaFullCPU.py => src/python/m5/objects/AlphaFullCPU.py rename : python/m5/objects/OzoneCPU.py => src/python/m5/objects/OzoneCPU.py extra : convert_revision : b7be30474dd03dd3970e737a9d0489aeb2ead84f | |||
| 2006-06-02 | Fixes to get compiling to work. This is mainly fixing up some includes; ↵ | Kevin Lim | |
| changing functions within the XCs; changing MemReqPtrs to Requests or Packets where appropriate. Currently the O3 and Ozone CPUs do not work in the new memory system; I still need to fix up the ports to work and handle responses properly. This check-in is so that the merge between m5 and newmem is no longer outstanding. src/SConscript: Need to include FU Pool for new CPU model. I'll try to figure out a cleaner way to handle this in the future. src/base/traceflags.py: Include new traces flags, fix up merge mess up. src/cpu/SConscript: Include the base_dyn_inst.cc as one of othe sources. Don't compile the Ozone CPU for now. src/cpu/base.cc: Remove an extra } from the merge. src/cpu/base_dyn_inst.cc: Fixes to make compiling work. Don't instantiate the OzoneCPU for now. src/cpu/base_dyn_inst.hh: src/cpu/o3/2bit_local_pred.cc: src/cpu/o3/alpha_cpu_builder.cc: src/cpu/o3/alpha_cpu_impl.hh: src/cpu/o3/alpha_dyn_inst.hh: src/cpu/o3/alpha_params.hh: src/cpu/o3/bpred_unit.cc: src/cpu/o3/btb.hh: src/cpu/o3/commit.hh: src/cpu/o3/commit_impl.hh: src/cpu/o3/cpu.cc: src/cpu/o3/cpu.hh: src/cpu/o3/fetch.hh: src/cpu/o3/fetch_impl.hh: src/cpu/o3/free_list.hh: src/cpu/o3/iew.hh: src/cpu/o3/iew_impl.hh: src/cpu/o3/inst_queue.hh: src/cpu/o3/inst_queue_impl.hh: src/cpu/o3/regfile.hh: src/cpu/o3/sat_counter.hh: src/cpu/op_class.hh: src/cpu/ozone/cpu.hh: src/cpu/checker/cpu.cc: src/cpu/checker/cpu.hh: src/cpu/checker/exec_context.hh: src/cpu/checker/o3_cpu_builder.cc: src/cpu/ozone/cpu_impl.hh: src/mem/request.hh: src/cpu/o3/fu_pool.hh: src/cpu/o3/lsq.hh: src/cpu/o3/lsq_unit.hh: src/cpu/o3/lsq_unit_impl.hh: src/cpu/o3/thread_state.hh: src/cpu/ozone/back_end.hh: src/cpu/ozone/dyn_inst.cc: src/cpu/ozone/dyn_inst.hh: src/cpu/ozone/front_end.hh: src/cpu/ozone/inorder_back_end.hh: src/cpu/ozone/lw_back_end.hh: src/cpu/ozone/lw_lsq.hh: src/cpu/ozone/ozone_impl.hh: src/cpu/ozone/thread_state.hh: Fixes to get compiling to work. src/cpu/o3/alpha_cpu.hh: Fixes to get compiling to work. Float reg accessors have changed, as well as MemReqPtrs to RequestPtrs. src/cpu/o3/alpha_dyn_inst_impl.hh: Fixes to get compiling to work. Pass in the packet to the completeAcc function. Fix up syscall function. --HG-- rename : cpu/activity.cc => src/cpu/activity.cc rename : cpu/activity.hh => src/cpu/activity.hh rename : cpu/checker/cpu.cc => src/cpu/checker/cpu.cc rename : cpu/checker/cpu.hh => src/cpu/checker/cpu.hh rename : cpu/checker/cpu_builder.cc => src/cpu/checker/cpu_builder.cc rename : cpu/checker/exec_context.hh => src/cpu/checker/exec_context.hh rename : cpu/checker/o3_cpu_builder.cc => src/cpu/checker/o3_cpu_builder.cc rename : cpu/o3/dep_graph.hh => src/cpu/o3/dep_graph.hh rename : cpu/o3/fu_pool.cc => src/cpu/o3/fu_pool.cc rename : cpu/o3/fu_pool.hh => src/cpu/o3/fu_pool.hh rename : cpu/o3/lsq.cc => src/cpu/o3/lsq.cc rename : cpu/o3/lsq.hh => src/cpu/o3/lsq.hh rename : cpu/o3/lsq_impl.hh => src/cpu/o3/lsq_impl.hh rename : cpu/o3/lsq_unit.cc => src/cpu/o3/lsq_unit.cc rename : cpu/o3/lsq_unit.hh => src/cpu/o3/lsq_unit.hh rename : cpu/o3/lsq_unit_impl.hh => src/cpu/o3/lsq_unit_impl.hh rename : cpu/o3/scoreboard.cc => src/cpu/o3/scoreboard.cc rename : cpu/o3/scoreboard.hh => src/cpu/o3/scoreboard.hh rename : cpu/o3/thread_state.hh => src/cpu/o3/thread_state.hh rename : cpu/ozone/back_end.cc => src/cpu/ozone/back_end.cc rename : cpu/ozone/back_end.hh => src/cpu/ozone/back_end.hh rename : cpu/ozone/back_end_impl.hh => src/cpu/ozone/back_end_impl.hh rename : cpu/ozone/cpu_builder.cc => src/cpu/ozone/cpu_builder.cc rename : cpu/ozone/dyn_inst.cc => src/cpu/ozone/dyn_inst.cc rename : cpu/ozone/dyn_inst.hh => src/cpu/ozone/dyn_inst.hh rename : cpu/ozone/dyn_inst_impl.hh => src/cpu/ozone/dyn_inst_impl.hh rename : cpu/ozone/front_end.cc => src/cpu/ozone/front_end.cc rename : cpu/ozone/front_end.hh => src/cpu/ozone/front_end.hh rename : cpu/ozone/front_end_impl.hh => src/cpu/ozone/front_end_impl.hh rename : cpu/ozone/inorder_back_end.cc => src/cpu/ozone/inorder_back_end.cc rename : cpu/ozone/inorder_back_end.hh => src/cpu/ozone/inorder_back_end.hh rename : cpu/ozone/inorder_back_end_impl.hh => src/cpu/ozone/inorder_back_end_impl.hh rename : cpu/ozone/inst_queue.cc => src/cpu/ozone/inst_queue.cc rename : cpu/ozone/inst_queue.hh => src/cpu/ozone/inst_queue.hh rename : cpu/ozone/inst_queue_impl.hh => src/cpu/ozone/inst_queue_impl.hh rename : cpu/ozone/lsq_unit.cc => src/cpu/ozone/lsq_unit.cc rename : cpu/ozone/lsq_unit.hh => src/cpu/ozone/lsq_unit.hh rename : cpu/ozone/lsq_unit_impl.hh => src/cpu/ozone/lsq_unit_impl.hh rename : cpu/ozone/lw_back_end.cc => src/cpu/ozone/lw_back_end.cc rename : cpu/ozone/lw_back_end.hh => src/cpu/ozone/lw_back_end.hh rename : cpu/ozone/lw_back_end_impl.hh => src/cpu/ozone/lw_back_end_impl.hh rename : cpu/ozone/lw_lsq.cc => src/cpu/ozone/lw_lsq.cc rename : cpu/ozone/lw_lsq.hh => src/cpu/ozone/lw_lsq.hh rename : cpu/ozone/lw_lsq_impl.hh => src/cpu/ozone/lw_lsq_impl.hh rename : cpu/ozone/null_predictor.hh => src/cpu/ozone/null_predictor.hh rename : cpu/ozone/ozone_impl.hh => src/cpu/ozone/ozone_impl.hh rename : cpu/ozone/rename_table.cc => src/cpu/ozone/rename_table.cc rename : cpu/ozone/rename_table.hh => src/cpu/ozone/rename_table.hh rename : cpu/ozone/rename_table_impl.hh => src/cpu/ozone/rename_table_impl.hh rename : cpu/ozone/simple_impl.hh => src/cpu/ozone/simple_impl.hh rename : cpu/ozone/simple_params.hh => src/cpu/ozone/simple_params.hh rename : cpu/ozone/thread_state.hh => src/cpu/ozone/thread_state.hh rename : cpu/quiesce_event.cc => src/cpu/quiesce_event.cc rename : cpu/quiesce_event.hh => src/cpu/quiesce_event.hh rename : cpu/thread_state.hh => src/cpu/thread_state.hh rename : python/m5/objects/FUPool.py => src/python/m5/objects/FUPool.py rename : python/m5/objects/OzoneCPU.py => src/python/m5/objects/OzoneCPU.py rename : python/m5/objects/SimpleOzoneCPU.py => src/python/m5/objects/SimpleOzoneCPU.py extra : convert_revision : ca7f0fbf65ee1a70d482fb4eda9a1840c7f9b8f8 | |||
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