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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.
2010-10-29X86: Fault on divide by zero instead of panicing.Gabe Black
2010-10-29X86: Make syscalls also serialize after.Gabe Black
2010-10-22X86: Make nop a regular, non-microcoded instruction.Gabe Black
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. --HG-- rename : src/arch/x86/isa/formats/syscall.isa => src/arch/x86/isa/formats/nop.isa
2010-10-22X86: Implement genMachineCheckFault.Gabe Black
Even though this shouldn't ever be used, it might get called speculatively and shouldn't panic.
2010-10-22X86: Make syscall instructions non-speculative in SE.Gabe Black
2010-10-22ISA: Simplify various implementations of completeAcc.Gabe Black
2010-10-22ARM: Don't pretend to writeback registers in initiateAcc.Gabe Black
2010-10-16Mem: Reclaim some request flags used by MIPS for alignment checking.Gabe Black
These flags were being used to identify what alignment a request needed, but the same information is available using the request size. This change also eliminates the isMisaligned function. If more complicated alignment checks are needed, they can be signaled using the ASI_BITS space in the flags vector like is currently done with ARM.
2010-10-15GetArgument: Rework getArgument so that X86_FS compiles again.Gabe Black
When no size is specified for an argument, push the decision about what size to use into the ISA by passing a size of -1.
2010-10-14SPARC: Get rid of the copy/pasted StackTrace stolen from Alpha.Gabe Black
2010-10-13Mem: Change the CLREX flag to CLEAR_LL.Gabe Black
CLREX is the name of an ARM instruction, not a name for this generic flag.
2010-10-10X86: Detect attempts to load a 32 bit kernel and panic.Gabe Black
2010-10-10SPARC: Make SPARC's ISA's clear function initialize everything it should.Gabe Black
Also make it not set some pointers to NULL potentially introducing a memory leak. That should be done in the constructor.
2010-10-10Alpha: Force all the IPRs to an initial, determinstic value when cleared.Gabe Black
2010-10-10Alpha: Initialize the data TLB mode IPR.Gabe Black
2010-10-04Alpha: Fix Alpha NumMiscArchRegs constant.Gabe Black
Also add asserts in O3's Scoreboard class to catch bad indexes.
2010-10-01Power: Fix compile error from previous push.Ali Saidi
2010-10-01ARM: Make the TLB a little bit faster by moving most recently used items to ↵Ali Saidi
front of list
2010-10-01ARM: Implement functional virtual to physical address translationAli Saidi
for debugging and program introspection.
2010-10-01Debug: Implement getArgument() and function skipping for ARM.Ali Saidi
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.
2010-10-01ARM: Clean up use of TBit and JBit.Ali Saidi
Rather tha constantly using ULL(1) << PcXBitShift define those directly. Additionally, add some helper functions to further clean up the code.
2010-09-29X86: Fix the RIP relative versions of the BT, BTC, BTR, and BTS instructions.Gabe Black
2010-09-14X86: Make the halt microop non-speculative.Gabe Black
Executing this microop makes the CPU halt even if it was misspeculated.
2010-09-14X86: Make unrecognized instructions behave better in x86.Gabe Black
2010-09-14CPU: Trim unnecessary includes from some common files.Gabe Black
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.
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.
2010-09-10style: fix sorting of includes and whitespace in some filesNathan Binkert
2010-08-31ARM: Get rid of the checkFpEnableFault function in ARM.Gabe Black
2010-08-31Alpha: Alpha's mt.hh was including mips header files.Gabe Black
2010-08-27X86: Change the copyright holder to AMD.Gabe Black
I accidentally left myself as a placeholder copyright holder on this file when I checked it in. Copyright should be assigned to AMD.
2010-08-25ARM: Support unaligned memory access.Min Kyu Jeong
Without this flag set, page-crossing requests were not split into two mem request. Depending on the alignment bit in the SCTLR, misaligned access could raise a fault. However it seems unnecessary to implement that.
2010-08-25ARM: Seperate the queues of L1 and L2 walker states.Gene WU
2010-08-25ARM: Adding a bogus fault that does nothing.Min Kyu Jeong
This fault can used to flush the pipe, not including the faulting instruction. The particular case I needed this was for a self-modifying code. It needed to drain the store queue and force the following instruction to refetch from icache. DCCMVAC cp15 mcr instruction is modified to raise this fault.
2010-08-25ARM: Remove ALPHA KSeg functions.William Wang
These were erronously copied years ago into the ARM directory.
2010-08-25ARM: Limited implementation of dprintk.Ali Saidi
Does not work with vfp arguments or arguments passed on the stack.
2010-08-25ARM: Fixed register flattening logic (FP_Base_DepTag was set too low)Min Kyu Jeong
When decoding a srs instruction, invalid mode encoding returns invalid instruction. This can happen when garbage instructions are fetched from mispredicted path
2010-08-25ARM: Make VMSR, RFE PC/LR etc non speculative, and serializingAli Saidi
2010-08-25ARM: Use fewer micro-ops for register update loads if possible.Gene WU
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.
2010-08-25ARM: Set the high bits in the part number so it's considered new by some code.Ali Saidi
2010-08-25ARM: Fix VFP enabled checks for mem instructionsAli Saidi
2010-08-25ARM: Seperate out the renamable bits in the FPSCR.Gabe Black
2010-08-25ARM: Eliminate some unused enums.Gabe Black
2010-08-25ARM: Fix type comparison warnings in Neon.Gabe Black
2010-08-25ARM: Implement CPACR register and return Undefined Instruction when FP ↵Gabe Black
access is disabled.
2010-08-25ARM: Implement all ARM SIMD instructions.Gabe Black
2010-08-25ARM: Expand the mode checking utility functions.Gabe Black
inUserMode now can take either a threadcontext or a CPSR value directly. If given a thread context it just extracts the CPSR and calls the other version. An inPrivelegedMode function was also implemented which just returns the opposite of inUserMode.
2010-08-23X86: Create a directory for files that define register indexes.Gabe Black
This is to help tidy up arch/x86. These files should not be used external to the ISA. --HG-- rename : src/arch/x86/apicregs.hh => src/arch/x86/regs/apic.hh rename : src/arch/x86/floatregs.hh => src/arch/x86/regs/float.hh rename : src/arch/x86/intregs.hh => src/arch/x86/regs/int.hh rename : src/arch/x86/miscregs.hh => src/arch/x86/regs/misc.hh rename : src/arch/x86/segmentregs.hh => src/arch/x86/regs/segment.hh
2010-08-23Power: Get rid of unused checkFpEnableFault.Gabe Black
This function was brought in from another ISA and doesn't actually do anything or get used.
2010-08-23ISA: Get rid of old, unused utility functions cluttering up the ISAs.Gabe Black