summaryrefslogtreecommitdiff
path: root/src/arch/arm/isa/insts/ldr.isa
AgeCommit message (Collapse)Author
2015-06-09arm: Fix typo in ldrsh instruction nameRune Holm
ldrsh was typoed as hdrsh, which is a bit annoying when printing instructions. This patch fixes it.
2014-01-24arm: Add support for ARMv8 (AArch64 & AArch32)ARM gem5 Developers
Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64 kernel you are restricted to AArch64 user-mode binaries. This will be addressed in a later patch. Note: Virtualization is only supported in AArch32 mode. This will also be fixed in a later patch. Contributors: Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation) Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation) Mbou Eyole (AArch64 NEON, validation) Ali Saidi (AArch64 Linux support, code integration, validation) Edmund Grimley-Evans (AArch64 FP) William Wang (AArch64 Linux support) Rene De Jong (AArch64 Linux support, performance opt.) Matt Horsnell (AArch64 MP, validation) Matt Evans (device models, code integration, validation) Chris Adeniyi-Jones (AArch64 syscall-emulation) Prakash Ramrakhyani (validation) Dam Sunwoo (validation) Chander Sudanthi (validation) Stephan Diestelhorst (validation) Andreas Hansson (code integration, performance opt.) Eric Van Hensbergen (performance opt.) Gabe Black
2011-09-26ISA parser: Use '_' instead of '.' to delimit type modifiers on operands.Gabe Black
By using an underscore, the "." is still available and can unambiguously be used to refer to members of a structure if an operand is a structure, class, etc. This change mostly just replaces the appropriate "."s with "_"s, but there were also a few places where the ISA descriptions where handling the extensions themselves and had their own regular expressions to update. The regular expressions in the isa parser were updated as well. It also now looks for one of the defined type extensions specifically after connecting "_" where before it would look for any sequence of characters after a "." following an operand name and try to use it as the extension. This helps to disambiguate cases where a "_" may legitimately be part of an operand name but not separate the name from the type suffix. Because leaving the "_" and suffix on the variable name still leaves a valid C++ identifier and all extensions need to be consistent in a given context, I considered leaving them on as a breadcrumb that would show what the intended type was for that operand. Unfortunately the operands can be referred to in code templates, the Mem operand in particular, and since the exact type of Mem can be different for different uses of the same template, that broke things.
2011-05-13ARM: Construct the predicate test register for more instruction programatically.Ali Saidi
If one of the condition codes isn't being used in the execution we should only read it if the instruction might be dependent on it. With the preeceding changes there are several more cases where we should dynamically pick instead of assuming as we did before.
2011-05-13ARM: Further break up condition code into NZ, C, V bits.Ali Saidi
Break up the condition code bits into NZ, C, V registers. These are individually written and this removes some incorrect dependencies between instructions.
2011-05-13ARM: Remove the saturating (Q) condition code from the renamed register.Ali Saidi
Move the saturating bit (which is also saturating) from the renamed register that holds the flags to the CPSR miscreg and adds a allows setting it in a similar way to the FP saturating registers. This removes a dependency in instructions that don't write, but need to preserve the Q bit.
2011-05-13ARM: Break up condition codes into normal flags, saturation, and simd.Ali Saidi
This change splits out the condcodes from being one monolithic register into three blocks that are updated independently. This allows CPUs to not have to do RMW operations on the flags registers for instructions that don't write all flags.
2011-04-04ARM: Tag appropriate instructions as IsReturnAli Saidi
2011-03-17ARM: Fix RFE macrop.Matt Horsnell
This changes the RFE macroop into 3 microops: URa = [sp]; URb = [sp+4]; // load CPSR,PC values from stack sp = sp + offset; // optionally auto-increment PC = URa; CPSR = URb; // write to the PC and CPSR. Importantly: - writing to PC is handled in the last micro-op. - loading occurs prior to state changes.
2011-01-18O3: Fix itstate prediction and recovery.Matt Horsnell
Any change of control flow now resets the itstate to 0 mask and 0 condition, except where the control flow alteration write into the cpsr register. These case, for example return from an iterrupt, require the predecoder to recover the itstate. As there is a window of opportunity between the return from an interrupt changing the control flow at the head of the pipe and the commit of the update to the CPSR, the predecoder needs to be able to grab the ITstate early. This is now handled by setting the forcedItState inside a PCstate for the control flow altering instruction. That instruction will have the correct mask/cond, but will not have a valid itstate until advancePC is called (note this happens to advance the execution). When the new PCstate is copy constructed it gets the itstate cond/mask, and upon advancing the PC the itstate becomes valid. Subsequent advancing invalidates the state and zeroes the cond/mask. This is handled in isolation for the ARM ISA and should have no impact on other ISAs. Refer arch/arm/types.hh and arch/arm/predecoder.cc for the details.
2010-12-09ARM: Take advantage of new PCState syntax.Gabe Black
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.
2010-08-25ARM: 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: Fix VFP enabled checks for mem instructionsAli Saidi
2010-08-23ARM: Exclusive accesses must be double word alignedAli Saidi
2010-08-23ARM: Clean up the ISA desc portion of the ARM memory instructions.Gabe Black
2010-06-02ARM: Implement the ARM TLB/Tablewalker. Needs performance improvements.Ali Saidi
2010-06-02ARM: Implement ARM CPU interruptsAli Saidi
2010-06-02ARM: Implement the VLDR instruction.Gabe Black
2010-06-02ARM: Implement the strex instructions.Gabe Black
2010-06-02ARM: Respect the E bit of the CPSR when doing loads and stores.Gabe Black
2010-06-02ARM: Implement the V7 version of alignment checking.Gabe Black
2010-06-02ARM: Implement the RFE instruction.Gabe Black
2010-06-02ARM: Explicitly keep track of the second destination for double loads/stores.Gabe Black
2010-06-02ARM: Implement the ldrex instruction.Gabe Black
2010-06-02ARM: Implemented prefetch instructions/decoding (pli, pld, pldw).Gabe Black
2010-06-02ARM: Make ldrs into the PC and ldm exception return do interworking branches.Gabe Black
2010-06-02ARM: Remove the special naming for the new memory instructions.Gabe Black
These are the only memory instructions now.
2010-06-02ARM: Pull double memory instructions out of the decoder.Gabe Black
2010-06-02ARM: Define the load instructions from outside the decoder.Gabe Black