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2018-03-26arch: Fix all override related warnings.Gabe Black
Clang has started(?) reporting override related warnings, something gcc apparently did before, but was disabled in the SConstruct. Rather than disable the warnings in for clang as well, this change fixes the warnings. A future change will re-enable the warnings for gcc. Change-Id: I3cc79e45749b2ae0f9bebb1acadc56a3d3a942da Reviewed-on: https://gem5-review.googlesource.com/9343 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Gabe Black <gabeblack@google.com>
2018-03-26arch: Add a virtual asBytes function to the StaticInst class.Gabe Black
This function takes a pointer to a buffer and the current size of the buffer as a pass by reference argument. If the size of the buffer is sufficient, the function stores a binary representation of itself (generally the ISA defined instruction encoding) in the buffer, and sets the size argument to how much space it used. This could be used by ISAs which have two instruction sizes (ARM and thumb, for example). If the buffer size isn't sufficient, then the size parameter should be set to what size is required, and then the function should return without modifying the buffer. The buffer itself should be aligned to the same standard as memory returned by new, specifically "The pointer returned shall be suitably aligned so that it can be converted to a pointer of any complete object type and then used to access the object or array in the storage allocated...". This will avoid having to memcpy buffers to avoid unaligned accesses. To standardize the representation of the data, it should be stored in the buffer as little endian. Since most hosts (including ARM and x86 hosts) will be little endian, this will almost always be a no-op. Change-Id: I2f31aa0b4f9c0126b44f47a881c2901243279bd6 Reviewed-on: https://gem5-review.googlesource.com/7562 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Gabe Black <gabeblack@google.com>
2018-01-10style: change C/C++ source permissions to noexecBKP
Several files in the repository were tracked with execute permissions even though the files are just normal C/C++ files (and the one .isa). Change-Id: I976b096acab4a1fc74c5699ef1f9b222c1e635c2 Reviewed-on: https://gem5-review.googlesource.com/7241 Reviewed-by: Gabe Black <gabeblack@google.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-12-22arch,cpu: "virtualize" the TLB interface.Gabe Black
CPUs have historically instantiated the architecture specific version of the TLBs to avoid a virtual function call, making them a little bit more dependent on what the current ISA is. Some simple performance measurement, the x86 twolf regression on the atomic CPU, shows that there isn't actually any performance benefit, and if anything the simulator goes slightly faster (although still within margin of error) when the TLB functions are virtual. This change switches everything outside of the architectures themselves to use the generic BaseTLB type, and then inside the ISA for them to cast that to their architecture specific type to call into architecture specific interfaces. The ARM TLB needed the most adjustment since it was using non-standard translation function signatures. Specifically, they all took an extra "type" parameter which defaulted to normal, and translateTiming returned a Fault. translateTiming actually doesn't need to return a Fault because everywhere that consumed it just stored it into a structure which it then deleted(?), and the fault is stored in the Translation object when the translation is done. A little more work is needed to fully obviate the arch/tlb.hh header, so the TheISA::TLB type is still visible outside of the ISAs. Specifically, the TlbEntry type is used in the generic PageTable which lives in src/mem. Change-Id: I51b68ee74411f9af778317eff222f9349d2ed575 Reviewed-on: https://gem5-review.googlesource.com/6921 Maintainer: Gabe Black <gabeblack@google.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-12-13cpu,alpha,mips,power,riscv,sparc: Get rid of eaComp and memAccInst.Gabe Black
Neither of these were used, particularly memAccInst. Change-Id: I4ac9e44cf624e5de42519d586d7b699f08a2cdfc Reviewed-on: https://gem5-review.googlesource.com/6601 Maintainer: Gabe Black <gabeblack@google.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
2017-11-07alpha,arm,mips,power,riscv,sparc,x86: Merge exec decl templates.Gabe Black
In the ISA instruction definitions, some classes were declared with execute, etc., functions outside of the main template because they had CPU specific signatures and would need to be duplicated with each CPU plugged into them. Now that the instructions always just use an ExecContext, there's no reason for those templates to be separate. This change folds those templates together. Change-Id: I13bda247d3d1cc07c0ea06968e48aa5b4aace7fa Reviewed-on: https://gem5-review.googlesource.com/5401 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Alec Roelke <ar4jc@virginia.edu> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-11-02alpha,arm,mips,power,riscv,sparc,x86,isa: De-specialize ExecContexts.Gabe Black
The ISA parser used to generate different copies of exec functions for each exec context class a particular CPU wanted to use. That's since been changed so that those functions take a pointer to the base ExecContext, so the code which would generate those extra functions can be removed, and some functions which used to be templated on an ExecContext subclass can be untemplated, or minimally less templated. Now that some functions aren't going to be instantiated multiple times with different signatures, there are also opportunities to collapse templates and make many instruction definitions simpler within the parser. Since those changes will be less mechanical, they're left for later changes and will probably be done in smaller increments. Change-Id: I0015307bb02dfb9c60380b56d2a820f12169ebea Reviewed-on: https://gem5-review.googlesource.com/5381 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-05cpu: Simplify the rename interface and use RegIdRekai Gonzalez-Alberquilla
With the hierarchical RegId there are a lot of functions that are redundant now. The idea behind the simplification is that instead of having the regId, telling which kind of register read/write/rename/lookup/etc. and then the function panic_if'ing if the regId is not of the appropriate type, we provide an interface that decides what kind of register to read depending on the register type of the given regId. Change-Id: I7d52e9e21fc01205ae365d86921a4ceb67a57178 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> [ Fix RISCV build issues ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2702
2017-07-05arch, cpu: Architectural Register structural indexingNathanael Premillieu
Replace the unified register mapping with a structure associating a class and an index. It is now much easier to know which class of register the index is referring to. Also, when adding a new class there is no need to modify existing ones. Change-Id: I55b3ac80763702aa2cd3ed2cbff0a75ef7620373 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> [ Fix RISCV build issues ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2700
2015-07-20syscall_emul: [patch 13/22] add system call retry capabilityBrandon Potter
This changeset adds functionality that allows system calls to retry without affecting thread context state such as the program counter or register values for the associated thread context (when system calls return with a retry fault). This functionality is needed to solve problems with blocking system calls in multi-process or multi-threaded simulations where information is passed between processes/threads. Blocking system calls can cause deadlock because the simulator itself is single threaded. There is only a single thread servicing the event queue which can cause deadlock if the thread hits a blocking system call instruction. To illustrate the problem, consider two processes using the producer/consumer sharing model. The processes can use file descriptors and the read and write calls to pass information to one another. If the consumer calls the blocking read system call before the producer has produced anything, the call will block the event queue (while executing the system call instruction) and deadlock the simulation. The solution implemented in this changeset is to recognize that the system calls will block and then generate a special retry fault. The fault will be sent back up through the function call chain until it is exposed to the cpu model's pipeline where the fault becomes visible. The fault will trigger the cpu model to replay the instruction at a future tick where the call has a chance to succeed without actually going into a blocking state. In subsequent patches, we recognize that a syscall will block by calling a non-blocking poll (from inside the system call implementation) and checking for events. When events show up during the poll, it signifies that the call would not have blocked and the syscall is allowed to proceed (calling an underlying host system call if necessary). If no events are returned from the poll, we generate the fault and try the instruction for the thread context at a distant tick. Note that retrying every tick is not efficient. As an aside, the simulator has some multi-threading support for the event queue, but it is not used by default and needs work. Even if the event queue was completely multi-threaded, meaning that there is a hardware thread on the host servicing a single simulator thread contexts with a 1:1 mapping between them, it's still possible to run into deadlock due to the event queue barriers on quantum boundaries. The solution of replaying at a later tick is the simplest solution and solves the problem generally.
2016-02-06style: remove trailing whitespaceSteve Reinhardt
Result of running 'hg m5style --skip-all --fix-white -a'.
2016-01-17cpu. arch: add initiateMemRead() to ExecContext interfaceSteve Reinhardt
For historical reasons, the ExecContext interface had a single function, readMem(), that did two different things depending on whether the ExecContext supported atomic memory mode (i.e., AtomicSimpleCPU) or timing memory mode (all the other models). In the former case, it actually performed a memory read; in the latter case, it merely initiated a read access, and the read completion did not happen until later when a response packet arrived from the memory system. This led to some confusing things, including timing accesses being required to provide a pointer for the return data even though that pointer was only used in atomic mode. This patch splits this interface, adding a new initiateMemRead() function to the ExecContext interface to replace the timing-mode use of readMem(). For consistency and clarity, the readMemTiming() helper function in the ISA definitions is renamed to initiateMemRead() as well. For x86, where the access size is passed in explicitly, we can also get rid of the data parameter at this level. For other ISAs, where the access size is determined from the type of the data parameter, we have to keep the parameter for that purpose.
2016-01-11scons: Enable -Wextra by defaultAndreas Hansson
Make best use of the compiler, and enable -Wextra as well as -Wall. There are a few issues that had to be resolved, but they are all trivial.
2014-10-16arch: Use shared_ptr for all FaultsAndreas Hansson
This patch takes quite a large step in transitioning from the ad-hoc RefCountingPtr to the c++11 shared_ptr by adopting its use for all Faults. There are no changes in behaviour, and the code modifications are mostly just replacing "new" with "make_shared".
2014-05-09arch: teach ISA parser how to split code across filesCurtis Dunham
This patch encompasses several interrelated and interdependent changes to the ISA generation step. The end goal is to reduce the size of the generated compilation units for instruction execution and decoding so that batch compilation can proceed with all CPUs active without exhausting physical memory. The ISA parser (src/arch/isa_parser.py) has been improved so that it can accept 'split [output_type];' directives at the top level of the grammar and 'split(output_type)' python calls within 'exec {{ ... }}' blocks. This has the effect of "splitting" the files into smaller compilation units. I use air-quotes around "splitting" because the files themselves are not split, but preprocessing directives are inserted to have the same effect. Architecturally, the ISA parser has had some changes in how it works. In general, it emits code sooner. It doesn't generate per-CPU files, and instead defers to the C preprocessor to create the duplicate copies for each CPU type. Likewise there are more files emitted and the C preprocessor does more substitution that used to be done by the ISA parser. Finally, the build system (SCons) needs to be able to cope with a dynamic list of source files coming out of the ISA parser. The changes to the SCons{cript,truct} files support this. In broad strokes, the targets requested on the command line are hidden from SCons until all the build dependencies are determined, otherwise it would try, realize it can't reach the goal, and terminate in failure. Since build steps (i.e. running the ISA parser) must be taken to determine the file list, several new build stages have been inserted at the very start of the build. First, the build dependencies from the ISA parser will be emitted to arch/$ISA/generated/inc.d, which is then read by a new SCons builder to finalize the dependencies. (Once inc.d exists, the ISA parser will not need to be run to complete this step.) Once the dependencies are known, the 'Environments' are made by the makeEnv() function. This function used to be called before the build began but now happens during the build. It is easy to see that this step is quite slow; this is a known issue and it's important to realize that it was already slow, but there was no obvious cause to attribute it to since nothing was displayed to the terminal. Since new steps that used to be performed serially are now in a potentially-parallel build phase, the pathname handling in the SCons scripts has been tightened up to deal with chdir() race conditions. In general, pathnames are computed earlier and more likely to be stored, passed around, and processed as absolute paths rather than relative paths. In the end, some of these issues had to be fixed by inserting serializing dependencies in the build. Minor note: For the null ISA, we just provide a dummy inc.d so SCons is never compelled to try to generate it. While it seems slightly wrong to have anything in src/arch/*/generated (i.e. a non-generated 'generated' file), it's by far the simplest solution.
2014-05-09arch: remove inline specifiers on all inst constrs, all ISAsCurtis Dunham
With (upcoming) separate compilation, they are useless. Only link-time optimization could re-inline them, but ideally feedback-directed optimization would choose to do so only for profitable (i.e. common) instructions.
2013-12-29mips: Floating point convert bug fixChristopher Torng
In mips architecture, floating point convert instructions use the FloatConvertOp format defined in src/arch/mips/isa/formats/fp.isa. The type of the operands in the ISA description file (_sw for signed word, or _sf for signed float, etc.) is used to create a type for the operand in C++. Then the operand is converted using the fpConvert() function in src/arch/mips/utility.cc. If we are converting from a word to a float, and we want to convert 0xffffffff, we expect -1 to be passed into fpConvert(). Instead, we see MAX_INT passed in. Then fpConvert() converts _val_ to MAX_INT in single-precision floating point, and we get the wrong value. To fix it, the signs of the convert operands are being changed from unsigned to signed in the MIPS ISA description. Then, the FloatConvertOp format is being changed to insert a int32_t into the C++ code instead of a uint32_t. Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2013-10-15cpu: rename *_DepTag constants to *_Reg_BaseSteve Reinhardt
Make these names more meaningful. Specifically, made these substitutions: s/FP_Base_DepTag/FP_Reg_Base/g; s/Ctrl_Base_DepTag/Misc_Reg_Base/g; s/Max_DepTag/Max_Reg_Index/g;
2013-02-19scons: Add warning for missing declarationsAndreas Hansson
This patch enables warnings for missing declarations. To avoid issues with SWIG-generated code, the warning is only applied to non-SWIG code.
2013-02-19scons: Add warning for overloaded virtual functionsAndreas Hansson
A derived function with a different signature than a base class function will result in the base class function of the same name being hidden. The parameter list and return type for the member function in the derived class must match those of the member function in the base class, otherwise the function in the derived class will hide the function in the base class and no polymorphic behaviour will occur. This patch addresses these warnings by ensuring a unique function name to avoid (unintentionally) hiding any functions.
2012-05-25ISA: Make the decode function part of the ISA's decoder.Gabe Black
2012-04-14clang/gcc: Fix compilation issues with clang 3.0 and gcc 4.6Andreas Hansson
This patch addresses a number of minor issues that cause problems when compiling with clang >= 3.0 and gcc >= 4.6. Most importantly, it avoids using the deprecated ext/hash_map and instead uses unordered_map (and similarly so for the hash_set). To make use of the new STL containers, g++ and clang has to be invoked with "-std=c++0x", and this is now added for all gcc versions >= 4.6, and for clang >= 3.0. For gcc >= 4.3 and <= 4.5 and clang <= 3.0 we use the tr1 unordered_map to avoid the deprecation warning. The addition of c++0x in turn causes a few problems, as the compiler is more stringent and adds a number of new warnings. Below, the most important issues are enumerated: 1) the use of namespaces is more strict, e.g. for isnan, and all headers opening the entire namespace std are now fixed. 2) another other issue caused by the more stringent compiler is the narrowing of the embedded python, which used to be a char array, and is now unsigned char since there were values larger than 128. 3) a particularly odd issue that arose with the new c++0x behaviour is found in range.hh, where the operator< causes gcc to complain about the template type parsing (the "<" is interpreted as the beginning of a template argument), and the problem seems to be related to the begin/end members introduced for the range-type iteration, which is a new feature in c++11. As a minor update, this patch also fixes the build flags for the clang debug target that used to be shared with gcc and incorrectly use "-ggdb".
2012-03-19clang: Fix recently introduced clang compilation errorsAndreas Hansson
This patch makes the code compile with clang 2.9 and 3.0 again by making two very minor changes. Firt, it maintains a strict typing in the forward declaration of the BaseCPUParams. Second, it adds a FullSystemInt flag of the type unsigned int next to the boolean FullSystem flag. The FullSystemInt variable can be used in decode-statements (expands to switch statements) in the instruction decoder.
2012-01-28MIPS: Fix a compiler warning from the eret instruction.Gabe Black
2012-01-16Merge yet again with the main repository.Gabe Black
2012-01-12mips: Fix decoder of two float-convert instructionsDeyuan Guo
2012-01-07Merge with main repository.Gabe Black
2011-10-31GCC: Get everything working with gcc 4.6.1.Gabe Black
And by "everything" I mean all the quick regressions.
2011-09-30SE/FS: Use the new FullSystem constant where possible.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.
2011-09-19MIPS: Get rid of cruft in the fault classes.Gabe Black
Get rid of Fault classes left over from when this file was copied from Alpha, and rename ArithmeticOverflowFault to be IntegerOverflowFault and get rid of the old IntegerOverflowFault stub. The Integer version is what's actually in the manual, but the Arithmetic version had the implementation.
2011-09-19MIPS: Get rid of #if style config checks in the ISA description.Gabe Black
2011-07-05ISA parser: Define operand types with a ctype directly.Gabe Black
2011-07-02ISA: Use readBytes/writeBytes for all instruction level memory operations.Gabe Black
2011-06-22mips: fix nmsub and nmadd definitionsDeyaun Guo
the -/+ signs were flipped for nmsub_s, nmsub_d, and nmadd_d
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
2011-02-12inorder: remove unused isa opsKorey Sewell
pass/fail ops were used for testing but arent part of isa
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.
2010-12-20Style: Replace some tabs with spaces.Gabe Black
2010-12-08MIPS: 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.
2010-10-22ISA: Simplify various implementations of completeAcc.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.
2010-03-23cpu: 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.
2009-12-31MIPS: Implement the SE mode version of rdhwr.Gabe Black
2009-12-31MIPS: Fix decoding of the rdhwr instruction.Gabe Black
2009-12-31MIPS: Create an artificial control register to hold the thread pointer.Gabe Black
In Linux, the set_thread_area system call stores the address of the thread local storage area into a field of the current thread_info structure. Later, to access that value, the program uses the rdhwr instruction to read a "hardware register" with index 29. The 64 bit MIPS manual, volume II, says that index 29 is reserved for a future ABI extension and should cause a "Reserved Instruction Exception". In Linux (and potentially other ISAs) that exception is trapped and emulated to return the value stored by set_thread_area as if that were actually stored by a physical register. The tp_value address (as named in the Linux kernel) is ironically stored as a control register so that it goes with a particular ThreadContext. Syscall emulation will use that to emulate storing to the OS's thread info structure, and rdhwr will emulate faulting and returning that value from software by returning the value itself, as if it was in hardware. In other words, we fake faking the register in SE mode. In an FS mode implementation it should work as specified in the manual.
2009-11-10Mem: Eliminate the NO_FAULT request flag.Gabe Black