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Diffstat (limited to 'cpu/ozone/lsq_unit.hh')
| -rw-r--r-- | cpu/ozone/lsq_unit.hh | 637 |
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diff --git a/cpu/ozone/lsq_unit.hh b/cpu/ozone/lsq_unit.hh deleted file mode 100644 index 4b600af67..000000000 --- a/cpu/ozone/lsq_unit.hh +++ /dev/null @@ -1,637 +0,0 @@ -/* - * Copyright (c) 2004-2005 The Regents of The University of Michigan - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer; - * redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution; - * neither the name of the copyright holders nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -#ifndef __CPU_OZONE_LSQ_UNIT_HH__ -#define __CPU_OZONE_LSQ_UNIT_HH__ - -#include <map> -#include <queue> -#include <algorithm> - -#include "arch/faults.hh" -#include "arch/isa_traits.hh" -#include "config/full_system.hh" -#include "base/hashmap.hh" -#include "cpu/inst_seq.hh" -#include "mem/mem_interface.hh" -//#include "mem/page_table.hh" -#include "sim/sim_object.hh" - -class PageTable; - -/** - * Class that implements the actual LQ and SQ for each specific thread. - * Both are circular queues; load entries are freed upon committing, while - * store entries are freed once they writeback. The LSQUnit tracks if there - * are memory ordering violations, and also detects partial load to store - * forwarding cases (a store only has part of a load's data) that requires - * the load to wait until the store writes back. In the former case it - * holds onto the instruction until the dependence unit looks at it, and - * in the latter it stalls the LSQ until the store writes back. At that - * point the load is replayed. - */ -template <class Impl> -class OzoneLSQ { - public: - typedef typename Impl::Params Params; - typedef typename Impl::FullCPU FullCPU; - typedef typename Impl::BackEnd BackEnd; - typedef typename Impl::DynInstPtr DynInstPtr; - typedef typename Impl::IssueStruct IssueStruct; - - typedef TheISA::IntReg IntReg; - - typedef typename std::map<InstSeqNum, DynInstPtr>::iterator LdMapIt; - - private: - class StoreCompletionEvent : public Event { - public: - /** Constructs a store completion event. */ - StoreCompletionEvent(int store_idx, Event *wb_event, OzoneLSQ *lsq_ptr); - - /** Processes the store completion event. */ - void process(); - - /** Returns the description of this event. */ - const char *description(); - - private: - /** The store index of the store being written back. */ - int storeIdx; - /** The writeback event for the store. Needed for store - * conditionals. - */ - Event *wbEvent; - /** The pointer to the LSQ unit that issued the store. */ - OzoneLSQ<Impl> *lsqPtr; - }; - - friend class StoreCompletionEvent; - - public: - /** Constructs an LSQ unit. init() must be called prior to use. */ - OzoneLSQ(); - - /** Initializes the LSQ unit with the specified number of entries. */ - void init(Params *params, unsigned maxLQEntries, - unsigned maxSQEntries, unsigned id); - - /** Returns the name of the LSQ unit. */ - std::string name() const; - - /** Sets the CPU pointer. */ - void setCPU(FullCPU *cpu_ptr) - { cpu = cpu_ptr; } - - /** Sets the back-end stage pointer. */ - void setBE(BackEnd *be_ptr) - { be = be_ptr; } - - /** Sets the page table pointer. */ - void setPageTable(PageTable *pt_ptr); - - /** Ticks the LSQ unit, which in this case only resets the number of - * used cache ports. - * @todo: Move the number of used ports up to the LSQ level so it can - * be shared by all LSQ units. - */ - void tick() { usedPorts = 0; } - - /** Inserts an instruction. */ - void insert(DynInstPtr &inst); - /** Inserts a load instruction. */ - void insertLoad(DynInstPtr &load_inst); - /** Inserts a store instruction. */ - void insertStore(DynInstPtr &store_inst); - - /** Executes a load instruction. */ - Fault executeLoad(DynInstPtr &inst); - - Fault executeLoad(int lq_idx); - /** Executes a store instruction. */ - Fault executeStore(DynInstPtr &inst); - - /** Commits the head load. */ - void commitLoad(); - /** Commits a specific load, given by the sequence number. */ - void commitLoad(InstSeqNum &inst); - /** Commits loads older than a specific sequence number. */ - void commitLoads(InstSeqNum &youngest_inst); - - /** Commits stores older than a specific sequence number. */ - void commitStores(InstSeqNum &youngest_inst); - - /** Writes back stores. */ - void writebackStores(); - - // @todo: Include stats in the LSQ unit. - //void regStats(); - - /** Clears all the entries in the LQ. */ - void clearLQ(); - - /** Clears all the entries in the SQ. */ - void clearSQ(); - - /** Resizes the LQ to a given size. */ - void resizeLQ(unsigned size); - - /** Resizes the SQ to a given size. */ - void resizeSQ(unsigned size); - - /** Squashes all instructions younger than a specific sequence number. */ - void squash(const InstSeqNum &squashed_num); - - /** Returns if there is a memory ordering violation. Value is reset upon - * call to getMemDepViolator(). - */ - bool violation() { return memDepViolator; } - - /** Returns the memory ordering violator. */ - DynInstPtr getMemDepViolator(); - - /** Returns if a load became blocked due to the memory system. It clears - * the bool's value upon this being called. - */ - inline bool loadBlocked(); - - /** Returns the number of free entries (min of free LQ and SQ entries). */ - unsigned numFreeEntries(); - - /** Returns the number of loads ready to execute. */ - int numLoadsReady(); - - /** Returns the number of loads in the LQ. */ - int numLoads() { return loads; } - - /** Returns the number of stores in the SQ. */ - int numStores() { return stores; } - - /** Returns if either the LQ or SQ is full. */ - bool isFull() { return lqFull() || sqFull(); } - - /** Returns if the LQ is full. */ - bool lqFull() { return loads >= (LQEntries - 1); } - - /** Returns if the SQ is full. */ - bool sqFull() { return stores >= (SQEntries - 1); } - - /** Debugging function to dump instructions in the LSQ. */ - void dumpInsts(); - - /** Returns the number of instructions in the LSQ. */ - unsigned getCount() { return loads + stores; } - - /** Returns if there are any stores to writeback. */ - bool hasStoresToWB() { return storesToWB; } - - /** Returns the number of stores to writeback. */ - int numStoresToWB() { return storesToWB; } - - /** Returns if the LSQ unit will writeback on this cycle. */ - bool willWB() { return storeQueue[storeWBIdx].canWB && - !storeQueue[storeWBIdx].completed && - !dcacheInterface->isBlocked(); } - - private: - /** Completes the store at the specified index. */ - void completeStore(int store_idx); - - /** Increments the given store index (circular queue). */ - inline void incrStIdx(int &store_idx); - /** Decrements the given store index (circular queue). */ - inline void decrStIdx(int &store_idx); - /** Increments the given load index (circular queue). */ - inline void incrLdIdx(int &load_idx); - /** Decrements the given load index (circular queue). */ - inline void decrLdIdx(int &load_idx); - - private: - /** Pointer to the CPU. */ - FullCPU *cpu; - - /** Pointer to the back-end stage. */ - BackEnd *be; - - /** Pointer to the D-cache. */ - MemInterface *dcacheInterface; - - /** Pointer to the page table. */ - PageTable *pTable; - - public: - struct SQEntry { - /** Constructs an empty store queue entry. */ - SQEntry() - : inst(NULL), req(NULL), size(0), data(0), - canWB(0), committed(0), completed(0) - { } - - /** Constructs a store queue entry for a given instruction. */ - SQEntry(DynInstPtr &_inst) - : inst(_inst), req(NULL), size(0), data(0), - canWB(0), committed(0), completed(0) - { } - - /** The store instruction. */ - DynInstPtr inst; - /** The memory request for the store. */ - MemReqPtr req; - /** The size of the store. */ - int size; - /** The store data. */ - IntReg data; - /** Whether or not the store can writeback. */ - bool canWB; - /** Whether or not the store is committed. */ - bool committed; - /** Whether or not the store is completed. */ - bool completed; - }; - - enum Status { - Running, - Idle, - DcacheMissStall, - DcacheMissSwitch - }; - - private: - /** The OzoneLSQ thread id. */ - unsigned lsqID; - - /** The status of the LSQ unit. */ - Status _status; - - /** The store queue. */ - std::vector<SQEntry> storeQueue; - - /** The load queue. */ - std::vector<DynInstPtr> loadQueue; - - // Consider making these 16 bits - /** The number of LQ entries. */ - unsigned LQEntries; - /** The number of SQ entries. */ - unsigned SQEntries; - - /** The number of load instructions in the LQ. */ - int loads; - /** The number of store instructions in the SQ (excludes those waiting to - * writeback). - */ - int stores; - /** The number of store instructions in the SQ waiting to writeback. */ - int storesToWB; - - /** The index of the head instruction in the LQ. */ - int loadHead; - /** The index of the tail instruction in the LQ. */ - int loadTail; - - /** The index of the head instruction in the SQ. */ - int storeHead; - /** The index of the first instruction that is ready to be written back, - * and has not yet been written back. - */ - int storeWBIdx; - /** The index of the tail instruction in the SQ. */ - int storeTail; - - /// @todo Consider moving to a more advanced model with write vs read ports - /** The number of cache ports available each cycle. */ - int cachePorts; - - /** The number of used cache ports in this cycle. */ - int usedPorts; - - //list<InstSeqNum> mshrSeqNums; - - //Stats::Scalar<> dcacheStallCycles; - Counter lastDcacheStall; - - /** Wire to read information from the issue stage time queue. */ - typename TimeBuffer<IssueStruct>::wire fromIssue; - - // Make these per thread? - /** Whether or not the LSQ is stalled. */ - bool stalled; - /** The store that causes the stall due to partial store to load - * forwarding. - */ - InstSeqNum stallingStoreIsn; - /** The index of the above store. */ - int stallingLoadIdx; - - /** Whether or not a load is blocked due to the memory system. It is - * cleared when this value is checked via loadBlocked(). - */ - bool isLoadBlocked; - - /** The oldest faulting load instruction. */ - DynInstPtr loadFaultInst; - /** The oldest faulting store instruction. */ - DynInstPtr storeFaultInst; - - /** The oldest load that caused a memory ordering violation. */ - DynInstPtr memDepViolator; - - // Will also need how many read/write ports the Dcache has. Or keep track - // of that in stage that is one level up, and only call executeLoad/Store - // the appropriate number of times. - - public: - /** Executes the load at the given index. */ - template <class T> - Fault read(MemReqPtr &req, T &data, int load_idx); - - /** Executes the store at the given index. */ - template <class T> - Fault write(MemReqPtr &req, T &data, int store_idx); - - /** Returns the index of the head load instruction. */ - int getLoadHead() { return loadHead; } - /** Returns the sequence number of the head load instruction. */ - InstSeqNum getLoadHeadSeqNum() - { - if (loadQueue[loadHead]) { - return loadQueue[loadHead]->seqNum; - } else { - return 0; - } - - } - - /** Returns the index of the head store instruction. */ - int getStoreHead() { return storeHead; } - /** Returns the sequence number of the head store instruction. */ - InstSeqNum getStoreHeadSeqNum() - { - if (storeQueue[storeHead].inst) { - return storeQueue[storeHead].inst->seqNum; - } else { - return 0; - } - - } - - /** Returns whether or not the LSQ unit is stalled. */ - bool isStalled() { return stalled; } -}; - -template <class Impl> -template <class T> -Fault -OzoneLSQ<Impl>::read(MemReqPtr &req, T &data, int load_idx) -{ - //Depending on issue2execute delay a squashed load could - //execute if it is found to be squashed in the same - //cycle it is scheduled to execute - assert(loadQueue[load_idx]); - - if (loadQueue[load_idx]->isExecuted()) { - panic("Should not reach this point with split ops!"); - - memcpy(&data,req->data,req->size); - - return NoFault; - } - - // Make sure this isn't an uncacheable access - // A bit of a hackish way to get uncached accesses to work only if they're - // at the head of the LSQ and are ready to commit (at the head of the ROB - // too). - // @todo: Fix uncached accesses. - if (req->flags & UNCACHEABLE && - (load_idx != loadHead || !loadQueue[load_idx]->readyToCommit())) { - - return TheISA::genMachineCheckFault(); - } - - // Check the SQ for any previous stores that might lead to forwarding - int store_idx = loadQueue[load_idx]->sqIdx; - - int store_size = 0; - - DPRINTF(OzoneLSQ, "Read called, load idx: %i, store idx: %i, " - "storeHead: %i addr: %#x\n", - load_idx, store_idx, storeHead, req->paddr); - - while (store_idx != -1) { - // End once we've reached the top of the LSQ - if (store_idx == storeWBIdx) { - break; - } - - // Move the index to one younger - if (--store_idx < 0) - store_idx += SQEntries; - - assert(storeQueue[store_idx].inst); - - store_size = storeQueue[store_idx].size; - - if (store_size == 0) - continue; - - // Check if the store data is within the lower and upper bounds of - // addresses that the request needs. - bool store_has_lower_limit = - req->vaddr >= storeQueue[store_idx].inst->effAddr; - bool store_has_upper_limit = - (req->vaddr + req->size) <= (storeQueue[store_idx].inst->effAddr + - store_size); - bool lower_load_has_store_part = - req->vaddr < (storeQueue[store_idx].inst->effAddr + - store_size); - bool upper_load_has_store_part = - (req->vaddr + req->size) > storeQueue[store_idx].inst->effAddr; - - // If the store's data has all of the data needed, we can forward. - if (store_has_lower_limit && store_has_upper_limit) { - - int shift_amt = req->vaddr & (store_size - 1); - // Assumes byte addressing - shift_amt = shift_amt << 3; - - // Cast this to type T? - data = storeQueue[store_idx].data >> shift_amt; - - req->cmd = Read; - assert(!req->completionEvent); - req->completionEvent = NULL; - req->time = curTick; - assert(!req->data); - req->data = new uint8_t[64]; - - memcpy(req->data, &data, req->size); - - DPRINTF(OzoneLSQ, "Forwarding from store idx %i to load to " - "addr %#x, data %#x\n", - store_idx, req->vaddr, *(req->data)); - - typename BackEnd::LdWritebackEvent *wb = - new typename BackEnd::LdWritebackEvent(loadQueue[load_idx], - be); - - // We'll say this has a 1 cycle load-store forwarding latency - // for now. - // FIXME - Need to make this a parameter. - wb->schedule(curTick); - - // Should keep track of stat for forwarded data - return NoFault; - } else if ((store_has_lower_limit && lower_load_has_store_part) || - (store_has_upper_limit && upper_load_has_store_part) || - (lower_load_has_store_part && upper_load_has_store_part)) { - // This is the partial store-load forwarding case where a store - // has only part of the load's data. - - // If it's already been written back, then don't worry about - // stalling on it. - if (storeQueue[store_idx].completed) { - continue; - } - - // Must stall load and force it to retry, so long as it's the oldest - // load that needs to do so. - if (!stalled || - (stalled && - loadQueue[load_idx]->seqNum < - loadQueue[stallingLoadIdx]->seqNum)) { - stalled = true; - stallingStoreIsn = storeQueue[store_idx].inst->seqNum; - stallingLoadIdx = load_idx; - } - - // Tell IQ/mem dep unit that this instruction will need to be - // rescheduled eventually - be->rescheduleMemInst(loadQueue[load_idx]); - - DPRINTF(OzoneLSQ, "Load-store forwarding mis-match. " - "Store idx %i to load addr %#x\n", - store_idx, req->vaddr); - - return NoFault; - } - } - - - // If there's no forwarding case, then go access memory - DynInstPtr inst = loadQueue[load_idx]; - - ++usedPorts; - - // if we have a cache, do cache access too - if (dcacheInterface) { - if (dcacheInterface->isBlocked()) { - isLoadBlocked = true; - // No fault occurred, even though the interface is blocked. - return NoFault; - } - - DPRINTF(OzoneLSQ, "D-cache: PC:%#x reading from paddr:%#x " - "vaddr:%#x flags:%i\n", - inst->readPC(), req->paddr, req->vaddr, req->flags); - - // Setup MemReq pointer - req->cmd = Read; - req->completionEvent = NULL; - req->time = curTick; - assert(!req->data); - req->data = new uint8_t[64]; - - assert(!req->completionEvent); - typedef typename BackEnd::LdWritebackEvent LdWritebackEvent; - - LdWritebackEvent *wb = new LdWritebackEvent(loadQueue[load_idx], be); - - req->completionEvent = wb; - - // Do Cache Access - MemAccessResult result = dcacheInterface->access(req); - - // Ugly hack to get an event scheduled *only* if the access is - // a miss. We really should add first-class support for this - // at some point. - // @todo: Probably should support having no events - if (result != MA_HIT) { - DPRINTF(OzoneLSQ, "D-cache miss!\n"); - DPRINTF(Activity, "Activity: ld accessing mem miss [sn:%lli]\n", - inst->seqNum); - - lastDcacheStall = curTick; - - _status = DcacheMissStall; - - wb->setDcacheMiss(); - - } else { -// DPRINTF(Activity, "Activity: ld accessing mem hit [sn:%lli]\n", -// inst->seqNum); - - DPRINTF(OzoneLSQ, "D-cache hit!\n"); - } - } else { - fatal("Must use D-cache with new memory system"); - } - - return NoFault; -} - -template <class Impl> -template <class T> -Fault -OzoneLSQ<Impl>::write(MemReqPtr &req, T &data, int store_idx) -{ - assert(storeQueue[store_idx].inst); - - DPRINTF(OzoneLSQ, "Doing write to store idx %i, addr %#x data %#x" - " | storeHead:%i [sn:%i]\n", - store_idx, req->paddr, data, storeHead, - storeQueue[store_idx].inst->seqNum); - - storeQueue[store_idx].req = req; - storeQueue[store_idx].size = sizeof(T); - storeQueue[store_idx].data = data; - - // This function only writes the data to the store queue, so no fault - // can happen here. - return NoFault; -} - -template <class Impl> -inline bool -OzoneLSQ<Impl>::loadBlocked() -{ - bool ret_val = isLoadBlocked; - isLoadBlocked = false; - return ret_val; -} - -#endif // __CPU_OZONE_LSQ_UNIT_HH__ |