rob.hh revision 9444:ab47fe7f03f0
1/* 2 * Copyright (c) 2012 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2004-2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Kevin Lim 41 * Korey Sewell 42 */ 43 44#ifndef __CPU_O3_ROB_HH__ 45#define __CPU_O3_ROB_HH__ 46 47#include <string> 48#include <utility> 49#include <vector> 50 51#include "arch/registers.hh" 52#include "base/types.hh" 53#include "config/the_isa.hh" 54 55/** 56 * ROB class. The ROB is largely what drives squashing. 57 */ 58template <class Impl> 59class ROB 60{ 61 protected: 62 typedef TheISA::RegIndex RegIndex; 63 public: 64 //Typedefs from the Impl. 65 typedef typename Impl::O3CPU O3CPU; 66 typedef typename Impl::DynInstPtr DynInstPtr; 67 68 typedef std::pair<RegIndex, PhysRegIndex> UnmapInfo; 69 typedef typename std::list<DynInstPtr>::iterator InstIt; 70 71 /** Possible ROB statuses. */ 72 enum Status { 73 Running, 74 Idle, 75 ROBSquashing 76 }; 77 78 /** SMT ROB Sharing Policy */ 79 enum ROBPolicy{ 80 Dynamic, 81 Partitioned, 82 Threshold 83 }; 84 85 private: 86 /** Per-thread ROB status. */ 87 Status robStatus[Impl::MaxThreads]; 88 89 /** ROB resource sharing policy for SMT mode. */ 90 ROBPolicy robPolicy; 91 92 public: 93 /** ROB constructor. 94 * @param _numEntries Number of entries in ROB. 95 * @param _squashWidth Number of instructions that can be squashed in a 96 * single cycle. 97 * @param _smtROBPolicy ROB Partitioning Scheme for SMT. 98 * @param _smtROBThreshold Max Resources(by %) a thread can have in the ROB. 99 * @param _numThreads The number of active threads. 100 */ 101 ROB(O3CPU *_cpu, unsigned _numEntries, unsigned _squashWidth, 102 std::string smtROBPolicy, unsigned _smtROBThreshold, 103 ThreadID _numThreads); 104 105 std::string name() const; 106 107 /** Sets pointer to the list of active threads. 108 * @param at_ptr Pointer to the list of active threads. 109 */ 110 void setActiveThreads(std::list<ThreadID> *at_ptr); 111 112 /** Perform sanity checks after a drain. */ 113 void drainSanityCheck() const; 114 115 /** Takes over another CPU's thread. */ 116 void takeOverFrom(); 117 118 /** Function to insert an instruction into the ROB. Note that whatever 119 * calls this function must ensure that there is enough space within the 120 * ROB for the new instruction. 121 * @param inst The instruction being inserted into the ROB. 122 */ 123 void insertInst(DynInstPtr &inst); 124 125 /** Returns pointer to the head instruction within the ROB. There is 126 * no guarantee as to the return value if the ROB is empty. 127 * @retval Pointer to the DynInst that is at the head of the ROB. 128 */ 129// DynInstPtr readHeadInst(); 130 131 /** Returns a pointer to the head instruction of a specific thread within 132 * the ROB. 133 * @return Pointer to the DynInst that is at the head of the ROB. 134 */ 135 DynInstPtr readHeadInst(ThreadID tid); 136 137 /** Returns a pointer to the instruction with the given sequence if it is 138 * in the ROB. 139 */ 140 DynInstPtr findInst(ThreadID tid, InstSeqNum squash_inst); 141 142 /** Returns pointer to the tail instruction within the ROB. There is 143 * no guarantee as to the return value if the ROB is empty. 144 * @retval Pointer to the DynInst that is at the tail of the ROB. 145 */ 146// DynInstPtr readTailInst(); 147 148 /** Returns a pointer to the tail instruction of a specific thread within 149 * the ROB. 150 * @return Pointer to the DynInst that is at the tail of the ROB. 151 */ 152 DynInstPtr readTailInst(ThreadID tid); 153 154 /** Retires the head instruction, removing it from the ROB. */ 155// void retireHead(); 156 157 /** Retires the head instruction of a specific thread, removing it from the 158 * ROB. 159 */ 160 void retireHead(ThreadID tid); 161 162 /** Is the oldest instruction across all threads ready. */ 163// bool isHeadReady(); 164 165 /** Is the oldest instruction across a particular thread ready. */ 166 bool isHeadReady(ThreadID tid); 167 168 /** Is there any commitable head instruction across all threads ready. */ 169 bool canCommit(); 170 171 /** Re-adjust ROB partitioning. */ 172 void resetEntries(); 173 174 /** Number of entries needed For 'num_threads' amount of threads. */ 175 int entryAmount(ThreadID num_threads); 176 177 /** Returns the number of total free entries in the ROB. */ 178 unsigned numFreeEntries(); 179 180 /** Returns the number of free entries in a specific ROB paritition. */ 181 unsigned numFreeEntries(ThreadID tid); 182 183 /** Returns the maximum number of entries for a specific thread. */ 184 unsigned getMaxEntries(ThreadID tid) 185 { return maxEntries[tid]; } 186 187 /** Returns the number of entries being used by a specific thread. */ 188 unsigned getThreadEntries(ThreadID tid) 189 { return threadEntries[tid]; } 190 191 /** Returns if the ROB is full. */ 192 bool isFull() 193 { return numInstsInROB == numEntries; } 194 195 /** Returns if a specific thread's partition is full. */ 196 bool isFull(ThreadID tid) 197 { return threadEntries[tid] == numEntries; } 198 199 /** Returns if the ROB is empty. */ 200 bool isEmpty() const 201 { return numInstsInROB == 0; } 202 203 /** Returns if a specific thread's partition is empty. */ 204 bool isEmpty(ThreadID tid) const 205 { return threadEntries[tid] == 0; } 206 207 /** Executes the squash, marking squashed instructions. */ 208 void doSquash(ThreadID tid); 209 210 /** Squashes all instructions younger than the given sequence number for 211 * the specific thread. 212 */ 213 void squash(InstSeqNum squash_num, ThreadID tid); 214 215 /** Updates the head instruction with the new oldest instruction. */ 216 void updateHead(); 217 218 /** Updates the tail instruction with the new youngest instruction. */ 219 void updateTail(); 220 221 /** Reads the PC of the oldest head instruction. */ 222// uint64_t readHeadPC(); 223 224 /** Reads the PC of the head instruction of a specific thread. */ 225// uint64_t readHeadPC(ThreadID tid); 226 227 /** Reads the next PC of the oldest head instruction. */ 228// uint64_t readHeadNextPC(); 229 230 /** Reads the next PC of the head instruction of a specific thread. */ 231// uint64_t readHeadNextPC(ThreadID tid); 232 233 /** Reads the sequence number of the oldest head instruction. */ 234// InstSeqNum readHeadSeqNum(); 235 236 /** Reads the sequence number of the head instruction of a specific thread. 237 */ 238// InstSeqNum readHeadSeqNum(ThreadID tid); 239 240 /** Reads the PC of the youngest tail instruction. */ 241// uint64_t readTailPC(); 242 243 /** Reads the PC of the tail instruction of a specific thread. */ 244// uint64_t readTailPC(ThreadID tid); 245 246 /** Reads the sequence number of the youngest tail instruction. */ 247// InstSeqNum readTailSeqNum(); 248 249 /** Reads the sequence number of tail instruction of a specific thread. */ 250// InstSeqNum readTailSeqNum(ThreadID tid); 251 252 /** Checks if the ROB is still in the process of squashing instructions. 253 * @retval Whether or not the ROB is done squashing. 254 */ 255 bool isDoneSquashing(ThreadID tid) const 256 { return doneSquashing[tid]; } 257 258 /** Checks if the ROB is still in the process of squashing instructions for 259 * any thread. 260 */ 261 bool isDoneSquashing(); 262 263 /** This is more of a debugging function than anything. Use 264 * numInstsInROB to get the instructions in the ROB unless you are 265 * double checking that variable. 266 */ 267 int countInsts(); 268 269 /** This is more of a debugging function than anything. Use 270 * threadEntries to get the instructions in the ROB unless you are 271 * double checking that variable. 272 */ 273 int countInsts(ThreadID tid); 274 275 /** Registers statistics. */ 276 void regStats(); 277 278 private: 279 /** Reset the ROB state */ 280 void resetState(); 281 282 /** Pointer to the CPU. */ 283 O3CPU *cpu; 284 285 /** Active Threads in CPU */ 286 std::list<ThreadID> *activeThreads; 287 288 /** Number of instructions in the ROB. */ 289 unsigned numEntries; 290 291 /** Entries Per Thread */ 292 unsigned threadEntries[Impl::MaxThreads]; 293 294 /** Max Insts a Thread Can Have in the ROB */ 295 unsigned maxEntries[Impl::MaxThreads]; 296 297 /** ROB List of Instructions */ 298 std::list<DynInstPtr> instList[Impl::MaxThreads]; 299 300 /** Number of instructions that can be squashed in a single cycle. */ 301 unsigned squashWidth; 302 303 public: 304 /** Iterator pointing to the instruction which is the last instruction 305 * in the ROB. This may at times be invalid (ie when the ROB is empty), 306 * however it should never be incorrect. 307 */ 308 InstIt tail; 309 310 /** Iterator pointing to the instruction which is the first instruction in 311 * in the ROB*/ 312 InstIt head; 313 314 private: 315 /** Iterator used for walking through the list of instructions when 316 * squashing. Used so that there is persistent state between cycles; 317 * when squashing, the instructions are marked as squashed but not 318 * immediately removed, meaning the tail iterator remains the same before 319 * and after a squash. 320 * This will always be set to cpu->instList.end() if it is invalid. 321 */ 322 InstIt squashIt[Impl::MaxThreads]; 323 324 public: 325 /** Number of instructions in the ROB. */ 326 int numInstsInROB; 327 328 /** Dummy instruction returned if there are no insts left. */ 329 DynInstPtr dummyInst; 330 331 private: 332 /** The sequence number of the squashed instruction. */ 333 InstSeqNum squashedSeqNum[Impl::MaxThreads]; 334 335 /** Is the ROB done squashing. */ 336 bool doneSquashing[Impl::MaxThreads]; 337 338 /** Number of active threads. */ 339 ThreadID numThreads; 340 341 // The number of rob_reads 342 Stats::Scalar robReads; 343 // The number of rob_writes 344 Stats::Scalar robWrites; 345}; 346 347#endif //__CPU_O3_ROB_HH__ 348