rob.hh revision 4329:52057dbec096
1/* 2 * Copyright (c) 2004-2006 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Kevin Lim 29 * Korey Sewell 30 */ 31 32#ifndef __CPU_O3_ROB_HH__ 33#define __CPU_O3_ROB_HH__ 34 35#include <string> 36#include <utility> 37#include <vector> 38 39/** 40 * ROB class. The ROB is largely what drives squashing. 41 */ 42template <class Impl> 43class ROB 44{ 45 protected: 46 typedef TheISA::RegIndex RegIndex; 47 public: 48 //Typedefs from the Impl. 49 typedef typename Impl::O3CPU O3CPU; 50 typedef typename Impl::DynInstPtr DynInstPtr; 51 52 typedef std::pair<RegIndex, PhysRegIndex> UnmapInfo; 53 typedef typename std::list<DynInstPtr>::iterator InstIt; 54 55 /** Possible ROB statuses. */ 56 enum Status { 57 Running, 58 Idle, 59 ROBSquashing 60 }; 61 62 /** SMT ROB Sharing Policy */ 63 enum ROBPolicy{ 64 Dynamic, 65 Partitioned, 66 Threshold 67 }; 68 69 private: 70 /** Per-thread ROB status. */ 71 Status robStatus[Impl::MaxThreads]; 72 73 /** ROB resource sharing policy for SMT mode. */ 74 ROBPolicy robPolicy; 75 76 public: 77 /** ROB constructor. 78 * @param _numEntries Number of entries in ROB. 79 * @param _squashWidth Number of instructions that can be squashed in a 80 * single cycle. 81 * @param _smtROBPolicy ROB Partitioning Scheme for SMT. 82 * @param _smtROBThreshold Max Resources(by %) a thread can have in the ROB. 83 * @param _numThreads The number of active threads. 84 */ 85 ROB(O3CPU *_cpu, unsigned _numEntries, unsigned _squashWidth, 86 std::string smtROBPolicy, unsigned _smtROBThreshold, 87 unsigned _numThreads); 88 89 std::string name() const; 90 91 /** Sets pointer to the list of active threads. 92 * @param at_ptr Pointer to the list of active threads. 93 */ 94 void setActiveThreads(std::list<unsigned>* at_ptr); 95 96 /** Switches out the ROB. */ 97 void switchOut(); 98 99 /** Takes over another CPU's thread. */ 100 void takeOverFrom(); 101 102 /** Function to insert an instruction into the ROB. Note that whatever 103 * calls this function must ensure that there is enough space within the 104 * ROB for the new instruction. 105 * @param inst The instruction being inserted into the ROB. 106 */ 107 void insertInst(DynInstPtr &inst); 108 109 /** Returns pointer to the head instruction within the ROB. There is 110 * no guarantee as to the return value if the ROB is empty. 111 * @retval Pointer to the DynInst that is at the head of the ROB. 112 */ 113// DynInstPtr readHeadInst(); 114 115 /** Returns a pointer to the head instruction of a specific thread within 116 * the ROB. 117 * @return Pointer to the DynInst that is at the head of the ROB. 118 */ 119 DynInstPtr readHeadInst(unsigned tid); 120 121 /** Returns pointer to the tail instruction within the ROB. There is 122 * no guarantee as to the return value if the ROB is empty. 123 * @retval Pointer to the DynInst that is at the tail of the ROB. 124 */ 125// DynInstPtr readTailInst(); 126 127 /** Returns a pointer to the tail instruction of a specific thread within 128 * the ROB. 129 * @return Pointer to the DynInst that is at the tail of the ROB. 130 */ 131 DynInstPtr readTailInst(unsigned tid); 132 133 /** Retires the head instruction, removing it from the ROB. */ 134// void retireHead(); 135 136 /** Retires the head instruction of a specific thread, removing it from the 137 * ROB. 138 */ 139 void retireHead(unsigned tid); 140 141 /** Is the oldest instruction across all threads ready. */ 142// bool isHeadReady(); 143 144 /** Is the oldest instruction across a particular thread ready. */ 145 bool isHeadReady(unsigned tid); 146 147 /** Is there any commitable head instruction across all threads ready. */ 148 bool canCommit(); 149 150 /** Re-adjust ROB partitioning. */ 151 void resetEntries(); 152 153 /** Number of entries needed For 'num_threads' amount of threads. */ 154 int entryAmount(int num_threads); 155 156 /** Returns the number of total free entries in the ROB. */ 157 unsigned numFreeEntries(); 158 159 /** Returns the number of free entries in a specific ROB paritition. */ 160 unsigned numFreeEntries(unsigned tid); 161 162 /** Returns the maximum number of entries for a specific thread. */ 163 unsigned getMaxEntries(unsigned tid) 164 { return maxEntries[tid]; } 165 166 /** Returns the number of entries being used by a specific thread. */ 167 unsigned getThreadEntries(unsigned tid) 168 { return threadEntries[tid]; } 169 170 /** Returns if the ROB is full. */ 171 bool isFull() 172 { return numInstsInROB == numEntries; } 173 174 /** Returns if a specific thread's partition is full. */ 175 bool isFull(unsigned tid) 176 { return threadEntries[tid] == numEntries; } 177 178 /** Returns if the ROB is empty. */ 179 bool isEmpty() 180 { return numInstsInROB == 0; } 181 182 /** Returns if a specific thread's partition is empty. */ 183 bool isEmpty(unsigned tid) 184 { return threadEntries[tid] == 0; } 185 186 /** Executes the squash, marking squashed instructions. */ 187 void doSquash(unsigned tid); 188 189 /** Squashes all instructions younger than the given sequence number for 190 * the specific thread. 191 */ 192 void squash(InstSeqNum squash_num, unsigned tid); 193 194 /** Updates the head instruction with the new oldest instruction. */ 195 void updateHead(); 196 197 /** Updates the tail instruction with the new youngest instruction. */ 198 void updateTail(); 199 200 /** Reads the PC of the oldest head instruction. */ 201// uint64_t readHeadPC(); 202 203 /** Reads the PC of the head instruction of a specific thread. */ 204// uint64_t readHeadPC(unsigned tid); 205 206 /** Reads the next PC of the oldest head instruction. */ 207// uint64_t readHeadNextPC(); 208 209 /** Reads the next PC of the head instruction of a specific thread. */ 210// uint64_t readHeadNextPC(unsigned tid); 211 212 /** Reads the sequence number of the oldest head instruction. */ 213// InstSeqNum readHeadSeqNum(); 214 215 /** Reads the sequence number of the head instruction of a specific thread. 216 */ 217// InstSeqNum readHeadSeqNum(unsigned tid); 218 219 /** Reads the PC of the youngest tail instruction. */ 220// uint64_t readTailPC(); 221 222 /** Reads the PC of the tail instruction of a specific thread. */ 223// uint64_t readTailPC(unsigned tid); 224 225 /** Reads the sequence number of the youngest tail instruction. */ 226// InstSeqNum readTailSeqNum(); 227 228 /** Reads the sequence number of tail instruction of a specific thread. */ 229// InstSeqNum readTailSeqNum(unsigned tid); 230 231 /** Checks if the ROB is still in the process of squashing instructions. 232 * @retval Whether or not the ROB is done squashing. 233 */ 234 bool isDoneSquashing(unsigned tid) const 235 { return doneSquashing[tid]; } 236 237 /** Checks if the ROB is still in the process of squashing instructions for 238 * any thread. 239 */ 240 bool isDoneSquashing(); 241 242 /** This is more of a debugging function than anything. Use 243 * numInstsInROB to get the instructions in the ROB unless you are 244 * double checking that variable. 245 */ 246 int countInsts(); 247 248 /** This is more of a debugging function than anything. Use 249 * threadEntries to get the instructions in the ROB unless you are 250 * double checking that variable. 251 */ 252 int countInsts(unsigned tid); 253 254 private: 255 /** Pointer to the CPU. */ 256 O3CPU *cpu; 257 258 /** Active Threads in CPU */ 259 std::list<unsigned>* activeThreads; 260 261 /** Number of instructions in the ROB. */ 262 unsigned numEntries; 263 264 /** Entries Per Thread */ 265 unsigned threadEntries[Impl::MaxThreads]; 266 267 /** Max Insts a Thread Can Have in the ROB */ 268 unsigned maxEntries[Impl::MaxThreads]; 269 270 /** ROB List of Instructions */ 271 std::list<DynInstPtr> instList[Impl::MaxThreads]; 272 273 /** Number of instructions that can be squashed in a single cycle. */ 274 unsigned squashWidth; 275 276 public: 277 /** Iterator pointing to the instruction which is the last instruction 278 * in the ROB. This may at times be invalid (ie when the ROB is empty), 279 * however it should never be incorrect. 280 */ 281 InstIt tail; 282 283 /** Iterator pointing to the instruction which is the first instruction in 284 * in the ROB*/ 285 InstIt head; 286 287 private: 288 /** Iterator used for walking through the list of instructions when 289 * squashing. Used so that there is persistent state between cycles; 290 * when squashing, the instructions are marked as squashed but not 291 * immediately removed, meaning the tail iterator remains the same before 292 * and after a squash. 293 * This will always be set to cpu->instList.end() if it is invalid. 294 */ 295 InstIt squashIt[Impl::MaxThreads]; 296 297 public: 298 /** Number of instructions in the ROB. */ 299 int numInstsInROB; 300 301 /** Dummy instruction returned if there are no insts left. */ 302 DynInstPtr dummyInst; 303 304 private: 305 /** The sequence number of the squashed instruction. */ 306 InstSeqNum squashedSeqNum[Impl::MaxThreads]; 307 308 /** Is the ROB done squashing. */ 309 bool doneSquashing[Impl::MaxThreads]; 310 311 /** Number of active threads. */ 312 unsigned numThreads; 313}; 314 315#endif //__CPU_O3_ROB_HH__ 316