rob.hh revision 2831:0a42b294727c
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(unsigned _numEntries, unsigned _squashWidth, std::string smtROBPolicy, 86 unsigned _smtROBThreshold, unsigned _numThreads); 87 88 std::string name() const; 89 90 /** Function to set the CPU pointer, necessary due to which object the ROB 91 * is created within. 92 * @param cpu_ptr Pointer to the implementation specific full CPU object. 93 */ 94 void setCPU(O3CPU *cpu_ptr); 95 96 /** Sets pointer to the list of active threads. 97 * @param at_ptr Pointer to the list of active threads. 98 */ 99 void setActiveThreads(std::list<unsigned>* at_ptr); 100 101 /** Switches out the ROB. */ 102 void switchOut(); 103 104 /** Takes over another CPU's thread. */ 105 void takeOverFrom(); 106 107 /** Function to insert an instruction into the ROB. Note that whatever 108 * calls this function must ensure that there is enough space within the 109 * ROB for the new instruction. 110 * @param inst The instruction being inserted into the ROB. 111 */ 112 void insertInst(DynInstPtr &inst); 113 114 /** Returns pointer to the head instruction within the ROB. There is 115 * no guarantee as to the return value if the ROB is empty. 116 * @retval Pointer to the DynInst that is at the head of the ROB. 117 */ 118// DynInstPtr readHeadInst(); 119 120 /** Returns a pointer to the head instruction of a specific thread within 121 * the ROB. 122 * @return Pointer to the DynInst that is at the head of the ROB. 123 */ 124 DynInstPtr readHeadInst(unsigned tid); 125 126 /** Returns pointer to the tail instruction within the ROB. There is 127 * no guarantee as to the return value if the ROB is empty. 128 * @retval Pointer to the DynInst that is at the tail of the ROB. 129 */ 130// DynInstPtr readTailInst(); 131 132 /** Returns a pointer to the tail instruction of a specific thread within 133 * the ROB. 134 * @return Pointer to the DynInst that is at the tail of the ROB. 135 */ 136 DynInstPtr readTailInst(unsigned tid); 137 138 /** Retires the head instruction, removing it from the ROB. */ 139// void retireHead(); 140 141 /** Retires the head instruction of a specific thread, removing it from the 142 * ROB. 143 */ 144 void retireHead(unsigned tid); 145 146 /** Is the oldest instruction across all threads ready. */ 147// bool isHeadReady(); 148 149 /** Is the oldest instruction across a particular thread ready. */ 150 bool isHeadReady(unsigned tid); 151 152 /** Is there any commitable head instruction across all threads ready. */ 153 bool canCommit(); 154 155 /** Re-adjust ROB partitioning. */ 156 void resetEntries(); 157 158 /** Number of entries needed For 'num_threads' amount of threads. */ 159 int entryAmount(int num_threads); 160 161 /** Returns the number of total free entries in the ROB. */ 162 unsigned numFreeEntries(); 163 164 /** Returns the number of free entries in a specific ROB paritition. */ 165 unsigned numFreeEntries(unsigned tid); 166 167 /** Returns the maximum number of entries for a specific thread. */ 168 unsigned getMaxEntries(unsigned tid) 169 { return maxEntries[tid]; } 170 171 /** Returns the number of entries being used by a specific thread. */ 172 unsigned getThreadEntries(unsigned tid) 173 { return threadEntries[tid]; } 174 175 /** Returns if the ROB is full. */ 176 bool isFull() 177 { return numInstsInROB == numEntries; } 178 179 /** Returns if a specific thread's partition is full. */ 180 bool isFull(unsigned tid) 181 { return threadEntries[tid] == numEntries; } 182 183 /** Returns if the ROB is empty. */ 184 bool isEmpty() 185 { return numInstsInROB == 0; } 186 187 /** Returns if a specific thread's partition is empty. */ 188 bool isEmpty(unsigned tid) 189 { return threadEntries[tid] == 0; } 190 191 /** Executes the squash, marking squashed instructions. */ 192 void doSquash(unsigned tid); 193 194 /** Squashes all instructions younger than the given sequence number for 195 * the specific thread. 196 */ 197 void squash(InstSeqNum squash_num, unsigned tid); 198 199 /** Updates the head instruction with the new oldest instruction. */ 200 void updateHead(); 201 202 /** Updates the tail instruction with the new youngest instruction. */ 203 void updateTail(); 204 205 /** Reads the PC of the oldest head instruction. */ 206// uint64_t readHeadPC(); 207 208 /** Reads the PC of the head instruction of a specific thread. */ 209// uint64_t readHeadPC(unsigned tid); 210 211 /** Reads the next PC of the oldest head instruction. */ 212// uint64_t readHeadNextPC(); 213 214 /** Reads the next PC of the head instruction of a specific thread. */ 215// uint64_t readHeadNextPC(unsigned tid); 216 217 /** Reads the sequence number of the oldest head instruction. */ 218// InstSeqNum readHeadSeqNum(); 219 220 /** Reads the sequence number of the head instruction of a specific thread. 221 */ 222// InstSeqNum readHeadSeqNum(unsigned tid); 223 224 /** Reads the PC of the youngest tail instruction. */ 225// uint64_t readTailPC(); 226 227 /** Reads the PC of the tail instruction of a specific thread. */ 228// uint64_t readTailPC(unsigned tid); 229 230 /** Reads the sequence number of the youngest tail instruction. */ 231// InstSeqNum readTailSeqNum(); 232 233 /** Reads the sequence number of tail instruction of a specific thread. */ 234// InstSeqNum readTailSeqNum(unsigned tid); 235 236 /** Checks if the ROB is still in the process of squashing instructions. 237 * @retval Whether or not the ROB is done squashing. 238 */ 239 bool isDoneSquashing(unsigned tid) const 240 { return doneSquashing[tid]; } 241 242 /** Checks if the ROB is still in the process of squashing instructions for 243 * any thread. 244 */ 245 bool isDoneSquashing(); 246 247 /** This is more of a debugging function than anything. Use 248 * numInstsInROB to get the instructions in the ROB unless you are 249 * double checking that variable. 250 */ 251 int countInsts(); 252 253 /** This is more of a debugging function than anything. Use 254 * threadEntries to get the instructions in the ROB unless you are 255 * double checking that variable. 256 */ 257 int countInsts(unsigned tid); 258 259 private: 260 /** Pointer to the CPU. */ 261 O3CPU *cpu; 262 263 /** Active Threads in CPU */ 264 std::list<unsigned>* activeThreads; 265 266 /** Number of instructions in the ROB. */ 267 unsigned numEntries; 268 269 /** Entries Per Thread */ 270 unsigned threadEntries[Impl::MaxThreads]; 271 272 /** Max Insts a Thread Can Have in the ROB */ 273 unsigned maxEntries[Impl::MaxThreads]; 274 275 /** ROB List of Instructions */ 276 std::list<DynInstPtr> instList[Impl::MaxThreads]; 277 278 /** Number of instructions that can be squashed in a single cycle. */ 279 unsigned squashWidth; 280 281 public: 282 /** Iterator pointing to the instruction which is the last instruction 283 * in the ROB. This may at times be invalid (ie when the ROB is empty), 284 * however it should never be incorrect. 285 */ 286 InstIt tail; 287 288 /** Iterator pointing to the instruction which is the first instruction in 289 * in the ROB*/ 290 InstIt head; 291 292 private: 293 /** Iterator used for walking through the list of instructions when 294 * squashing. Used so that there is persistent state between cycles; 295 * when squashing, the instructions are marked as squashed but not 296 * immediately removed, meaning the tail iterator remains the same before 297 * and after a squash. 298 * This will always be set to cpu->instList.end() if it is invalid. 299 */ 300 InstIt squashIt[Impl::MaxThreads]; 301 302 public: 303 /** Number of instructions in the ROB. */ 304 int numInstsInROB; 305 306 /** Dummy instruction returned if there are no insts left. */ 307 DynInstPtr dummyInst; 308 309 private: 310 /** The sequence number of the squashed instruction. */ 311 InstSeqNum squashedSeqNum; 312 313 /** Is the ROB done squashing. */ 314 bool doneSquashing[Impl::MaxThreads]; 315 316 /** Number of active threads. */ 317 unsigned numThreads; 318}; 319 320#endif //__CPU_O3_ROB_HH__ 321