rob.hh revision 2733:e0eac8fc5774
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 */ 30 31#ifndef __CPU_O3_ROB_HH__ 32#define __CPU_O3_ROB_HH__ 33 34#include <string> 35#include <utility> 36#include <vector> 37 38/** 39 * ROB class. The ROB is largely what drives squashing. 40 */ 41template <class Impl> 42class ROB 43{ 44 protected: 45 typedef TheISA::RegIndex RegIndex; 46 public: 47 //Typedefs from the Impl. 48 typedef typename Impl::O3CPU O3CPU; 49 typedef typename Impl::DynInstPtr DynInstPtr; 50 51 typedef std::pair<RegIndex, PhysRegIndex> UnmapInfo; 52 typedef typename std::list<DynInstPtr>::iterator InstIt; 53 54 /** Possible ROB statuses. */ 55 enum Status { 56 Running, 57 Idle, 58 ROBSquashing 59 }; 60 61 /** SMT ROB Sharing Policy */ 62 enum ROBPolicy{ 63 Dynamic, 64 Partitioned, 65 Threshold 66 }; 67 68 private: 69 /** Per-thread ROB status. */ 70 Status robStatus[Impl::MaxThreads]; 71 72 /** ROB resource sharing policy for SMT mode. */ 73 ROBPolicy robPolicy; 74 75 public: 76 /** ROB constructor. 77 * @param _numEntries Number of entries in ROB. 78 * @param _squashWidth Number of instructions that can be squashed in a 79 * single cycle. 80 * @param _smtROBPolicy ROB Partitioning Scheme for SMT. 81 * @param _smtROBThreshold Max Resources(by %) a thread can have in the ROB. 82 * @param _numThreads The number of active threads. 83 */ 84 ROB(unsigned _numEntries, unsigned _squashWidth, std::string smtROBPolicy, 85 unsigned _smtROBThreshold, unsigned _numThreads); 86 87 std::string name() const; 88 89 /** Function to set the CPU pointer, necessary due to which object the ROB 90 * is created within. 91 * @param cpu_ptr Pointer to the implementation specific full CPU object. 92 */ 93 void setCPU(O3CPU *cpu_ptr); 94 95 /** Sets pointer to the list of active threads. 96 * @param at_ptr Pointer to the list of active threads. 97 */ 98 void setActiveThreads(std::list<unsigned>* at_ptr); 99 100 /** Switches out the ROB. */ 101 void switchOut(); 102 103 /** Takes over another CPU's thread. */ 104 void takeOverFrom(); 105 106 /** Function to insert an instruction into the ROB. Note that whatever 107 * calls this function must ensure that there is enough space within the 108 * ROB for the new instruction. 109 * @param inst The instruction being inserted into the ROB. 110 */ 111 void insertInst(DynInstPtr &inst); 112 113 /** Returns pointer to the head instruction within the ROB. There is 114 * no guarantee as to the return value if the ROB is empty. 115 * @retval Pointer to the DynInst that is at the head of the ROB. 116 */ 117// DynInstPtr readHeadInst(); 118 119 /** Returns a pointer to the head instruction of a specific thread within 120 * the ROB. 121 * @return Pointer to the DynInst that is at the head of the ROB. 122 */ 123 DynInstPtr readHeadInst(unsigned tid); 124 125 /** Returns pointer to the tail 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 tail of the ROB. 128 */ 129// DynInstPtr readTailInst(); 130 131 /** Returns a pointer to the tail instruction of a specific thread within 132 * the ROB. 133 * @return Pointer to the DynInst that is at the tail of the ROB. 134 */ 135 DynInstPtr readTailInst(unsigned tid); 136 137 /** Retires the head instruction, removing it from the ROB. */ 138// void retireHead(); 139 140 /** Retires the head instruction of a specific thread, removing it from the 141 * ROB. 142 */ 143 void retireHead(unsigned tid); 144 145 /** Is the oldest instruction across all threads ready. */ 146// bool isHeadReady(); 147 148 /** Is the oldest instruction across a particular thread ready. */ 149 bool isHeadReady(unsigned tid); 150 151 /** Is there any commitable head instruction across all threads ready. */ 152 bool canCommit(); 153 154 /** Re-adjust ROB partitioning. */ 155 void resetEntries(); 156 157 /** Number of entries needed For 'num_threads' amount of threads. */ 158 int entryAmount(int num_threads); 159 160 /** Returns the number of total free entries in the ROB. */ 161 unsigned numFreeEntries(); 162 163 /** Returns the number of free entries in a specific ROB paritition. */ 164 unsigned numFreeEntries(unsigned tid); 165 166 /** Returns the maximum number of entries for a specific thread. */ 167 unsigned getMaxEntries(unsigned tid) 168 { return maxEntries[tid]; } 169 170 /** Returns the number of entries being used by a specific thread. */ 171 unsigned getThreadEntries(unsigned tid) 172 { return threadEntries[tid]; } 173 174 /** Returns if the ROB is full. */ 175 bool isFull() 176 { return numInstsInROB == numEntries; } 177 178 /** Returns if a specific thread's partition is full. */ 179 bool isFull(unsigned tid) 180 { return threadEntries[tid] == numEntries; } 181 182 /** Returns if the ROB is empty. */ 183 bool isEmpty() 184 { return numInstsInROB == 0; } 185 186 /** Returns if a specific thread's partition is empty. */ 187 bool isEmpty(unsigned tid) 188 { return threadEntries[tid] == 0; } 189 190 /** Executes the squash, marking squashed instructions. */ 191 void doSquash(unsigned tid); 192 193 /** Squashes all instructions younger than the given sequence number for 194 * the specific thread. 195 */ 196 void squash(InstSeqNum squash_num, unsigned tid); 197 198 /** Updates the head instruction with the new oldest instruction. */ 199 void updateHead(); 200 201 /** Updates the tail instruction with the new youngest instruction. */ 202 void updateTail(); 203 204 /** Reads the PC of the oldest head instruction. */ 205// uint64_t readHeadPC(); 206 207 /** Reads the PC of the head instruction of a specific thread. */ 208// uint64_t readHeadPC(unsigned tid); 209 210 /** Reads the next PC of the oldest head instruction. */ 211// uint64_t readHeadNextPC(); 212 213 /** Reads the next PC of the head instruction of a specific thread. */ 214// uint64_t readHeadNextPC(unsigned tid); 215 216 /** Reads the sequence number of the oldest head instruction. */ 217// InstSeqNum readHeadSeqNum(); 218 219 /** Reads the sequence number of the head instruction of a specific thread. 220 */ 221// InstSeqNum readHeadSeqNum(unsigned tid); 222 223 /** Reads the PC of the youngest tail instruction. */ 224// uint64_t readTailPC(); 225 226 /** Reads the PC of the tail instruction of a specific thread. */ 227// uint64_t readTailPC(unsigned tid); 228 229 /** Reads the sequence number of the youngest tail instruction. */ 230// InstSeqNum readTailSeqNum(); 231 232 /** Reads the sequence number of tail instruction of a specific thread. */ 233// InstSeqNum readTailSeqNum(unsigned tid); 234 235 /** Checks if the ROB is still in the process of squashing instructions. 236 * @retval Whether or not the ROB is done squashing. 237 */ 238 bool isDoneSquashing(unsigned tid) const 239 { return doneSquashing[tid]; } 240 241 /** Checks if the ROB is still in the process of squashing instructions for 242 * any thread. 243 */ 244 bool isDoneSquashing(); 245 246 /** This is more of a debugging function than anything. Use 247 * numInstsInROB to get the instructions in the ROB unless you are 248 * double checking that variable. 249 */ 250 int countInsts(); 251 252 /** This is more of a debugging function than anything. Use 253 * threadEntries to get the instructions in the ROB unless you are 254 * double checking that variable. 255 */ 256 int countInsts(unsigned tid); 257 258 private: 259 /** Pointer to the CPU. */ 260 O3CPU *cpu; 261 262 /** Active Threads in CPU */ 263 std::list<unsigned>* activeThreads; 264 265 /** Number of instructions in the ROB. */ 266 unsigned numEntries; 267 268 /** Entries Per Thread */ 269 unsigned threadEntries[Impl::MaxThreads]; 270 271 /** Max Insts a Thread Can Have in the ROB */ 272 unsigned maxEntries[Impl::MaxThreads]; 273 274 /** ROB List of Instructions */ 275 std::list<DynInstPtr> instList[Impl::MaxThreads]; 276 277 /** Number of instructions that can be squashed in a single cycle. */ 278 unsigned squashWidth; 279 280 public: 281 /** Iterator pointing to the instruction which is the last instruction 282 * in the ROB. This may at times be invalid (ie when the ROB is empty), 283 * however it should never be incorrect. 284 */ 285 InstIt tail; 286 287 /** Iterator pointing to the instruction which is the first instruction in 288 * in the ROB*/ 289 InstIt head; 290 291 private: 292 /** Iterator used for walking through the list of instructions when 293 * squashing. Used so that there is persistent state between cycles; 294 * when squashing, the instructions are marked as squashed but not 295 * immediately removed, meaning the tail iterator remains the same before 296 * and after a squash. 297 * This will always be set to cpu->instList.end() if it is invalid. 298 */ 299 InstIt squashIt[Impl::MaxThreads]; 300 301 public: 302 /** Number of instructions in the ROB. */ 303 int numInstsInROB; 304 305 /** Dummy instruction returned if there are no insts left. */ 306 DynInstPtr dummyInst; 307 308 private: 309 /** The sequence number of the squashed instruction. */ 310 InstSeqNum squashedSeqNum; 311 312 /** Is the ROB done squashing. */ 313 bool doneSquashing[Impl::MaxThreads]; 314 315 /** Number of active threads. */ 316 unsigned numThreads; 317}; 318 319#endif //__CPU_O3_ROB_HH__ 320