ltage.cc (13494:ed4ed5351b16) | ltage.cc (13626:d6a6358aa6db) |
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1/* 2 * Copyright (c) 2014 The University of Wisconsin 3 * 4 * Copyright (c) 2006 INRIA (Institut National de Recherche en 5 * Informatique et en Automatique / French National Research Institute 6 * for Computer Science and Applied Mathematics) 7 * 8 * All rights reserved. --- 154 unchanged lines hidden (view full) --- 163 if (bi->loopPredValid) { 164 if (taken != bi->loopPred) { 165 // free the entry 166 ltable[idx].numIter = 0; 167 ltable[idx].age = 0; 168 ltable[idx].confidence = 0; 169 ltable[idx].currentIter = 0; 170 return; | 1/* 2 * Copyright (c) 2014 The University of Wisconsin 3 * 4 * Copyright (c) 2006 INRIA (Institut National de Recherche en 5 * Informatique et en Automatique / French National Research Institute 6 * for Computer Science and Applied Mathematics) 7 * 8 * All rights reserved. --- 154 unchanged lines hidden (view full) --- 163 if (bi->loopPredValid) { 164 if (taken != bi->loopPred) { 165 // free the entry 166 ltable[idx].numIter = 0; 167 ltable[idx].age = 0; 168 ltable[idx].confidence = 0; 169 ltable[idx].currentIter = 0; 170 return; |
171 } else if (bi->loopPred != bi->tagePred) { | 171 } else if (bi->loopPred != bi->tageBranchInfo->tagePred) { |
172 DPRINTF(LTage, "Loop Prediction success:%lx\n",pc); | 172 DPRINTF(LTage, "Loop Prediction success:%lx\n",pc); |
173 unsignedCtrUpdate(ltable[idx].age, true, loopTableAgeBits); | 173 TAGEBase::unsignedCtrUpdate(ltable[idx].age, true, 174 loopTableAgeBits); |
174 } 175 } 176 177 ltable[idx].currentIter = 178 (ltable[idx].currentIter + 1) & loopNumIterMask; 179 if (ltable[idx].currentIter > ltable[idx].numIter) { 180 ltable[idx].confidence = 0; 181 if (ltable[idx].numIter != 0) { 182 // free the entry 183 ltable[idx].numIter = 0; 184 ltable[idx].age = 0; 185 ltable[idx].confidence = 0; 186 } 187 } 188 189 if (taken != (useDirectionBit ? ltable[idx].dir : true)) { 190 if (ltable[idx].currentIter == ltable[idx].numIter) { 191 DPRINTF(LTage, "Loop End predicted successfully:%lx\n", pc); 192 | 175 } 176 } 177 178 ltable[idx].currentIter = 179 (ltable[idx].currentIter + 1) & loopNumIterMask; 180 if (ltable[idx].currentIter > ltable[idx].numIter) { 181 ltable[idx].confidence = 0; 182 if (ltable[idx].numIter != 0) { 183 // free the entry 184 ltable[idx].numIter = 0; 185 ltable[idx].age = 0; 186 ltable[idx].confidence = 0; 187 } 188 } 189 190 if (taken != (useDirectionBit ? ltable[idx].dir : true)) { 191 if (ltable[idx].currentIter == ltable[idx].numIter) { 192 DPRINTF(LTage, "Loop End predicted successfully:%lx\n", pc); 193 |
193 unsignedCtrUpdate(ltable[idx].confidence, true, | 194 TAGEBase::unsignedCtrUpdate(ltable[idx].confidence, true, |
194 loopTableConfidenceBits); 195 //just do not predict when the loop count is 1 or 2 196 if (ltable[idx].numIter < 3) { 197 // free the entry 198 ltable[idx].dir = taken; // ignored if no useDirectionBit 199 ltable[idx].numIter = 0; 200 ltable[idx].age = 0; 201 ltable[idx].confidence = 0; --- 11 unchanged lines hidden (view full) --- 213 ltable[idx].age = 0; 214 ltable[idx].confidence = 0; 215 } 216 } 217 ltable[idx].currentIter = 0; 218 } 219 220 } else if (useDirectionBit ? | 195 loopTableConfidenceBits); 196 //just do not predict when the loop count is 1 or 2 197 if (ltable[idx].numIter < 3) { 198 // free the entry 199 ltable[idx].dir = taken; // ignored if no useDirectionBit 200 ltable[idx].numIter = 0; 201 ltable[idx].age = 0; 202 ltable[idx].confidence = 0; --- 11 unchanged lines hidden (view full) --- 214 ltable[idx].age = 0; 215 ltable[idx].confidence = 0; 216 } 217 } 218 ltable[idx].currentIter = 0; 219 } 220 221 } else if (useDirectionBit ? |
221 ((bi->loopPredValid ? bi->loopPred : bi->tagePred) != taken) : | 222 ((bi->loopPredValid ? 223 bi->loopPred : bi->tageBranchInfo->tagePred) != taken) : |
222 taken) { 223 //try to allocate an entry on taken branch | 224 taken) { 225 //try to allocate an entry on taken branch |
224 int nrand = random_mt.random<int>(); | 226 int nrand = TAGEBase::getRandom(); |
225 for (int i = 0; i < (1 << logLoopTableAssoc); i++) { 226 int loop_hit = (nrand + i) & ((1 << logLoopTableAssoc) - 1); 227 idx = bi->loopIndex + loop_hit; 228 if (ltable[idx].age == 0) { 229 DPRINTF(LTage, "Allocating loop pred entry for branch %lx\n", 230 pc); 231 ltable[idx].dir = !taken; // ignored if no useDirectionBit 232 ltable[idx].tag = bi->loopTag; --- 10 unchanged lines hidden (view full) --- 243 } 244 245} 246 247//prediction 248bool 249LTAGE::predict(ThreadID tid, Addr branch_pc, bool cond_branch, void* &b) 250{ | 227 for (int i = 0; i < (1 << logLoopTableAssoc); i++) { 228 int loop_hit = (nrand + i) & ((1 << logLoopTableAssoc) - 1); 229 idx = bi->loopIndex + loop_hit; 230 if (ltable[idx].age == 0) { 231 DPRINTF(LTage, "Allocating loop pred entry for branch %lx\n", 232 pc); 233 ltable[idx].dir = !taken; // ignored if no useDirectionBit 234 ltable[idx].tag = bi->loopTag; --- 10 unchanged lines hidden (view full) --- 245 } 246 247} 248 249//prediction 250bool 251LTAGE::predict(ThreadID tid, Addr branch_pc, bool cond_branch, void* &b) 252{ |
251 LTageBranchInfo *bi = new LTageBranchInfo(nHistoryTables+1); | 253 LTageBranchInfo *bi = new LTageBranchInfo(*tage); |
252 b = (void*)(bi); 253 | 254 b = (void*)(bi); 255 |
254 bool pred_taken = tagePredict(tid, branch_pc, cond_branch, bi); | 256 bool pred_taken = tage->tagePredict(tid, branch_pc, cond_branch, 257 bi->tageBranchInfo); |
255 256 if (cond_branch) { 257 // loop prediction 258 bi->loopPred = getLoop(branch_pc, bi, useSpeculation); 259 260 if ((loopUseCounter >= 0) && bi->loopPredValid) { 261 pred_taken = bi->loopPred; | 258 259 if (cond_branch) { 260 // loop prediction 261 bi->loopPred = getLoop(branch_pc, bi, useSpeculation); 262 263 if ((loopUseCounter >= 0) && bi->loopPredValid) { 264 pred_taken = bi->loopPred; |
262 bi->provider = LOOP; | 265 bi->tageBranchInfo->provider = LOOP; |
263 } 264 DPRINTF(LTage, "Predict for %lx: taken?:%d, loopTaken?:%d, " 265 "loopValid?:%d, loopUseCounter:%d, tagePred:%d, altPred:%d\n", 266 branch_pc, pred_taken, bi->loopPred, bi->loopPredValid, | 266 } 267 DPRINTF(LTage, "Predict for %lx: taken?:%d, loopTaken?:%d, " 268 "loopValid?:%d, loopUseCounter:%d, tagePred:%d, altPred:%d\n", 269 branch_pc, pred_taken, bi->loopPred, bi->loopPredValid, |
267 loopUseCounter, bi->tagePred, bi->altTaken); | 270 loopUseCounter, bi->tageBranchInfo->tagePred, 271 bi->tageBranchInfo->altTaken); |
268 269 if (useSpeculation) { 270 specLoopUpdate(pred_taken, bi); 271 } 272 } 273 274 return pred_taken; 275} 276 277void | 272 273 if (useSpeculation) { 274 specLoopUpdate(pred_taken, bi); 275 } 276 } 277 278 return pred_taken; 279} 280 281void |
278LTAGE::condBranchUpdate(Addr branch_pc, bool taken, 279 TageBranchInfo* tage_bi, int nrand) | 282LTAGE::update(ThreadID tid, Addr branch_pc, bool taken, void* bp_history, 283 bool squashed, const StaticInstPtr & inst, Addr corrTarget) |
280{ | 284{ |
281 LTageBranchInfo* bi = static_cast<LTageBranchInfo*>(tage_bi); | 285 assert(bp_history); |
282 | 286 |
283 if (useSpeculation) { 284 // recalculate loop prediction without speculation 285 // It is ok to overwrite the loop prediction fields in bi 286 // as the stats have already been updated with the previous 287 // values 288 bi->loopPred = getLoop(branch_pc, bi, false); | 287 LTageBranchInfo* bi = static_cast<LTageBranchInfo*>(bp_history); 288 289 if (squashed) { 290 if (tage->isSpeculativeUpdateEnabled()) { 291 // This restores the global history, then update it 292 // and recomputes the folded histories. 293 tage->squash(tid, taken, bi->tageBranchInfo, corrTarget); 294 squashLoop(bi); 295 } 296 return; |
289 } 290 | 297 } 298 |
291 if (bi->loopPredValid) { 292 if (bi->tagePred != bi->loopPred) { 293 ctrUpdate(loopUseCounter, 294 (bi->loopPred == taken), 295 withLoopBits); | 299 int nrand = TAGEBase::getRandom() & 3; 300 if (bi->tageBranchInfo->condBranch) { 301 DPRINTF(LTage, "Updating tables for branch:%lx; taken?:%d\n", 302 branch_pc, taken); 303 tage->updateStats(taken, bi->tageBranchInfo); 304 // update stats 305 if (bi->tageBranchInfo->provider == LOOP) { 306 if (taken == bi->loopPred) { 307 loopPredictorCorrect++; 308 } else { 309 loopPredictorWrong++; 310 } |
296 } | 311 } |
312 // cond Branch Update 313 if (useSpeculation) { 314 // recalculate loop prediction without speculation 315 // It is ok to overwrite the loop prediction fields in bi 316 // as the stats have already been updated with the previous 317 // values 318 bi->loopPred = getLoop(branch_pc, bi, false); 319 } 320 if (bi->loopPredValid) { 321 if (bi->tageBranchInfo->tagePred != bi->loopPred) { 322 TAGEBase::ctrUpdate(loopUseCounter, 323 (bi->loopPred == taken), 324 withLoopBits); 325 } 326 } 327 328 loopUpdate(branch_pc, taken, bi); 329 330 tage->condBranchUpdate(tid, branch_pc, taken, bi->tageBranchInfo, 331 nrand, corrTarget); |
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297 } 298 | 332 } 333 |
299 loopUpdate(branch_pc, taken, bi); | 334 tage->updateHistories(tid, branch_pc, taken, bi->tageBranchInfo, false, 335 inst, corrTarget); |
300 | 336 |
301 TAGE::condBranchUpdate(branch_pc, taken, bi, nrand); | 337 delete bi; |
302} 303 304void | 338} 339 340void |
305LTAGE::squash(ThreadID tid, bool taken, void *bp_history) | 341LTAGE::squashLoop(LTageBranchInfo* bi) |
306{ | 342{ |
307 TAGE::squash(tid, taken, bp_history); 308 309 LTageBranchInfo* bi = (LTageBranchInfo*)(bp_history); 310 311 if (bi->condBranch) { | 343 if (bi->tageBranchInfo->condBranch) { |
312 if (bi->loopHit >= 0) { 313 int idx = finallindex(bi->loopIndex, 314 bi->loopLowPcBits, 315 bi->loopHit); 316 ltable[idx].currentIterSpec = bi->currentIter; 317 } 318 } 319} 320 321void 322LTAGE::squash(ThreadID tid, void *bp_history) 323{ 324 LTageBranchInfo* bi = (LTageBranchInfo*)(bp_history); | 344 if (bi->loopHit >= 0) { 345 int idx = finallindex(bi->loopIndex, 346 bi->loopLowPcBits, 347 bi->loopHit); 348 ltable[idx].currentIterSpec = bi->currentIter; 349 } 350 } 351} 352 353void 354LTAGE::squash(ThreadID tid, void *bp_history) 355{ 356 LTageBranchInfo* bi = (LTageBranchInfo*)(bp_history); |
325 if (bi->condBranch) { 326 if (bi->loopHit >= 0) { 327 int idx = finallindex(bi->loopIndex, 328 bi->loopLowPcBits, 329 bi->loopHit); 330 ltable[idx].currentIterSpec = bi->currentIter; 331 } | 357 358 if (bi->tageBranchInfo->condBranch) { 359 squashLoop(bi); |
332 } 333 334 TAGE::squash(tid, bp_history); 335} 336 | 360 } 361 362 TAGE::squash(tid, bp_history); 363} 364 |
337 | |
338void | 365void |
339LTAGE::updateStats(bool taken, TageBranchInfo* bi) 340{ 341 TAGE::updateStats(taken, bi); 342 343 LTageBranchInfo * ltage_bi = static_cast<LTageBranchInfo *>(bi); 344 345 if (ltage_bi->provider == LOOP) { 346 if (taken == ltage_bi->loopPred) { 347 loopPredictorCorrect++; 348 } else { 349 loopPredictorWrong++; 350 } 351 } 352} 353 354 355 356void | |
357LTAGE::regStats() 358{ 359 TAGE::regStats(); 360 361 loopPredictorCorrect 362 .name(name() + ".loopPredictorCorrect") 363 .desc("Number of times the loop predictor is the provider and " 364 "the prediction is correct"); --- 14 unchanged lines hidden --- | 366LTAGE::regStats() 367{ 368 TAGE::regStats(); 369 370 loopPredictorCorrect 371 .name(name() + ".loopPredictorCorrect") 372 .desc("Number of times the loop predictor is the provider and " 373 "the prediction is correct"); --- 14 unchanged lines hidden --- |