1 //===-- tsan_update_shadow_word_inl.h ---------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of ThreadSanitizer (TSan), a race detector. 11 // 12 // Body of the hottest inner loop. 13 // If we wrap this body into a function, compilers (both gcc and clang) 14 // produce sligtly less efficient code. 15 //===----------------------------------------------------------------------===// 16 do { 17 StatInc(thr, StatShadowProcessed); 18 const unsigned kAccessSize = 1 << kAccessSizeLog; 19 unsigned off = cur.ComputeSearchOffset(); 20 u64 *sp = &shadow_mem[(idx + off) % kShadowCnt]; 21 old = LoadShadow(sp); 22 if (old.IsZero()) { 23 StatInc(thr, StatShadowZero); 24 if (store_word) 25 StoreIfNotYetStored(sp, &store_word); 26 // The above StoreIfNotYetStored could be done unconditionally 27 // and it even shows 4% gain on synthetic benchmarks (r4307). 28 break; 29 } 30 // is the memory access equal to the previous? 31 if (Shadow::Addr0AndSizeAreEqual(cur, old)) { 32 StatInc(thr, StatShadowSameSize); 33 // same thread? 34 if (Shadow::TidsAreEqual(old, cur)) { 35 StatInc(thr, StatShadowSameThread); 36 if (OldIsInSameSynchEpoch(old, thr)) { 37 if (OldIsRWStronger(old, kAccessIsWrite)) { 38 // found a slot that holds effectively the same info 39 // (that is, same tid, same sync epoch and same size) 40 StatInc(thr, StatMopSame); 41 return; 42 } 43 StoreIfNotYetStored(sp, &store_word); 44 break; 45 } 46 if (OldIsRWWeaker(old, kAccessIsWrite)) 47 StoreIfNotYetStored(sp, &store_word); 48 break; 49 } 50 StatInc(thr, StatShadowAnotherThread); 51 if (HappensBefore(old, thr)) { 52 StoreIfNotYetStored(sp, &store_word); 53 break; 54 } 55 if (BothReads(old, kAccessIsWrite)) 56 break; 57 goto RACE; 58 } 59 60 // Do the memory access intersect? 61 if (Shadow::TwoRangesIntersect(old, cur, kAccessSize)) { 62 StatInc(thr, StatShadowIntersect); 63 if (Shadow::TidsAreEqual(old, cur)) { 64 StatInc(thr, StatShadowSameThread); 65 break; 66 } 67 StatInc(thr, StatShadowAnotherThread); 68 if (HappensBefore(old, thr)) 69 break; 70 71 if (BothReads(old, kAccessIsWrite)) 72 break; 73 74 goto RACE; 75 } 76 // The accesses do not intersect. 77 StatInc(thr, StatShadowNotIntersect); 78 break; 79 } while (0); 80