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