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 u64 *sp = &shadow_mem[idx]; 20 old = LoadShadow(sp); 21 if (old.IsZero()) { 22 StatInc(thr, StatShadowZero); 23 if (store_word) 24 StoreIfNotYetStored(sp, &store_word); 25 // The above StoreIfNotYetStored could be done unconditionally 26 // and it even shows 4% gain on synthetic benchmarks (r4307). 27 break; 28 } 29 // is the memory access equal to the previous? 30 if (Shadow::Addr0AndSizeAreEqual(cur, old)) { 31 StatInc(thr, StatShadowSameSize); 32 // same thread? 33 if (Shadow::TidsAreEqual(old, cur)) { 34 StatInc(thr, StatShadowSameThread); 35 if (old.IsRWWeakerOrEqual(kAccessIsWrite, kIsAtomic)) 36 StoreIfNotYetStored(sp, &store_word); 37 break; 38 } 39 StatInc(thr, StatShadowAnotherThread); 40 if (HappensBefore(old, thr)) { 41 StoreIfNotYetStored(sp, &store_word); 42 break; 43 } 44 if (old.IsBothReadsOrAtomic(kAccessIsWrite, kIsAtomic)) 45 break; 46 goto RACE; 47 } 48 // Do the memory access intersect? 49 if (Shadow::TwoRangesIntersect(old, cur, kAccessSize)) { 50 StatInc(thr, StatShadowIntersect); 51 if (Shadow::TidsAreEqual(old, cur)) { 52 StatInc(thr, StatShadowSameThread); 53 break; 54 } 55 StatInc(thr, StatShadowAnotherThread); 56 if (old.IsBothReadsOrAtomic(kAccessIsWrite, kIsAtomic)) 57 break; 58 if (HappensBefore(old, thr)) 59 break; 60 goto RACE; 61 } 62 // The accesses do not intersect. 63 StatInc(thr, StatShadowNotIntersect); 64 break; 65 } while (0); 66