diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp index da3e0ca9efd..48a9396a956 100644 --- a/llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp +++ b/llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp @@ -57,6 +57,14 @@ static cl::opt<bool> ClInstrumentMemIntrinsics( "esan-instrument-memintrinsics", cl::init(true), cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden); +// Experiments show that the performance difference can be 2x or more, +// and accuracy loss is typically negligible, so we turn this on by default. +static cl::opt<bool> ClAssumeIntraCacheLine( + "esan-assume-intra-cache-line", cl::init(true), + cl::desc("Assume each memory access touches just one cache line, for " + "better performance but with a potential loss of accuracy."), + cl::Hidden); + STATISTIC(NumInstrumentedLoads, "Number of instrumented loads"); STATISTIC(NumInstrumentedStores, "Number of instrumented stores"); STATISTIC(NumFastpaths, "Number of instrumented fastpaths"); @@ -65,6 +73,8 @@ STATISTIC(NumAccessesWithIrregularSize, STATISTIC(NumIgnoredStructs, "Number of ignored structs"); STATISTIC(NumIgnoredGEPs, "Number of ignored GEP instructions"); STATISTIC(NumInstrumentedGEPs, "Number of instrumented GEP instructions"); +STATISTIC(NumAssumedIntraCacheLine, + "Number of accesses assumed to be intra-cache-line"); static const uint64_t EsanCtorAndDtorPriority = 0; static const char *const EsanModuleCtorName = "esan.module_ctor"; @@ -715,8 +725,12 @@ bool EfficiencySanitizer::instrumentFastpathWorkingSet( // (and our shadow memory setup assumes 64-byte cache lines). assert(TypeSize <= 64); if (!(TypeSize == 8 || - (Alignment % (TypeSize / 8)) == 0)) - return false; + (Alignment % (TypeSize / 8)) == 0)) { + if (ClAssumeIntraCacheLine) + ++NumAssumedIntraCacheLine; + else + return false; + } // We inline instrumentation to set the corresponding shadow bits for // each cache line touched by the application. Here we handle a single |
