From 5764cd92b929fefc1fef703c32e59516a0468d0b Mon Sep 17 00:00:00 2001 From: Francis Ricci Date: Tue, 25 Jul 2017 18:16:58 +0000 Subject: Only scan global sections containing data in LSan on darwin Summary: __DATA segments on Darwin contain a large number of separate sections, many of which cannot actually contain pointers, and contain const values or objc metadata. Not scanning sections which cannot contain pointers significantly improves performance. On a medium-sized (~4000 files) internal project, I saw a speedup of about 30% in standalone LSan's execution time (30% improvement in the time spent running LSan, not the total program time). Reviewers: kcc, kubamracek, alekseyshl Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D35432 git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@308999 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/lsan/lsan_common_mac.cc | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'lib/lsan') diff --git a/lib/lsan/lsan_common_mac.cc b/lib/lsan/lsan_common_mac.cc index ade94340a..ac27c7af6 100644 --- a/lib/lsan/lsan_common_mac.cc +++ b/lib/lsan/lsan_common_mac.cc @@ -92,8 +92,25 @@ LoadedModule *GetLinker() { return nullptr; } // required on Darwin. void InitializePlatformSpecificModules() {} +// Sections which can't contain contain global pointers. This list errs on the +// side of caution to avoid false positives, at the expense of performance. +// +// Other potentially safe sections include: +// __all_image_info, __crash_info, __const, __got, __interpose, __objc_msg_break +// +// Sections which definitely cannot be included here are: +// __objc_data, __objc_const, __data, __bss, __common, __thread_data, +// __thread_bss, __thread_vars, __objc_opt_rw, __objc_opt_ptrs +static const char *kSkippedSecNames[] = { + "__cfstring", "__la_symbol_ptr", "__mod_init_func", + "__mod_term_func", "__nl_symbol_ptr", "__objc_classlist", + "__objc_classrefs", "__objc_imageinfo", "__objc_nlclslist", + "__objc_protolist", "__objc_selrefs", "__objc_superrefs"}; + // Scans global variables for heap pointers. void ProcessGlobalRegions(Frontier *frontier) { + for (auto name : kSkippedSecNames) CHECK(ARRAY_SIZE(name) < kMaxSegName); + MemoryMappingLayout memory_mapping(false); InternalMmapVector modules(/*initial_capacity*/ 128); memory_mapping.DumpListOfModules(&modules); @@ -107,6 +124,10 @@ void ProcessGlobalRegions(Frontier *frontier) { // Sections storing global variables are writable and non-executable if (range.executable || !range.writable) continue; + for (auto name : kSkippedSecNames) { + if (!internal_strcmp(range.name, name)) continue; + } + ScanGlobalRange(range.beg, range.end, frontier); } } -- cgit v1.2.3