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

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/sanitizer_common/sanitizer_common.h b/lib/sanitizer_common/sanitizer_common.h
index 9c801f151..9e65639b9 100644
--- a/lib/sanitizer_common/sanitizer_common.h
+++ b/lib/sanitizer_common/sanitizer_common.h
@@ -624,6 +624,7 @@ inline const char *ModuleArchToString(ModuleArch arch) {
 }
 
 const uptr kModuleUUIDSize = 16;
+const uptr kMaxSegName = 16;
 
 // Represents a binary loaded into virtual memory (e.g. this can be an
 // executable or a shared object).
@@ -642,7 +643,8 @@ class LoadedModule {
   void set(const char *module_name, uptr base_address, ModuleArch arch,
            u8 uuid[kModuleUUIDSize], bool instrumented);
   void clear();
-  void addAddressRange(uptr beg, uptr end, bool executable, bool writable);
+  void addAddressRange(uptr beg, uptr end, bool executable, bool writable,
+                       const char *name = nullptr);
   bool containsAddress(uptr address) const;
 
   const char *full_name() const { return full_name_; }
@@ -658,13 +660,17 @@ class LoadedModule {
     uptr end;
     bool executable;
     bool writable;
+    char name[kMaxSegName];
 
-    AddressRange(uptr beg, uptr end, bool executable, bool writable)
+    AddressRange(uptr beg, uptr end, bool executable, bool writable,
+                 const char *name)
         : next(nullptr),
           beg(beg),
           end(end),
           executable(executable),
-          writable(writable) {}
+          writable(writable) {
+      internal_strncpy(this->name, (name ? name : ""), ARRAY_SIZE(this->name));
+    }
   };
 
   const IntrusiveList<AddressRange> &ranges() const { return ranges_; }