[asan] performance optimization: make sure the check for poisoned shadow inside inteceptors is inlined

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@152767 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/asan/asan_mapping.h b/lib/asan/asan_mapping.h
index 63aba10a2..4824bf109 100644
--- a/lib/asan/asan_mapping.h
+++ b/lib/asan/asan_mapping.h
@@ -95,6 +95,18 @@ static inline bool AddrIsAlignedByGranularity(uintptr_t a) {
   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 }
 
+static inline bool AddressIsPoisoned(uintptr_t a) {
+  const size_t kAccessSize = 1;
+  uint8_t *shadow_address = (uint8_t*)MemToShadow(a);
+  int8_t shadow_value = *shadow_address;
+  if (shadow_value) {
+    uint8_t last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
+                                 + kAccessSize - 1;
+    return (last_accessed_byte >= shadow_value);
+  }
+  return false;
+}
+
 }  // namespace __asan
 
 #endif  // ASAN_MAPPING_H