folly: define FOLLY_SANITIZE_DATAFLOW macro for DFSan.

Summary: This defines the macro `FOLLY_SANITIZER_DATAFLOW` as other sanitizers do.

Reviewed By: yfeldblum

Differential Revision: D33747374

fbshipit-source-id: 3c8aa58f43ed72c4ca259bd2434e1f79d12dc65b

folly/CPortability.h

@@ -133,13 +133,30 @@
 #define FOLLY_DISABLE_MEMORY_SANITIZER
 #endif
 
+/**
+ * Define a convenience macro to test when dataflow sanitizer is being used
+ * across the different compilers (e.g. clang, gcc)
+ */
+#ifndef FOLLY_SANITIZE_DATAFLOW
+#if FOLLY_HAS_FEATURE(dataflow_sanitizer) || defined(__SANITIZE_DATAFLOW__)
+#define FOLLY_SANITIZE_DATAFLOW 1
+#endif
+#endif
+
+#ifdef FOLLY_SANITIZE_DATAFLOW
+#define FOLLY_DISABLE_DATAFLOW_SANITIZER \
+  __attribute__((no_sanitize_dataflow, noinline))
+#else
+#define FOLLY_DISABLE_DATAFLOW_SANITIZER
+#endif
+
 /**
  * Define a convenience macro to test when ASAN, UBSAN, TSAN or MSAN sanitizer
  * are being used
  */
 #ifndef FOLLY_SANITIZE
 #if defined(FOLLY_SANITIZE_ADDRESS) || defined(FOLLY_SANITIZE_THREAD) || \
-    defined(FOLLY_SANITIZE_MEMORY)
+    defined(FOLLY_SANITIZE_MEMORY) || defined(FOLLY_SANITIZE_DATAFLOW)
 #define FOLLY_SANITIZE 1
 #endif
 #endif

folly/Portability.h

@@ -149,6 +149,12 @@ constexpr bool kIsSanitizeThread = true;
 constexpr bool kIsSanitizeThread = false;
 #endif
 
+#ifdef FOLLY_SANITIZE_DATAFLOW
+constexpr bool kIsSanitizeDataflow = true;
+#else
+constexpr bool kIsSanitizeDataflow = false;
+#endif
+
 #ifdef FOLLY_SANITIZE
 constexpr bool kIsSanitize = true;
 #else