[sanitizer] fix a performance regression in sanitizer coverage: move a small perf-critical function to a header. ALso set the coverage guard to 1 before the early return from CoverageData::Add

llvm-svn: 224660

3 files changed, 21 insertions, 19 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
index 3fa8a18696f..3e521d1620a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
@@ -234,15 +234,15 @@ void CoverageData::Extend(uptr npcs) {
 // If the function is called more than once for a given PC it will
 // be inserted multiple times, which is fine.
 void CoverageData::Add(uptr pc, u8 *guard) {
+  // Set the guard.
+  atomic_uint8_t *atomic_guard = reinterpret_cast<atomic_uint8_t*>(guard);
+  atomic_store(atomic_guard, 1, memory_order_relaxed);
   if (!pc_array) return;
   uptr idx = atomic_fetch_add(&pc_array_index, 1, memory_order_relaxed);
   CHECK_LT(idx * sizeof(uptr),
            atomic_load(&pc_array_size, memory_order_acquire));
   pc_array[idx] = pc;
   atomic_fetch_add(&coverage_counter, 1, memory_order_relaxed);
-  // Set the guard.
-  atomic_uint8_t *atomic_guard = reinterpret_cast<atomic_uint8_t*>(guard);
-  atomic_store(atomic_guard, 1, memory_order_relaxed);
 }
 
 // Registers a pair caller=>callee.
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
index 13549c4f80a..17b2ef3576a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
@@ -17,21 +17,6 @@
 
 namespace __sanitizer {
 
-uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
-#if defined(__arm__)
-  // Cancel Thumb bit.
-  pc = pc & (~1);
-#endif
-#if defined(__powerpc__) || defined(__powerpc64__)
-  // PCs are always 4 byte aligned.
-  return pc - 4;
-#elif defined(__sparc__) || defined(__mips__)
-  return pc - 8;
-#else
-  return pc - 1;
-#endif
-}
-
 uptr StackTrace::GetNextInstructionPc(uptr pc) {
 #if defined(__mips__)
   return pc + 8;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
index e755c052cb7..79be2879248 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
@@ -57,12 +57,29 @@ struct StackTrace {
   }
 
   static uptr GetCurrentPc();
-  static uptr GetPreviousInstructionPc(uptr pc);
+  static inline uptr GetPreviousInstructionPc(uptr pc);
   static uptr GetNextInstructionPc(uptr pc);
   typedef bool (*SymbolizeCallback)(const void *pc, char *out_buffer,
                                     int out_size);
 };
 
+// Performance-critical, must be in the header.
+ALWAYS_INLINE
+uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
+#if defined(__arm__)
+  // Cancel Thumb bit.
+  pc = pc & (~1);
+#endif
+#if defined(__powerpc__) || defined(__powerpc64__)
+  // PCs are always 4 byte aligned.
+  return pc - 4;
+#elif defined(__sparc__) || defined(__mips__)
+  return pc - 8;
+#else
+  return pc - 1;
+#endif
+}
+
 // StackTrace that owns the buffer used to store the addresses.
 struct BufferedStackTrace : public StackTrace {
   uptr trace_buffer[kStackTraceMax];