diff --git a/compiler-rt/lib/asan/asan_stack.cc b/compiler-rt/lib/asan/asan_stack.cc
--- a/compiler-rt/lib/asan/asan_stack.cc
+++ b/compiler-rt/lib/asan/asan_stack.cc
@@ -29,31 +29,34 @@
 }  // namespace __asan
 
 void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
-                                uptr pc, uptr bp, void *context, bool fast) {
+                                uptr pc, uptr bp, void *context,
+                                bool request_fast_unwind) {
   using namespace __asan;
-#if SANITIZER_WINDOWS
-  stack->Unwind(max_depth, pc, 0, context, 0, 0, false);
-#else
-  AsanThread *t;
-  stack->size = 0;
-  if (LIKELY(asan_inited)) {
-    if ((t = GetCurrentThread()) && !t->isUnwinding()) {
-      uptr stack_top = t->stack_top();
-      uptr stack_bottom = t->stack_bottom();
-      ScopedUnwinding unwind_scope(t);
-      if (!SANITIZER_MIPS || IsValidFrame(bp, stack_top, stack_bottom)) {
-        if (StackTrace::WillUseFastUnwind(fast))
-          stack->Unwind(max_depth, pc, bp, nullptr, stack_top, stack_bottom,
-                      true);
-        else
-          stack->Unwind(max_depth, pc, 0, context, 0, 0, false);
-      }
-    } else if (!t && !fast) {
-      /* If GetCurrentThread() has failed, try to do slow unwind anyways. */
-      stack->Unwind(max_depth, pc, bp, context, 0, 0, false);
-    }
+  stack->size = 0; // TODO(yln): investigate why this is needed
+
+  if (UNLIKELY(!asan_inited)) return;
+
+  AsanThread *t = GetCurrentThread();
+  if (t && t->isUnwinding()) return;
+
+  // TODO(yln): no scope during "best effort" slow unwind without thread
+  // TODO(yln): use SymbolizerScope sym_scope; here instead of unwind_scope?
+  if (!t) {
+    MAYBE_UNWIND_SLOW(stack, pc, context, max_depth);
+    return;
+  }
+
+  ScopedUnwinding unwind_scope(t);
+  if (StackTrace::WillUseFastUnwind(request_fast_unwind)) {
+    uptr top = t->stack_top();
+    uptr bottom = t->stack_bottom();
+    if (IsValidFrame(bp, top, bottom))
+      UNWIND_FAST(stack, pc, bp, top, bottom, max_depth);
+    else
+      MAYBE_UNWIND_SLOW(stack, pc, context, max_depth);
+  } else {
+    UNWIND_SLOW(stack, pc, context, max_depth);
   }
-#endif // SANITIZER_WINDOWS
 }
 
 // ------------------ Interface -------------- {{{1
diff --git a/compiler-rt/lib/hwasan/hwasan.cc b/compiler-rt/lib/hwasan/hwasan.cc
--- a/compiler-rt/lib/hwasan/hwasan.cc
+++ b/compiler-rt/lib/hwasan/hwasan.cc
@@ -244,26 +244,25 @@
 
 } // namespace __hwasan
 
-void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_s, uptr pc,
-                                uptr bp, void *context,
+void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
+                                uptr pc, uptr bp, void *context,
                                 bool request_fast_unwind) {
   using namespace __hwasan;
+  stack->size = 0; // TODO(yln): investigate why this is needed
+
   Thread *t = GetCurrentThread();
-  if (!t) {
-    // the thread is still being created.
-    stack->size = 0;
-    return;
-  }
-  if (!StackTrace::WillUseFastUnwind(request_fast_unwind)) {
-    // Block reports from our interceptors during _Unwind_Backtrace.
-    SymbolizerScope sym_scope;
-    return stack->Unwind(max_s, pc, bp, context, 0, 0, request_fast_unwind);
+  if (!t) return;
+  // TODO(yln): no attempt to slow unwind if we can't get current thread?
+
+  SymbolizerScope sym_scope;
+  if (StackTrace::WillUseFastUnwind(request_fast_unwind)) {
+    uptr top = t->stack_top();
+    uptr bottom = t->stack_bottom();
+    // TODO(yln): no check for IsValidFrame ???
+    UNWIND_FAST(stack, pc, bp, top, bottom, max_depth);
+  } else {
+    UNWIND_SLOW(stack, pc, context, max_depth);
   }
-  if (StackTrace::WillUseFastUnwind(request_fast_unwind))
-    stack->Unwind(max_s, pc, bp, nullptr, t->stack_top(), t->stack_bottom(),
-                  true);
-  else
-    stack->Unwind(max_s, pc, 0, context, 0, 0, false);
 }
 
 // Interface.
diff --git a/compiler-rt/lib/lsan/lsan.cc b/compiler-rt/lib/lsan/lsan.cc
--- a/compiler-rt/lib/lsan/lsan.cc
+++ b/compiler-rt/lib/lsan/lsan.cc
@@ -33,20 +33,26 @@
 }  // namespace __lsan
 
 void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
-                                uptr pc, uptr bp, void *context, bool fast) {
+                                uptr pc, uptr bp, void *context,
+                                bool request_fast_unwind) {
   using namespace __lsan;
-  uptr stack_top = 0, stack_bottom = 0;
-  ThreadContext *t;
-  if (StackTrace::WillUseFastUnwind(fast) &&
-      (t = CurrentThreadContext())) {
-    stack_top = t->stack_end();
-    stack_bottom = t->stack_begin();
+
+  ThreadContext *t = CurrentThreadContext();
+  if (!t) {
+    MAYBE_UNWIND_SLOW(stack, pc, context, max_depth);
+    return;
   }
-  if (!SANITIZER_MIPS || IsValidFrame(bp, stack_top, stack_bottom)) {
-    if (StackTrace::WillUseFastUnwind(fast))
-      stack->Unwind(max_depth, pc, bp, nullptr, stack_top, stack_bottom, true);
+
+  // TODO(yln): No unwinding scope?
+  if (StackTrace::WillUseFastUnwind(request_fast_unwind)) {
+    uptr top = t->stack_end();  // TODO(yln): naming is end/begin
+    uptr bottom = t->stack_begin(); // instead of top/bottom
+    if (IsValidFrame(bp, top, bottom))
+      UNWIND_FAST(stack, pc, bp, top, bottom, max_depth);
     else
-      stack->Unwind(max_depth, pc, 0, context, 0, 0, false);
+      MAYBE_UNWIND_SLOW(stack, pc, context, max_depth);
+  } else {
+    UNWIND_SLOW(stack, pc, context, max_depth);
   }
 }
 
diff --git a/compiler-rt/lib/msan/msan.cc b/compiler-rt/lib/msan/msan.cc
--- a/compiler-rt/lib/msan/msan.cc
+++ b/compiler-rt/lib/msan/msan.cc
@@ -301,21 +301,26 @@
 
 } // namespace __msan
 
-void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_s, uptr pc,
-                                uptr bp, void *context,
+void __sanitizer::GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
+                                uptr pc, uptr bp, void *context,
                                 bool request_fast_unwind) {
   using namespace __msan;
+  SymbolizerScope sym_scope;
+
   MsanThread *t = GetCurrentThread();
-  if (!t || !StackTrace::WillUseFastUnwind(request_fast_unwind)) {
-    // Block reports from our interceptors during _Unwind_Backtrace.
-    SymbolizerScope sym_scope;
-    return stack->Unwind(max_s, pc, bp, context, 0, 0, false);
+  if (!t) {
+    MAYBE_UNWIND_SLOW(stack, pc, context, max_depth);
+    return;
+  }
+
+  if (StackTrace::WillUseFastUnwind(request_fast_unwind)) {
+    uptr top = t->stack_top();
+    uptr bottom = t->stack_bottom();
+    // TODO(yln): no check for IsValidFrame ???
+    UNWIND_FAST(stack, pc, bp, top, bottom, max_depth);
+  } else {
+    UNWIND_SLOW(stack, pc, context, max_depth);
   }
-  if (StackTrace::WillUseFastUnwind(request_fast_unwind))
-    stack->Unwind(max_s, pc, bp, nullptr, t->stack_top(), t->stack_bottom(),
-                  true);
-  else
-    stack->Unwind(max_s, pc, 0, context, 0, 0, false);
 }
 
 // Interface.
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
@@ -100,6 +100,15 @@
   void Init(const uptr *pcs, uptr cnt, uptr extra_top_pc = 0);
   void Unwind(u32 max_depth, uptr pc, uptr bp, void *context, uptr stack_top,
               uptr stack_bottom, bool request_fast_unwind);
+  void UnwindFast(uptr pc, uptr bp, uptr stack_top, uptr stack_bottom,
+                  u32 max_depth);
+
+  void UnwindSlowWithOptionalContext(uptr pc, void *context, u32 max_depth) {
+    if (context)
+      UnwindSlow(pc, max_depth);
+    else
+      UnwindSlow(pc, context, max_depth);
+  }
 
   void Reset() {
     *static_cast<StackTrace *>(this) = StackTrace(trace_buffer, 0);
@@ -107,8 +116,6 @@
   }
 
  private:
-  void UnwindFast(uptr pc, uptr bp, uptr stack_top, uptr stack_bottom,
-                  u32 max_depth);
   void UnwindSlow(uptr pc, u32 max_depth);
   void UnwindSlow(uptr pc, void *context, u32 max_depth);
   void PopStackFrames(uptr count);
@@ -156,4 +163,26 @@
   uptr pc = StackTrace::GetCurrentPc();
 
 
+#if SANITIZER_CAN_FAST_UNWIND
+  #define UNWIND_FAST(stack, pc, bp, top, bottom, max_depth) \
+    (stack)->UnwindFast((pc), (bp), (top), (bottom), (max_depth))
+  #define MAYBE_UNWIND_FAST(stack, pc, bp, top, bottom, max_depth) \
+    UNWIND_FAST(stack, pc, bp, top, bottom, max_depth)
+#else
+  #define UNWIND_FAST(stack, pc, bp, top, bottom, max_depth) \
+    UNREACHABLE("Fast unwinder is unsupported")
+  #define MAYBE_UNWIND_FAST(stack, pc, bp, top, bottom, max_depth)
+#endif
+
+#if SANITIZER_CAN_SLOW_UNWIND
+  #define UNWIND_SLOW(stack, pc, context, max_depth) \
+    (stack)->UnwindSlowWithOptionalContext((pc), (context), (max_depth));
+  #define MAYBE_UNWIND_SLOW(stack, pc, context, max_depth) \
+    UNWIND_SLOW(stack, pc, context, max_depth)
+#else
+  #define UNWIND_SLOW(stack, pc, context, max_depth) \
+    UNREACHABLE("Slow unwinder is unsupported")
+  #define MAYBE_UNWIND_SLOW(stack, pc, context, max_depth)
+#endif
+
 #endif  // SANITIZER_STACKTRACE_H