From ae52ac74790fe041dee7724f32b6132c7ca3c7e1 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter@pcc.me.uk>
Date: Thu, 15 Aug 2013 18:51:07 +0000
Subject: [PATCH] [dfsan] Runtime support for -dfsan-debug-nonzero-labels
 feature.

Reviewers: eugenis

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1406

llvm-svn: 188471
---
 compiler-rt/lib/dfsan/dfsan.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler-rt/lib/dfsan/dfsan.cc b/compiler-rt/lib/dfsan/dfsan.cc
index 162549f2569b..7e84337bd19d 100644
--- a/compiler-rt/lib/dfsan/dfsan.cc
+++ b/compiler-rt/lib/dfsan/dfsan.cc
@@ -136,6 +136,11 @@ void __dfsan_unimplemented(char *fname) {
          fname);
 }
 
+// Use '-mllvm -dfsan-debug-nonzero-labels' and break on this function
+// to try to figure out where labels are being introduced in a nominally
+// label-free program.
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __dfsan_nonzero_label() {}
+
 // Like __dfsan_union, but for use from the client or custom functions.  Hence
 // the equality comparison is done here before calling __dfsan_union.
 SANITIZER_INTERFACE_ATTRIBUTE dfsan_label