[docs] provide the specific sanitizer option to detect junk-in-the-ftrunc

llvm-svn: 330958

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 43c6c9a30e9..cf00ae2ad56 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -63,7 +63,8 @@ Non-comprehensive list of changes in this release
 
 * Optimization of floating-point casts is improved. This may cause surprising
   results for code that is relying on undefined behavior. Code sanitizers can
-  be used to detect affected patterns such as this:
+  be used to detect affected patterns. The option for detecting this problem 
+  alone is "-fsanitize=float-cast-overflow":
 
 .. code-block:: c
 
@@ -76,7 +77,7 @@ Non-comprehensive list of changes in this release
 
 .. code-block:: bash
 
-    clang -O1 ftrunc.c -fsanitize=undefined ; ./a.out 
+    clang -O1 ftrunc.c -fsanitize=float-cast-overflow ; ./a.out 
     ftrunc.c:5:15: runtime error: 4.29497e+09 is outside the range of representable values of type 'int'
     junk in the ftrunc: 0.000000