[AMDGPU] gfx1010 wave32 clang support

Differential Revision: https://reviews.llvm.org/D63209

llvm-svn: 363341
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index 5a34c96..30ac27f 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -2401,6 +2401,10 @@
 CU wavefront execution mode is used if enabled and WGP wavefront execution mode
 is used if disabled (AMDGPU only)
 
+.. option:: -mwavefrontsize64, -mno-wavefrontsize64
+
+Wavefront size 64 is used if enabled and wavefront size 32 if disabled (AMDGPU only)
+
 .. option:: -mxnack, -mno-xnack
 
 Enable XNACK (AMDGPU only)