Add another reason for direct mode miss but preprocessor mode hit

diff --git a/manual.txt b/manual.txt
index 77c68eed07d4ee546271e44fd13f57a761ec10b4..ad419b2270ba2bf46d1d51027cb6ff3c65da4757 100644 (file)
--- a/manual.txt
+++ b/manual.txt
@@ -581,6 +581,9 @@ problems and what may be done to increase the hit rate:
 * If ``cache hit (preprocessed)'' has been incremented instead of ``cache hit
   (direct)'', ccache has fallen back to preprocessor mode, which is generally
   slower. Some possible reasons are:
+** Compiler arguments that are hashed in the direct mode but not in the
+   preprocessor mode have changed (*-I*, *-include*, *-D*, etc) and they didn't
+   affect the preprocessor output.
 ** The compiler option *-Xpreprocessor* or *-Wp,_X_* (except *-Wp,-MD,_path_*
    and *Wp,-MMD,_path_*) is used.
 ** This was the first compilation with a new value of *CCACHE_BASEDIR*.