Add another reason for direct mode miss but preprocessor mode hit

diff --git a/manual.txt b/manual.txt
index 34dffded3ebe50688da53b7e7eb06c94515d2a45..40a2c1f9c6ca78ae4201ab448b5f06271728507c 100644 (file)
--- a/manual.txt
+++ b/manual.txt
@@ -576,6 +576,8 @@ 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:
+** The source code has been modified in such a way that the preprocessor output
+   is not affected.
 ** 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.