The VHDL mode that comes with emacs need a upgrade. The current 3.34 that comes with emacs has a pretty annoying bug that will mess up find-grep result. 

The bug is fixed in 3.36 and the latest stable release is 3.38.

VHDL mode: http://www.iis.ee.ethz.ch/~zimmi/emacs/vhdl-mode.html

Thanks

Ritchie