I've tried using the output provided by "gcc -v -save-temps ..." and then invoke cc1 from inside gdb, but thats not immediately working, and its a pain to have to copy and paste huge chunks of text everytime I want to trace my new changes. You can do it like that or use the scripts here http://www.cs.auckland.ac.nz/~sgov008/code/gcc.htm . They were written by Alexandre Oliva.