GCC and GIMPLE One of the very first thing GCC asks the GSoC applicants to do, even before writing the application, is to try various different debugging techniques using GCC. I was personally familiar with the basic, compile-with-g-flag-and-use-gdb method. Turns out, there's more: GIMPLE. A Simple but Non-trivial Program Problem Description The instruction asks to compile a simple but non-trivial program with some flags that generates debugging information: -O3 -S -fdump-tree-all -fdump-ipa-all -fdump-rtl-all . Because I was keep reading on ways to debug GCC just prior to the statement, I immediately thought "GCC" and tried make -j8 CXXFLAGS="-O3 -S -fdump-tree-all -fdump-ipa-all -fdump-rtl-all" . This was a mistake: turns out, GCC can't be compiled with those flags. Thankfully, GCC developers have a very active IRC channel for me to signal SOS. Resolution jakub and segher were quick to respond to my call for help. jakub: it isn't meant that y...