-where you built Emacs. That directory has a .gdbinit file that defines
-various "user-defined" commands for debugging Emacs.
+where the executable was made. That directory has a .gdbinit file
+that defines various "user-defined" commands for debugging Emacs.
+
+** When you are trying to analyze failed assertions, it will be
+essential to compile Emacs either completely without optimizations or
+at least (when using GCC) with the -fno-crossjumping option. Failure
+to do so may make the compiler recycle the same abort call for all
+assertions in a given function, rendering the stack backtrace useless
+for identifying the specific failed assertion.