I just added a section on "Debugging tree code generated by gfortran"
to https://gcc.gnu.org/wiki/GFortranHacking , by using -fverbose-asm -S
without -g, doing the assembly in a separate step (with -g this time)
and then single-stepping through the commented assembly. I learned this
Maybe you've all been doing this for years :-), but I found it useful
enough to document.