-g with -native

The -Wa,--gstabs introduces one slight problem. You want to do it if you get
a .s file from the native back end, but you probably don't want to do that if
the .s file comes from another source. (I.e., I could have my own library
routines written in assembler.)

What kinds of stabs information does the -Wa,--gstabs actually put in? Line
number stuff? Local symbols? Any thing else?