We have no targets that emit SDB debug info by default. We dropped all of the SVR3 Unix and embedded COFF targets a while ago. The only targets that are still able to emit SDB debug info are cygwin, mingw, and msdosdjgpp.
I tried a cygwin build with sources modified to emit SDB by default, to see if the support was still usable. I ran into multiple problems. There is no SDB support for IMPORTED_DECL which was added in 2008. - freorder-functions and -freorder-blocks-and-partition did not work and had to be disabled. I hit a cgraph assert because sdbout.c uses assemble_name on types, which fails if there is a function and type with the same name. This also causes types to be added to the debug info with prepended underscores which is wrong. I then ran into a problem with the i386_pe_declare_function_type call from i386_pe_file_end and gave up because I didn't see an easy workaround. It seems clear that the SDB support is no longer usable, and probably hasn't been for a while. This support should just be removed. SDB is both a debug info format and an old Unix debugger. There were some references to the debugger that I left in, changing to past tense, as the comments are useful history to explain why the code was written the was it was. Otherwise, I tried to eliminate all references to sdb as a debug info format. This patch series was tested with a C only cross compiler build for all modified embedded targets, a default languages build for power aix, i686 cygwin, and x86_64 linux. I also did gdb testsuite runs for cygwin and linux. There were no regressions. As a debug info maintainer, I can self approve some of this stuff, would be would be good to get a review from one of the other global reviewers, and/or target maintainers. Jim
