On Tue, Jun 2, 2020 at 8:10 PM Alan Modra <amo...@gmail.com> wrote: > > On Tue, Jun 02, 2020 at 11:06:10AM -0700, David Blaikie via Binutils wrote: > > On Tue, Jun 2, 2020 at 9:50 AM Mark Wielaard <m...@klomp.org> wrote: > > > where I > > > would argue the compiler simply needs to make sure that if it generates > > > code in separate sections it also should create the DWARF separate > > > section (groups). > > > > I don't think that's practical - the overhead, I believe, is too high. > > Headers for each section contribution (ELF headers but DWARF headers > > moreso - having a separate .debug_addr, .debug_line, etc section for > > each function would be very expensive) would make for very large > > object files. > > With a little linker magic I don't see the neccesity of duplicating > the DWARF headers. Taking .debug_line as an example, a compiler could > emit the header, opcode, directory and file tables to a .debug_line > section with line statements for function foo emitted to > .debug_line.foo and for bar to .debug_line.bar, trusting that the > linker will combine these sections in order to create an output > .debug_line section. If foo code is excluded then .debug_line.foo > info will also be dropped if section groups are used.
I don't think this would apply to debug_addr - where the entries are referenced from elsewhere via index, or debug_rnglist where the rnglist header (or the debug_info directly) contains offsets into this section, so taking chunks out would break those offsets. (or to the file/directory name part of debug_line - where you might want to remove file/line entries that were eliminated as dead code - but that'd throw off the indexes)
