Are there any plans to make GCC and/or GAS emit the version 4 variants of the .debug_line and/or .debug_frame formats?
The .debug_line version 4 format only adds the "maximum operations per instruction" header field and associated logic, which is only meaningful for VLIW machines (i.e. ia64--are there others?). The old format is specified such that it's always safe to use the new line-number program operations without changing the header version field, so there is no real reason to emit the new header format unless using the VLIW support. But it seems consistent with the rest of the behavior of -gdwarf-4 to emit the v4 format with that option. I'd like to know when or if to expect ever to see this format. Similarly, the .debug_frame version 4 format only adds the address_size and segment_size header fields. I don't know if there are any GCC/GAS target configurations that support segmented addresses for code so as to need segment_size, or any that support using an address size other than that implied by the ELF file class (or another container format's explicit or implicit address size, or the architecture's implicit address size) so as to need address_size. But the same logic and questions apply as for .debug_line even so. OTOH, e.g. x86-64 -mcmodel=small could use address_size 4 and save some space in the .debug_frame output. Thanks, Roland
