On 2020-06-03, Alan Modra 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.
--
Alan Modra
Australia Development Lab, IBM
sizeof(Elf64_Shdr) = 64.
If we create a .debug_line fragment and a .debug_info fragment for a
function, we waste 128 bytes.
https://sourceware.org/pipermail/binutils/2020-May/111361.html
.debug_line.bar
We should use the unique linkage feature
https://sourceware.org/bugzilla/show_bug.cgi?id=25380
otherwise we also waste lots of bytes for the .debug_*.* section names.
