similar to: [LLD] Support DWARF64, debug_info "sorting"

+James for context too (always good to include the folks from the original threads for continuity) Yeah, my general attitude there was just twofold, one that the discussion had strayed fairly far from the review (so interested parties might not see it, both because it's a targeted review thread on the noisy llvm-commits, and because fo the title not having much connection to the discussion)

(Adding back Cc: which got dropped) > (Igor - I don't know what happened, but your email split the mail thread in gmail for me.) The problem is that https://lists.llvm.org/pipermail/llvm-dev/2020-November/146528.html does not have an In-Reply-To: header. Added Igor to the Cc: list. If we go down the route (sorting DWARF64 after DWARF32), compared with a lightweight parse, I'd prefer

On Wed, Nov 11, 2020 at 12:55 AM James Henderson <jh7370.2008 at my.bristol.ac.uk> wrote: > > > > On Wed, 11 Nov 2020 at 05:41, David Blaikie <dblaikie at gmail.com> wrote: >> >> +James for context too (always good to include the folks from the >> original threads for continuity) >> >> Yeah, my general attitude there was just twofold, one that

On 2020-11-14, Alexander Yermolovich wrote: >Thanks for doing a diff and asking in other groups. > >So if I understand your concern with using first reloc as it relates to .debug_str. > >In DWARF4 for .debug_str is referenced from .debug_info, .debug_type using DW_FORM_strp. For DWARF32 it's 32bit unsigned, for DWARF64 it's 64bit unsigned. So in relocation section for some

On Wed, Nov 11, 2020 at 12:19 AM Alexander Yermolovich via llvm-dev < llvm-dev at lists.llvm.org> wrote: > This year Igor Kudrin put in a lot of work in enabling DWARF64 support in > LLVM. At Facebook we are looking into it as one of the options for handling > debug information over 4gigs in production environment. One concern is that > due to mix of third party libraries and

Looks like there is an agreement that this path, modifying lld to order sections using relocations, should be explored. If Igor doesn't object, since he was primary one driving DWARF64 so far, I would like to give it a shot at implementing and collecting some performance numbers. 🙂 Alex ________________________________ From: James Henderson <jh7370.2008 at my.bristol.ac.uk> Sent:

On Wed, 11 Nov 2020 at 05:41, David Blaikie <dblaikie at gmail.com> wrote: > +James for context too (always good to include the folks from the > original threads for continuity) > > Yeah, my general attitude there was just twofold, one that the > discussion had strayed fairly far from the review (so interested > parties might not see it, both because it's a targeted

On Fri, Nov 13, 2020 at 11:29 AM David Blaikie <dblaikie at gmail.com> wrote: > > On Fri, Nov 13, 2020 at 11:24 AM Fāng-ruì Sòng <maskray at google.com> wrote: > > > > On Fri, Nov 13, 2020 at 11:17 AM David Blaikie <dblaikie at gmail.com> wrote: > > > > > > On Fri, Nov 13, 2020 at 11:05 AM Fāng-ruì Sòng <maskray at google.com> wrote: >

In https://groups.google.com/g/generic-abi/c/i2Xio-47QdQ (you need to join the group before making a post) Cary Coutant raised yet another idea: whether we can use ".debug64" as the section prefix. I like the idea because of: * It is immediately obvious whether DWARF64 is used and whether DWARF32 is used along with DWARF64. * In a relocatable link mixing DWARF32 and DWARF64 sections,

On 2020-11-17, Igor Kudrin wrote: > >On 17.11.2020 14:05, Fāng-ruì Sòng wrote: >>On Mon, Nov 16, 2020 at 10:42 PM Igor Kudrin <ikudrin at accesssoftek.com> wrote: >>> >>>On 14.11.2020 3:42, Fāng-ruì Sòng wrote: >>>>For .debug_* in object files: >>>> >>>>DWARF32 -> SHT_PROGBITS (unchanged) >>>>DWARF64 ->

On Mon, Nov 16, 2020 at 10:42 PM Igor Kudrin <ikudrin at accesssoftek.com> wrote: > > On 14.11.2020 3:42, Fāng-ruì Sòng wrote: > > For .debug_* in object files: > > > > DWARF32 -> SHT_PROGBITS (unchanged) > > DWARF64 -> SHT_DWARF64 or SHT_GNU_DWARF64 > > > > In LLD, we will need to allow mixed SHT_PROGBITS and SHT_DWARF64. If > > all

On 2020-11-12, Alexander Yermolovich wrote: >Thanks for feedback. > >I agree with patch and numbers this will be a more concrete discussion, but I wanted to judge overall receptiveness to this approach and see maybe there was a better way. > >"Whilst the majority of objects will only have a single CU in them, there will be exceptions (LTO-generated objects, -r merged objects

Thanks for feedback. I agree with patch and numbers this will be a more concrete discussion, but I wanted to judge overall receptiveness to this approach and see maybe there was a better way. "Whilst the majority of objects will only have a single CU in them, there will be exceptions (LTO-generated objects, -r merged objects etc), so we do need to consider this approach." David can you

On 19.11.2020 03:21, Cary Coutant wrote: >>> If the .debug_str section *by itself* exceeds 4GB, then yes any string >>> with a 32-bit reference to it must be in the first 4GB. Strings that >>> have only 64-bit references to them can be sorted to the end of the >>> section, if necessary. I wouldn't think anyone guarantees or cares >>> about the

> -----Original Message----- > From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of David > Blaikie via llvm-dev > Sent: Wednesday, November 11, 2020 12:46 PM > To: James Henderson <jh7370.2008 at my.bristol.ac.uk> > Cc: llvm-dev at lists.llvm.org > Subject: Re: [llvm-dev] [LLD] Support DWARF64, debug_info "sorting" > > On Wed, Nov 11,

I got replies from Nick Clifton and Michael Matz: https://sourceware.org/pipermail/binutils/2020-November/114116.html (and its reply). I have mentioned (a) the difficulty of the detecting-DWARF64-by-first-relocation approach and (b) the section type approach in my reply there https://sourceware.org/pipermail/binutils/2020-November/114125.html (a) My prototype has made me feel uneasy with this

On Fri, Nov 13, 2020 at 11:17 AM David Blaikie <dblaikie at gmail.com> wrote: > > On Fri, Nov 13, 2020 at 11:05 AM Fāng-ruì Sòng <maskray at google.com> wrote: > > > > I got replies from Nick Clifton and Michael Matz: > > https://sourceware.org/pipermail/binutils/2020-November/114116.html > > (and its reply). > > I have mentioned (a) the difficulty

> Thinking about it, I wouldn't expect an LTO generated object itself to have a mixture of DWARF32/64, although I guess the 32/64 bit state could be encoded in the IR (I am not familiar enough with it to know if it actually is or not). It might be necessary to find ways to configure LTO to generate DWARF64, possibly via a link-time option. I don’t think we need to encode dwarf32/64 in IR

Thanks Alexander for bringing this up! > The major drawback in sorting, is the need to parse DWARF, even a little bit > of it (only the first 4 bytes of a section to tell which version it is - first 12 if you > want to be able to jump over contributions and check /all/ contributions > coming from a given input object file (it might contain a combination of > DWARFv4 and DWARFv5)

> -----Original Message----- > From: Fāng-ruì Sòng <maskray at google.com> > Sent: Tuesday, November 17, 2020 1:51 AM > To: Alexander Yermolovich <ayermolo at fb.com> > Cc: David Blaikie <dblaikie at gmail.com>; Wenlei He <wenlei at fb.com>; llvm- > dev at lists.llvm.org; Robinson, Paul <paul.robinson at sony.com>; James > Henderson