similar to: Remove obsolete debug info while garbage collecting

On Tue, Sep 24, 2019 at 11:22 PM Rui Ueyama via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Alexay, > > Thank you for the detailed explanation. The other question I have is, as > discussed above, about dsymutil. You said that dsymutil is not usable at > link-time. What does that mean? If we only have to emit an output file in > the usual way and then automatically

17.09.2019 3:12, David Blaikie пишет: > > > On Wed, Sep 11, 2019 at 3:32 PM Alexey Lapshin via llvm-dev > <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > > Debuginfo and linker folks, we (AccessSoftek) would like to > suggest a proposal for removing obsolete debug info. If you find > it useful we will be happy to work on

So, after many shenanigans, we finally have -gmlt-like inline summary debug info in .debug_info when using -gsplit-dwarf (see r221306). Hooray \o/ Testing this with asan, it seems to be working: Given a simple example of inlining failure: $ cat asan.cpp __attribute__((always_inline)) inline void func(int* i) { *i = 3; } int main() { func(nullptr); } The failures before this change: #0

19.09.2019 4:24, David Blaikie пишет: > > > On Wed, Sep 18, 2019 at 7:25 AM Alexey Lapshin <a.v.lapshin at mail.ru > <mailto:a.v.lapshin at mail.ru>> wrote: > > >> > Generally speaking, dsymutil does a very similar thing. It parses > DWARF DIEs, analyzes relocations, scans through references and > throws out unused DIEs. But it`s current

Hi all ! We have an issue with LLD, it is "relocation R_X86_64_32 out of range" (PR31109) which occurs during resolving relocations in debug sections. It looks happens because .debug_info section can be too large sometimes and 32x relocation is not enough to represent the value. One of possible solutions looks to be to deduplicate information to reduce .debug_info size. The rest of

Thanks for providing the experimental data! It clearly shows the value of type sections in DWARF. Regarding why type sections are off by default, aside from the issue of consumers needing to understand them, there is a size penalty to type sections that becomes more evident in smaller projects (meaning, fewer compilation units). The size penalty can be balanced against the amount of

At least one proprietary linker put a lot of effort into deduplicating and rewriting debug information. This took up the majority of the link time despite serious engineering time on performance optimisation. For example, some sections were written from scratch by the linker because that proved faster than parsing the input. Teaching LLD to dedup DWARF should be expected to dramatically slow it

On 01.09.2020 06:27, David Blaikie wrote: > A quick note: The feature as currently proposed sounds like it's an > exact match for 'dwz'? Is there any benefit to this over the existing > dwz project? Is it different in some ways I'm not aware of? (I haven't > actually used dwz, so I might have some mistaken ideas about how it > should work) > > If

On 01.09.2020 20:07, David Blaikie wrote: > Fair enough - thanks for clarifying the differences! (I'd still lean a > bit towards this being dwz-esque, as you say "an extension of classic dwz" I doubt a little about "llvm-dwz" since it might confuse people who would expect exactly the same behavior. But if we think of it as "an extension of classic dwz" and

On 02.09.2020 21:44, David Blaikie wrote: > > > On Wed, Sep 2, 2020 at 9:56 AM Alexey <avl.lapshin at gmail.com > <mailto:avl.lapshin at gmail.com>> wrote: > > > On 01.09.2020 20:07, David Blaikie wrote: >> Fair enough - thanks for clarifying the differences! (I'd still >> lean a bit towards this being dwz-esque, as you say "an

Great, thanks! Those results are about roughly what I was expecting. I assume "compilation time" is actually just the link time? I find it particularly interesting that the DWARFLinker rewriting solution produces the same size improvement in .debug_line as the fragmented DWARF approach. That suggests that in that case, fragmented DWARF output is probably about as optimal as it can get.

Hi,   We propose llvm-dwarfutil - a dsymutil-like tool for ELF.   Any thoughts on this?   Thanks in advance, Alexey. ====================================================================== llvm-dwarfutil(Apndx A) - is a tool that is used for processing debug info(DWARF) located in built binary files to improve debug info quality, reduce debug info size and accelerate debug info processing.

Folks, we work on optimization of binary size and improvement of debug info quality. To reduce the size of the binary we use -ffunction-sections so that unused code would be garbage collected. When the linker does garbage collection, a lot of abandoned debug info is left behind. Besides inflated debug info size, we ended up with overlapping address ranges and no way to say valid vs garbage

>*nod* That's been the historic ELF+DWARF approach, but both MacOS (with dsyms+DWARF) and Windows >(COFF+CodeView+PDB) don't do it that way, and instead involve the linker to a degree. >Mostly I'm wondering if it'd be reasonable to (and if anyone would be interested in doing it) do >something more like the PDB support - fully debug-aware linking. Honestly saying I only

On 03.09.2020 01:36, David Blaikie wrote: > > > On Wed, Sep 2, 2020 at 3:26 PM Alexey <avl.lapshin at gmail.com > <mailto:avl.lapshin at gmail.com>> wrote: > > > On 02.09.2020 21:44, David Blaikie wrote: >> >> >> On Wed, Sep 2, 2020 at 9:56 AM Alexey <avl.lapshin at gmail.com >> <mailto:avl.lapshin at gmail.com>>

>If you're interested in things you can do in the linker for this - you might consider something more aggressive: Fully DWARF aware deduplication. > >This could be done hopefully by reusing some of the code in the dsymutil implementation in LLVM. > >This would be much more effective (and without the possible context-sensitive tradeoffs) than using type units. >Though

On Thu, Dec 15, 2016 at 11:35 AM Mehdi Amini <mehdi.amini at apple.com> wrote: > > > On Dec 15, 2016, at 10:54 AM, David Blaikie via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > > > > Branching off from a discussion of improvements to DIGlobalVariable > representations that Adrian's working on - got me thinking about related > changes that have

On 2020-05-28, David Blaikie wrote: >On Thu, May 28, 2020 at 2:52 PM Robinson, Paul <paul.robinson at sony.com> >wrote: > >> As has been mentioned elsewhere, Sony generally fixes up references from >> debug info to stripped functions (of any length) using -1, because that’s a >> less-likely-to-be-real address than 0x0 or 0x1. (0x0 is a typical base >>

"On Thu, Jun 4, 2020 at 3:11 PM Robinson, Paul <paul.robinson at sony.com> wrote: > > + Ben Dunbobbin, whose name I take in vain below. > He's my local expert on weird ELF features. > > > -----Original Message----- > > From: David Blaikie <dblaikie at gmail.com> > > Sent: Thursday, June 4, 2020 2:43 PM > > To: Robinson, Paul

On Fri, May 29, 2020 at 9:21 AM Robinson, Paul <paul.robinson at sony.com> wrote: > > > > > -----Original Message----- > > From: Fangrui Song <maskray at google.com> > > Sent: Friday, May 29, 2020 1:07 AM > > To: David Blaikie <dblaikie at gmail.com> > > Cc: Robinson, Paul <paul.robinson at sony.com>; Alexey Lapshin > >