search for: gdb_index

I personally haven't tried gdb_index, and I don't know the quality of the produced index. Most of the code was written by George. One thing I noticed about the feature (and filed as http://bugs.llvm.org/show_bug.cgi?id=32228) is that our gdb_index feature is much slower than the gold. Apparently there's room for improvement....

...ssing information? I'd like to file that as a bug so that we can fix this later. On Thu, Mar 16, 2017 at 2:34 PM, David Blaikie <dblaikie at gmail.com> wrote: > FWIW - selfhosting I did find that GDB wasn't able to find the source code > for some functions when using LLD's gdb_index, so I've switched back to > gold+gdb_index for now (given the performance problems you mentioned, > sounds like I wasn't gaining much/anything in terms of link time by using > lld anyway). > > > On Thu, Mar 16, 2017 at 11:17 AM Rui Ueyama <ruiu at google.com> wrote:...

>FWIW - selfhosting I did find that GDB wasn't able to find the source code >for some functions when using LLD's gdb_index, so I've switched back to >gold+gdb_index for now (given the performance problems you mentioned, >sounds like I wasn't gaining much/anything in terms of link time by using >lld anyway). > >On Thu, Mar 16, 2017 at 11:17 AM Rui Ueyama <ruiu at google.com> wrote: > >...

Hi all, LLVM 4.0.0 is out, and I can say that LLD/ELF is now ready for production use at least for x86-64 (and probably for AArch64 and MIPS). I believe you've heard a few good news about the linker -- it just works <http://lld.llvm.org/#features> and is very fast <http://lld.llvm.org/#performance>, clean, compact and supported by the active community. I don't think I need to

...he tool would do:   - Remove obsolete debug info which refers to code deleted by the linker     doing the garbage collection (gc-sections).   - Deduplicate debug type definitions for reducing resulting size of binary.   - Build accelerator/index tables.     = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, .debug_pubtypes.   - Strip unneeded tables.     = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, .debug_pubtypes.   - Compress or decompress debug info as requested. Possible feature:   - Join split dwarf .dwo files in a single file containing all debug info...

...e deleted by > the linker >      doing the garbage collection (gc-sections). > >    - Deduplicate debug type definitions for reducing resulting > size of > binary. > >    - Build accelerator/index tables. >      = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, > .debug_pubtypes. > >    - Strip unneeded tables. >      = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, > .debug_pubtypes. > >    - Compress or decompress debug info as requested. > > Possible feature: > >...

...e deleted by > the linker >      doing the garbage collection (gc-sections). > >    - Deduplicate debug type definitions for reducing resulting > size of > binary. > >    - Build accelerator/index tables. >      = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, > .debug_pubtypes. > >    - Strip unneeded tables. >      = .debug_aranges, .debug_names, .gdb_index, .debug_pubnames, > .debug_pubtypes. > >    - Compress or decompress debug info as requested. > > Possible feature: > >...

...inary is 8x bigger than the usual linking time. Linking clang binary with DWARFLinker takes 72 sec, linking with the only lld takes 9 sec. 2. "Removing obsolete debug info" could not be switched off. Thus, lld could not use DWARFLinker for other tasks(like generation of index tables - .gdb_index, .debug_names) without significant performance degradation. 3. DWARFLinker does not support split dwarf at the moment. All these reasons are not blockers. And I believe implementation from D74169 might be integrated and incrementally improved if there would be agreement on that. Using DWARFLin...

...oing the garbage collection (gc-sections). >> >>    - Deduplicate debug type definitions for reducing >> resulting size of >> binary. >> >>    - Build accelerator/index tables. >>      = .debug_aranges, .debug_names, .gdb_index, >> .debug_pubnames, >> .debug_pubtypes. >> >>    - Strip unneeded tables. >>      = .debug_aranges, .debug_names, .gdb_index, >> .debug_pubnames, >> .debug_pubtypes. >> >>    - Compress or...

...gt;> >>>    - Deduplicate debug type definitions for reducing >>> resulting size of >>> binary. >>> >>>    - Build accelerator/index tables. >>>      = .debug_aranges, .debug_names, .gdb_index, >>> .debug_pubnames, >>> .debug_pubtypes. >>> >>>    - Strip unneeded tables. >>>      = .debug_aranges, .debug_names, .gdb_index, >>> .debug_pubnames, >>> .debug_...

...esource.com/magenta/+/master/make/build.mk#20) When is it useful: For kernels and embedded applications that need just the raw segments. 8. Use Case: Adding a gdb index Who uses it: Chromium ```sh gdb -batch foo -ex "save gdb-index dir" -ex quit objcopy --add-section .gdb_index="dir/foo.gdb-index" \ --set-section-flags .gdb_index=readonly foo foo ``` [Example use]( https://cs.chromium.org/chromium/src/build/gdb-add-index?type=cs&q=objcopy&l=71 ) When is it useful: Adding a gdb index reduces startup time for debugging an applicati...

Hi, In the file lld/ELF/Driver.cpp in function getCompressDebugSections we can see that the current default for lld is no debug section compression. It looks like tools like gdb, valgrind, elfutils, gcc's backtrace lib currently support compressed symbols. Since perf can use libdw from elfutils, I guess it supports it too. Do you think it's time to enable compressed debug section by

...Linking clang binary with DWARFLinker > takes 72 sec, > linking with the only lld takes 9 sec. > > 2. "Removing obsolete debug info" could not be switched off. Thus, > lld could not use DWARFLinker for > other tasks(like generation of index tables - .gdb_index, > .debug_names) without significant performance > degradation. > > 3. DWARFLinker does not support split dwarf at the moment. > > All these reasons are not blockers. And I believe implementation > from D74169 might be integrated and > incrementally i...

...- Deduplicate debug type definitions for >>>> reducing resulting size of >>>> binary. >>>> >>>>    - Build accelerator/index tables. >>>>      = .debug_aranges, .debug_names, .gdb_index, >>>> .debug_pubnames, >>>> .debug_pubtypes. >>>> >>>>    - Strip unneeded tables. >>>>      = .debug_aranges, .debug_names, .gdb_index, >>>> .debu...

...o read ODR tables produced by the N-1th and >>> possibly the N-2th release. >>> >> >> Still strikes me as a bit awkward - wonder how that compared to other >> (similar or different) linker features. >> > > I think the most similar existing feature is .gdb_index. They have already > gone through a few format revisions: > https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html > and have deprecated/removed support for older formats. > > Because the requirements for ODR tables are simpler than those for > .gdb_index, I'd exp...

...o read ODR tables produced by the N-1th and >>> possibly the N-2th release. >>> >> >> Still strikes me as a bit awkward - wonder how that compared to other >> (similar or different) linker features. >> > > I think the most similar existing feature is .gdb_index. They have already > gone through a few format revisions: > https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html > and have deprecated/removed support for older formats. > Not sure it's quite the same - that's an output of the linker & produces a performance...

...d. [r313744](http://reviews.llvm.org/rL313744). * A new Cross Translation Unit support library has been introduced, which can be used to load function definitions from external AST files. [r313975](http://reviews.llvm.org/rL313975). ## Other project commits * The speed of linking objects with `.gdb_index` has been improved. [r314090](http://reviews.llvm.org/rL314090), [r134092](http://reviews.llvm.org/rL314092). * The LLDB test suite can be run against (developer) armv7 and arm64 iOS devices. A public bot will soon be set up to report results. [r314038](http://reviews.llvm.org/rL314038). * What i...

...possibly the N-2th release. >>>>> >>>> >>>> Still strikes me as a bit awkward - wonder how that compared to other >>>> (similar or different) linker features. >>>> >>> >>> I think the most similar existing feature is .gdb_index. They have >>> already gone through a few format revisions: >>> https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html >>> and have deprecated/removed support for older formats. >>> >> >> Not sure it's quite the same - that's an o...

...; >>>>>> >>>>>> Still strikes me as a bit awkward - wonder how that compared to other >>>>>> (similar or different) linker features. >>>>>> >>>>> >>>>> I think the most similar existing feature is .gdb_index. They have >>>>> already gone through a few format revisions: >>>>> https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html >>>>> and have deprecated/removed support for older formats. >>>>> >>>> >>>> No...

On Tue, Jun 13, 2017, 11:30 PM Peter Collingbourne <peter at pcc.me.uk> wrote: > On Tue, Jun 13, 2017 at 11:06 PM, David Blaikie <dblaikie at gmail.com> > wrote: > >> >> >> On Tue, Jun 13, 2017 at 10:05 PM Peter Collingbourne <peter at pcc.me.uk> >> wrote: >> >>> On Tue, Jun 13, 2017 at 8:48 PM, David Blaikie <dblaikie at