similar to: RFC: LLD symbol table redesign

On Tue, Feb 28, 2017 at 11:39 PM, Rui Ueyama <ruiu at google.com> wrote: > I also did a quick profiling a few months ago and noticed just like you > that scanRelocations consumes a fairly large percentage of overall > execution time. That caught my attention because at the time I was looking > for a place that I can parallelize. > > scanRelocations is not parallelizable

On Tue, Feb 28, 2017 at 12:10 PM, Rui Ueyama <ruiu at google.com> wrote: > I don't think getVA is particularly expensive, and if it is not expensive > I wouldn't cache its result. Did you experiment to cache getVA results? I > think you can do that fairly easily by adding a std::atomic_uint64_t to > SymbolBody and use it as a cache for getVA. > You're right,

tl;dr: it looks like we call SymbolBody::getVA about 5x more times than we need to Should we cache it or something? (careful with threads). Here is a link to a PDF of my Mathematica notebook which has all the details of my investigation: https://drive.google.com/open?id=0B8v10qJ6EXRxVDQ3YnZtUlFtZ1k There seem to be two main regimes that we redundantly call SymbolBody::getVA: 1. most

Hi, Rafael took some measurements to try to investigate the effect of the local symbols changes. I've been taking a look at the measurements he got and there were some interesting things we noticed. For starters, in the range of revisions tested (r263214 through r263471), we found that the commit for --build-id was the most noticeable, with slowdowns from 7% to 23% (note: these were

We have fairly large and complex code to handle relocations in Writer.cpp, Target.cpp, OutputSections.cpp and InputSections.cpp. They started with simple code, but because each patch added a small piece of code to the existing one, it is becoming out of control now. For example, we have lots of entangled boolean flags in the functions that interfere with each other in an obscure fashion. Even I

I've been working on supporting ARM/Thumb interworking thunks in LLD and have encountered a limitation that I think it is worth bringing up in a wider context. This is all LLD specific, apologies if I've abused llvm-dev here. TL;DR summary: - Thunks in lld may not work if they are added to InputSections that have already been scanned. - There is a short term fix, but in the longer term I

I'm copying some LLD code into my codebase like this: // workaround for LLD not exposing ability to convert .def to .lib #include <set> namespace lld { namespace coff { class SymbolBody; class StringChunk; struct Symbol; struct Export { StringRef Name; // N in /export:N or /export:E=N StringRef ExtName; // E in /export:E=N SymbolBody *Sym = nullptr; uint16_t Ordinal

On Tue, Feb 21, 2017 at 2:05 PM, Rafael Avila de Espindola via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Carlo Kok <ck at remobjects.com> writes: > > > On 2017-02-21 20:33, Rafael Avila de Espindola wrote: > >>> Input files: > >>> https://www.dropbox.com/s/8yn3dggx05atn47/binLinux.zip?dl=0 > >> > >> If you pass --reproduce

On Wed, Jun 14, 2017 at 7:37 PM, Rui Ueyama <ruiu at google.com> wrote: > On Wed, Jun 14, 2017 at 4:24 PM, Andrew Kelley via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> I'm copying some LLD code into my codebase like this: >> >> // workaround for LLD not exposing ability to convert .def to .lib >> >> #include <set> >>

Slowdown by "[ELF] - Early continue in InputSectionBase<ELFT>::relocate(). NFC.?" looks wierd for me. I do not see any reasons for any impact on perfomance by this change. Good news is that since it was NFC it can easily be reverted. But I think slowdown in results is unrelative with that change and reverting will not give us 2-3% boost back. Best regards, George.

I saw this change come in yesterday: commit 572ad839e2f66eaa82ffc71b1061eb3d06a4d126 Author: Saleem Abdulrasool <compnerd at compnerd.org> Date: Thu Jun 15 20:39:58 2017 +0000 COFF: add support for lib mode usage When link is invoked with `/def:` and no input files, it behaves as if `lib.exe` was invoked. Emulate this behaviour, generating the import library from the

On Sat, Mar 25, 2017 at 6:56 AM, Hal Finkel via llvm-dev < llvm-dev at lists.llvm.org> wrote: > > On 03/24/2017 11:42 PM, Sean Silva via llvm-dev wrote: > > > > On Mar 24, 2017 5:22 PM, "Reid Kleckner" <rnk at google.com> wrote: > > I figured you might consider moving the basenames of the filename earlier > in the diagnostic, something like: >

I am late on the thread, but I just want to say that the new format looks awesome! Thanks, Rafael On 29 March 2017 at 15:18, Rui Ueyama via llvm-dev <llvm-dev at lists.llvm.org> wrote: > My bad. I intended this. > > Undefined symbol error: > > bin/ld.lld: error: undefined symbol: > lld::elf::EhFrameSection<llvm::object::ELFType<(llvm::support::endianness)0, >

On Mar 24, 2017 5:22 PM, "Reid Kleckner" <rnk at google.com> wrote: I figured you might consider moving the basenames of the filename earlier in the diagnostic, something like: bin/ld.lld: *error:* duplicate symbol: lld::elf::MipsGotSection::addEntry(lld::elf::SymbolBody&, long, lld::elf::RelExpr) *>>> defined at* Writer.cpp:38 in

Folks, I'd like propose a new error message format for LLD so that error message for undefined or duplicated symbols are more informative and easy to read. Below are examples of the current error messages (note that characters in red are actually red on terminal): *Undefined symbols* /ssd/clang/bin/ld.lld: error: /ssd/llvm-project/lld/ELF/Writer.cpp:207: undefined symbol

On Fri, Mar 24, 2017 at 2:04 PM, Sean Silva <chisophugis at gmail.com> wrote: > I lile the idea of having it more structured and I think your suggested > format is the right direction. > > I think one principle should be that we assume that file names and symbol > names are "really long" (possibly wrapped by the terminal etc.). > Right. That's what we should

On 3/29/17 12:53 PM, Rui Ueyama via llvm-dev wrote: > Put it all together, the following error messages should work for > everybody. I'll create a patch to make this change and send it for > review. Thank you guys for the inputs! > > > Undefined symbol error: > > bin/ld.lld: error: undefined symbol: >

E.g. Is it intended to be allowed to call lld::elf::link in 2 different threads at the same time? Follows is an example Valgrind error I ran into when doing the above. I'll try putting a global resource lock on invoking LLD and see if it solves the problem. ==5467== Invalid write of size 8 ==5467== at 0x525509: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,

On Mon, Nov 7, 2016 at 5:53 PM, Davide Italiano <davide at freebsd.org> wrote: > On Mon, Nov 7, 2016 at 4:43 PM, Kostya Serebryany via llvm-dev > <llvm-dev at lists.llvm.org> wrote: >> The asan bootstrap bot is unhappy with lld. >> Rui, os someone, please take a look. >> >>

On 9 May 2013 19:13, John McCall <rjmccall at apple.com> wrote: > On May 9, 2013, at 6:34 PM, Nick Lewycky <nlewycky at google.com> wrote: > > I'm looking into how we can improve devirtualization in clang, and there > a language in C++ feature I'd like to take advantage of which would let us > perform elimination of more vptr loads. In this code: > > >