similar to: [lld] RFC: Allow custom sections to be under GNU_RELRO

Peter, Thanks for the great feedback! > The first is the use of a custom suffix, all other linker conventions, that I know of, use prefixes as these are much easier and faster to match against names. > This can be important in large programs compiled -ffunction-sections as there can be millions of sections to match. I understand the reason of having these conventions in linkers. On the

Hello Leslie, I think we are going to need to know a bit more about the ELF ABI for what looks like the ArcCompact before we can help you. LLD's calculation of P (the place to be relocated) is as it is in the generic ELF specification. The Rel.Offset corresponds to the ELF r_offset field. This is covered by: "For a relocatable file, the value is the byte offset from the beginning of the

Hello Leslie, The errors coming from the gnu assembler are due to the file being assembled in Arm state, to get rid of the errors you'll either need to put a .thumb directive in the file, or pass -mthumb to the assembler via arm-linux-gnu-gcc -Wa,-mthumb (I think). I'm not able to explain what you are seeing in your print out as it doesn't quite match the map file. Looking at your

Hello Leslie, I don't know quite what to say as I don't know precisely what your question is? If I am not being precise enough please can you put some explicit questions in? From what I can see in the output, here are some comments. >From your arc mapfiles it looks like that in the output both linker's have given the .text output section the correct base address given the

>Thank you for taking a look. I think that the answer depends on how much slower GNU linkers are with separate .eh_frame sections. If it is not too slow, it may make >sense to generate split .eh_frame sections unconditionally. Otherwise, we might want to add a new option so that clang doesn't produce split .eh_frame sections by >default. I'll start investigating the

Hi Andrew, Thanks for the background and context. "In your issue, just to clarify, is the ELF output from LLD also "large", or is it just the output from the llvm-objcopy operating on that ELF that is "large"? Do you have a simple sample to demonstrate this issue?" The ELF size is actually smaller, compared to what was generated from LLVM 7.x. (~900Kb vs

Hi, Many linkers including lld have a feature to eliminate unused sections from output to make output smaller (which is essentially a mark-sweep gc where sections are vertices and relocations are edges). lld and GNU gold have yet another feature, ICF, to merge functions by contents to save more space. When we remove or merge a function, we want to eliminate its exception handling information as

This idea popped up in the review thread for https://reviews.llvm.org/D25627 . Problem: Currently, LLD creates special sections that are not just concatenations of input sections but need link-time data generation, such as .got, .plt, interp, .mips.options, etc., as output sections. We have OutputSectionBase subclasses (e.g. GotSection, PltSection, etc.) to create data. Even though this scheme

No I haven't. Thank you for the pointer. Looks like the problem of the inverted edges was discussed there. But I guess my bigger question is this: why do we still create one big .eh_frame even if -ffunction-sections is given? When the option is given, Clang creates .text, .rela.text and .gcc_exception_table sections for each function, but it still creates a monolithic .eh_frame that covers

I would suggest converting only part of linker generated sections to input sections to reduce amount of code changes. For example it's unlikely that SymbolTableSection or StringTableSection would ever require such treatment, so why converting them to input sections? 2016-10-19 11:03 GMT+03:00 George Rimar <grimar at accesssoftek.com>: >>This idea popped up in the review thread

On Wed, Oct 19, 2016 at 3:34 AM, Peter Smith via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Thanks for the RFC. > > I'm in favour of the option of creating InputSections for some linker > generated content. I think it would add extra flexibility to the > linker. ARM's proprietary linker uses the equivalent of InputSections > with a pseudo linker defined

I've noticed that lld keeps the data section more isolated than the gold or bfd linkers. For example, readelf -l applied to the "same" executable linked with those three linkers reveals the following under "Section to Segment mapping": lld: 05 .data .got.plt .bss gold: 03 .eh_frame .init_array .fini_array .preinit_array .dynamic .got .got.plt .data .bss bfd: 05

Hi, There will be problems with eh_frame_hdr. Eh_frame_hdr is needed to use the binary search instead of the linear search. Having eh_frame per a function will cause no eh_frame_hdr or multiple eh_frame_hdr and will degrade search from binary to linear. As we create eh_frame_hdr in most cases there is no problem to filter out garbage eh_frame sections. If there is information about unused

Hi llvm-dev, I'm currently looking for alternatives to the synthetic references that XRay uses to keep some side-tables live, to avoid linker garbage collection from deleting those sections. Before going any further, let me give a backgrounder on what XRay does today. Background ========== XRay has two side tables we use at runtime to identify the location of the sleds for the functions

We need to build with -mno-pic to disable all uses of GP, as well as use a custom linker script to avoid collisions between klibc.so's and the executable's segments. Signed-off-by: James Clarke <jrtc27 at jrtc27.com> --- usr/klibc/arch/ia64/MCONFIG | 3 + usr/klibc/arch/ia64/crt0.S | 4 - usr/klibc/arch/ia64/klibc.ld | 267 ++++++++++++++++++++++++++++++++++++++++++

Commit-ID: 8418552770110e9864ab24d60d8481fac58d3a65 Gitweb: http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=8418552770110e9864ab24d60d8481fac58d3a65 Author: James Clarke <jrtc27 at jrtc27.com> AuthorDate: Mon, 21 Jan 2019 21:26:57 +0000 Committer: Ben Hutchings <ben at decadent.org.uk> CommitDate: Mon, 21 Jan 2019 22:51:27 +0000 [klibc] ia64: Fix shared build We

>Keeping .eh_frame separated should still simplifies the linker because >until the last step of building .eh_frame and .eh_frame_hdr, we don't >really need to parse .eh_frame sections. So, if we have separate .eh_frame >sections on -ffunction-sections, all we have to do is (1) garbage-collect >sections and (2) construct .eh_frame and .eh_frame_hdr sections from live

Hi all, At the recent LLVM developers' meeting, I presented a lightning talk on an approach to reduce the amount of dead debug data left in an executable following operations such as --gc-sections and duplicate COMDAT removal. In that presentation, I presented some figures based on linking a game that had been built by our downstream clang port and fragmented using the described approach.

Are you suggesting other linker jobs such as creating _end symbols to the linker script? The linker script support was implemented after we wrote the current Writer class, so it is somewhat "plugged in" to the Writer. It might not be the best design, and not many other options have been explored. So there might be room to improve code by moving work loads from the Writer to the

Rafael, This is very good information and extremely useful. On 3/12/2015 11:49 AM, Rafael Espíndola wrote: > I tried benchmarking it on linux by linking clang Release+asserts (but > lld itself with no asserts). The first things I noticed were: > > missing options: > > warning: ignoring unknown argument: --no-add-needed > warning: ignoring unknown argument: -O3 > warning: