similar to: [LLVMdev] [lld] Representation of lld::Reference with a fake target

Hi, I need an advice on implementation of a very specific kind of relocations used by MIPS N64 ABI. As usual the main problem is how to pass target specific data over Native/YAML conversion barrier. In this ABI relocation record r_info field in fact consists of five subfields: * r_sym - symbol index * r_ssym - special symbol * r_type3 - third relocation type * r_type2 - second relocation type

Hi, The round trip passes just tries to load a *complete* object file in YAML/Native format back. The internal state should be the complete object file in native/yaml format. If some state is not recorded and that is really needed in the writer, we should add that to the Atom model. Shankar Easwaran On 2/9/2015 1:29 PM, Rui Ueyama wrote: > I want to bring this again because I think

Can we remove Native format support? I'd like to get input from anyone who wants to keep the current Native format in LLD. On Thu, Feb 5, 2015 at 2:03 PM, Shankar Easwaran <shankare at codeaurora.org> wrote: > The only way currently is to create a new reference, unless we can think > of adding some target specific metadata information in the Atom model. > > This has come up

I'm not planning to remove YAML. YAML is important for testing. On Fri, Feb 6, 2015 at 3:57 PM, Shankar Easwaran <shankare at codeaurora.org> wrote: > I am fine with it. I hope you are not planning to remove YAML. > > > On 2/6/2015 4:54 PM, Rui Ueyama wrote: > > Can we remove Native format support? I'd like to get input from anyone who > wants to keep the

On Fri, Feb 6, 2015 at 5:42 PM, Michael Spencer <bigcheesegs at gmail.com> wrote: > On Fri, Feb 6, 2015 at 5:31 PM, Rui Ueyama <ruiu at google.com> wrote: > > There are two questions. > > > > Firstly, do you think the on-disk format needs to compatible with a C++ > > struct so that we can cast that memory buffer to the struct? That may be > >

There are two questions. Firstly, do you think the on-disk format needs to compatible with a C++ struct so that we can cast that memory buffer to the struct? That may be super-fast but that also comes with many limitations. It's hard to extend, for example. Every time we want to store variable-length objects we need to define string-table-like data structure. And I'm not very sure that

I think no one is opposing the idea of reading and writing YAML. The problem here is that why we need to force all developers to write code to serialize intermediate data in the middle of link, which no one except the round-trip passes needs. On Fri, Feb 6, 2015 at 6:41 PM, Shankar Easwaram <shankarke at gmail.com> wrote: > Doing it for every input file is not useful as some of the

Not all input files have to be able to represented in YAML/Native format. There are many unrealistic use cases there. No one wants to write an executable file in Native because there's no operating system that can run that file. So is YAML. So is the combination of .so file and Native/YAML unless we have an operating system whose loader is able to loads a YAML .so file. We might want to write

On Sat, Nov 21, 2015 at 10:08 AM, Rui Ueyama <ruiu at google.com> wrote: > On Fri, Nov 20, 2015 at 11:02 PM, Simon Atanasyan <simon at atanasyan.com> > wrote: >> >> On Sat, Nov 21, 2015 at 9:28 AM, Rui Ueyama <ruiu at google.com> wrote: >> > On Fri, Nov 20, 2015 at 10:13 PM, Simon Atanasyan <simon at atanasyan.com> >> > wrote: >>

On Sat, Nov 21, 2015 at 9:28 AM, Rui Ueyama <ruiu at google.com> wrote: > On Fri, Nov 20, 2015 at 10:13 PM, Simon Atanasyan <simon at atanasyan.com> > wrote: >> >> In case of MIPS O32 ABI we have to find a matching R_MIPS_LO16 >> relocation to calculate R_MIPS_HI16 one because R_MIPS_HI16 uses >> combined addend (AHI << 16) + (short)ALO where AHI is

Initial issue is related to R_MIPS_GPREL16/32 relocations. When we calculate such relocations we need to know _gp symbol's value. This value might come from different sources. Usually we setup it using constant offset from the .got section. Also it might be defined by a linker script. And in rare but possible case it comes from .reginfo / .MIPS.options sections. Got example, GNU bfd linker

On Sun, Nov 22, 2015 at 1:28 AM, Rui Ueyama <ruiu at google.com> wrote: > I'm not sure if I understand the semantics of HI16 and LO16 relocations. If > my understanding is correct, a pair of HI16 and LO16 represents an addend > AHL. AHL is computed by (AHI<<16) | (ALO&0xFFFF). Can't we apply HI16 and > LO16 relocations separately and produce the same relocation

You are right. LLD does not have this problem. Initially I bumped into the MIPS specific bug related to GP relative relocations calculation. I tried to make reproduction script as general as possible and mistakenly make it too general. So now with your help I realized that the problem solely affects MIPS. On Tue, Sep 27, 2016 at 8:46 PM, Peter Smith <peter.smith at linaro.org> wrote: >

Nothing wrong with going ahead with a temporary measure if the temporary measure is reasonable (besides the discussion if checking in binary files is desirable). Even if you plan to add a test written in YAML, it's better to check in a binary at least for now than checking it in without any tests. On Mon, Apr 20, 2015 at 7:59 AM, Shankar Easwaram <shankarke at gmail.com> wrote: > I

Hi, I am working on support R_MIPS_HI16 / R_MIPS_LO16 in the new LLD and have a couple of questions. == Q1 In case of MIPS O32 ABI we have to find a matching R_MIPS_LO16 relocation to calculate R_MIPS_HI16 one because R_MIPS_HI16 uses combined addend (AHI << 16) + (short)ALO where AHI is original R_MIPS_HI16 addend and ALO is addend of the matching R_MIPS_LO16 relocation [1]. There are two

On Mon, Apr 20, 2015 at 1:44 AM, Shankar Easwaran <shankarke at gmail.com> wrote: > Attached patch fixes the issue. Thanks for the quick fix. The patch LGTM if you add a test case. Unfortunately yaml2obj does not support duplicated section names but we can use a binary input file. -- Simon Atanasyan

Hi, Now in case of relocatable object generation LLD merges and copies REL/RELA sections as is and does not touch any addends. But it is incorrect. If we have a relocation which targets a section, we have to adjust the relocation's addend to take in account that the section might be merged with other ones. Here is the reproduction script: % cat t1.s .data .long 0 .text bar: movl $1,

We are modeling target specific functionally using references, Doesn't your idea defeat the purpose of the atom model? Atoms are mostly target neutral and yaml/native format represents just an atom. Having a derived class for atoms will have a impact on the testing method with lld IMO. We could continue to model using references in my opinion and add some meta data information in the atom

Hi, FYI LLD cannot handle ELF sections with non-unique names. An object file with such sections can be generated by the Clang since r234143. I am not sure that Clang works absolutely correct but bfd linker works fine. Right now I do not have a time to investigate this problem. If nobody take, I will try to solve it later. Here is the reproduction script for x86_64 host: $ cat test.cc template

When LLD builds a shared library for x86_64 it puts _GLOBAL_OFFSET_TABLE_ to the both .symtab and .dynsym and defines it as a GLOBAL symbol. If later this shared library participates in executable file linking and GNU BFD linked is used for that, this linker shows an error: /usr/bin/ld: a.out: hidden symbol `_GLOBAL_OFFSET_TABLE_' in /usr/lib/x86_64-linux-gnu/crt1.o is referenced by DSO Gold