[PATCH] D26327: Convert MIPS .reginfo section to synthetic input section.

[Simon Atanasyan via llvm-commits]

Hi,

Here is the patch fixes all issues mentioned below. It also converts
.MIPS.options section to synthetic one. The only failed test is the
mips-options-r.test. The linker creates .MIPS.options section, but
does not create a corresponding section symbol. I'm going to
investigate it.

Rui, what do you think about the patch?

On Mon, Nov 7, 2016 at 12:40 AM, Simon Atanasyan <simon at atanasyan.com> wrote:
> atanasyan added inline comments.
>
> ================
> Comment at: ELF/InputFiles.cpp:166
>      return MipsOptions->Reginfo->ri_gp_value;
> -  if (!ELFT::Is64Bits && MipsReginfo && MipsReginfo->Reginfo)
> -    return MipsReginfo->Reginfo->ri_gp_value;
> ----------------
> When we calculate R_MIPS_GPREL16/32 relocations we need to know `GP0` value stored in the .MIPS.options or .reginfo sections (take a look at the `computeAddend` routine). Each file might have it's own value. Usually `GP0` is equal to zero but it is not always true. After this change `getMipsGp0()` does not take in account `GP0` value stored in the .reginfo section and the `mips-gprel32-relocs-gp0.s` test case starts to fail.
>
> To solve the problem we can add `MipsGp0` field to the `ObjectFile` class and retrieve and save `GP0` value to this field in the say `ObjectFile::initializeSections` function.
>
> If you want I can work on that and convert MipsOptionsInputSection to synthetic input section too. It looks like it is better to convert .reginfo and .MIPS.options sections in a single patch.
>
>
> ================
> Comment at: ELF/SyntheticSections.cpp:110
> +    if (Config->Relocatable && RI->ri_gp_value)
> +      error("supported non-zero ri_gp_value");
> +    Reginfo.ri_gprmask |= RI->ri_gprmask;
> ----------------
> - s/supported/unsupported/
> - it is not very important, but it would be nice to continue to show a file's name in this error message. maybe add an argument to the `getSectionContents` routine to be able to pass a //validate// function.
>
>
> https://reviews.llvm.org/D26327

-- 
Simon Atanasyan
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