Reducing code size of Position Independent Executables (PIE) by shrinking the size of dynamic relocations section

[Sriraman Tallam via binutils]

+llvm-dev

Discussion here: https://sourceware.org/ml/gnu-gabi/2017-q2/msg00000.html

On Tue, May 2, 2017 at 10:17 AM, Suprateeka R Hegde
<hegdesmailbox@gmail.com> wrote:
> On 02-May-2017 12:05 AM, Florian Weimer wrote:
>> On 05/01/2017 08:28 PM, Suprateeka R Hegde wrote:
>>> So the ratio shows ~96% is RELATIVE reloc. And only ~4% others. This is
>>> not the case on HP-UX/Itanium. But as I said, this comparison does not
>>> make sense as the runtime architecture and ISA are totally different.
>>
>> It could be that HP-UX was written in a way to reduce relative
>> relocations,
>
> Rather, the Itanium runtime architecture itself provides a way to reduce
> them.
>
>> or that the final executables aren't actually PIC anymore.
>
> I was referring to shlibs (PIC) on HP-UX and it was implicit in my mind.
> Sorry for that.
>
> I just built a large C++ shlib both on HP-UX/Itanium with our aCC
> compiler and Linux x86-64 using GCC-6.2. The sources are almost same
> with only a couple of lines differing between platforms.
>
> (HP-UX/Linux)
> Total:    12224/38311
> RELATIVE: 18/6397
>
> I will try to check the reason for such a huge difference in RELATIVE
> reloc count. It might be useful for this discussion (just a guess)
>
> --
> Supra