Re: [PowerPC 64]r12 is not updated to GEP when control transferred from virtual thunk function .

[Segher Boessenkool <segher at kernel dot crashing dot org>]

Hi Umesh,

Please spell out "global entry point", almost everything and everyone does.

On Wed, May 15, 2019 at 08:57:29PM +0530, Umesh Kalappa wrote:

>         .set    .LTHUNK0,_ZN12Intermediate1vEv

> _ZThn8_N12Intermediate1vEv:
> .LCF2:
> 0:      addis 2,12,.TOC.-.LCF2@ha
>         addi 2,2,.TOC.-.LCF2@l
>         .localentry     _ZThn8_N12Intermediate1vEv,.-_ZThn8_N12Intermediate1vEv
>         b .LTHUNK0

> _ZN12Intermediate1vEv:
> .LCF1:
> 0:      addis 2,12,.TOC.-.LCF1@ha
>         addi 2,2,.TOC.-.LCF1@l

> like above the control  from "_ZThn8_N12Intermediate1vEv" (support
> function for this pointer update)  is transferred
> "_ZN12Intermediate1vEv" by b  inst (where its not updating the r12)
> and in the beginning  of   "_ZN12Intermediate1vEv" we are loading the
> toc base from r12 (which is incorrect ) ,we are investigating the
> issue and one way to fix the issue is that make THUNK to update the
> r12 ,the cal like bctrl  or  load the r12 with the function address in
> the _ZN12Intermediate1vEv prologue code .

The thunk should point to the local entry point instead, I guess?

Please open a PR, with compilable testcase, and other relevant info (if
you need some specific -mcpu= for example, or other flags, do mention
that!)  See https://gcc.gnu.org/bugs.html for more info.  Thanks!


Segher