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* How to debug LTO-related failures?
@ 2018-03-16 14:33 Manuel Lauss
  2018-03-20 14:56 ` Martin Sebor
  0 siblings, 1 reply; 2+ messages in thread
From: Manuel Lauss @ 2018-03-16 14:33 UTC (permalink / raw)
  To: gcc-help

Hello,

Is there a guideline on how to best investigate LTO-related runtime
failures?  I've found
that gcc-8 r258566 miscompiles ffmpeg-3.4.2 when built with lto, and
I'd like to prepare a proper bug report.

Thanks!
    Manuel Lauss

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: How to debug LTO-related failures?
  2018-03-16 14:33 How to debug LTO-related failures? Manuel Lauss
@ 2018-03-20 14:56 ` Martin Sebor
  0 siblings, 0 replies; 2+ messages in thread
From: Martin Sebor @ 2018-03-20 14:56 UTC (permalink / raw)
  To: Manuel Lauss, gcc-help

On 03/16/2018 08:32 AM, Manuel Lauss wrote:
> Hello,
>
> Is there a guideline on how to best investigate LTO-related runtime
> failures?  I've found
> that gcc-8 r258566 miscompiles ffmpeg-3.4.2 when built with lto, and
> I'd like to prepare a proper bug report.

The GCC Wiki has some suggestions:

   https://gcc.gnu.org/wiki/DebuggingGCC
   https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction

I described the approach to debugging general optimizer problems
that involve large numbers of functions or multiple files and that
has worked for me in this response:

   https://gcc.gnu.org/ml/gcc/2018-02/msg00040.html

Martin

^ permalink raw reply	[flat|nested] 2+ messages in thread

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