Cryptic bug for DMD v2.087.x

[Guillaume Piolat]

On Monday, 12 August 2019 at 01:45:24 UTC, Peter Jacobs wrote:
> We have a flow simulation code 
> (http://cfcfd.mechmining.uq.edu.au/eilmer/) that fails to build 
> optimized with DMD v2.087.0 or v2.087.1.  The cryptic message 
> at the end of the attempt to build is:
>   tym = x14
>   makefile:414: recipe for target 'e4shared' failed
>   make: *** [e4shared] Illegal instruction (core dumped)
> and the compiler flags are:
>   dmd -w -O -release -inline -boundscheck=off -dip1008 ...
>
> The build is successful if we omit the -O flag.
>
> In contrast, we have successful optimized builds for DMD 
> 2.086.1 and LDC 1.17.0-beta1.
>
> I can provide more details but I was thinking that the "tym = 
> x14" might already mean something to someone familiar with the 
> insides of DMD.
>
> Best regards,
> Peter J.

Hello,

This is a DMD backend bug. If you could spend the few hours (much 
less with habit) needed to reduce it to a small piece of code 
that still triggers the bug, it would really help the community.

What I do is just delete code and get to that small reproducible 
example with manual dichotomy.