[PATCH] Maybe fix PR87134

[Iain Sandoe]

> On 6 Sep 2018, at 17:24, Gerald Pfeifer <gerald@pfeifer.com> wrote:
> 
> On Wed, 5 Sep 2018, Richard Biener wrote:
>> So I'm testing the following then, leaving the placement new untouched
>> (no init is fine) and then assign from vNULL.
>> 
>> 2018-09-05  Richard Biener  <rguenther@suse.de>
>> 
>> 	PR bootstrap/87134
>> 	* tree-ssa-sccvn.c (rpo_elim::eliminate_push_avail): Make sure
>> 	to zero-init the emplaced vec.
> 
> Unfortunately it does not fix the build on i586-unknown-freebsd10.4.
> 
> (Yes, I am trying various things to nail this one down and provide
> more input or make it reproducible for you, alas without success so
> far.)
> 
> Some things I found is that 
> 
> - building for i686-unknown-freebsd10.4 instead of 
>   i586-unknown-freebsd10.4 does not make a difference.
>   (I tried, since Jeff referred to successful i686 builds).
> 
> - not just builds with the system compiler (clang 3.4.1) fail, 
>   but also those with GCC mainline from 20180827 do -- with the 
>   same failure mode

I can confirm the same, repeatable, fail on i686-darwin10 (and it reproduces with -save-temps)
(and the vNULL change does not fix it there either) - don’t have access to the machine now until
later in the month tho.

I produced a back-trace here:

https://gist.github.com/iains/5ef0cd177ea17f6dc50f6c88cb5ac929

Iain