"Serious" validation failures on i686

A very recent run of ./validate on i686 revealed 6 failures, 4 of which I'm hopefully fixing with D5031, but the other two look more serious.

The circle ci build logs are here: https://circleci.com/gh/ghc/ghc/7578

One of the remaining failures in particular seems somewhat critical:

Wrong exit code for heapprof001(prof_hc_hb)(expected 0 , actual 139 )
Stdout ( heapprof001 ):
a <= 
a <= 
a <= 
a <= 
a <= 
a <= 
a <=
Stderr ( heapprof001 ):
Segmentation fault
*** unexpected failure for heapprof001(prof_hc_hb)

While the other one might be a lot simpler:

Actual stdout output differs from expected:
--- ./ghci/should_run/T3171.run/T3171.stdout.normalised	2018-07-31 05:27:01.821192706 +0000
+++ ./ghci/should_run/T3171.run/T3171.run.stdout.normalised	2018-07-31 05:27:01.821192706 +0000
@@ -1 +0,0 @@
-Interrupted.
*** unexpected failure for T3171(normal)

I have not investigated any of those yet, but the first one does seem like a bug.

Trac metadata

Trac field	Value
Version	8.5
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
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Blocking
CC
Operating system
Architecture