GHC goes into an apparently infinite loop at -O2

I ran across a peculiar case this evening: a benchmark that I can't compile with -O2, because GHC goes into an infinite loop.

I have a very small repro at https://github.com/bos/inttable/blob/2d529c693f4c9a2903dae8f640759a05e7d20c69/Repro.hs

You can grab the necessary code and reproduce as follows:

git clone git://github.com/bos/inttable.git
cd inttable
ghc -O2 --make Repro

With GHC 7.6.3, this goes into an infinite loop. If I compile with -v3, I see that GHC freezes here:

*** SpecConstr:
Result size of SpecConstr

This never prints any output. Since the compiler isn't allocating more memory, I assume that it's stuck in a loop, rather than doing something productive.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	MacOS X
Architecture