Hi,

when compiling the testcase in the patch (reduced from ira-color.c) with 
-O2 -ftree-parallelize-loops=2, we run into an ICE:
...
prephitmp_39 = PHI <_40(16), &conflicting_regs(7)>
ira-color.c:69:8: internal compiler error: verify_gimple failed
...

The variable conflicting_regs is a local array in the original function, 
and it's the job of eliminate_local_variables to rewrite 
'&conflicting_regs' into a thread function argument relative expression.

However, eliminate_local_variables iterates over the statements of a 
block but ignored the PHIs.


The patch fixes the problem conservatively by bailing out of 
parallelizing loops with a phi with an address expression in a phi argument.

Bootstrapped and reg-tested on x86_64.

Committed to trunk.

Thanks,
- Tom