RFR(S): 8231550: C2: ShouldNotReachHere() in verify_strip_mined_scheduling

[Vladimir Ivanov]

Looks good.

(Submitted for testing.)

Best regards,
Vladimir Ivanov

On 03/10/2019 11:48, Roland Westrelin wrote:
> 
> http://cr.openjdk.java.net/~roland/8231550/webrev.00/
> 
> This is another case where too conservative alias analysis pushes a load
> in the outer strip mined loop and causes loop strip mining verification
> to fail. The regression test contains two subtests. In both cases, a
> load (either of the array length or of a field) depends on a CastPP
> that's control dependent on the counted loop. A store that's unrelated
> is sunk in the outer strip mined loop. Because the load can't float
> above the counted loop and because anti dependence analysis is too
> conservative, the load ends up in the outer strip mined loop. I see no
> way around this one other than to relax anti dependence analysis.
> 
> This also causes my recent fix for Shenandoah bug 8231761 to fail
> (because it relied on anti-dependence analysis to be conservative) so I
> also had to rework it.
> 
> Roland.
>