Request for reviews (S): 7026700: regression in 6u24-rev-b23: Crash in C2 compiler in PhaseIdealLoop::build_loop_late_post

[Tom Rodriguez]

On Apr 20, 2011, at 12:11 PM, Vladimir Kozlov wrote:

> This is fix for jdk7.
> 
> http://cr.openjdk.java.net/~kvn/7026700/webrev
> 
> Fixed 7026700: regression in 6u24-rev-b23: Crash in C2 compiler in PhaseIdealLoop::build_loop_late_post
> 
> With EA memory slices should be created explicitly for non-static fields regardless the value of ReduceFieldZeroing flag.

Do these really need to guarded?  Couldn't we just always do it?  

> LoadNode::split_through_phi() should not check profitability since we want to eliminate loads from non-escaping allocations.

What about this logic?

  // Skip the split if the region dominates some control edge of the address.
  if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
    return NULL;

Why should we give up when cnt == 3 and not others?

> I also want to disable memory split verification code in EA until the fix for 6984348. It produces false negative results since the verification code does not cover all cases.

Could you normal // comments or use #if 0 instead.  It's should have a comment explaining why it's disabled too.

tom