[15] RFR: 8242895: failed: sanity at src/hotspot/share/opto/escape.cpp:2361

[Jamsheed C M]

Hi,

request to hold the review. need to change the code for dealing with 
unsafe access. as current capture code go for more execution time 
analyzing things.

Best regards,

Jamsheed

On 09/07/2020 13:01, Jamsheed C M wrote:
>
> Hi all,
>
> JBS:https://bugs.openjdk.java.net/browse/JDK-8242895
>
> Request for review changes made to offset computation and field write 
> detection for init captured stores due to phis addition between alloc 
> and init. This happen if init node in different outer loop wrt to 
> alloc node and there is a loop opt.  This was required as a result of 
> enhancement [1].
>
> Normally init are not associated with multiple alloc node during EA 
> phase, but changes done for [1] caused the code shapes of the form 
> [2]  to generate inits associated with multiple alloc node.
>
> This had implication in offset computation and field write detection 
> related to initializing stores.
>
> Attempt to fix in EA:
>
>      webrev: http://cr.openjdk.java.net/~jcm/8242895/webrev_fix_EA/
>
> Alternate fix:
>
>      Minimize the scenario in compiler generated code by throwing only 
> j.l.Error from slowpath(all exception async/sync are handled in 
> runtime exit).
>
>      Stub epilog doesn't poll or throw any exceptions. Disable full 
> loop opt before EA for detectable patterns and bailout EA for late 
> detected patterns.
>
>      webrev: http://cr.openjdk.java.net/~jcm/8242895/webrev_deopt/
>
> Please advice.
>
> Testing : mach tier1-5 (logs in jbs)
>
> Best regards,
>
> Jamsheed
>
>
> [1] JDK-8231291 <https://bugs.openjdk.java.net/browse/JDK-8231291>C2: 
> loop opts before EA should maximally unroll loops
>
> [2] that have its init node in different outer loop wrt to alloc node.
>
>
> loop begin
>
>    try{
>
>    return new obj()/  throw new obj()/ uncommon trap after allocation, 
> in a loop
>
>    } catch(ex) {
>
>    }
>
> loop end
>
>   42     public static IntA test(int n) {
>    43         for (int i=0; i<2; i++) {
>    44             try {
>    45                   return new IntA(n + i);
>    46             } catch (Exception e) {
>    47             }
>    48         }
>    49
>