[lworld] Integrated: 8251046: [lworld] [lw3] C1 should avoid heap allocations in withfield when possible

[Frederic Parain]

On Wed, 5 Aug 2020 13:14:12 GMT, Frederic Parain <fparain at openjdk.org> wrote:

> Please review this patch which reduces the number of heap allocations when executing the withfield bytecode with C1.
> The CR linked below contains a more detailed description of the optimization:
> 
> CR: https://bugs.openjdk.java.net/browse/JDK-8251046
> 
> A rudimentary benchmark shows encouraging numbers:
> Measuring inline type creation time with -XX:TieredStopAtLevel=1
> Inline class Point has two int fields.
> Inline class Rectangle has four int fields.
> 
> Without the optimization:
> Benchmark                                Mode  Samples   Score  Score error  Units
> o.s.MyBenchmark.testPointCreation        avgt      200   7.573        0.027  ns/op
> o.s.MyBenchmark.testRectangleCreation    avgt      200  21.387        0.067  ns/op
> 
> With the optimization:
> Benchmark                                Mode  Samples  Score  Score error  Units
> o.s.MyBenchmark.testPointCreation        avgt      200  5.284        0.014  ns/op
> o.s.MyBenchmark.testRectangleCreation    avgt      200  7.750        0.082  ns/op
> 
> Tested manually and with Mach5, tiers 1 to 3 (with Tobias' changes enabling more C1 testing).
> 
> Thank you,
> 
> Fred

This pull request has now been integrated.

Changeset: 59d8f6b4
Author:    Frederic Parain <fparain at openjdk.org>
URL:       https://git.openjdk.java.net/valhalla/commit/59d8f6b4
Stats:     240 lines in 6 files changed: 55 ins; 155 del; 30 mod

8251046: [lworld] [lw3] C1 should avoid heap allocations in withfield when possible

Reviewed-by: thartmann

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PR: https://git.openjdk.java.net/valhalla/pull/137