RFR: 8324345: Stack overflow during C2 compilation when splitting memory phi [v2]

[Daniel Lundén]

On Fri, 19 Jul 2024 10:44:56 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Limit test to only compile problematic method
>
> test/hotspot/jtreg/compiler/escapeAnalysis/TestFindInstMemRecursion.java line 30:
> 
>> 28:  *          overflow.
>> 29:  *
>> 30:  * @run main/othervm -Xcomp -XX:CompileThreshold=10 -XX:-TieredCompilation
> 
> This will lead to **a lot** of compilations and therefore increase the runtime of the test. I assume there is only one problematic method, so couldn't you limit compilation to that one?

Good point, now fixed and checked that it still reproduces the issue.

> test/hotspot/jtreg/compiler/vectorapi/VectorReplicateLongSpecialImmTest.java line 39:
> 
>> 37:  * @requires os.arch == "aarch64"
>> 38:  * @modules jdk.incubator.vector
>> 39:  * @run testng/othervm -XX:UseSVE=0 -XX:-TieredCompilation -XX:CompileThreshold=100 -XX:+IgnoreUnrecognizedVMOptions -XX:CompileCommand=MemLimit,*.*,0 compiler.vectorapi.VectorReplicateLongSpecialImmTest
> 
> Does that mean we hit the bailout here and re-compilations hits the memory limit?

Yes, exactly. We hit the memory limit later on, in register allocation. I suggest investigating in a separate issue, if there are no objections.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/20238#discussion_r1684297560
PR Review Comment: https://git.openjdk.org/jdk/pull/20238#discussion_r1684300433