RFR: 8313672: C2: PhaseCCP does not correctly track analysis dependencies involving shift, convert, and mask [v3]

[Daniel Lundén]

On Tue, 31 Oct 2023 16:24:04 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Fixed now. `-XX:RepeatCompilation=20` is fast and seems enough to practically always trigger the failure (although it is non-deterministic due to `-XX:+StressIGVN`).
>> 
>> I have not managed to reproduce the bug without `-Xcomp`.
>> 
>> Running the test with only `-Xcomp` is quite slow (~1 minute on my system). I added the below instead (the test itself completes in <1 second).
>> 
>> /*
>>  * @test
>>  * @bug 8313672
>>  * @summary Test CCP notification for value update of AndL through LShiftI and
>>  *          ConvI2L (reduced set of flags).
>>  * @run main/othervm -XX:CompileCommand=compileonly,compiler.ccp.TestShiftConvertAndNotification::test
>>  *                   -Xcomp
>>  *                   compiler.ccp.TestShiftConvertAndNotification
>>  *
>>  */
>
> `-Xcomp` is always very slow (after all it compiles everything), unless you restrict compilation.
> So here, I would remove both `-Xcomp` and the compilation restriction. That will make the run fast again. But then it is important to have enough repetitions of your test method, see comment lower down.

Done, both flags removed now (and number of iterations increased).

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PR Review Comment: https://git.openjdk.org/jdk/pull/16429#discussion_r1379860714