RFR: 8283641: Large value for CompileThresholdScaling causes assert [v2]

[Vladimir Kozlov]

On Thu, 24 Mar 2022 18:00:32 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> src/hotspot/share/compiler/compilerDefinitions.cpp line 133:
>> 
>>> 131:     if (v > max_intx) {
>>> 132:       return max_intx;
>>> 133:     } else if (v < min_intx) {
>> 
>> This check is meaningless since `v` can't be negative. If you want you can add assert.
>
> I removed the `min_intx` check and added the asserts. I ran with the following tests and it didn't trigger the asserts. I'll rerun tiers 1-3 again.
> 
> 
> java -XX:CompileThreshold=-1         -XX:CompileThresholdScaling=1 -version
> java -XX:Tier0InvokeNotifyFreqLog=-2 -XX:CompileThresholdScaling=1 -version
> java -XX:Tier4BackEdgeThreshold=-2   -XX:CompileThresholdScaling=1 -version

Yes, there is `range()` checks for these flags declarations:

java -XX:CompileThreshold=-1         -XX:CompileThresholdScaling=1 -version
OnStackReplacePercentage cannot be validated because CompileThreshold value is invalid
CompileThreshold (-1) must be between 0 and 1073741823
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.


You can't specify negative Threshold values on command line. The assert is for some future case if we pass incorrect value.

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PR: https://git.openjdk.java.net/jdk/pull/7944