RFR: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports [v6]

[Vladimir Kozlov]

On Wed, 2 Dec 2020 18:02:14 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> A number of jtreg tests require a specific GC. These tests should be ignored when EnableJVMCI is true and the JVMCI compiler does not support the required GC.
>> 
>> This PR adds `JVMCICompiler.isGCSupported` and makes use of it in `WhiteBox.isGCSupported`.
>> 
>> Prior to this PR, a test requiring a GC not yet supported by a JVMCI compiler fail as follows:
>> Error occurred during initialization of VM
>> JVMCI Compiler does not support selected GC: epsilon gc
>
> Doug Simon has updated the pull request incrementally with one additional commit since the last revision:
> 
>   added jvmci tag to new warning and improved its message

Marked as reviewed by kvn (Reviewer).

src/hotspot/share/jvmci/jvmci_globals.cpp line 207:

> 205:     // Check if selected GC is supported by JVMCI and Java compiler
> 206:     if (!(UseSerialGC || UseParallelGC || UseG1GC)) {
> 207:       log_warning(gc, jvmci)("Setting EnableJVMCI to false as selected GC does not support JVMCI: %s", GCConfig::hs_err_name());

Now message is:
[0.001s][warning][gc,jvmci] Setting EnableJVMCI to false as selected GC does not support JVMCI: z gc

Okay.

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PR: https://git.openjdk.java.net/jdk/pull/1423