RFR: 8355798: Implement JEP 514: Ahead-of-Time Command Line Ergonomics

[Vladimir Kozlov]

On Tue, 29 Apr 2025 04:50:42 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> This is the implementation of the draft [JEP: Ahead-of-time Command Line Ergonomics](https://bugs.openjdk.org/browse/JDK-8350022)
> 
> - Implemented new flag `AOTCacheOutput`, which can be used to create an AOT cache using the "one-command workflow"
> - Added processing of the `AOT_TOOL_OPTIONS` environment variable that can supply extra VM options when creating an AOT cache
> - Added `%p` substitution for `AOTCache`, `AOTCacheOutput`, and `AOTConfiguration` options
> 
> Please see the [JEP](https://bugs.openjdk.org/browse/JDK-8350022) and [CSR](https://bugs.openjdk.org/browse/JDK-8356010) for detailed specification.
> 
> Examples:
> 
> 
> # Create an AOT cache with a single command:
> $ java -cp HelloWorld.jar -XX:AOTMode=record -XX:AOTCacheOutput=foo.aot HelloWorld
> Hello World
> Temporary AOTConfiguration recorded: foo.aot.config
> Launching child process /usr/bin/java to assemble AOT cache foo.aot using configuration foo.aot.config
> Picked up JAVA_TOOL_OPTIONS: -Djava.class.path=HelloWorld.jar -XX:AOTCacheOutput=foo.aot -XX:AOTConfiguration=foo.aot.config -XX:AOTMode=create
> Reading AOTConfiguration foo.aot.config and writing AOTCache foo.aot
> AOTCache creation is complete: foo.aot 10240000 bytes
> 
> # Create logging file for the AOT cache assembly phase
> $ export AOT_TOOL_COMMAND=-Xlog:cds:file=log.txt
> $ java -cp HelloWorld.jar -XX:AOTMode=record -XX:AOTCacheOutput=foo.aot HelloWorld
> 
> 
> Note: the child process is launched with Java API because the HotSpot native APIs are not sufficient (no way to set env vars for child process).

Few comments.

JEP and CSR call env var :`JAVA_AOT_OPTIONS`. This description and changes call it `AOT_TOOL_OPTIONS`. Please, fix.

src/hotspot/share/cds/metaspaceShared.cpp line 1068:

> 1066:   }
> 1067: 
> 1068:   // Pass all arguments. These include those from JAVA_TOOL_OPTIONS and _JAVA_OPTIONS.

`_JAVA_OPTIONS`. Do you mean `JAVA_AOT_OPTIONS`?

src/hotspot/share/cds/metaspaceShared.cpp line 1071:

> 1069:   for (int i = 0; i < Arguments::num_jvm_args(); i++) {
> 1070:     const char* arg = Arguments::jvm_args_array()[i];
> 1071:     if (strncmp("-XX:AOTMode", arg, 11) == 0) {

In arguments.cpp you do `strncmp("-XX:AOTMode=", arg, 12) == 0`. I think you need to be consistent.

src/java.base/share/classes/jdk/internal/misc/CDS.java line 510:

> 508: 
> 509:             Map<String, String> env = pb.environment();
> 510:             env.put("JAVA_TOOL_OPTIONS", sb.toString());

What about `JAVA_AOT_OPTIONS`?

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PR Review: https://git.openjdk.org/jdk/pull/24942#pullrequestreview-2804218715
PR Comment: https://git.openjdk.org/jdk/pull/24942#issuecomment-2839405664
PR Review Comment: https://git.openjdk.org/jdk/pull/24942#discussion_r2066881980
PR Review Comment: https://git.openjdk.org/jdk/pull/24942#discussion_r2066888741
PR Review Comment: https://git.openjdk.org/jdk/pull/24942#discussion_r2066892210