On Wed, 18 Oct 2023 12:45:05 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> Add the ability to pass heap segments to native code. This requires using >> `Linker.Option.critical(true)` as a linker option. It has the same >> limitations as normal critical calls, namely: upcalls into Java are not >> allowed, and the native function should return relatively quickly. Heap >> segments are exposed to native code through temporary native addresses that >> are valid for the duration of the native call. >> >> The motivation for this is supporting existing Java array-based APIs that >> might have to pass multi-megabyte size arrays to native code, and are >> current relying on Get-/ReleasePrimitiveArrayCritical from JNI. Where making >> a copy of the array would be overly prohibitive. >> >> Components of this patch: >> >> - New binding operator `SegmentBase`, which gets the base object of a >> `MemorySegment`. >> - Rename `UnboxAddress` to `SegmentOffset`. Add flag to specify whether >> processing heap segments should be allowed. >> - `CallArranger` impls use new binding operators when >> `Linker.Option.critical(/* allowHeap= */ true)` is specified. >> - `NativeMethodHandle`/`NativeEntryPoint` allow `Object` in their signatures. >> - The object/oop + offset is exposed as temporary address to native code. >> - Since we stay in the `_thread_in_Java` state, we can safely expose the >> oops passed to the downcall stub to native code, without needing GCLocker. >> These oops are valid until we poll for safepoint, which we never do >> (invoking pure native code). >> - Only x64 and AArch64 for now. >> - I've refactored `ArgumentShuffle` in the C++ code to no longer rely on >> callbacks to get the set of source and destination registers (using >> `CallingConventionClosure`), but instead just rely on 2 equal size arrays >> with source and destination registers. This allows filtering the input java >> registers before passing them to `ArgumentShuffle`, which is required to >> filter out registers holding segment offsets. Replacing placeholder >> registers is also done as a separate pre-processing step now. See changes >> in: >> https://github.com/openjdk/jdk/pull/16201/commits/d2b40f1117d63cc6d74e377bf88cdcf6d15ff866 >> - I've factored out `DowncallStubGenerator` in the x64 and AArch64 code to >> use a common `DowncallLinker::StubGenerator`. >> - Fallback linker is also supported using JNI's >> `GetPrimitiveArrayCritical`/`ReleasePrimitiveArrayCritical` >> >> Aside: fixed existing issue with `DowncallLinker` not properly acquiring >> segments in interpreted mode. >> >> Numbers for the included benchmark on my machine are: >> >> >> Benchmar... > > Jorn Vernee has updated the pull request incrementally with six additional > commits since the last revision: > > - Add xor benchmark > - add readOnly heap segment test > - shorten linker doc > - use allocateFrom in benchmarks > - use unsafeGetBase in fallback linker > - remove impl note from isCritical PPC64 code is here: [PPC64_Panama_heap_segments.patch](https://github.com/openjdk/jdk/files/13025334/PPC64_Panama_heap_segments.patch) All tests are passing on linux PPC64le. One single test case is failing on Big Endian: test TestLayoutPaths.testBadAlignmentOfRoot(): failure java.lang.AssertionError: expected [true] but found [false] at org.testng.Assert.fail(Assert.java:99) at org.testng.Assert.failNotEquals(Assert.java:1037) at org.testng.Assert.assertTrue(Assert.java:45) at org.testng.Assert.assertTrue(Assert.java:55) at TestLayoutPaths.testBadAlignmentOfRoot(TestLayoutPaths.java:157) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132) at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:599) at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174) at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46) at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822) at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128) at java.base/java.util.ArrayList.forEach(ArrayList.java:1597) at org.testng.TestRunner.privateRun(TestRunner.java:764) at org.testng.TestRunner.run(TestRunner.java:585) at org.testng.SuiteRunner.runTest(SuiteRunner.java:384) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337) at org.testng.SuiteRunner.run(SuiteRunner.java:286) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1218) at org.testng.TestNG.runSuitesLocally(TestNG.java:1140) at org.testng.TestNG.runSuites(TestNG.java:1069) at org.testng.TestNG.run(TestNG.java:1037) at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:102) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:333) at java.base/java.lang.Thread.run(Thread.java:1570) ------------- PR Comment: https://git.openjdk.org/jdk/pull/16201#issuecomment-1768430267
