On Tue, 15 Jul 2025 20:24:04 GMT, Volkan Yazici <vyaz...@openjdk.org> wrote:
>> Validate input in `java.lang.StringCoding` intrinsic Java wrappers, improve >> their documentation, enhance the checks in the associated IR or assembly >> code, and adapt them to cause VM crash on invalid input. >> >> ## Implementation notes >> >> The goal of the associated umbrella issue >> [JDK-8156534](https://bugs.openjdk.org/browse/JDK-8156534) is to, for >> `java.lang.String*` classes, >> >> 1. Move `@IntrinsicCandidate`-annotated `public` methods<sup>1</sup> (in >> Java code) to `private` ones, and wrap them with a `public` ["front door" >> method](https://github.com/openjdk/jdk/pull/24982#discussion_r2087493446) >> 2. Since we moved the `@IntrinsicCandidate` annotation to a new method, >> intrinsic mappings – i.e., associated `do_intrinsic()` calls in >> `vmIntrinsics.hpp` – need to be updated too >> 3. Add necessary input validation (range, null, etc.) checks to the newly >> created public front door method >> 4. Place all input validation checks in the intrinsic code (add if missing!) >> behind a `VerifyIntrinsicChecks` VM flag >> >> Following preliminary work needs to be carried out as well: >> >> 1. Add a new `VerifyIntrinsicChecks` VM flag >> 2. Update `generate_string_range_check` to produce a `HaltNode`. That is, >> crash the VM if `VerifyIntrinsicChecks` is set and a Java wrapper fails to >> spot an invalid input. >> >> <sup>1</sup> `@IntrinsicCandidate`-annotated constructors are not subject >> to this change, since they are a special case. >> >> ## Functional and performance tests >> >> - `tier1` (which includes `test/hotspot/jtreg/compiler/intrinsics/string`) >> passes on several platforms. Further tiers will be executed after >> integrating reviewer feedback. >> >> - Performance impact is still actively monitored using >> `test/micro/org/openjdk/bench/java/lang/String{En,De}code.java`, among other >> tests. If you have suggestions on benchmarks, please share in the comments. >> >> ## Verification of the VM crash >> >> I've tested the VM crash scenario as follows: >> >> 1. Created the following test program: >> >> public class StrIntri { >> public static void main(String[] args) { >> Exception lastException = null; >> for (int i = 0; i < 1_000_000; i++) { >> try { >> >> jdk.internal.access.SharedSecrets.getJavaLangAccess().countPositives(new >> byte[]{1,2,3}, 2, 5); >> } catch (Exception exception) { >> lastException = exception; >> } >> } >> if (lastException != null) { >> lastException.printStackTrace... > > Volkan Yazici has updated the pull request with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains 12 additional > commits since the last revision: > > - Merge remote-tracking branch 'upstream/master' into strIntrinCheck > - Apply review feedback (styling changes) > - Minimize the number of touched lines in `vmIntrinsics.hpp` > - Remove Markdown-styling in comments > - Improve wording of the `VerifyIntrinsicChecks` flag > - Merge remote-tracking branch 'upstream/master' into strIntrinCheck > - Fix `EUC_JP.java.template` broken due to `encodeASCII` rename > - Remove `StringCodingCountPositives`, `String{En,De}code` already cover our > cases > > This reverts commit 196fc5d406851b8e7070c97ac53ca59c4615aad9. > - Improve intrinsics in `StringCoding` > - Add `StringCodingCountPositives` benchmark > - ... and 2 more: https://git.openjdk.org/jdk/compare/32d96877...85f19864 Thanks a lot for working on this, Volkan! The changes look good to me, I just added two comments. src/hotspot/share/opto/c2_globals.hpp line 665: > 663: "prints attempted and successful inlining of intrinsics") > \ > 664: > \ > 665: develop(bool, VerifyIntrinsicChecks, false, > \ We should add testing that uses this new flag. Maybe we could add a run to the tests that check the affected intrinsics? We could also add it to our (Oracle internal) stress test jobs at higher tiers. src/hotspot/share/opto/library_call.cpp line 971: > 969: } else { > 970: PreserveJVMState pjvms(this); > 971: set_control(_gvn.transform(bailout)); Suggestion: bailout = _gvn.transform(bailout); if (halt) { Node* frame = _gvn.transform(new ParmNode(C->start(), TypeFunc::FramePtr)); Node* halt = _gvn.transform(new HaltNode(bailout, frame, "unexpected guard failure in intrinsic")); C->root()->add_req(halt); } else { PreserveJVMState pjvms(this); set_control(bailout); ------------- Marked as reviewed by thartmann (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/25998#pullrequestreview-3023137214 PR Review Comment: https://git.openjdk.org/jdk/pull/25998#discussion_r2209259866 PR Review Comment: https://git.openjdk.org/jdk/pull/25998#discussion_r2209245394
