## Issue This is a redo of [JDK-8361842](https://bugs.openjdk.org/browse/JDK-8361842) which was backed out by [JDK-8374210](https://bugs.openjdk.org/browse/JDK-8374210) due to C2-related regressions. The original change moved input validation checks for java.lang.StringCoding from the intrinsic to Java code (leaving the intrinsic check only with the `VerifyIntrinsicChecks` flag). Refer to the [original PR](https://github.com/openjdk/jdk/pull/25998) for details.
This additional issue happens because, in some cases, for instance when the Java checking code is not inlined and we give an out-of-range constant as input, we fold the data path but not the control path and we crash in the backend. ## Causes The cause of this is that the out-of-range constant (e.g. -1) floats into the intrinsic and there (assuming the input is valid) we add a constraint to its type to positive integers (e.g. to compute the array address) which makes it top. ## Fix A possible fix is to introduce an opaque node (OpaqueGuardNode) similar to what we do in `must_be_not_null` for values that we know cannot be null: https://github.com/openjdk/jdk/blob/ce721665cd61d9a319c667d50d9917c359d6c104/src/hotspot/share/opto/graphKit.cpp#L1484 This will temporarily add the range check to ensure that C2 figures that out-of-range values cannot reach the intrinsic. Then, during macro expansion, we replace the opaque node with the corresponding constant (true/false) in product builds such that the actually unneeded guards are folded and do not end up in the emitted code. # Testing * Tier 1-3+ * 2 JTReg tests added * `TestRangeCheck.java` as regression test for the reported issue * `TestOpaqueGuardNodes.java` to check that opaque guard nodes are added when parsing and removed at macro expansion ------------- Commit messages: - JDK-8374852: revert unchanged tests - JDK-8374852: shorten line lenght in test - JDK-8374852: revert comment change - JDK-8374852: correct comment and make more concise - Update test/hotspot/jtreg/compiler/intrinsics/string/TestRangeCheck.java - JDK-8374852: fix generate_limit_guard opaque handling and remove unneeded positive flag - JDK-8374852: remove compileonly - JDK-8374852: remove VerifyIntrinsicChecks and refactor opaque flag - JDK-8374852: add forgotten opaque guard node handling in clone_iff - JDK-8374852: 120 max char for comment - ... and 8 more: https://git.openjdk.org/jdk/compare/6d1bfdf7...ff228576 Changes: https://git.openjdk.org/jdk/pull/29164/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29164&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8374582 Stats: 435 lines in 28 files changed: 328 ins; 20 del; 87 mod Patch: https://git.openjdk.org/jdk/pull/29164.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/29164/head:pull/29164 PR: https://git.openjdk.org/jdk/pull/29164
