RFR: 8356865: C2: Unreasonable values for debug flag FastAllocateSizeLimit can lead to left-shift-overflow, which is UB [v3]
Benoît Maillard
bmaillard at openjdk.org
Fri Jun 20 16:39:51 UTC 2025
> This PR adds a range constraint for the `-XX:FastAllocateSizeLimit` debug flag. This prevents undefined behavior caused by left-shift overflow of the flag value in `GraphKit::new_array`.
>
> ### Testing
> - [x] [GitHub Actions](https://github.com/benoitmaillard/jdk/actions?query=branch%3AJDK-8356865)
> - [x] tier1-3, plus some internal testing
> - [x] Manual testing with values known to previously cause undefined behavior
>
> Thanks!
Benoît Maillard has updated the pull request incrementally with one additional commit since the last revision:
8356865: Change assert
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/25834/files
- new: https://git.openjdk.org/jdk/pull/25834/files/c8904a29..97f52b45
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=25834&range=02
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=25834&range=01-02
Stats: 3 lines in 1 file changed: 2 ins; 1 del; 0 mod
Patch: https://git.openjdk.org/jdk/pull/25834.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/25834/head:pull/25834
PR: https://git.openjdk.org/jdk/pull/25834
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