RFR: 8324858: [vectorapi] Bounds checking issues when accessing memory segments

[Maurizio Cimadamore]

On Mon, 29 Jan 2024 19:45:41 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> The implementation of method `VectorSpecies::fromMemorySegment`, in `AbstractSpecies::fromMemorySegment`, neglects to perform bounds checks on the offset argument when the method is compiled by C2 (bounds checks are performed when interpreted and by C1).
> 
> This is an oversight and explicit bounds checks are required, as is already case for the other load and store memory access methods (including storing to memory memory segments).
> 
> The workaround is to call the static method `{T}Vector::fromMemorySegment`.
> 
> The fix is for the implementation(s) of `VectorSpecies::fromMemorySegment` to do the same and call `{T}Vector::fromMemorySegment`, following the same pattern for implementations of `VectorSpecies::fromArray`.
> 
> The tests have been conservatively updated to call the species access method where possible in the knowledge that it calls the vector access method (the tests were intended to test out of bounds access when compiled by C2).
> 
> Thinking ahead its tempting to remove the species access methods, simplifying functionality that is duplicated.

test/jdk/jdk/incubator/vector/templates/X-LoadStoreTest.java.template line 271:

> 269:     @DontInline
> 270:     static $abstractvectortype$ fromArray($type$[] a, int i) {
> 271:         return ($abstractvectortype$) SPECIES.fromArray(a, i);

These new tests focus on the species method - but should we also test the statics factories in the record class, just in case a regression is introduced and the two implementation start diverging again?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17621#discussion_r1472143425