RFR: 8335221: Some C2 intrinsics incorrectly assume that type argument is compile-time constant

[Roland Westrelin]

On Thu, 27 Jun 2024 02:15:20 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> Problems were found in some C2 intrinsics while testing Leyden Early Release.
> 
> [`inline_array_partition()`](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/library_call.cpp#L5493) and [`inline_array_sort()`](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/library_call.cpp#L5559) intrinsics incorrectly assume that `elementType` argument is always compile-time constant. Which is not true for Leyden (and in general) when constant folding optimization is switched off (or did not executed for particular type).
> 
> Note, other intrinsics are very careful about that. For example, see [`inline_Class_cast()`](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/library_call.cpp#L3963) intrinsic.
> 
> Add similar checks to `inline_array_partition()` and `inline_array_sort()`.
> 
> An other problem is that `null_check()` (which adds new control nodes to graph) was executed in these intrinsics before bailouts from intrinsic generation. We hit next assert if bailout happens:
> 
>   assert(ctrl == kit.control(), "Control flow was added although the intrinsic bailed out");
> 
> 
> I moved `null_check()` after bailouts.
> 
> An other issue with `null_check()` is it checks for `null` first argument which is `Class`. It can't be `null` because corresponding Java methods are `private` and each call site passed `<primitive_type>.class` as first argument.
> For example: [DualPivotQuicksort.java#L260](https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/util/DualPivotQuicksort.java#L260)
> On other hand there is no null check for passed array (second argument). I changed `null_check()` for array.
> 
> These 2 intrinsics were added by [JDK-8309130](https://bugs.openjdk.org/browse/JDK-8309130) in JDK 22.
> 
> Testing tier1-6, hs-stress, hs-xcomp

Looks good to me.

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Marked as reviewed by roland (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19918#pullrequestreview-2144652566