RFR: 8316414: C2: large byte array clone triggers "failed: malformed control flow" assertion failure on linux-x86 [v2]

[Tobias Hartmann]

On Wed, 27 Sep 2023 11:29:55 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> `GraphKit::new_array()` computes the maximum array length as:
>> 
>> 
>> BasicType bt = ary_type->isa_aryptr()->elem()->array_element_basic_type();
>> jint max = TypeAryPtr::max_array_length(bt);
>> 
>> 
>> while `AllocateArrayNode::make_ideal_length()` calls
>> `TypeAryPtr::narrow_size_type()` which in turn uses:
>> 
>> 
>> jint max_hi = max_array_length(elem()->basic_type());
>> 
>> 
>> That is, one uses `elem()->array_element_basic_type()` and the other
>> `elem()->basic_type()`. As a result, the test that guarantees a new
>> array allocation doesn't exceed the maximum array size and the
>> `CastII` that narrows the length on the success path for the
>> allocation don't use the same maximum array size values. The `CastII`
>> one is lower and it is transformed to top. The fallthrough path should
>> die but doesn't.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   copyright fix

Looks good and trivial to me.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15914#pullrequestreview-1654392091