RFR: 8343700: ceil_log2 should not loop endlessly [v2]

[Aleksey Shipilev]

On Wed, 13 Nov 2024 18:29:04 GMT, Sonia Zaldana Calles <szaldana at openjdk.org> wrote:

>> Hi all, 
>> 
>> This PR addresses [8343700](https://bugs.openjdk.org/browse/JDK-8343700) where ceil_log2 looped endlessly if the input value has the highest bit set. 
>> 
>> I also dealt with the case where we try to find ceil_log2(1) which would've returned 1 as opposed to 0. 
>> 
>> Cheers, 
>> Sonia
>
> Sonia Zaldana Calles has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into JDK-8343700
>  - 8343700: ceil_log2 should not loop endlessly

src/hotspot/share/utilities/powerOfTwo.hpp line 127:

> 125: inline T ceil_log2(T value) {
> 126:   assert(value > 0, "Invalid value");
> 127:   if (value == 1) return 0;

Is this the same as starting the loop from `ret = 0`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22074#discussion_r1840980246