RFR: 8308031: Linkers should reject unpromoted variadic parameters [v4]

[Jorn Vernee]

On Thu, 1 Jun 2023 15:28:33 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> In C, arguments smaller than `int` are promoted to (`unsigned`) `int`, and `float` is promoted to `double`, when being passed as variadic argument (see e.g. https://en.cppreference.com/w/c/language/conversion#Default_argument_promotions). This patch restricts the layouts that can be used as variadic layouts to what is allowed by the C specification.
>> 
>> The fallback linker is also updated to use to correct function to link variadic calls (not doing this turned out not to be a problem so far, but it is problematic for instance on Mac/AArch64 when using the fallback linker). Adding the restriction on layouts for all linkers is also partly motivated by the fallback linker rejecting such unsupported variadic layouts already.
>> 
>> I've added a small paragraph to the Linker javadoc as well that explains the restriction. Comments on that are welcome, but please explain.
>> 
>> The tests are updated to no longer try to link variadic functions with the illegal layouts, and I've added some more negative tests to TestIllegalLink.
>> 
>> Testing:
>> - local testing on Windows/x64
>> - tier1-3 + jdk-tier5 (ongoing)
>> - manual test run on mac/aarch64 with the fallback linker to verify the correctness of the fallback linker changes.
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move prototype-less name

Thanks for the review! I've updated the CSR with the finalized version of the javadoc. Could you take a look at that as well? https://bugs.openjdk.org/browse/JDK-8309205

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PR Comment: https://git.openjdk.org/jdk/pull/14225#issuecomment-1572275551