[libc] implement memalignment

[michaelrj-google]

Described in C23 (page 374): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=387

memalignment takes a void*and returns its alignment.

Here's a checklist for what you'll need to do for this:

• Add the implementation of memalignment in /src/stdlib
• Add tests for memalignment in /test/src/stdlib
• Add memalignment to entrypoints.txt for at least x86_64 and whatever you're building on
• Add memalignment to include/stdlib.yaml

Comment if you're interested in working on this, and feel free to reach out if you need help.

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-libc

Author: Michael Jones (michaelrj-google)

Described in C23 (page 374): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=387

memalignment takes a void*and returns its alignment.

Here's a checklist for what you'll need to do for this:

• Add the implementation of memalignment in /src/stdlib
• Add tests for memalignment in /test/src/stdlib
• Add memalignment to entrypoints.txt for at least x86_64 and whatever you're building on
• Add memalignment to include/stdlib.yaml

Comment if you're interested in working on this, and feel free to reach out if you need help.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Michael Jones (michaelrj-google)

Described in C23 (page 374): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=387

memalignment takes a void*and returns its alignment.

Here's a checklist for what you'll need to do for this:

• Add the implementation of memalignment in /src/stdlib
• Add tests for memalignment in /test/src/stdlib
• Add memalignment to entrypoints.txt for at least x86_64 and whatever you're building on
• Add memalignment to include/stdlib.yaml

Comment if you're interested in working on this, and feel free to reach out if you need help.

[hulxv]

I would like to work on it 😄
please assign me

[monadbobo]

I'm also interested in this.

[michaelrj-google]

It looks like @hulxv got a head start, I will assign it to you.