[X86][ConstExpr] Replace interp__builtin_blend with interp__builtin_ia32_shuffle_generic implementation

[RKSimon]

The ExprConstant handling of BI__builtin_ia32_blend / BI__builtin_ia32_pblend builtins can be similarly updated to use evalShuffleGeneric

[llvmbot]

@llvm/issue-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

The ExprConstant handling of BI__builtin_ia32_blend / BI__builtin_ia32_pblend builtins can be similarly updated to use evalShuffleGeneric

[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 is working on this issue. If someone is assigned to the issue or claimed to be working on it, ping the person. After one week without a response, the assignee may be changed.
2. Leave a comment indicating that you are working on the issue, 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-good-first-issue

Author: Simon Pilgrim (RKSimon)

The ExprConstant handling of BI__builtin_ia32_blend / BI__builtin_ia32_pblend builtins can be similarly updated to use evalShuffleGeneric

[adbox53]

Hi! I’m a first-time contributor and would like to work on this issue as part of a class project. Since it isn’t currently assigned, could I be assigned to it? Thanks!