[DAG] SDPatternMatch m_Zero/m_One/m_AllOnes have inconsistent undef handling

[RKSimon]

m_Zero/m_One uses ISD::isConstantSplatVector which allows undefs in the BUILD_VECTOR node by default
m_AllOnes uses isAllOnesOrAllOnesSplat which doesn't allow undefs in the BUILD_VECTOR node by default

All of these need to be consistent with their default and with/without undefs handling to be configurable

This needs to be handled in conjunction with #140745 which will revise m_Zero handling to be closed to m_AllOnes

[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)

m_Zero/m_One uses ISD::isConstantSplatVector which allows undefs in the BUILD_VECTOR node by default m_AllOnes uses isAllOnesOrAllOnesSplat which doesn't allow undefs in the BUILD_VECTOR node by default

All of these need to be consistent with their default and with/without undefs handling to be configurable

This needs to be handled in conjunction with #140745 which will revise m_Zero handling to be closed to m_AllOnes

[woruyu]

hello, I would like to contribute this! Thank you @RKSimon ！

[woruyu]

add pr