[DAG] SDPatternMatch - extend MinMax matchers to detect flippable signed/unsigned cases

[RKSimon]

Blocked by #174327

The m_SMaxLike/m_SMinLike/m_UMaxLike/m_UMinLike matchers can be extended to match the unsigned/signed equivalents if the operand signbits are known to be both zero or one.

You will have to investigate the best approach, but this can probably best be achieved by using the m_Negative/m_StrictlyPositive/m_NonNegative/m_NonPositive matchers proposed from #174327, extending the MinMaxLike matchers with additional patterns that include them.

Related to #174325

[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)

Details

Follow up to #174327

The m_SMaxLike/m_SMinLike/m_UMaxLike/m_UMinLike matchers can be extended to match the unsigned/signed equivalents if the operand signbits are known to be both zero or one.

You will have to investigate the best approach, but this is can probably best be achieved by using the m_Negative/m_StrictlyPositive/m_NonNegative/m_NonPositive matchers proposed from #174327, extending the MinMaxLike matchers with additional patterns that include them.

Related to #174325

[sweiglbosker]

Can i work on this when it is unblocked?

[RKSimon]

Can i work on this when it is unblocked?

Keep an eye on #174327 - once @ak1932 has an draft patch available you should be able to use that for your initial work.