Optimize x * !x to 0 for vector

[k-arrows]

Consider the following test case from https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.dg/tree-ssa/pr114009.c

typedef int V __attribute__((vector_size (4 * sizeof (int))));

V qux (V x)
{
  return x * (x == 0);
}

Godbolt: https://godbolt.org/z/dfGacerv8
Alive2: https://alive2.llvm.org/ce/z/uijB4T

[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. In the comments of the issue, request for it to be assigned to you.
2. Fix the issue locally.
3. 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.
4. Create a Git commit.
5. Run git clang-format HEAD~1 to format your changes.
6. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation.

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: None (k-arrows)

Consider the following test case from https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.dg/tree-ssa/pr114009.c ```c typedef int V __attribute__((vector_size (4 * sizeof (int))));

V qux (V x)
{
return x * (x == 0);
}

Godbolt: https://godbolt.org/z/dfGacerv8
Alive2: https://alive2.llvm.org/ce/z/uijB4T
</details>

[dtcxzyw]

Alive2: https://alive2.llvm.org/ce/z/-XEPRP

[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. In the comments of the issue, request for it to be assigned to you.
2. Fix the issue locally.
3. 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.
4. Create a Git commit.
5. Run git clang-format HEAD~1 to format your changes.
6. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation.

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: None (k-arrows)

Consider the following test case from https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.dg/tree-ssa/pr114009.c ```c typedef int V __attribute__((vector_size (4 * sizeof (int))));

V qux (V x)
{
return x * (x == 0);
}

Godbolt: https://godbolt.org/z/dfGacerv8
Alive2: https://alive2.llvm.org/ce/z/uijB4T
</details>

[SahilPatidar]

@dtcxzyw,
I would like to work on this one.

[SahilPatidar]

Alive2: https://alive2.llvm.org/ce/z/-XEPRP

This case also needs to be handled. Additionally, I couldn't find any such pattern in the existing code in InstCombineMulDivRem.cpp, so it likely needs to be implemented from scratch.