[llvm] [VPlan] Don't emit VPBlendRecipes with only one incoming value. NFC (PR #171804)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 128563 tests passed
* 2805 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM-Unit
<details>
<summary>LLVM-Unit.Transforms/Vectorize/_/VectorizeTests_exe/26/35</summary>

```
Script(shard):
--
GTEST_OUTPUT=json:C:\_work\llvm-project\llvm-project\build\unittests\Transforms\Vectorize\.\VectorizeTests.exe-LLVM-Unit-67748-26-35.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=35 GTEST_SHARD_INDEX=26 C:\_work\llvm-project\llvm-project\build\unittests\Transforms\Vectorize\.\VectorizeTests.exe
--

Note: This is test shard 27 of 35.

[==========] Running 2 tests from 2 test suites.

[----------] Global test environment set-up.

[----------] 1 test from VPRecipeTest

[ RUN      ] VPRecipeTest.CastVPInterleaveEVLRecipeToVPUser

[       OK ] VPRecipeTest.CastVPInterleaveEVLRecipeToVPUser (0 ms)

[----------] 1 test from VPRecipeTest (0 ms total)



[----------] 1 test from VPVerifierTest

[ RUN      ] VPVerifierTest.VPBlendUseBeforeDefDifferentBB

Assertion failed: Operands.size() >= 2 && "Expected at least two operands!", file C:\_work\llvm-project\llvm-project\llvm\include\../lib/Transforms/Vectorize/VPlan.h, line 2520

unknown file: error: SEH exception with code 0x3221225501 thrown in the test body.

Stack trace:





Assertion failed: Users.empty() && "trying to delete a VPValue with remaining users", file C:\_work\llvm-project\llvm-project\llvm\lib\Transforms\Vectorize\VPlan.cpp, line 101


--
exit: 3
--
shard JSON output does not exist: C:\_work\llvm-project\llvm-project\build\unittests\Transforms\Vectorize\.\VectorizeTests.exe-LLVM-Unit-67748-26-35.json
```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/171804