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

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 167058 tests passed
* 2933 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/61/69</summary>

```
Script(shard):
--
GTEST_OUTPUT=json:/home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/Transforms/Vectorize/./VectorizeTests-LLVM-Unit-1178113-61-69.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=69 GTEST_SHARD_INDEX=61 /home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/Transforms/Vectorize/./VectorizeTests
--

Note: This is test shard 62 of 69.
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from VPVerifierTest
[ RUN      ] VPVerifierTest.VPBlendUseBeforeDefDifferentBB
VectorizeTests: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/include/../lib/Transforms/Vectorize/VPlan.h:2520: llvm::VPBlendRecipe::VPBlendRecipe(PHINode *, ArrayRef<VPValue *>, DebugLoc): Assertion `Operands.size() >= 2 && "Expected at least two operands!"' failed.
 #0 0x0000000000981328 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Unix/Signals.inc:834:13
 #1 0x000000000097edfc llvm::sys::RunSignalHandlers() /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Signals.cpp:105:18
 #2 0x00000000009820e1 SignalHandler(int, siginfo_t*, void*) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Unix/Signals.inc:426:38
 #3 0x000079b8bff83330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
 #4 0x000079b8bffdcb2c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9eb2c)
 #5 0x000079b8bff8327e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
 #6 0x000079b8bff668ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
 #7 0x000079b8bff6681b (/lib/x86_64-linux-gnu/libc.so.6+0x2881b)
 #8 0x000079b8bff79517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
 #9 0x0000000000547cca (/home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/Transforms/Vectorize/./VectorizeTests+0x547cca)
#10 0x0000000000996850 os_stack_trace_getter /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:6240:7
#11 0x0000000000996850 testing::Test::Run() /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:2695:9
#12 0x0000000000997640 os_stack_trace_getter /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:6240:7
#13 0x0000000000997640 testing::TestInfo::Run() /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:2842:11
#14 0x0000000000998253 testing::TestSuite::Run() /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:3018:35
#15 0x00000000009a9474 testing::internal::UnitTestImpl::RunAllTests() /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:5922:41
#16 0x00000000009a8839 testing::UnitTest::Run() /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/src/gtest.cc:5485:10
#17 0x0000000000982c4a main /home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/UnitTestMain/TestMain.cpp:55:3
#18 0x000079b8bff681ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#19 0x000079b8bff6828b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#20 0x00000000004cf7a5 _start (/home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/Transforms/Vectorize/./VectorizeTests+0x4cf7a5)

--
exit: -6
--
shard JSON output does not exist: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/Transforms/Vectorize/./VectorizeTests-LLVM-Unit-1178113-61-69.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