[llvm] [VectorCombine] foldShuffleToIdentity - peek through bitcasts to see if they come from the same value to form identity sequence (PR #98334)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vla` running on `linaro-g3-02` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/17/builds/858

Here is the relevant piece of the build log for the reference:
```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clangd Unit Tests :: ./ClangdTests/26/78' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-3555992-26-78.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=78 GTEST_SHARD_INDEX=26 /home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests
--

Note: This is test shard 27 of 78.
[==========] Running 16 tests from 15 test suites.
[----------] Global test environment set-up.
[----------] 1 test from BackgroundQueueTest
[ RUN      ] BackgroundQueueTest.Duplicates
[       OK ] BackgroundQueueTest.Duplicates (0 ms)
[----------] 1 test from BackgroundQueueTest (22 ms total)

[----------] 2 tests from CompletionTest
[ RUN      ] CompletionTest.DynamicIndexMultiFile
ASTWorker building file /clangd-test/foo.cpp version null with command 
[/clangd-test]
clang -ffreestanding /clangd-test/foo.cpp
Driver produced command: cc1 -cc1 -triple aarch64-unknown-linux-gnu -fsyntax-only -disable-free -clear-ast-before-backend -main-file-name foo.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=non-leaf -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -ffreestanding -target-cpu generic -target-feature +v8a -target-feature +fp-armv8 -target-feature +neon -target-abi aapcs -debugger-tuning=gdb -fdebug-compilation-dir=/clangd-test -fcoverage-compilation-dir=/clangd-test -resource-dir lib/clang/19 -internal-isystem lib/clang/19/include -internal-isystem /usr/local/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -no-round-trip-args -target-feature -fmv -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x c++ /clangd-test/foo.cpp
Building first preamble for /clangd-test/foo.cpp version null
not idle after addDocument
UNREACHABLE executed at ../llvm/clang-tools-extra/clangd/unittests/SyncAPI.cpp:22!
 #0 0x0000aaaac10de980 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1d7e980)
 #1 0x0000aaaac10dc9b0 llvm::sys::RunSignalHandlers() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1d7c9b0)
 #2 0x0000aaaac10df048 SignalHandler(int) (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1d7f048)
 #3 0x0000ffffb5b349d0 (linux-vdso.so.1+0x9d0)
 #4 0x0000ffffb5687d78 raise /build/glibc-Q8DG8B/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #5 0x0000ffffb5674aac abort /build/glibc-Q8DG8B/glibc-2.31/stdlib/abort.c:81:7
 #6 0x0000aaaac10726e4 (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1d126e4)
 #7 0x0000aaaac0f0907c (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1ba907c)
 #8 0x0000aaaac0a7ef80 clang::clangd::(anonymous namespace)::CompletionTest_DynamicIndexMultiFile_Test::TestBody() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x171ef80)
 #9 0x0000aaaac1102ec8 testing::Test::Run() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1da2ec8)
#10 0x0000aaaac1104158 testing::TestInfo::Run() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1da4158)
#11 0x0000aaaac1104db0 testing::TestSuite::Run() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1da4db0)
#12 0x0000aaaac1114e04 testing::internal::UnitTestImpl::RunAllTests() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1db4e04)
#13 0x0000aaaac11142f0 testing::UnitTest::Run() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1db42f0)
#14 0x0000aaaac10f01a8 main (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x1d901a8)
#15 0x0000ffffb5674e10 __libc_start_main /build/glibc-Q8DG8B/glibc-2.31/csu/../csu/libc-start.c:342:3
#16 0x0000aaaac08a94c4 _start (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests+0x15494c4)

--
exit: -6
--
shard JSON output does not exist: /home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-3555992-26-78.json
********************


```

https://github.com/llvm/llvm-project/pull/98334