[llvm] [InstCombine] Fix assertion failure in `foldVariableSignZeroExtensionOfVariableHighBitExtract` (PR #205148)

Mon Jul 6 23:11:43 PDT 2026

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-ubuntu-x-aarch64-pac-ret` running on `as-builder-11` while building `llvm` at step 12 "build-default-test-suite".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/229/builds/2779

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 12 (build-default-test-suite) failure: cmake (failure)
...
1.779 [5619/130/519] Linking C executable SingleSource/UnitTests/HashRecognize/crc16.be.data8
1.780 [5618/130/520] Linking C executable SingleSource/UnitTests/HashRecognize/crc16.le.data8
1.782 [5617/130/521] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.be.data8
1.787 [5616/130/522] Linking C executable SingleSource/Benchmarks/Misc/oourafft
1.789 [5615/130/523] Linking C executable SingleSource/UnitTests/HashRecognize/crc32.be
1.792 [5614/130/524] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-14-initialize-string.dir/2003-05-14-initialize-string.c.o
1.796 [5613/130/525] Linking CXX executable SingleSource/Benchmarks/Shootout-C++/Shootout-C++-moments
1.798 [5612/130/526] Linking CXX executable SingleSource/Benchmarks/Adobe-C++/stepanov_abstraction
1.800 [5611/130/527] Linking C executable SingleSource/UnitTests/HashRecognize/crc16.be.nodata
1.804 [5610/130/528] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc32.be
FAILED: SingleSource/UnitTests/HashRecognize/no-hr-crc32.be 
: && /home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/build/llvm-test-suite/tools/timeit --summary SingleSource/UnitTests/HashRecognize/no-hr-crc32.be.link.time /home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/build/bin/clang -march=armv8l+pauth -mbranch-protection=pac-ret -O2    -O3 -DNDEBUG -march=armv8l+pauth -O2 -Wl,--emit-relocs       -Xlinker --dependency-file=SingleSource/UnitTests/HashRecognize/CMakeFiles/no-hr-crc32.be.dir/link.d SingleSource/UnitTests/HashRecognize/CMakeFiles/no-hr-crc32.be.dir/crc32.be.c.o -o SingleSource/UnitTests/HashRecognize/no-hr-crc32.be   && cd /home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/build/llvm-test-suite/SingleSource/UnitTests/HashRecognize && /usr/bin/cmake -E copy /home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/llvm-test-suite/SingleSource/UnitTests/HashRecognize/crc32.be.reference_output /home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/build/llvm-test-suite/SingleSource/UnitTests/HashRecognize/crc32.be.reference_output
Error copying file "/home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/llvm-test-suite/SingleSource/UnitTests/HashRecognize/crc32.be.reference_output" to "/home/buildbot/worker/as-builder-11/x-aarch64-pac-ret/build/llvm-test-suite/SingleSource/UnitTests/HashRecognize/crc32.be.reference_output".
1.805 [5610/129/529] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc8.be
1.805 [5610/128/530] Linking C executable SingleSource/UnitTests/Vector/NEON/Vector-NEON-simple
1.805 [5610/127/531] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.be
1.805 [5610/126/532] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-21-UnionBitfields.dir/2003-05-21-UnionBitfields.c.o
1.807 [5610/125/533] Building CXX object SingleSource/Benchmarks/Shootout-C++/CMakeFiles/Shootout-C++-lists1.dir/lists1.cpp.o
1.808 [5610/124/534] Linking C executable SingleSource/UnitTests/HashRecognize/crc8.le
1.810 [5610/123/535] Linking CXX executable tools/not
1.818 [5610/122/536] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.be.data32
1.819 [5610/121/537] Linking CXX executable SingleSource/Benchmarks/Shootout-C++/Shootout-C++-random
1.819 [5610/120/538] Linking CXX executable SingleSource/Benchmarks/Shootout-C++/Shootout-C++-lists
1.819 [5610/119/539] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.le
1.819 [5610/118/540] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.le.data32
1.821 [5610/117/541] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-21-UnionTest.dir/2003-05-21-UnionTest.c.o
1.822 [5610/116/542] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.le.nodata
1.824 [5610/115/543] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-21-BitfieldHandling.dir/2003-05-21-BitfieldHandling.c.o
1.831 [5610/114/544] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.le.data8
1.840 [5610/113/545] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2004-03-15-IndirectGoto.dir/2004-03-15-IndirectGoto.c.o
1.841 [5610/112/546] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc32.le
1.844 [5610/111/547] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc8.le
1.849 [5610/110/548] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-22-VarSizeArray.dir/2003-05-22-VarSizeArray.c.o
1.852 [5610/109/549] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-06-16-InvalidInitializer.dir/2003-06-16-InvalidInitializer.c.o
1.852 [5610/108/550] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2004-08-12-InlinerAndAllocas.dir/2004-08-12-InlinerAndAllocas.c.o
1.858 [5610/107/551] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-22-LocalTypeTest.dir/2003-05-22-LocalTypeTest.c.o
1.860 [5610/106/552] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-06-16-VolatileError.dir/2003-06-16-VolatileError.c.o
1.861 [5610/105/553] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc16.be.nodata
1.865 [5610/104/554] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc8.le.data16
1.866 [5610/103/555] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2008-01-07-LongDouble.dir/2008-01-07-LongDouble.c.o
1.870 [5610/102/556] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2004-02-03-AggregateCopy.dir/2004-02-03-AggregateCopy.c.o
1.870 [5610/101/557] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-05-23-TransparentUnion.dir/2003-05-23-TransparentUnion.c.o
1.870 [5610/100/558] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2005-05-06-LongLongSignedShift.dir/2005-05-06-LongLongSignedShift.c.o
1.871 [5610/99/559] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-2003-10-12-GlobalVarInitializers.dir/2003-10-12-GlobalVarInitializers.c.o
1.873 [5610/98/560] Linking C executable SingleSource/UnitTests/HashRecognize/no-hr-crc8.be.data16
1.877 [5610/97/561] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-ConstructorDestructorAttributes.dir/ConstructorDestructorAttributes.c.o
1.879 [5610/96/562] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-PR491.dir/PR491.c.o
1.879 [5610/95/563] Linking C executable SingleSource/Regression/C/Regression-C-2003-05-14-initialize-string
1.880 [5610/94/564] Building C object SingleSource/Regression/C/CMakeFiles/Regression-C-PR1386.dir/PR1386.c.o

```

</details>

https://github.com/llvm/llvm-project/pull/205148