[llvm] ValueTracking: log may never return -0 (PR #173380)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-flang-rhel-clang` running on `ppc64le-flang-rhel-test` while building `llvm` at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/43316

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

```
Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
...
PASS: Flang :: Driver/fcc_override.f90 (2361 of 4066)
PASS: Flang :: Evaluate/fold-erfc-scaled.f90 (2362 of 4066)
PASS: Flang :: Driver/fintegrated-as.f90 (2363 of 4066)
PASS: Flang :: Driver/funroll-loops.f90 (2364 of 4066)
PASS: Flang :: Evaluate/fold-ieee.f90 (2365 of 4066)
PASS: Flang :: Driver/hlfir-no-hlfir-error.f90 (2366 of 4066)
PASS: Flang :: Evaluate/fold-dble.f90 (2367 of 4066)
PASS: Flang :: Driver/unsafe-cray-pointers.f90 (2368 of 4066)
PASS: Flang :: Lower/OpenMP/rtl-flags.f90 (2369 of 4066)
PASS: Flang :: Intrinsics/math-codegen.fir (2370 of 4066)
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3354.556729
Step 7 (test-build-unified-tree-check-flang-rt) failure: 1200 seconds without output running [b'ninja', b'check-flang-rt'], attempting to kill
...
60.526 [4/6/34] Building CXX object flang-rt/unittests/Runtime/CMakeFiles/RuntimeTests.dir/NumericalFormatTest.cpp.o
60.591 [4/5/35] Building CXX object flang-rt/unittests/Runtime/CMakeFiles/RuntimeTests.dir/ExternalIOTest.cpp.o
60.662 [4/4/36] Building CXX object flang-rt/unittests/Runtime/CMakeFiles/RuntimeTests.dir/Transformational.cpp.o
60.662 [4/3/37] Linking CXX static library flang-rt/lib/Testing/libNonGTestTesting.a
63.401 [2/4/38] Linking CXX executable flang-rt/unittests/Evaluate/ISO-Fortran-binding.test
64.490 [2/3/39] Linking CXX executable flang-rt/unittests/Evaluate/reshape.test
71.112 [2/2/40] Building CXX object flang-rt/unittests/Runtime/CMakeFiles/RuntimeTests.dir/CharacterTest.cpp.o
98.184 [2/1/41] Building CXX object flang-rt/unittests/Runtime/CMakeFiles/RuntimeTests.dir/Reduction.cpp.o
104.023 [1/1/42] Linking CXX executable flang-rt/unittests/Runtime/RuntimeTests
104.024 [0/1/42] Running the Flang-RT regression tests
command timed out: 1200 seconds without output running [b'ninja', b'check-flang-rt'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1321.069179

```

</details>

https://github.com/llvm/llvm-project/pull/173380