[llvm] [AggressiveInstCombine] Recognize table based log2 and replace with ctlz+sub. (PR #185160)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-amdgpu-runtime-2` running on `rocm-worker-hw-02` while building `llvm` at step 10 "Add check check-libc-amdgcn-amd-amdhsa".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/24590

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

```
Step 10 (Add check check-libc-amdgcn-amd-amdhsa) failure: test (failure)
...
[2570/3360] Running hermetic test libc.test.src.stdbit.stdc_trailing_ones_ull_test.__hermetic__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcStdcTrailingOnesUllTest.ALL
[       OK ] LlvmLibcStdcTrailingOnesUllTest.ALL (1 us)
[ RUN      ] LlvmLibcStdcTrailingOnesUllTest.ZeroHot
[       OK ] LlvmLibcStdcTrailingOnesUllTest.ZeroHot (4 us)
Ran 2 tests.  PASS: 2  FAIL: 0
[2571/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.atan2l_test.__hermetic__.__build__
[2572/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.atan_test.__hermetic__.__build__
[2573/3360] Running hermetic test libc.test.src.stdbit.stdc_first_leading_zero_us_test.__hermetic__
FAILED: libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_us_test.__hermetic__.__cmd__ /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_us_test.__hermetic__.__cmd__ 
cd /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit && /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-gpu-loader /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_us_test.__hermetic__.__build__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUsTest.ALL
[       OK ] LlvmLibcStdcFirstLeadingZeroUsTest.ALL (1 us)
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUsTest.ZeroHot
[       OK ] LlvmLibcStdcFirstLeadingZeroUsTest.ZeroHot (2 us)
Ran 2 tests.  PASS: 2  FAIL: 0
[2574/3360] Running hermetic test libc.test.src.stdbit.stdc_first_leading_zero_uc_test.__hermetic__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUcTest.ALL
[       OK ] LlvmLibcStdcFirstLeadingZeroUcTest.ALL (2 us)
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUcTest.ZeroHot
[       OK ] LlvmLibcStdcFirstLeadingZeroUcTest.ZeroHot (1 us)
Ran 2 tests.  PASS: 2  FAIL: 0
[2575/3360] Running hermetic test libc.test.src.stdbit.stdc_first_leading_zero_ui_test.__hermetic__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUiTest.ALL
[       OK ] LlvmLibcStdcFirstLeadingZeroUiTest.ALL (2 us)
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUiTest.ZeroHot
[       OK ] LlvmLibcStdcFirstLeadingZeroUiTest.ZeroHot (4 us)
Ran 2 tests.  PASS: 2  FAIL: 0
[2576/3360] Running hermetic test libc.test.src.stdbit.stdc_first_leading_zero_ul_test.__hermetic__
FAILED: libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_ul_test.__hermetic__.__cmd__ /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_ul_test.__hermetic__.__cmd__ 
cd /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit && /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-gpu-loader /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/runtimes/runtimes-amdgcn-amd-amdhsa-bins/libc/test/src/stdbit/libc.test.src.stdbit.stdc_first_leading_zero_ul_test.__hermetic__.__build__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUlTest.ALL
[       OK ] LlvmLibcStdcFirstLeadingZeroUlTest.ALL (2 us)
[ RUN      ] LlvmLibcStdcFirstLeadingZeroUlTest.ZeroHot
[       OK ] LlvmLibcStdcFirstLeadingZeroUlTest.ZeroHot (3 us)
Ran 2 tests.  PASS: 2  FAIL: 0
[2577/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalorder_test.__hermetic__.__build__
[2578/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalordermag_test.__hermetic__.__build__
[2579/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalordermagf_test.__hermetic__.__build__
[2580/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalorderf16_test.__hermetic__.__build__
[2581/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalorderl_test.__hermetic__.__build__
[2582/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.totalordermagf16_test.__hermetic__.__build__
[2583/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.erff_test.__hermetic__.__build__
[2584/3360] Linking CXX executable libc/test/src/math/smoke/libc.test.src.math.smoke.atanf16_test.__hermetic__.__build__

```

</details>

https://github.com/llvm/llvm-project/pull/185160