[llvm] [FlattenCFG] Fix an Imprecise Usage of AA (PR #128117)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `sanitizer-aarch64-linux-bootstrap-msan` running on `sanitizer-buildbot10` while building `llvm` at step 2 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/94/builds/6329

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

```
Step 2 (annotate) failure: 'python ../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py' (failure)
...
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 900 seconds was requested on the command line. Forcing timeout to be 900 seconds.
-- Testing: 84839 tests, 72 workers --
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70
FAIL: LLVM :: Other/spirv-sim/constant.spv (62889 of 84839)
******************** TEST 'LLVM :: Other/spirv-sim/constant.spv' FAILED ********************
Exit Code: 139

Command Output (stderr):
--
RUN: at line 1 has no command after substitutions
'/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=a --wave=1 --expects=2 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv # RUN: at line 2
+ /usr/bin/python3 /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=a --wave=1 --expects=2 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv
'/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv # RUN: at line 3
+ /usr/bin/python3 /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv
/home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/test/Other/spirv-sim/Output/constant.spv.script: line 3: 1722737 Segmentation fault      (core dumped) '/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv

--

********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90.. 
Slowest Tests:
--------------------------------------------------------------------------
27.03s: Clang :: Driver/fsanitize.c
23.88s: LLVM :: tools/llvm-reduce/parallel-workitem-kill.ll
19.96s: Clang :: Preprocessor/riscv-target-features.c
18.10s: Clang :: OpenMP/target_defaultmap_codegen_01.cpp
17.73s: Clang :: OpenMP/target_update_codegen.cpp
17.25s: Clang :: Driver/arm-cortex-cpus-2.c
16.83s: Clang :: Driver/arm-cortex-cpus-1.c
14.89s: Clang :: CodeGen/AArch64/sve-intrinsics/acle_sve_reinterpret.c
14.70s: Clang :: Preprocessor/aarch64-target-features.c
14.35s: Clang :: Preprocessor/arm-target-features.c
12.63s: Clang :: Analysis/a_flaky_crash.cpp
11.88s: Clang :: Preprocessor/predefined-arch-macros.c
11.71s: Clang :: CodeGen/AArch64/sve-intrinsics/acle_sve_reinterpret-bfloat.c
11.37s: Clang :: Driver/clang_f_opts.c
11.32s: Clang :: Driver/linux-ld.c
10.10s: lit :: shtest-define.py
10.07s: Clang :: Driver/cl-options.c
10.02s: Clang :: Driver/x86-target-features.c
10.02s: LLVM-Unit :: Support/./SupportTests/ProgramEnvTest/TestExecuteNoWaitDetached
9.31s: Clang :: Analysis/runtime-regression.c
Step 13 (stage3/msan check) failure: stage3/msan check (failure)
...
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using lld-link: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/lld-link
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using ld64.lld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/ld64.lld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/llvm/config.py:520: note: using wasm-ld: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/bin/wasm-ld
llvm-lit: /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/lit/lit/main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 900 seconds was requested on the command line. Forcing timeout to be 900 seconds.
-- Testing: 84839 tests, 72 workers --
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70
FAIL: LLVM :: Other/spirv-sim/constant.spv (62889 of 84839)
******************** TEST 'LLVM :: Other/spirv-sim/constant.spv' FAILED ********************
Exit Code: 139

Command Output (stderr):
--
RUN: at line 1 has no command after substitutions
'/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=a --wave=1 --expects=2 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv # RUN: at line 2
+ /usr/bin/python3 /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=a --wave=1 --expects=2 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv
'/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv # RUN: at line 3
+ /usr/bin/python3 /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv
/home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm_build2_msan/test/Other/spirv-sim/Output/constant.spv.script: line 3: 1722737 Segmentation fault      (core dumped) '/usr/bin/python3' /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/utils/spirv-sim/spirv-sim.py --function=b --wave=1 --expects=1 -i /home/b/sanitizer-aarch64-linux-bootstrap-msan/build/llvm-project/llvm/test/Other/spirv-sim/constant.spv

--

********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90.. 
Slowest Tests:
--------------------------------------------------------------------------
27.03s: Clang :: Driver/fsanitize.c
23.88s: LLVM :: tools/llvm-reduce/parallel-workitem-kill.ll
19.96s: Clang :: Preprocessor/riscv-target-features.c
18.10s: Clang :: OpenMP/target_defaultmap_codegen_01.cpp
17.73s: Clang :: OpenMP/target_update_codegen.cpp
17.25s: Clang :: Driver/arm-cortex-cpus-2.c
16.83s: Clang :: Driver/arm-cortex-cpus-1.c
14.89s: Clang :: CodeGen/AArch64/sve-intrinsics/acle_sve_reinterpret.c
14.70s: Clang :: Preprocessor/aarch64-target-features.c
14.35s: Clang :: Preprocessor/arm-target-features.c
12.63s: Clang :: Analysis/a_flaky_crash.cpp
11.88s: Clang :: Preprocessor/predefined-arch-macros.c
11.71s: Clang :: CodeGen/AArch64/sve-intrinsics/acle_sve_reinterpret-bfloat.c
11.37s: Clang :: Driver/clang_f_opts.c
11.32s: Clang :: Driver/linux-ld.c
10.10s: lit :: shtest-define.py
10.07s: Clang :: Driver/cl-options.c
10.02s: Clang :: Driver/x86-target-features.c
10.02s: LLVM-Unit :: Support/./SupportTests/ProgramEnvTest/TestExecuteNoWaitDetached
9.31s: Clang :: Analysis/runtime-regression.c

```

</details>

https://github.com/llvm/llvm-project/pull/128117