[clang] [clang][CodeGen] Zero init unspecified fields in initializers in C (PR #97121)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-cmake-x86_64-avx512-linux` running on `avx512-intel64` while building `clang` at step 13 "test-suite".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/133/builds/4196

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

```
Step 13 (test-suite) failure: test (failure)
...
cd /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/MultiSource/Benchmarks/tramp3d-v4 && /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1.install/bin/llvm-size --format=sysv /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4 > /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4.size
cd /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/MultiSource/Benchmarks/tramp3d-v4 && /usr/bin/cmake -E create_symlink /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/test-suite/MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4.reference_output /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4.reference_output
gmake[2]: Leaving directory '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build'
[ 36%] Built target tramp3d-v4
gmake[1]: Leaving directory '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build'
gmake: *** [Makefile:136: all] Error 2
2024-09-24 19:12:47 INFO: Testing...
2024-09-24 19:12:47 INFO: Execute: /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/bin/llvm-lit -v -j 32 /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build -o /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/outputc9h6rhng.json
-- Testing: 2514 tests, 32 workers --
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_blendvps_253.test (1 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_blendvps_253.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_blendvps_253' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_blendvps_299.test (2 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_blendvps_299.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_blendvps_299' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_205.test (3 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_205.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_addpd_205' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_190.test (4 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_190.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_addpd_190' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_197.test (5 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_197.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_197' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_addps_117.test (6 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_addps_117.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_addps_117' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_212.test (7 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_212.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_212' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_addps_165.test (8 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_addps_165.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_addps_165' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_227.test (9 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_227.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_cmpeqpd_227' is missing
********************
NOEXE: test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_220.test (10 of 2514)
******************** TEST 'test-suite :: Bitcode/simd_ops/simd_ops_test_op_addpd_220.test' FAILED ********************
Executable '/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/test/sandbox/build/Bitcode/simd_ops/simd_ops_test_op_addpd_220' is missing
********************

```

</details>

https://github.com/llvm/llvm-project/pull/97121