[llvm] [RISCV][llvm-exegesis] Add unittests. NFC (PR #121862)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-s390x-linux` running on `systemz-1` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/42/builds/2680

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'libFuzzer-s390x-default-Linux :: reduce_inputs.test' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 3: rm -rf /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
+ rm -rf /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
RUN: at line 4: mkdir -p /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
+ mkdir -p /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
RUN: at line 5: /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/./bin/clang    -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta   --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/ShrinkControlFlowSimpleTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/./bin/clang -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/ShrinkControlFlowSimpleTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest
RUN: at line 6: /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/./bin/clang    -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta   --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/ShrinkControlFlowTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowTest
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/./bin/clang -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/ShrinkControlFlowTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowTest
RUN: at line 7: /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest  -exit_on_item=0eb8e4ed029b774d80f2b66408203801cb982a60   -runs=1000000 /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C 2>&1 | FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest -exit_on_item=0eb8e4ed029b774d80f2b66408203801cb982a60 -runs=1000000 /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
+ FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test
RUN: at line 11: /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest -runs=0 /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C 2>&1 | FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test --check-prefix=COUNT
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp-ShrinkControlFlowSimpleTest -runs=0 /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C
+ FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test --check-prefix=COUNT
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test:12:8: error: COUNT: expected string not found in input
COUNT: seed corpus: files: 4
       ^
<stdin>:1:1: note: scanning from here
INFO: Running with entropic power schedule (0xFF, 100).
^
<stdin>:7:7: note: possible intended match here
INFO: seed corpus: files: 3 min: 2b max: 3b total: 7b rss: 31Mb
      ^

Input file: <stdin>
Check file: /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/compiler-rt/test/fuzzer/reduce_inputs.test

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: INFO: Running with entropic power schedule (0xFF, 100). 
check:12'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
            2: INFO: Seed: 1357852141 
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~
            3: INFO: Loaded 1 modules (6 inline 8-bit counters): 6 [0x2aa08fcee68, 0x2aa08fcee6e),  
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            4: INFO: Loaded 1 PC tables (6 PCs): 6 [0x2aa08fcee70,0x2aa08fceed0),  
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            5: INFO: 3 files found in /home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/reduce_inputs.test.tmp/C 
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            6: INFO: -max_len is not provided; libFuzzer will not generate inputs larger than 4096 bytes 
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            7: INFO: seed corpus: files: 3 min: 2b max: 3b total: 7b rss: 31Mb 
check:12'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/121862