[llvm] [memprof] Refactor readMemProf (NFC) (PR #149663)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-s390x-linux-lnt` running on `systemz-1` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/136/builds/4654

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

```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'libFuzzer-s390x-default-Linux :: fuzzer-timeout.test' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/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-lnt/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest # RUN: at line 1
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/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-lnt/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/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-lnt/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutEmptyTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutEmptyTest # RUN: at line 2
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/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-lnt/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutEmptyTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutEmptyTest
not  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 2>&1 | FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=TimeoutTest # RUN: at line 3
+ not /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1
+ FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=TimeoutTest
not  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/hi.txt 2>&1 | FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=SingleInputTimeoutTest # RUN: at line 12
+ FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=SingleInputTimeoutTest
+ not /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/hi.txt
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 -timeout_exitcode=0 # RUN: at line 16
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 -timeout_exitcode=0
INFO: Running with entropic power schedule (0xFF, 100).
INFO: Seed: 3784540391
INFO: Loaded 1 modules   (13 inline 8-bit counters): 13 [0x2aa0f4d0e80, 0x2aa0f4d0e8d), 
INFO: Loaded 1 PC tables (13 PCs): 13 [0x2aa0f4d0e90,0x2aa0f4d0f60), 
INFO: -max_len is not provided; libFuzzer will not generate inputs larger than 4096 bytes
INFO: A corpus is not provided, starting from an empty corpus
#2	INITED cov: 2 ft: 2 corp: 1/1b exec/s: 0 rss: 31Mb
#208	NEW    cov: 3 ft: 3 corp: 2/2b lim: 6 exec/s: 0 rss: 31Mb L: 1/1 MS: 1 ChangeByte-
#220	NEW    cov: 4 ft: 4 corp: 3/8b lim: 6 exec/s: 0 rss: 32Mb L: 6/6 MS: 2 CopyPart-InsertRepeatedBytes-
#287	REDUCE cov: 4 ft: 4 corp: 3/6b lim: 6 exec/s: 0 rss: 32Mb L: 4/4 MS: 2 CopyPart-EraseBytes-
#306	REDUCE cov: 4 ft: 4 corp: 3/5b lim: 6 exec/s: 0 rss: 32Mb L: 3/3 MS: 4 ChangeByte-ShuffleBytes-InsertByte-EraseBytes-
#317	REDUCE cov: 4 ft: 4 corp: 3/4b lim: 6 exec/s: 0 rss: 32Mb L: 2/2 MS: 1 EraseBytes-
#7159	REDUCE cov: 5 ft: 5 corp: 4/6b lim: 68 exec/s: 0 rss: 32Mb L: 2/2 MS: 2 ChangeBinInt-ChangeByte-
#7276	REDUCE cov: 6 ft: 6 corp: 5/9b lim: 68 exec/s: 0 rss: 32Mb L: 3/3 MS: 2 CrossOver-InsertByte-
ALARM: working on the last Unit for 1 seconds
       and the timeout value is 1 (use -timeout=N to change)
MS: 2 InsertByte-EraseBytes-; base unit: 57f5a44fdd9cf767b127bf151b0b86e0e73505fe
0x48,0x69,0x21,
Hi!
artifact_prefix='./'; Test unit written to ./timeout-c0a0ad26a634840c67a210fefdda76577b03a111
Base64: SGkh
==2911608== ERROR: libFuzzer: timeout after 1 seconds
AddressSanitizer:DEADLYSIGNAL
=================================================================
AddressSanitizer:DEADLYSIGNAL
=================================================================
AddressSanitizer: CHECK failed: asan_report.cpp:227 "((current_error_.kind)) == ((kErrorKindInvalid))" (0x1, 0x0) (tid=2911608)
    <empty stack>

MS: 2 InsertByte-EraseBytes-; base unit: 57f5a44fdd9cf767b127bf151b0b86e0e73505fe
0x48,0x69,0x21,
Hi!
artifact_prefix='./'; Test unit written to ./crash-c0a0ad26a634840c67a210fefdda76577b03a111
...

```

</details>

https://github.com/llvm/llvm-project/pull/149663