[llvm] [AArch64] Don't tail call memset if it would convert to a bzero. (PR #98969)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/1398

Here is the relevant piece of the build log for the reference:
```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'SanitizerCommon-lsan-powerpc64le-Linux :: Linux/soft_rss_limit_mb_test.cpp' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/./bin/clang  --driver-mode=g++ -gline-tables-only -fsanitize=leak  -m64 -fno-function-sections -funwind-tables  -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test -ldl -O2 /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/lsan-powerpc64le-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
+ /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/./bin/clang --driver-mode=g++ -gline-tables-only -fsanitize=leak -m64 -fno-function-sections -funwind-tables -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test -ldl -O2 /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/lsan-powerpc64le-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
RUN: at line 5: env LSAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=1      /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/lsan-powerpc64le-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp 2>&1 | FileCheck /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_1
+ env LSAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=1 /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/lsan-powerpc64le-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
+ FileCheck /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_1
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp:68:24: error: CHECK_MAY_RETURN_1: expected string not found in input
// CHECK_MAY_RETURN_1: allocating 512 times
                       ^
<stdin>:54:44: note: scanning from here
Some of the malloc calls returned non-null: 256
                                           ^
<stdin>:55:14: note: possible intended match here
==2666978==LeakSanitizer: soft rss limit unexhausted (220Mb vs 8Mb)
             ^

Input file: <stdin>
Check file: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp

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

Input was:
<<<<<<
            .
            .
            .
           49:  [256] 
           50:  [320] 
           51:  [384] 
           52:  [448] 
           53: Some of the malloc calls returned null: 256 
           54: Some of the malloc calls returned non-null: 256 
check:68'0                                                X~~~~ error: no match found
           55: ==2666978==LeakSanitizer: soft rss limit unexhausted (220Mb vs 8Mb) 
check:68'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
check:68'1                  ?                                                       possible intended match
>>>>>>

--

********************


```

https://github.com/llvm/llvm-project/pull/98969