[llvm] [CodeGen] Allow negative frame indicies in Register class. (PR #164459)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-multistage` running on `ppc64le-clang-multistage-test` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/76/builds/13343

<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 'SanitizerCommon-asan-powerpc64le-Linux :: Linux/getpwnam_r_invalid_user.cpp' FAILED ********************
Exit Code: 134

Command Output (stderr):
--
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/./bin/clang  --driver-mode=g++ -gline-tables-only -fsanitize=address  -m64 -fno-function-sections -funwind-tables  -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/llvm/compiler-rt/test -ldl -O0 -g /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/llvm/compiler-rt/test/sanitizer_common/TestCases/Linux/getpwnam_r_invalid_user.cpp -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.tmp &&  /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.tmp # RUN: at line 2
+ /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/./bin/clang --driver-mode=g++ -gline-tables-only -fsanitize=address -m64 -fno-function-sections -funwind-tables -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/llvm/compiler-rt/test -ldl -O0 -g /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/llvm/compiler-rt/test/sanitizer_common/TestCases/Linux/getpwnam_r_invalid_user.cpp -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.tmp
+ /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.tmp
Result: 110
getpwnam_r_invalid_user.cpp.tmp: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/llvm/compiler-rt/test/sanitizer_common/TestCases/Linux/getpwnam_r_invalid_user.cpp:19: int main(): Assertion `res == 0 || res == ENOENT' failed.
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.script: line 1: 445305 Aborted                 /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-powerpc64le-Linux/Linux/Output/getpwnam_r_invalid_user.cpp.tmp

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/164459