[llvm] [SandboxIR] Add pointer-diff utility function (PR #110343)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

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

Full details are available at: https://lab.llvm.org/buildbot/#/builders/98/builds/425

<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 'LLVM :: CodeGen/BPF/BTF/atomics.ll' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 1: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/llc -march=bpfel -mcpu=v3 -filetype=obj -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/llc -march=bpfel -mcpu=v3 -filetype=obj -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
RUN: at line 2: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/llvm-objcopy --dump-section='.BTF'=/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/llvm-objcopy --dump-section=.BTF=/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1
RUN: at line 3: "/home/uweigand/sandbox/bin/python3.10" /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 | /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
+ /home/uweigand/sandbox/bin/python3.10 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
Traceback (most recent call last):
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 295, in <module>
    print_btf(sys.argv[1])
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 137, in print_btf
    name_off, info, size = unpack("III")
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 100, in unpack
    r = st.unpack_from(buf, off)
struct.error: unpack_from requires a buffer of at least 402653196 bytes for unpacking 12 bytes at offset 402653184 (actual buffer size is 479)
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage1/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll

--

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

Step 11 (ninja check 2) failure: stage 2 checked (failure)
******************** TEST 'LLVM :: CodeGen/BPF/BTF/atomics.ll' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 1: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/llc -march=bpfel -mcpu=v3 -filetype=obj -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/llc -march=bpfel -mcpu=v3 -filetype=obj -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
RUN: at line 2: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/llvm-objcopy --dump-section='.BTF'=/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/llvm-objcopy --dump-section=.BTF=/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp1
RUN: at line 3: "/home/uweigand/sandbox/bin/python3.10" /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2 | /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
+ /home/uweigand/sandbox/bin/python3.10 /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/CodeGen/BPF/BTF/Output/atomics.ll.tmp2
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll
Traceback (most recent call last):
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 295, in <module>
    print_btf(sys.argv[1])
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 137, in print_btf
    name_off, info, size = unpack("III")
  File "/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/print_btf.py", line 100, in unpack
    r = st.unpack_from(buf, off)
struct.error: unpack_from requires a buffer of at least 402653196 bytes for unpacking 12 bytes at offset 402653184 (actual buffer size is 479)
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/FileCheck -check-prefixes=CHECK /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/llvm/llvm/test/CodeGen/BPF/BTF/atomics.ll

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/110343