[llvm] [Transforms][Utils] Add LoopSplitUtils for iteration-space loop splitting (PR #205995)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `profcheck` running on `profcheck-b2` while building `llvm` at step 5 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/223/builds/8524

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

```
Step 5 (annotate) failure: '../llvm-zorg/zorg/buildbot/builders/annotated/profcheck.sh --jobs=64' (failure)
...
UNSUPPORTED: LLVM :: CodeGen/DirectX/idot.ll (45919 of 45938)
UNSUPPORTED: LLVM :: CodeGen/DirectX/scalarize-dynamic-vector-index.ll (45920 of 45938)
UNSUPPORTED: LLVM :: CodeGen/DirectX/strip-module-md.ll (45921 of 45938)
UNSUPPORTED: LLVM :: CodeGen/M68k/Bits/btst.ll (45922 of 45938)
UNSUPPORTED: LLVM :: CodeGen/Xtensa/cpus-invalid.ll (45923 of 45938)
UNSUPPORTED: LLVM :: MC/Disassembler/Xtensa/prid.txt (45924 of 45938)
UNSUPPORTED: LLVM :: MC/Disassembler/Xtensa/timer.txt (45925 of 45938)
UNSUPPORTED: LLVM :: MC/M68k/Arith/Classes/MxBiArOp_RFRR_xEA.s (45926 of 45938)
UNSUPPORTED: LLVM :: tools/lto/no-bitcode.s (45927 of 45938)
UNSUPPORTED: LLVM :: tools/dxil-dis/vla.ll (45928 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/basic.ll (45929 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/constant-trip-count.ll (45930 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/descending.ll (45931 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/multiple-partitions.ll (45932 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/nested-loop.ll (45933 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/partition-value-map.ll (45934 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/four-partitions.ll (45935 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/reduction.ll (45936 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/empty-leading-partition.ll (45937 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/optional-guard.ll (45938 of 45938)
********************
Failed Tests (10):
  LLVM :: Transforms/LoopSplit/basic.ll
  LLVM :: Transforms/LoopSplit/constant-trip-count.ll
  LLVM :: Transforms/LoopSplit/descending.ll
  LLVM :: Transforms/LoopSplit/empty-leading-partition.ll
  LLVM :: Transforms/LoopSplit/four-partitions.ll
  LLVM :: Transforms/LoopSplit/multiple-partitions.ll
  LLVM :: Transforms/LoopSplit/nested-loop.ll
  LLVM :: Transforms/LoopSplit/optional-guard.ll
  LLVM :: Transforms/LoopSplit/partition-value-map.ll
  LLVM :: Transforms/LoopSplit/reduction.ll


Testing Time: 158.56s

Total Discovered Tests: 55852
  Excluded   :   257 (0.46%)
  Skipped    :    17 (0.03%)
  Unsupported:  1207 (2.16%)
  Passed     : 54361 (97.33%)
  Failed     :    10 (0.02%)
FAILED: test/CMakeFiles/check-llvm /b/profcheck-build/build/test/CMakeFiles/check-llvm 
cd /b/profcheck-build/build/test && /usr/bin/python3 /b/profcheck-build/build/./bin/llvm-lit --exclude-xfail /b/profcheck-build/build/test
ninja: build stopped: subcommand failed.
Step 7 (Ninja) failure: Ninja (failure)
...
UNSUPPORTED: LLVM :: CodeGen/DirectX/idot.ll (45919 of 45938)
UNSUPPORTED: LLVM :: CodeGen/DirectX/scalarize-dynamic-vector-index.ll (45920 of 45938)
UNSUPPORTED: LLVM :: CodeGen/DirectX/strip-module-md.ll (45921 of 45938)
UNSUPPORTED: LLVM :: CodeGen/M68k/Bits/btst.ll (45922 of 45938)
UNSUPPORTED: LLVM :: CodeGen/Xtensa/cpus-invalid.ll (45923 of 45938)
UNSUPPORTED: LLVM :: MC/Disassembler/Xtensa/prid.txt (45924 of 45938)
UNSUPPORTED: LLVM :: MC/Disassembler/Xtensa/timer.txt (45925 of 45938)
UNSUPPORTED: LLVM :: MC/M68k/Arith/Classes/MxBiArOp_RFRR_xEA.s (45926 of 45938)
UNSUPPORTED: LLVM :: tools/lto/no-bitcode.s (45927 of 45938)
UNSUPPORTED: LLVM :: tools/dxil-dis/vla.ll (45928 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/basic.ll (45929 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/constant-trip-count.ll (45930 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/descending.ll (45931 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/multiple-partitions.ll (45932 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/nested-loop.ll (45933 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/partition-value-map.ll (45934 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/four-partitions.ll (45935 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/reduction.ll (45936 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/empty-leading-partition.ll (45937 of 45938)
FAIL: LLVM :: Transforms/LoopSplit/optional-guard.ll (45938 of 45938)
********************
Failed Tests (10):
  LLVM :: Transforms/LoopSplit/basic.ll
  LLVM :: Transforms/LoopSplit/constant-trip-count.ll
  LLVM :: Transforms/LoopSplit/descending.ll
  LLVM :: Transforms/LoopSplit/empty-leading-partition.ll
  LLVM :: Transforms/LoopSplit/four-partitions.ll
  LLVM :: Transforms/LoopSplit/multiple-partitions.ll
  LLVM :: Transforms/LoopSplit/nested-loop.ll
  LLVM :: Transforms/LoopSplit/optional-guard.ll
  LLVM :: Transforms/LoopSplit/partition-value-map.ll
  LLVM :: Transforms/LoopSplit/reduction.ll


Testing Time: 158.56s

Total Discovered Tests: 55852
  Excluded   :   257 (0.46%)
  Skipped    :    17 (0.03%)
  Unsupported:  1207 (2.16%)
  Passed     : 54361 (97.33%)
  Failed     :    10 (0.02%)
FAILED: test/CMakeFiles/check-llvm /b/profcheck-build/build/test/CMakeFiles/check-llvm 
cd /b/profcheck-build/build/test && /usr/bin/python3 /b/profcheck-build/build/./bin/llvm-lit --exclude-xfail /b/profcheck-build/build/test
ninja: build stopped: subcommand failed.
program finished with exit code 1
elapsedTime=341.441687

```

</details>

https://github.com/llvm/llvm-project/pull/205995