[clang] [OpenMP] Restore loop variable values after loop-tranformation constructs. (PR #208533)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `intel-sycl-gpu` running on `intel-sycl-gpu-01` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/225/builds/13974

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'libomp :: transform/tile/iterfor.cpp' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 3
/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/clang++ -fopenmp   -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src  -fno-omit-frame-pointer -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/ompt -std=c++20 /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp -o /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp -lm -latomic && /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp | tee /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp.out | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/FileCheck /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp --match-full-lines
# executed command: /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/clang++ -fopenmp -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -fno-omit-frame-pointer -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/ompt -std=c++20 /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp -o /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp -lm -latomic
# executed command: /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp
# executed command: tee /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/test/transform/tile/Output/iterfor.cpp.tmp.out
# executed command: /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/FileCheck /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp --match-full-lines
# .---command stderr------------
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp:227:16: error: CHECK-NEXT: is not on the line after the previous match
# | // CHECK-NEXT: [B] iterator dtor
# |                ^
# | <stdin>:90:1: note: 'next' match was here
# | [B] iterator dtor
# | ^
# | <stdin>:83:18: note: previous match ended here
# | [A] iterator dtor
# |                  ^
# | <stdin>:84:1: note: non-matching line after previous match is here
# | [A] iterator distance: 3
# | ^
# | 
# | Input file: <stdin>
# | Check file: /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/openmp/runtime/test/transform/tile/iterfor.cpp
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |            78: [B] iterator move assign 
# |            79: [A] iterator deref: 2 
# |            80: [B] iterator deref: 2 
# |            81: i=2 j=2 
# |            82: [B] iterator dtor 
# |            83: [A] iterator dtor 
# | next:227'0                     {   search range start (exclusive)
# |            84: [A] iterator distance: 3 
# |            85: [A] iterator advance: 0 += 3 
# |            86: [A] iterator move assign 
# |            87: [B] iterator distance: 3 
# |            88: [B] iterator advance: 0 += 3 
# |            89: [B] iterator move assign 
# |            90: [B] iterator dtor 
# | next:227'1     !~~~~~~~~~~~~~~~~   error: match on wrong line
...

```

</details>

https://github.com/llvm/llvm-project/pull/208533