This commit fixes some but not all memory leaks in Flang. There are
still 91 tests that fail with ASAN.
- Use `mlir::OwningOpRef` instead of `std::unique_ptr`. The latter does
not free allocations of nested blocks.
- Pass `ModuleOp` as value instead of reference.
- Add few missing deallocations in test cases and other places.
As specified in the docs,
1) raw_string_ostream is always unbuffered and
2) the underlying buffer may be used directly
( 65b13610a5226b84889b923bae884ba395ad084d for further reference )
Avoid unneeded calls to raw_string_ostream::str(), to avoid excess indirection.
If `generateLLVMIR()` fails, we still continue using the module we
failed to generate which causes a seg fault if LLVM code-gen failed for
some reason or another. This commit fixes this issue.
Re-applies PR #78269 and adds LLVM and MLIR dependencies that were
missed in the PR. The missing libs were: `LLVMCore` & `MLIRIR`.
This reverts commit 4fc75062745eb5232ea60c37b9ffe61177efa12a.
This reverts commit 99cae9a44fca4cfbd6ee82f196051cbdf6571fa1.
Temporarily until I reproduce and fix a linker issue:
```
FAILED: tools/flang/unittests/Frontend/FlangFrontendTests
...
/usr/bin/ld: tools/flang/unittests/Frontend/CMakeFiles/FlangFrontendTests.dir/CodeGenActionTest.cpp.o: undefined reference to symbol '_ZN4llvm11LLVMContextC1Ev'
/usr/bin/ld: /work1/omp-nightly/build/git/trunk18.0/build/llvm-project/lib/libLLVMCore.so.18git: error adding symbols: DSO missing from command line
```
