[clang] [llvm] [openmp] [mlir] [OpenMP] Remove `register_requires` global constructor (PR #80460)

[Sergio Afonso via cfe-commits]

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@@ -6872,35 +6883,6 @@ void OpenMPIRBuilder::loadOffloadInfoMetadata(StringRef HostFilePath) {
   loadOffloadInfoMetadata(*M.get());
 }
 
-Function *OpenMPIRBuilder::createRegisterRequires(StringRef Name) {
----------------
skatrak wrote:

Flang already picks up your changes to `createOffloadEntriesAndInfoMetadata()` and it appears to be putting the corresponding flags into a structure, though I'm not sure it's the right one.

I ran `flang-new -fc1 -emit-llvm -fopenmp flang/test/Lower/OpenMP/requires.f90 -o -` for a simple test with a single target region and I'm seeing two offloading entries being produced, which I'm not sure whether it's expected behavior. It looks like only one of them has the requires flags and the other one is the one that's properly linked with the kernel.

```llvmir
@.omp_offloading.entry_name = internal unnamed_addr constant [43 x i8] c"__omp_offloading_10307_d2a215c__QQmain_l12\00"
@.omp_offloading.entry.__omp_offloading_10307_d2a215c__QQmain_l12 = weak constant %struct.__tgt_offload_entry { ptr @.__omp_offloading_10307_d2a215c__QQmain_l12.region_id, ptr @.omp_offloading.entry_name, i64 0, i32 0, i32 0 }, section "omp_offloading_entries", align 1

@.omp_offloading.entry_name.1 = internal unnamed_addr constant [1 x i8] zeroinitializer
@.omp_offloading.entry. = weak constant %struct.__tgt_offload_entry { ptr null, ptr @.omp_offloading.entry_name.1, i64 0, i32 22, i32 10 }, section "omp_offloading_entries", align 1

...
%14 = call i32 @__tgt_target_kernel(ptr @1, i64 -1, i32 -1, i32 0, ptr @.__omp_offloading_10307_d2a215c__QQmain_l12.region_id, ptr %kernel_args)
```

https://github.com/llvm/llvm-project/pull/80460